Journal of Colloid And Interface Science (v.354, #1)

Cover 1 (OFC).

A new method was developed for the superhydrophilic surface modification of copper using versatile solution-based fabrication techniques including Layer-by-Layer self-assembly and Liquid Phase Deposition.Display Omitted► Hydrophilic films can enhance the efficiency of copper cooling devices. ► TiO2 thin film changes copper from hydrophobic to superhydrophilic. ► LbL and TiO2 LPD hybrid film demonstrates excellent adhesion and 0° contact angle. ► Temperature-controlled nanoparticle growth characteristics determine robustness. ► Properly grown dense thin films remain resilient under harsh thermal stress.A new method has been developed for the superhydrophilic surface modification of copper using versatile solution-based fabrication techniques. The high surface area of TiO2 nanoparticles was exploited to create a thin film with increased surface energy that transformed copper materials from relatively hydrophobic to superhydrophilic. Copper exposed to ambient conditions resulting in a thin layer of copper oxide has a water contact angle near 90°, but following TiO2 modification, the contact angle dropped to 0°. The thin film responsible for this drastic improvement in wettability proved durable by retaining its excellent properties throughout an extended application of thermal stress. SEM and Raman Spectroscopic analysis confirmed the structural integrity of the film before and after a durability test.
Keywords: Self assembly; Liquid Phase Deposition; Nanoparticle; TiO2;

Mixed motion in deterministic ratchets due to anisotropic permeability by T. Kulrattanarak; R.G.M. van der Sman; Y.S. Lubbersen; C.G.P.H. Schroën; H.T.M. Pham; P.M. Sarro; R.M. Boom (7-14).
2D flow simulation in compact deterministic ratchets show asymmetric flow lane distribution, which implies a new type of particle motion.Display Omitted► Mixed motion observed in deterministic ratchets. ► Asymmetric flow lane distributions found with simulations. ► Anisotropy of permeability to is the cause of mixed motion.Nowadays microfluidic devices are becoming popular for cell/DNA sorting and fractionation. One class of these devices, namely deterministic ratchets, seems most promising for continuous fractionation applications of suspensions (Kulrattanarak et al., 2008 ). Next to the two main types of particle behavior, zigzag and displacement motion as noted by the inventors (Huang et al., 2004 ]) and (Inglis et al., 2006 ), we have shown recently the existence of a intermediate particle behavior, which we named ‘mixed motion’. In this paper we formulate the hypothesis that the occurrence of mixed motion is correlated with anisotropy in the permeability of the obstacle array. This hypothesis we base on the comparison of experimental observations of mixed motion and the flow lane distribution as obtained from 2-D flow simulations.
Keywords: Deterministic ratchet; Fractionation; Flow field simulation;

Synthesis of high quality and stability CdS quantum dots with overlapped nucleation-growth process in large scale by Xinmei Liu; Yang Jiang; Xinzheng Lan; Shanying Li; Di Wu; Tingting Han; Honghai Zhong; Zhongping Zhang (15-22).
With no aid of any nucleation initiators, a low-cost, green, and reproducibly one-pot approach was reported for the highly monodispersed CdS QDs with a narrow size distribution and excellent optical properties.Display Omitted► A one-pot approach was developed for the synthesis of high-quality CdS QDs at the absence of any nucleation initiators. ► A new, air-stable, and low-cost benign solvent of N-oleoylmorpholine was used. ► An overlapped nucleation-growth mechanism was proposed. ► The long-term continuous PL enhancement and QY increase were observed.A low-cost, green, and reproducibly non-injection one-pot synthesis of high-quality CdS quantum dots (QDs) is reported. The synthesis was performed in the open air by mixing precursors cadmium stearate and S powder into a new solvent N-oleoylmorpholine. An overlapped nucleation-growth stage followed by a dominated growth stage was observed. The resulting QDs exhibited well-resolved absorption fine substructure and a dominant band-edge emission with a narrow size distribution (the full width at half maximum (fwhm) was only 22–24 nm). The maximum photoluminescence (PL) quantum yield (QY) was as high as 46.5%. Highly monodispersed CdS QDs with tunable sizes and similar PL fwhm and QYs could also be obtained from the CdS QDs in a large-scale synthesis. The high-resolution transmission electron microscopy (HRTEM) images and powder X-ray diffraction (XRD) pattern suggested that the as-prepared QDs with high crystallinity had a cubic structure. A significant PL improvement and a continuous QY increase for the CdS QDs were observed during a long storage time in air and in a glovebox under room temperature. A slow surface reconstruction was proposed to be the cause for the PL enhancement of CdS QDs.
Keywords: CdS quantum dots; One-pot synthesis; Overlapped nucleation-growth; N-oleoylmorpholine;

Deagglomeration and surface modification of thermally annealed nanoscale diamond by Yuejiang Liang; Thomas Meinhardt; Gerald Jarre; Masaki Ozawa; Pavo Vrdoljak; Achim Schöll; Friedrich Reinert; Anke Krueger (23-30).
Thermally annealed nanodiamond is surface arylated. The established terminal groups are sites for the grafting of larger moieties but also achieve the chemical deagglomeration of the material in various solvents.Display Omitted► Nanodiamond is deagglomerated using thermal annealing and surface functionalization. ► sp2 carbon on diamond readily reacts with diazonium salts. ► Stable C–C bonds are formed by arylation of nanodiamond. ► ND solubility can be tuned by selecting suitable terminal groups.Thermally annealed nanodiamond has been functionalized by C–C coupling of the partially graphitized diamond surface using aryl diazonium salts. Depending on the terminal functional groups, the modified bucky diamond nanoparticles show good solubility (up to 0.63 mg mL−1) in different solvents. The agglomerate size of the originally strongly bound detonation diamond (>0.5 μm) is substantially reduced to ∼20–50 nm by this chemical procedure and without using mechanical techniques such as strong ultrasound or milling. Arylation with functionalized aryl diazonium salts carrying COOH, SO3H, NO2 or bromoethyl groups opens the way for further covalent grafting of organic structures. Arylation with Ar–COOH or Ar–SO3H leads to the formation of stable colloidal solutions in water and physiological media (i.e. PBS buffer), an important prerequisite for biomedical applications.
Keywords: Nanodiamond; Arylation; Deagglomeration; Nanoparticle; Solubilization; Surface functionalization;

Adsorption of IgG on/in a PAH/PSS multilayer film: Layer structure and cell response by Zsombor Feldötö; Maria Lundin; Sten Braesch-Andersen; Eva Blomberg (31-37).
Schematic drawing of the antigen secreting cells on antigen (IgG) coated polyelectrolyte multilayers and there cytokine response.Display Omitted► LbL assembly of oppositely charged polyelectrolytes (PAH/PSS) with incorporated/adsorbed IgG. ► Aim is to increase the surface density of IgG and sensitivity of the conventional ELISpot assay. ► PAH/PSS multilayer structure is very compact with a low water content. ► Its rigid structure does not do them appropriate for forming a 3D antibody-binding support. ► The cytotoxicity of PAH terminated layers induced cytokine response whereas PSS terminated ones did not.The binding of immunogloblulins (IgG) (mouse monoclonal recognizing IFNγ) on precoated polystyrene or silica surfaces by the layer-by-layer technique has been investigated with QCM-D and DPI. The aim of the work was to increase the sensitivity of the conventional enzyme-linked immunosorbent spot (ELISpot) assay. The polyelectrolytes used to build the multilayers were poly(allylamine hydrochloride) (PAH)/poly(sodium 4-styrenesulfonate) (PSS) alternately adsorbed from 150 mM NaCl. The multilayer build up is linear and the internal structure of the PAH/PSS multilayer is compact and rigid as observed by low relative water content (20–25%) and high layer refractive index (n  ∼ 1.5) after the formation of five bilayers. Incorporation of IgG within the PAH/PSS multilayer did not give rise to overcharging and did not affect the linear build up. ELISpot test on PAH/PSS multilayer modified polystyrene wells showed that the cytokine response was significantly smaller than on the regular PVDF backed polystyrene wells. This may be due to the compact and rigid nature of the PAH/PSS multilayer, which does not allow formation of the kind of three dimensional support needed to achieve bioactive IgG binding to the surface. Immunological tests of the polyelectrolyte multilayers in the absence of IgG showed that PSS terminated PAH/PSS multilayer did not induce any cytokine response whereas PAH terminated did, which suggests that PSS totally covers the surface from the cells point of view.
Keywords: PAH; PSS; Polyelectrolyte multilayer; Layer-by-layer deposition; IgG; Incorporation; Adsorption; QCM; DPI; ELISpot; Cytokine; Cell response;

Photoinduced electron accumulation in colloidally dispersed wide band-gap semiconductor nanosheets by Teruyuki Nakato; Yoshimi Yamada; Mari Nakamura; Atsushi Takahashi (38-44).
Colloidal nanosheets of layered niobate, a photocatalytically active semiconductor, accumulate electrons by band-gap photoexcitation, and the electron-accumulated state is stabilized in the presence of photochemically inert clay nanosheets.Display Omitted► Colloidal niobate nanosheets accumulate electrons by band-gap photoexcitation. ► The reaction is enhanced in the presence of photochemically inert clay. ► The reaction is not enhanced by the addition of molecular electron donors. ► The molecular donors diminish the enhancement effect of clay.We investigated photoinduced electron accumulation in a colloidal system of layered hexaniobate that is known as a photocatalytically active wide band-gap semiconductor, and attempted to control the photoresponse by introducing additives into the colloid. The inorganic nanosheets were obtained by exfoliation of the layered oxide. UV-irradiation of the colloids led to electron accumulation in the nanosheets to generate reduced niobate species. Propylammonium ions introduced as the exfoliating reagent and present as the counter ions of niobate nanosheets were indicated as the electron donor that stabilized the electron-accumulating state. Yield and half-life of the reduced niobate species greatly increased by adding an appropriate amount of photochemically inert clay nanosheets, while they increased only a little by the addition of molecular electron donors such as EDTA and triethanolamine. Moreover, the molecular species diminished the enhancement effect of the clay nanosheets. The results suggested that the photochemical event was not explained by direct interactions between the semiconductor nanosheets and the additives at molecular level but governed by indirect interactions between the colloid components regulated by the colloid structure.
Keywords: Wide band-gap semiconductor; Structured colloid; Inorganic nanosheets; Layered niobate; Clay;

Sketch of the formation of asymmetric bilayer structures produced by oblique drop impact with the drop and target liquid being covered with lipid monolayers..Display Omitted► Asymmetric bilayers are formed by coupling of two liquid surfaces with monolayers. ► Unsaturated phospholipids without cholesterol additionally form symmetric bilayers. ► Two mechanisms for asymmetrical and symmetrical bilayer synthesis were proposed. ► Surface rheology influences drop impact patterns and bilayer symmetry or asymmetry. ► An unknown fluid state of DPPC/cholesterol monolayers shown by oblique drop impact.Bilayer structures are formed by approaching two liquid surfaces with phospholipid monolayers, which are brought into contact by oblique drop impact on a liquid surface. Asymmetric bilayers can be produced by the coupling of drop and target monolayers. In contrast, symmetric bilayers or multilayers are formed by collapse of the compressed target monolayer. We show that under all studied conditions bilayer/multilayer synthesis takes place. The experimental conditions for the synthesis of asymmetric or symmetric bilayers are described quantitatively in terms of the surface rheological (surface elasticity and dilational viscosity) and the hydrodynamical parameters (Weber number and impact angle). The composition and mechanical properties of the phospholipid monolayers strongly influences the patterns of drop impact and the bilayer/multilayer formation. Cholesterol stiffens unsaturated phospholipid monolayers and fluidifies saturated monolayers. All monolayers form asymmetric vesicle-like structures, which are stable in the aqueous medium. Additionally, unsaturated phospholipid monolayers without cholesterol form symmetric vesicles by folding parts of the target monolayer. Sufficient presence of cholesterol in unsaturated phospholipid monolayers inhibits the folding of the target monolayer and the subsequent formation of symmetric bilayers. The rheological properties of saturated and unsaturated phospholipid monolayers and their mixtures with cholesterol are discussed. Based on drop impact results it is shown that the state of a so far undefined region in the DPPC/cholesterol phase diagram is a fluid phase.
Keywords: Oblique drop impact; Phospholipid-monolayers; Bilayer formation; Asymmetric bilayers; Vesicles; Surface rheology;

The superlattices of N-acetylglutathione-protected gold nanoparticles experience fcc-to-bcc structural transformation through the interparticle mediation by 4-pyridinecarboxyic acid.Display Omitted► N-acetylglutathione-protected gold nanoparticles self-assemble to form fcc-type superlattices. ► 4-Pyridinecarboxylic acid (PyC) mediator promotes the formation of the superlattices. ► The PyC-induced nanoparticle superlattices experience structural transformation into a bct phase. ► The transformation is explained by elongation or contraction of the lattice parameters under strain. N-acetylglutathione (NAG)-protected gold nanoparticles self-assemble into three-dimensional (3D) face-centered cubic (fcc)-type superlattices at an air/water interface under highly acidic conditions. To prepare the well-defined superlattices, 1 month’s incubation is at least necessary since the size growth of the as-prepared nanoparticles is essential. Addition of 4-pyridinecarboxyic acid (PyC), a bifunctional hydrogen-bonding mediator, promotes the formation of the superlattices, which are created for about 2 weeks’ storage. Interestingly, PyC-induced nanoparticle superlattices are in a body-centered tetragonal (bct) structure. The fcc-to-bct phase transformation would be due to stronger interaction between NAG and PyC than that between NAG molecules on the gold nanoparticle surfaces.
Keywords: Gold nanoparticles; Superlattice; Organic mediator; Structural transformation; Pyridinecarboxylic acid;

The fraction of segments belonging to tails as a function of the short-range surface interactions ΔW for various grafting densities.Display Omitted► Simple model to calculate the structure of grafted adsorbed neutral polymer brushes. ► Distribution of trains, loops and tails in the brush. ► Simple approximations for the loops-to-tails and loops-to trains structural transformations.The structure of grafted adsorbing polymers on surfaces is described as a statistical ensemble of loops generated by an one-dimensional random walk perpendicular to the surface. The configuration of each chain is considered as a succession of closed loops ended by an open loop (a tail). The probability of formation of each individual loop is the product between the probability of first return to the surface and a Boltzmann factor containing the free energy of the Flory–Huggins kind, which is approximated by the minimum free energy of all possible configurations of that loop. At high grafting densities, the attractive interactions between monomers and surface control the fraction of polymer belonging to either closed loops or tails, hence the formation of a stretched grafted brush. At low grafting densities, the increase of that interaction above a critical value generates an abrupt collapse of the brush on the surface. Whereas for long polymers (with more than about 100 Kuhn segments), the structure of the brush can be determined, in general, only via Monte-Carlo sampling, it is argued that the two structural transitions indicated above can be well predicted by simple approximations.
Keywords: Polymer brushes; Grafted adsorbing polymers; Structural transitions;

The same core-shell particles can exhibit different salt-induced behavior depending of the preparation history, i.e. depending on whether a compact or stretched conformation of the polymer shell was induced.Display Omitted► The swelling of carboxylated core–shell particles can be tuned. ► Salt-induced swelling of promoted particles (A-2) follows the SCF theory. ► Promoted particles at pH = 10 behave as a quenched brush. ► Hindered particles (B-1) at pH = 8–10 behave as an annealed brush. ► B-1 swelling (at pH = 8.6) resembles the predicted Pincus regime (as yet unobserved).In a previous work we showed that the swelling behavior of carboxylated core–shell particles (PS–PC) can be modified using a specific sample preparation route or favoring the hydrophobic attractive interaction by other way, i.e. controlling the temperature. In that paper, we found that the swelling was promoted in those particles which were initially in a highly swollen state (pH ⩾ 10) while it was hindered for those particles which were not previously in this trigger pH. In this work, we present a discussion of the salt-induced swelling of the same carboxylated core–shell system (PS–PC) with two tuned swelling behaviors: the former, called A-2, exhibits promoted swelling while in the latter, called B-1, the swelling is greatly suppressed because of a compact conformation of the polymer shell is induced . Good agreement between experimental, numerical and theoretical results at all pH values is obtained for promoted particles (A-2). On the other hand, the salt-induced swelling behaviors shown by hindered particles (B-1) corroborate that polymer restructuring includes assembly among ionic groups which affect their ionization degree and also the electrosteric interaction between particles. Finally, the salt-induced swelling behavior shown by the B-1 system at pH 8.6 resembles the Pincus regime predicted by scaling theory.
Keywords: Polycarboxylated core–shell particles; Polyelectrolytes; Swelling and de-swelling; Polymer brushes;

Highly water-soluble nanocrystal powders of magnetite (Fe3O4, S1), partially oxidized magnetite (S2–S6) and maghemite (γ-Fe2O3, S7–S8), coated with gluconic acid (GLA).Display Omitted► Highly water-soluble nanocrystal powders of magnetite and maghemite coated with gluconic acid (GLA) have been prepared and characterized. ► Raman spectra analysis is a rapid and simple method for qualitatively identifying the oxidation degree of spinel iron oxides. ► The proposed coordination modes of the surface iron atom with GLA well explain the chemical stability and the high solubility of the products.A simple method was developed to prepare highly water-soluble nanocrystal powders of magnetic iron oxides with different oxidation degree from magnetite (Fe3O4) to maghemite (γ-Fe2O3) coated with gluconic acid (GLA). X-ray diffraction and transmission electron microscopy measurements show that the products have a narrow size distribution, and the cores are inverse spinel iron oxides and completely crystallized. Vibrating sample magnetometry measurements reveal that all the samples exhibit superparamagnetic behavior at room temperature. Fourier transform infrared (FTIR) and Raman spectra were used to identify the products. It is shown that GLA molecules are immobilized on the nanoparticle surface by chemical bonding and the carboxyl is asymmetrically bound to the surface iron atom, and the vacancies in the γ-Fe2O3 cores are disordered. Compared with FTIR, Raman spectrum analysis is a rapid, simple, and accurate method for identifying inverse spinel iron oxides. The chemical stability and the high solubility of the products are explained in terms of the proposed coordination modes of the surface iron atom with GLA.
Keywords: Magnetic iron oxides; Nanocrystals; Gluconic acid; Water-soluble; Preparation; Structure characterization;

The size of particle aggregates produced by flocculation with PNIPAM, as a function of temperature by Elizaveta Burdukova; Naoyuki Ishida; Timothy Shaddick; George V. Franks (82-88).
The size of alumina aggregates formed in the presence of temperature responsive Poly(N-Isopropylacrylamide) is primarily affected by the force of adhesion between alumina particles, which increases with increasing temperature.Display Omitted► Size of aggregates formed with PINPAM increases with increasing temperature. ► Aggregate size increase is attributed to an increase in the adhesive force. ► The adhesive force is caused by increase in temperature above the LCST of PNIPAM. ► The rate of particle collision and aggregate breakage is constant with temperature.This work investigates the effect of temperature on the size of alumina aggregates formed by flocculation with temperature responsive Poly(N-Isopropylacrylamide)(PNIPAM). The results are discussed in terms of the effects of temperature on particle collision, particle adhesion and aggregate breakage. It was found that the size of alumina aggregates increases with increasing solution temperature. Particle/particle collision and aggregate breakage are largely unaffected by increasing solution temperature and therefore could not account for the change in aggregate size. The dominant factor in aggregate growth with increasing temperature was found to be the increase in the force of adhesion between alumina particles. The appearance of the adhesive force is triggered by the increase in temperature above the lower critical solution temperature of PNIPAM.
Keywords: Temperature-sensitive polymer; Solid–liquid separation; Solids dewatering; Aggregate size;

Hierarchical In2O3 microbundles were prepared through the triblock copolymer F127 self-assembled micelle template, which exhibited enhanced gas sensing performance toward toxic 2-chloroethanol.Hierarchical In2O3 rod-like microbundles were fabricated via the Pluronic F127–(EO106PO70EO106–) assisted hydrothermal reaction followed by calcining the In(OH)3 precursors. The results revealed that the In2O3 microarchitectures were constructed with well-aligned one-dimensional (1D) single-crystalline nanorods with highly uniform morphologies and particular exposed facets. Structural analysis suggested that the In2O3 nanorods were enclosed by {1 1 0} and {0 0 1} facets. The triblock copolymer acted as a structure-directing agent and played a key role in the formation of In(OH)3 microbundles. The formation of the precursors In(OH)3 microbundles was studied through contrastive experiments and computational simulation, which can be contributed to the soft-template-directed self-assembly mechanism. The gas sensing properties of the as-prepared In2O3 microbundles were investigated. Compared to the samples prepared in the absence of F127, the In2O3 microbundles exhibited a superior sensing performance toward 2-chloroethanol vapor, which can be explained by hierarchically ordered structures and exposed crystal surfaces.
Keywords: Indium oxide; Microbundle; Pluronic F127; Micelle; Gas sensor; Chloroethanol;

A facile method is presented for the preparation of raspberry-like monodisperse hollow hybrid nanospheres with γ-Fe2O3@SiO2 particles as the outer shell via sol–gel process.Display Omitted► A facile method for preparing raspberry-like magnetic hollow nanospheres was developed. ► The Fe3O4@SiO2 particles were shapely coated on the surface of PS templates. ► The hollow nanospheres were well monodisperse and uniform with a size of 253 nm. ► The hollow nanospheres possessed large cavities and excellent magnetic properties.In this paper, we present a novel method for the preparation of raspberry-like monodisperse magnetic hollow hybrid nanospheres with γ-Fe2O3@SiO2 particles as the outer shell. PS@Fe3O4@SiO2 composite nanoparticles were successfully prepared on the principle of the electrostatic interaction between negatively charged silica and positively charged polystyrene, and then raspberry-like magnetic hollow hybrid nanospheres with large cavities were achieved by means of calcinations, simultaneously, the magnetite (Fe3O4) was transformed into maghemite (γ-Fe2O3). Transmission electron microscopy (TEM) demonstrated that the obtained magnetic hollow silica nanospheres with the perfect spherical profile were well monodisperse and uniform with the mean size of 253 nm. The Fourier transform infrared (FTIR) spectrometry, energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) provided the sufficient evidences for the presence of Fe3O4 in the silica shell. Moreover, the magnetic hollow silica nanospheres possessed a characteristic of superparamagnetic with saturation magnetization value of about 7.84 emu/g by the magnetization curve measurement. In addition, the nitrogen adsorption–desorption measurement exhibited that the pore size, BET surface area, pore volume of magnetic hollow silica nanospheres were 3.5–5.5 nm, 307 m2  g−1 and 1.33 cm3  g−1, respectively. Therefore, the magnetic hollow nanospheres possess a promising future in controlled drug delivery and targeted drug applications.
Keywords: Raspberry-like; Magnetic; Hollow; SiO2;

Pt–Au nanowires supported on FSM-16 presented high catalytic activities toward water–gas shift reaction compared with individual monometallics of circular structures..Display Omitted► Facile synthesis of Pt–Au bimetallics of nanowires structures. ► Significant catalytic activity for Pt–Au nanowires was depicted towards WGSR. ► Monometallic analogue of circular structures presented lower activity comparatively. ► Magnificent characteristics of this system is declared.A facile, previously unexplored, method to synthesize bimetallic Pt–Au nanowires (20 nm diameter × 120–170 nm long) on mesoporous FSM-16 (2.7 nm) was fabricated by co-impregnation of H2PtCl6 with HAuCl4 followed by evacuation at 300 K and finally exposure to the CO/H2O gas mixture (60:5 Torr) at 323 K for 1.0 h. On the other hand, spherical monometallic nanoparticles of pure Pt (7.0 nm diameter) and Au (7–26 nm diameter) were synthesized as well, by impregnation, at the same reaction conditions. The catalysts were characterized by in situ FTIR spectroscopy, UV–vis absorption spectroscopy, TEM, TPR and TPCOR. The catalytic activities toward the water–gas shift reaction (WGSR) were also examined under atmospheric pressure and at the margin of 323–373 K. The optical absorption spectra showed a remarkable shift and broadening of Pt–Au surface Plasmon resonance band at 515 nm apart from those of individual analogue emphasizing bimetallic formation. Results from in situ FTIR spectroscopy indicated that incorporation of Au assisted and stabilized the formation of carbonyl clusters of Pt–Au–CO (2084 cm−1) and Pt–CO (1888 cm−1) inside the host FSM-16. The Pt–Au carbonyl clusters built up at the moment of vanishing the linear carbonyl band of the charged Au (Au+–CO, 2186 cm−1) along with a concomitant increase in the reduced gold (Au0–CO, 2124 cm−1) species. TPR profiles showed that the H2 consumed was higher for Pt/FSM-16 than for Pt–Au/FSM-16 verifying the facile reduction of Pt moieties after addition of Au. The CO adsorption peak maximum, in TPCOR, for Pt/FSM-16 occurred at higher temperature than that of Pt–Au/FSM-16, which exhibited higher amounts of CO2 produced. The relative decrease in CO bindings on bimetallic surface was responsible for increasing the CO oxidation activity mainly through an association mechanism. Accordingly, the activity of Pt–Au/FSM-16 towards WGS showed a marked increase (8–23 times) compared with those of monometallics emphasizing the dependence of this reaction on the electronic defects of the nanowires. A straightforward reduction mechanism was deduced for Pt–Au alloy formation in view of the results obtained.
Keywords: Bimetallic Pt–Au clusters; Nanowires; FSM-16; FTIR; UV–vis; TPR; TPRSR; TEM; WGSR;

High-performance TiO2 from Baker’s yeast by Wen He; Jingjie Cui; Yuanzheng Yue; Xudong Zhang; Xi Xia; Hong Liu; Suwen Lui (109-115).
AFM image shows the surface structure of yeast–TiO2. The surface displays an ordered hierarchical mesoporous structure. The yeast–TiO2 exhibits highly decolourazing efficiency for paper industrial waste water.Display Omitted► A novel approach has been developed to synthesize high-performance mesoporous yeast–TiO2. ► The mechanism of formation of the yeast–TiO2 is revealed. ► The yeast–TiO2 exhibits outstanding photocatalytic performance. ► The approach may open new vistas for fabricating advanced mesoporous materials.Based on the biomineralization assembly concept, a biomimetic approach has been developed to synthesize high-performance mesoporous TiO2. The key step of this approach is to apply Baker’s yeast cells as biotemplates for deriving the hierarchically ordered mesoporous anatase structure. The mechanism of formation of the yeast–TiO2 is revealed by characterizing its morphology, microstructure, and chemical composition. The yeast–TiO2 exhibits outstanding photocatalytic performance. Under visible-light irradiation, the removal efficiency of chemical oxygen demand (COD) and color of the paper industry wastewater has reached 80.3% and nearly 100%, respectively. The approach may open new vistas for fabricating advanced mesoporous materials under ambient condition.
Keywords: Mesoporous TiO2; Yeast cells; Biomimetic synthesis; Catalytic activity; Paper wastewater;

Curcumin-loaded PLGA-PEG-PLGA triblock copolymeric micelles: Preparation, pharmacokinetics and distribution in vivo by Zhimei Song; Runliang Feng; Min Sun; Chenyu Guo; Yan Gao; Lingbing Li; Guangxi Zhai (116-123).
Curcumin-loaded PLGA-PEG-PLGA micelles significantly increased the distribution of curcumin in lung and brain and reduced uptake by liver and spleen.Display Omitted► Micelles were firstly prepared with this triblock copolymers using solvent-dialysis method and successfully encapsulated hydrophobic CUR. ► The pharmacokinetic parameters of CUR micelles were improved compared to the CUR solution, respectively. ► The biodistribution study in mice showed that the PLGA-PEG-PLGA micelle formulation decreased drug uptake by the liver and spleen, and increased the distribution of drug in lung and brain.The aim of this study was to assess the potential of new copolymeric micelles to modify the pharmacokenetics and tissue distribution of Curcumin (CUR), a hydrophobic drug. In the present study, a poly (d,l-lactide-co-glycolide)-b-poly(ethylene glycol)-b-poly(d,l-lactide-co-glycolide) (PLGA-PEG-PLGA) copolymer was synthesized and characterized by 1H NMR, gel permeation chromatography and FTIR analysis. The CUR-loaded PLGA-PEG-PLGA micelles were prepared by dialysis method and the physicochemical parameters of the micelles such as zeta potential, size distribution and drug encapsulation were characterized. The pharmacokinetics and biodistribution of CUR-loaded micelles in vivo were evaluated. The results showed that the zeta potential of CUR-loaded micelles was about −0.71 mV and the average size was 26.29 nm. CUR was encapsulated into PLGA-PEG-PLGA micelles with loading capacity of 6.4 ± 0.02% and entrapment efficiency of 70 ± 0.34%. The plasma AUC(0– ), t 1/2α, t 1/2β and MRT of CUR micelles were increased by 1.31, 2.48, 4.54 and 2.67 fold compared to the CUR solution, respectively. The biodistribution study in mice showed that the micelles decreased drug uptake by liver and spleen and enhanced drug distribution in lung and brain. These results suggested that PLGA-PEG-PLGA micelles would be a potential carrier for CUR.
Keywords: PLGA-PEG-PLGA micelle; Curcumin; Pharmacokinetics; Biodistribution;

Visualization of the microemulsion disposition using the laser scanning confocal microscopy explores its major penetration pathway.Display Omitted► Laser scanning confocal microscopy was used to visualize the penetration and the distribution of a fluorescently labeled microemulsion. ► Dermatopharmacokinetic analysis determines the rates and extents of penetration of the microemulsion different components and suggests the breakage of the microemulsion during its passage through the stratum corneum. ► The stratum corneum lipids packing and architecture were perturbed by all the components of the microemulsion. ► Tween 20 modified the oleic acid molecular effects on the stratum corneum lipids. ► The microemulsion components have different synergistic mechanisms of penetration enhancement.The use of nano-systems such as the microemulsions is considered as an increasingly implemented strategy in order to enhance the percutaneous transport into and across the skin barrier. The determination of the major pathway of penetration and the mechanisms by which these formulations work remains crucial. In this study, laser confocal scanning microscopy was used to visualize the penetration and the distribution of a fluorescently-labelled microemulsion (using 0.1% w/v Nile red) consisting of (%, w/w) 15.4% oleic acid, 30.8% Tween 20, 30.8% Transcutol® and 23% water. The surface images revealed that the microemulsion accumulated preferentially in the intercellular domains of the stratum corneum. Additionally, by analysis of the images taken across the whole stratum corneum (SC), the penetration was found to occur along its whole depth. The latter result was confirmed using tape stripping and the subsequent sensitive analysis using liquid chromatography mass spectroscopy. Dermatopharmacokinetic parameters were obtained for the microemulsion different components. These values proved the breakage of the microemulsion during its penetration across the stratum corneum. Moreover, the mechanisms of penetration enhancement and the micro molecular effects on the skin stratum corneum were investigated using attenuated Fourier transform infra-red spectroscopy. The results revealed the penetration of all the microemulsion components in the stratum corneum and demonstrated the microemulsion interaction with the skin barrier perturbing its architecture structure.
Keywords: Microemulsion; Confocal microscopy; Tape stripping; Skin permeation; Infra-red spectroscopy;

Synthesis of Agcore/Aushell bimetallic nanoparticles with size of 1.6 nm using rapid injection of NaBH4.Display Omitted► Agcore/Aushell bimetallic nanoparticles (BNPs) of less than 2 nm in diameter were prepared with rapid injection of NaBH4. ► The catalytic activity on glucose oxidation of the BNPs is several times higher than that of pure Au nanoparticles. ► The prepared BNPs exhibit not only a high instantaneous catalytic activity but also a high long-time catalytic stability. ► A possible activation mechanism through electronic charge transfer in the BNPs is proposed.PVP-protected Agcore/Aushell bimetallic nanoparticles of enough small size, i.e., 1.4 nm in diameter were synthesized in one-vessel using simultaneous reduction of the corresponding ions with rapid injection of NaBH4, and characterized by HR-TEM. The Agcore/Aushell bimetallic nanoparticles show a high and durable catalytic activity for the aerobic glucose oxidation, and the catalyst can be stably kept for more than 2 months under ambient conditions. The highest activity (16,890 mol-glucose h−1  mol-metal−1) was observed for the bimetallic nanoparticles with Ag/Au atomic ratio of 2/8, the TOF value of which is several times higher than that of Au nanoparticles with nearly the same particle size. The higher catalytic activity of the prepared bimetallic nanoparticles than the usual Au nanoparticles can be ascribed to: (1) the small average diameter, usually less than 2.0 nm, and (2) the electronic charge transfer effect from adjacent Ag atoms and protecting PVP to Au active sites. In contrast, the Ag–Au alloy nanoparticles, synthesized by dropwise addition of NaBH4 into the starting solution and having the large mean particle size, showed a low catalytic activity.
Keywords: Ag–Au bimetallic nanoparticles; Core/shell structure; Aerobic glucose oxidation; Gold catalyst; One-pot synthesis;

Preparation of magnetic polymer particles with nanoparticles of Fe(0) by S. Buendía; G. Cabañas; G. Álvarez-Lucio; H. Montiel-Sánchez; M.E. Navarro-Clemente; M. Corea (139-143).
Nanoparticles of Fe(0) were encapsulated with different amount of PMMA. The magnetization properties were a function of final average diameter of composite particle.Display Omitted► The magnetic polymers exhibit a fast and very strong response to external magnetic fields. ► Particles of Fe(0) were encapsulated with different quantity of polymethyl methacrylate. ► The magnetization values of the Fe(0) nanoparticles naked and encapsulated were largest than those reported for magnetite.Iron nanoparticles (Fe(0)), were encapsulated into polymethyl methacrylate (PMMA), by means of emulsion polymerization techniques in a semicontinuous process. The final average diameter of the composite particle was calculated until three times of average particle of iron particles and were stabilized with a non-ionic surfactant. They were then characterized by scanning electron microscopy and dynamic light scattering. Their magnetic properties were determined by parallel field vibrating-sample magnetometry method. The results indicated that the magnetic properties are a function of polymer concentration in the nanocomposite particle.
Keywords: Magnetic polymers; Iron particles; Nanocomposites; Magnetic properties;

Understanding surfactant aided aqueous dispersion of multi-walled carbon nanotubes by Michael D. Clark; Sachin Subramanian; Ramanan Krishnamoorti (144-151).
The effect of surfactant concentration, nanotube diameter, and pH on surfactant assisted aqueous carbon nanotube dispersions is presented. Shown is a schematic representation of ionic surfactant adsorption under varying pH.Display Omitted► Nanotube diameter an important parameter in the efficacy of surfactant assisted dispersion. ► pH has limited role in controlling dispersibility caused by non-ionic surfactants. ► pH dependent dispersibility using ionic surfactants is understood based on surface ionization and Debye length variation.Dispersions of multi-walled carbon nanotubes (MWNTs) assisted by surfactant adsorption were prepared for a number of ionic and non-ionic surfactants including sodium 4-dodecylbenzenesulfonate (NaDDBS), hexadecyl(trimethyl)azanium bromide (CTAB), sodium dodecane-1-sulfonate (SDS), Pluronic® F68, Pluronic® F127, and Triton® X-100 to examine the effects of nanotube diameter, surfactant concentration, and pH on nanotube dispersability. Nanotube diameter was found to be an important role in surfactant adsorption rendering single-walled carbon nanotube studies as unreliable in predicting MWNT dispersive behavior. Similar to other reports, increasing surfactant concentrations resulted in a solubility plateau. Quantification of nanotube solubility at these plateaus demonstrated that CTAB is the best surfactant for MWNTs at neutral pH conditions. Deviations from neutral pH demonstrated negligible influence on non-ionic surfactant adsorption. In contrast, both cationic and anionic surfactants were found to be poor dispersing aids for highly acidic solutions while, CTAB remained a good surfactant under strongly basic conditions. These pH dependent results were explained in the context of nanotube surface ionization and Debye length variation.
Keywords: Carbon nanotubes; Surfactant; Colloid dispersion; pH Variation; Nanotube; Dispersion; Ionic; Cationic; Anionic; Non-ionic;

Synthesis and antibacterial activity of copper-immobilized membrane comprising grafted poly(4-vinylpyridine) chains by Jian-Hua Qiu; Yan-Wu Zhang; Ya-Tao Zhang; Hao-Qin Zhang; Jin-Dun Liu (152-159).
The modification of chloromethylated polysulfone (CMPSF) membranes with poly(4-vinylpyridine) (P4VP) polymer brush was achieved by surface-initiated atom transfer radical polymerization (SI-ATRP). .Display Omitted► Preparation of chloromethylated polysulfone membrane. ► Surface-initiated atom transfer radical polymerization of poly(4-vinylpyridine). ► Immobilized copper (II) ions on modified membranes. ► Copper-loaded membrane leads to improve the antibacterial property.Poly(4-vinylpyridine) (P4VP) brushes were grafted onto microporous polysulfone (PSF) membranes via surface-initiated atom transfer radical polymerization (SI-ATRP) and then immobilized copper (II) ions on the modified membrane. Copper-loaded membranes exhibited excellent antibacterial properties with the added advantage of repeated use. The chemical composition and surface morphology of the functionalized membrane was characterized by ATR-FTIR, XPS, SEM, and AFM. The results showed that P4VP brushes clustered to rod-shaped covering and the sub-layer of membrane maintained sponge-like structures at the same time. Additionally, the kinetic study of SI-ATRP reaction revealed that the chain length of P4VP brushes increased linearly as the polymerization time increased. The antibacterial effects of copper-loaded CMPSF-g-P4VP membrane against Escherichia coli were examined and the antibacterial efficiency reached 100% when 2.49 wt.% of copper (II) ions was immobilized on membrane. The presented results could serve as a good starting point for the fabrication of antibacterial CMPSF membranes for waste-water treatment applications.
Keywords: Surface-initiated atom transfer radical polymerization (SI-ATRP); Polysulfone (PSF) membrane; Antibacterial; 4-Vinylpyridine;

Poly(ethylene oxide) and low molecular weight poly(ethylene glycol) were covalently immobilized on silicon wafers and gold films via the CH insertion reaction of perfluorophenyl azides by either photolysis or thermolysis. High grafting density was observed for the thermally-immobilized films, which also showed the lowest protein adsorption by surface plasmon resonance imaging.Display Omitted► A simple, fast, and general method for the immobilization of un-derivatized PEO and PEG films using perfluorophenyl azides. ► High grafting density comparable to PEG films prepared by other graft-to approach. ► Lowest protein adsorption on thermally-immobilized films, corresponding to the highest film thickness and quality.Poly(ethylene oxide) (PEO) and low molecular weight poly(ethylene glycol) (PEG) were covalently immobilized on silicon wafers and gold films by way of the CH insertion reaction of perfluorophenyl azides (PFPAs) by either photolysis or thermolysis. The immobilization does not require chemical derivatization of PEO or PEG, and polymers of different molecular weights were successfully attached to the substrate to give uniform films. Microarrays were also generated by printing polymer solutions on PFPA-functionalized wafer or Au slides followed by light activation. For low molecular weight PEG, the immobilization was highly dependent on the quality of the film deposited on the substrate. While the spin-coated and printed PEG showed poor immobilization efficiency, thermal treatment of the PEG melt on PFPA-functionalized surfaces resulted in excellent film quality, giving, for example, a grafting density of 9.2 × 10−4Å−2 and an average distance between grafted chains of 33 Å for PEG 20,000. The anti-fouling property of the films was evaluated by fluorescence microscopy and surface plasmon resonance imaging (SPRi). Low protein adsorption was observed on thermally-immobilized PEG whereas the photoimmobilized PEG showed increased protein adsorption. In addition, protein arrays were created using polystyrene (PS) and PEG based on the differential protein adsorption of the two polymers.
Keywords: PEG; Covalent immobilization; Non-fouling surface; Polymer arrays; Protein patterning;

Tuning the surface potential of Ag surfaces by chemisorption of oppositely-oriented thiolated carborane dipoles by Jörn F. Lübben; Tomáš Baše; Patrick Rupper; Tina Künniger; Jan Macháček; Sébastien Guimond (168-174).
The presented thiolated carborane isomer clusters have oppositely oriented dipole moments. These isomers are a potential tool for tuning the surface potential of a silver surface.Display Omitted► Two well-designed carborane isomeric clusters chemisorb on Ag with oppositely oriented dipoles. ► These isomers represent a tool for tuning the surface potential of a Ag surface within a range of 430 mV. ► Competitive self-assembly of these isomers leads to preferential adsorption of the isomer having the smaller dipole moment and showing with its negative pole upwards.Two selected carboranethiol isomers were used to modify flat silver surfaces. Both isomers, 1,2-(HS)2–1,2-C2B10H10 (a) and 9,12-(HS)2–1,2-C2B10H10 (b), are relatively strong dipoles with two SH groups per molecule. They are both anchored to the surface via two SH groups per molecule. Topography and surface potential changes of the modified silver surfaces were studied using Scanning Kelvin Probe Force Microscopy (SKPFM). These measurements proved that both isomers are oppositely oriented on the surface. The former isomer increases, and the latter one decreases the surface potential of a modified silver film. The relative changes of the surface potential correlate well with the dipole moments of the isomers. Competitive chemisorption from a 1:1 mixture of both isomers shows that the isomer (a) is found in a significantly higher concentration on the surface than the isomer (b). This has been proved by both SKPFM and X-ray photoelectron spectroscopy (XPS) techniques. Additionally, contact angle measurements were carried out to characterise the modified surfaces, and these and XPS results show the presence of hydrophobic hydrocarbon contaminants.
Keywords: Adsorption; Thiolated carboranes; Silver surface; Surface potential; Scanning Kelvin Probe Force Microscopy; X-ray photoelectron spectroscopy; Contact angle; Self-assembled monolayers; Dipole orientation;

Synthesis of highly efficient C-doped TiO2 photocatalyst and its photo-generated charge-transfer properties by Haiyan Li; Dejun Wang; Haimei Fan; Ping Wang; Tengfei Jiang; Tengfeng Xie (175-180).
Carbon-doped anatase TiO2 nanoparticles were prepared by a facile hydrothermal process without adding additional carbon source, they demonstrated outstanding advancement over Degussa P25 in the photodegradation of MO dye.Display Omitted► A facile fabrication method without adding additional carbon source. ► The as-prepared C-TiO2 extended photoresponse into visible range of solar spectrum. ► Sample shows highly efficient photocatalytic activity, only 4 min in degradation of MO. ► Relationship between photo-generated charges behavior and photocatalysis is discussed.Carbon-doped anatase TiO2 was prepared by a facile hydrothermal process without adding additional carbon source. The as-prepared sample shows highly efficient photocatalytic activity, which only requires 4 min and is about 11 times higher than that of Degussa P25 TiO2 in degradation of methyl orange (MO) dye under UV light irradiation. Moreover, a highly visible-light activity is also observed. UV–vis diffuse reflectance spectra and X-ray photoelectron spectroscopy confirm that the carbon atoms are incorporated into the interstitial positions of TiO2 lattice and form a strong interaction with titanium atoms and extend photoresponding range to 700 nm. Surface photovoltage spectra (SPS) and transient photovoltage (TPV) suggest that the presence of interstitial carbons induce several localized occupied states in the gap, enhance the separation extent and restrain the recombination of the photo-induced electron and hole carriers in TiO2.
Keywords: C-TiO2; Nanoparticle; Anatase; Photocatalysis; Photovoltage;

Colloid-chemical processes in the growth and design of the bio-inorganic aragonite structure in the scleractinian coral Cladocora caespitosa by Ivan Sondi; Branka Salopek-Sondi; Srečo D. Škapin; Suzana Šegota; Irena Jurina; Bojana Vukelić (181-189).
Field-emission scanning electron microphotography of aragonite fibers in the exoskeleton structure of the coral Cladocora caespitosa.Display Omitted► Colloid-chemical mechanisms govern formation of fibrous aragonite. ► Aragonite nucleation is organic-matrix mediated process. ► Submicrometer scale aggregation and coalescence processes are the main formation mechanisms. ► Exoskeleton’s SOM has a crucial role in the phase formation and growth of aragonite. ► Exoskeleton’s SOM indicates the significant presence of acidic hydrolase proteins.This study describes the morphological properties and discusses the colloid-chemical mechanisms of the formation of hierarchically structured aragonite fibers in the exoskeleton structure of the Mediterranean zooxanthellate scleractinian coral Cladocora caespitosa. The study is based on a detailed structural and morphological examination of the coral exoskeleton and on a preliminary biochemical and molecular identification of the isolated soluble proteinaceus organic matrix. The biomineral structure was examined by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and atomic-force microscopy (AFM), while the isolated protein organic constituents were analyzed by sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE) and mass spectrometry (MALDI-TOF-MS). The SDS–PAGE analysis of the soluble protein matrix showed three major protein bands at 15, 41, and 80 kDa. Based on the MALDI-TOF-MS analyses, the identified peptides tend to exhibit an acidic character. The results obtained confirm and complement the existing hypotheses relating to the significant role of the soluble acidic protein matrix and the biologically induced colloid-chemical processes in the phase formation and growth of scleractinian submicrometer fibrous aragonite units. It was also shown that the general strategy for the morphogenesis of fibrous structured aragonite lies in the nanoscale aggregation and subsequent coalescence processes that occur simultaneously. The subsequent morphological conversion of the initially formed submicrometer fibrous aragonite units into well-defined, micrometer-sized, prismatic facets in the skeletal structures of the corals is demonstrated.
Keywords: Aggregation; Aragonite; Coalescence; Corals; Hydrolase; Mesocrystals; Proteins; Submicrometer fibrous units;

Growth of Ag-nanoparticles using aspartic acid in aqueous solutions by Abu Rafey; K.B.L. Shrivastavaa; Sayed Aftab Iqbal; Zaheer Khan (190-195).
Adsorbed Ag+ ions on the surface of Ag2O formed by the reaction of Ag+ ions and OH, are reduced by the adsorbed aspartic acid.Display Omitted► Alkaline solution is required to the formation of perfect transparent silver sol. ► Size and rates of silver nanoparticle formation strongly depends on the aspartic acid concentrations. ► Amino and α-carboxylate groups undergo chemical transformation. ► Aspartic acid oxidized by the adsorbed silver ions onto the surface of silver oxide.Spectrophotometric, kinetic, and transmission electron microscopic (TEM) data for the formation of Ag-nanoparticles using aspartic acid (Asp) as reductant are reported for the first time. In the formation of transparent silver sols, an alkaline medium is required. The silver nanoparticles are spherical, uniform particle size, and strongly depend on the [Asp]. The apparent rate constant decreases with [Asp] (from 4.0 to 24.0 × 10−4  mol dm−3, the rate constants decreased from 2.6 × 10−4 to 0.3 × 10−4  s−1). For a certain reaction time, i.e., 30 min, the absorbance of the silver sol first increased until it reached a maximum, and then decreased with [Asp]. Kinetic and TEM results indicate that the size of the Ag-nanoparticles depends on the [Asp]. It is proposed that the oxidation of Asp occurs by the adsorbed Ag+ ions on the surface of Ag2O particles.
Keywords: Aspartic acid; Silver nanoparticles; Micelles; Silver nitrate;

A new type of h-SiO2/TiO2 core/shell microspheres exhibited excellent photocatalytic activity was prepared using carboxyl group modified silica particle as core and anatase titania as shell.Display Omitted► Surface of h-SiO2 was modified by carboxyl moieties via thiol-ene click reaction. ► The carboxyl groups promoted the formation of a dense and smooth titania layer under well control. ► Anatase titania shell showed good photocatalytic performance in degradation of methyl orange.The monodisperse hybrid silica particles (h-SiO2) were firstly prepared by a modified sol–gel process and the surface was modified in situ with double bonds, then abundant carboxyl moieties were introduced onto the surface of the silica core via thiol–ene click reaction. Afterward, the h-SiO2/TiO2 core/shell microspheres were prepared by hydrolysis of titanium tetrabutoxide (TBOT) via sol–gel process in mixed ethanol/acetonitrile solvent, in which the activity of TBOT could be easily controlled. The carboxyl groups on the surface of silica particles promote the formation of a dense and smooth titania layer under well control, and the layer thickness of titania could be tuned from 12 to 100 nm. The well-defined h-SiO2/TiO2 core/shell structures have been confirmed by electron microscopy and X-ray photoelectron spectroscopy studies. After calcination at 500 °C for 2 h, the amorphous TiO2 layer turned into anatase titania. These anatase titania-coated silica particles showed good photocatalytic performance in degradation of methyl orange aqueous solution under UV light.
Keywords: Core/shell; Hybrid silica particles; Anatase titania shell; Click reaction; Photocatalyst;

Folate-functionalized nanoparticles for controlled 5-Fluorouracil delivery by Yan Zhang; Jiashi Li; Meidong Lang; Xiaolin Tang; Lei Li; Xizhong Shen (202-209).
The nanoparticles based poly(ε-caprolactone) have improved the solubility of the anticancer drug 5-Fluorouracil, and increased the concentration at the site of the tumor to improve the tumor inhibition.Display OmittedIn this paper, folate conjugated poly(ε-caprolactone-co-4-maleate-ε-caprolactone) (P(CL-co-MCL)-folate) was prepared by a carbodiimide coupling reaction, i.e., the vitamin folic acid (FA) was covalently linked to the main chain of the maleate-functionalized polymer, poly(ε-caprolactone-co-4-maleate-ε-caprolactone) (P(CL-co-MCL)). Then the 5-Fluorouracil (5-FU) loaded nanoparticles of P(CL-co-MCL)-folate were achieved by solvent-evaporation method. Their properties were extensively studied by dynamic light scattering (DLS) and scan electron microscopy (SEM). DLS and SEM showed that the nanoparticles were in a well-defined spherical shape with a uniform size distribution. We also investigated the entrapment and in vitro release behavior, which indicated that the release speed of 5-FU could be well controlled and the release half-life period could reach 16.86 h, which was 26.4 times longer than that of pure 5-FU. The in vitro targeting test displayed that the 5-FU loaded P(CL-co-MCL)-folate nanoparticles exhibited an enhanced cell inhibition because folate targeting increased the concentration of 5-FU loaded P(CL-co-MCL)-folate nanoparticles in the tumor cells with folate receptor overexpressed. Meanwhile, the tumor inhibition of 5-FU loaded P(CL-co-MCL)-folate nanoparticles was much higher than that of pure 5-FU and that of 5-FU loaded P(CL-co-MCL) nanoparticles. Therefore, P(CL-co-MCL)-folate nanoparticles would be highly beneficial for biomedical and pharmaceutical applications.
Keywords: Poly(ε-caprolactone-co-4-maleate-ε-caprolactone); Nanoparticles; Folate; 5-Fluorouracil; Anti-tumor effect;

Single crystals of PbS in the form pyramids with a high proportion of high energy {3 3 1} faces are 24 obtained by the use of a novel reaction technique at the interface of water and toluene. The pyramids 25 spontaneously form a monolayer spread across the entire water–toluene interface.Display Omitted► Nanoscopic single-crystalline pyramids of PbS are obtained by deposition at the water–oil interface. ► The pyramids have a high proportion of high energy {331} faces. ► Deposition parameters strongly influence the form of the product.Single crystals of PbS in the form pyramids with a high proportion of high energy {3 3 1} faces are obtained by the use of a novel reaction technique at the interface of water and toluene. The pyramids spontaneously form a monolayer spread across the entire water–toluene interface. The influence of deposition parameters such as temperature, solution concentration, reaction time on the nature and properties of interfacial films are studied. In addition, the effect of solvo-static parameters such as column height and interfacial area are investigated. The obtained films are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM).
Keywords: Deposition at liquid–liquid interfaces; PbS nanostructures; PbS pyramids; Oil–water interface; High energy faces; Deposition of PbS; Solution deposition;

Interface interaction within nanopores in thin films of an amphiphilic block copolymer and CTAB by Chengyin Wang; Deyan Wang; Xiaoya Hu; Guoxiu Wang (219-225).
Interface interactions between a solid thin micro-porous film of an amphiphilic diblock copolymer formed by self-assembly and a cationic surfactant are investigated by in-situ atomic force microscopy.Display Omitted► Morphological investigations of microporous copolymer film interacting with CTAB. ► AFM technology applied to observe in-situ surface morphological changes. ► Dynamic light scattering (DLS) results and electrochemical behaviors of a Pt ultra-microelectrode modified by the microporous thin film.With water droplets as sacrificed templates at a particular humidity, micro-porous solid thin films were successfully fabricated by self-assembly using an amphiphilic block polymer, polystyrene-b-polyacrylic acid (PS-b-PAA). Interface interactions between the micro-porous thin film and a cationic surfactant, cetyltrimethylammonium bromide (CTAB), are investigated by in-situ AFM in aqueous solutions. An interesting phenomenon was observed in water and CTAB solution, which the dimensions of the micropores are remarkably larger than the dimensions of those in air. The solid thin films exhibit different surface morphologies in response to stimulus by different concentrations of CTAB. These observations were explained by positing that the PAA chains in the micropores stretch and contract with interface interactions between PAA and CTAB. A promising electrochemical application of this film is suggested. This study is aimed at strategies for the functionalization of stimulus-responsive micro-porous solid thin films with tunable surface morphologies, and exploring new smart materials.
Keywords: Micro-porous thin film; Self-assembly; PS-b-PAA; Block polymers; Surface analysis; CTAB;

Fluorescence image and schematic diagram for the complex structure of 15 wt.% PDADMAC and DPPG bilayers.Display Omitted► Charge reversal causes the main transition temperature to shift back. ► Distinct microstructures are formed for different polycation molecular weights. ► Chain bridging leads to interconnected vesicle-polymer complexes.The influence of cationic poly(diallyldimethylammonium chloride) on the morphology and phase behavior of anionic phospholipid vesicles was investigated using differential scanning calorimetry, fluorescent microscopy and light scattering technique. A wide range of polymer concentration has been examined for the first time. The polycation can bind electrostatically to the vesicles to compensate, neutralize and reverse the vesicular charge, depending on the molar ratio of cationic to anionic group R. For R  < 1, charge compensation weakened the electrostatic repulsion between the lipid molecules, leading to formation of polymer-modified vesicles, each with an increased number of bilayers. The bilayer exhibits a rising main phase transition temperature from a gel to liquid crystalline state. This behavior persisted until R  ≈ 1 around the neutralization condition, where the complexes became largest and precipitate. With R  > 1, charge reversal took place, the complex size reduced. Interestingly, the main phase transition temperature was found for the first time to shift back towards the original value in the absence of polymer for large enough R. Although the thermal behavior was nearly independent of the polymer molecular weight, the complex morphology could be different.
Keywords: Vesicles; Polyelectrolyte; Phospholipid; Electrostatics; Complex; Charge;

Structural changes in bovine α-lactalbumin in presence of cationic and anionic surfactants and the role of different interactions in the stability of molten globule state.Display Omitted► Both surfactants at very low concentration → stable molten globule (overall stability: HTAB > SDS). ► Major unfolding of α-LA, in HTAB → electrostatic interactions, in SDS → only hydrophobic interactions. ► Hydrodynamic diameter of molten globule in SDS: 7.38 ± 0.41 nm, HTAB under same condition → aggregation. ► The energetics of ANS binding in HTAB → enthalpically driven (ΔH 1  = −12.2 ± 0.3; ΔH 2  = −35.7 ± 1.5). ► α-LA molten globule thus obtained in HTAB and SDS was very different than the conventional ones.The role of different types of interactions and their contribution in the stabilization of bovine α-lactalbumin (α-LA) molten globule in presence of cationic surfactant, hexadecyl trimethyl ammonium bromide (HTAB) and anionic surfactant, sodium dodecyl sulphate (SDS) have been examined using a combination of spectroscopic, light scattering and calorimetric techniques. The results correlated well with each other and were used to characterize the partially folded states of the protein both qualitatively and quantitatively. At lower concentration of the surfactants, the thermodynamic parameters obtained from UV–visible spectroscopy suggested an increased exposure of non-polar groups in HTAB while a possible restructuring of non-polar groups were indicated in SDS. The fluorescence and circular dichroism spectroscopy showed the formation of an intermediate state at various concentrations of HTAB and SDS while the lifetime measurements supported the assumption of protein–surfactant complex stability in HTAB as compared to SDS. The hydrodynamic diameter and the ζ-potential were analyzed by dynamic light scattering (DLS) which also implicated the combined influence of electrostatic and hydrophobic interactions in protein unfolding in HTAB and only hydrophobic interactions in SDS. The binding parameters for ANS obtained from isothermal titration calorimetric (ITC) measurements suggested a high stability of α-LA molten globule and the role of enthalpic and entropic contribution in the binding of ANS in HTAB. It also indicated the fragility of α-LA molten globule in SDS. The possible binding sites as well as the interactions of ANS with the partially folded protein were also studied from the thermodynamic parameters obtained from the ITC.
Keywords: α-LA; Molten globule; Electrostatic interaction; Hydrophobic interaction; ζ-Potential; Hydrodynamic diameter;

DTABr–Brij35 mixtures in 0.3 M NaBr can be well described by an ideal behavior supposing that the DTABr generated 1.4 particles.Display Omitted► Transposition of the usual thermodynamic behavior models of solvent mixtures to mixed micelles is not always obvious. ► Ionic surfactants in mixed micelles can be either totally associated to their counterions or partly or completely dissociated. ► Clint’s equation must be applied carefully for mixed micelles of charged and uncharged surfactants. ► Application of RST to mixed micelles depends on the presence or not of ionic surfactants.Solutions of mixed surfactants are often considered as solvent mixtures. Usually, mixed micellar aggregates are considered as a homogeneous mixture of solvents dispersed in a solution. But the transposition of the usual thermodynamic models of solvent mixtures to mixed micelles is not always so obvious. We discussed this point in this paper by considering several cases of surfactant mixtures. A major problem is to define the molar fraction of each surfactant in the aggregate especially when a charged surfactant is employed in the mixture, because possible dissociation of the components of the mixture must be considered in the bulk as well in the micelle. This definition is crucial especially for the characterization of the ideal behavior which is usually described by the Clint relation, as well as for the application of regular solution theory (RST) which is the most frequently applied model for interpreting the behavior of surfactant mixtures. We show in this paper how the definition of the molar fraction can change the equations and the interpretations.
Keywords: Surfactant; Mixed micelle; Thermodynamics; Behavior model;

A surfactant type fluorescence probe for detecting micellar growth by Lining Gao; Li Zhao; Xi Huang; Baocai Xu; Yun Yan; Jianbin Huang (256-260).
The growth of surfactant micelles can be sensitively detected by measuring the fluorescence anisotropy or the fluorescence maximum of a surfactant type fluorescence probe 12-DAN-ADA.Display Omitted► A novel anionic surfactant type fluorescence probe with the fluorescent group attached to the end of the chain was designed. ► The fluorescent group can be tethered deep into the micellar cores. ► The growth of micelles can be detected by using this new type of fluorescence probe. ► The sensibility of the probe can be enhanced considerably if the background fluorescence is quenched by water soluble quenchers.We report on the detection of micellar growth in anionic, cationic, and catanionic surfactant systems using a novel surfactant type fluorescence probe, sodium 12-(N-dansyl)amino-dodecanate (12-DAN-ADA). The fluorescent group was incorporated in the tail of the surfactant which tethers the fluorescent group deep inside the apolar micellar cores. The fluorescence anisotropy of 12-DAN-ADA was found to be very sensitive for directly detecting the micellar growth in micelles containing oppositely charged surfactants, including cationic CTAB systems and mixed systems of oppositely charged surfactants (DEAB/SDS); in regard to the like charged SDS micellar systems, the sensitivity can be greatly enhanced by addition of a water soluble quencher which quenches the background fluorescence from the equilibrium population of free 12-DAN-ADA.
Keywords: Fluorescence probe; Dansyl; Spherical micelle; Rod-like micelle; Worm-like micelle;

The adsorption of tetracycline onto the zeolite beta is highly pH-dependent. The aluminum atoms in the zeolite beta play a crucial role in the adsorption.Display Omitted► The presence of aluminum in the zeolite beta causes the tetracycline uptake. ► The sorption is spontaneous and endothermic. ► The optimum tetracycline sorption occurs at pH 5. ► The adsorption kinetics is well described by an intraparticle diffusion model. ► The amino group is involved in the complexation with the zeolite.Extensive usage of tetracycline has resulted in its contamination in surface water and groundwater. The adsorption of tetracycline on zeolite beta was systematically investigated for the decontamination of the antibiotic polluted water in this study. Ninety percent of uptake by the zeolite beta occured in 0.25 h, and the adsorption equilibrium was obtained within 3 h, which was well described by an intraparticle diffusion model. The adsorption generally increased when pH was increased from 4.0 to 5.0, and then decreased significantly as the pH was further increased, which was caused by the pH-dependent speciation of tetracycline and surface charge of zeolite beta. Both Freundlich and Langmuir equations well described the adsorption isotherm. A thermodynamic analysis showed that the sorption process was spontaneous and endothermic. Aluminum atoms in the zeolite played a crucial role in the uptake; the adsorption increased with the increasing aluminum content in zeolite. The UV–Visible spectroscopy study showed that the spectra of tetracycline changed upon the interaction with zeolite beta, which could be ascribed to the formation of complexes of tetracycline and aluminum atoms in the zeolite surface. Nuclear magnetic resonance spectroscopy study further confirmed the participation of Al in the tetracycline adsorption. Fourier transform infrared spectroscopy studies showed that the amino functional groups in tetracycline were involved in the complexation with the zeolite surface.
Keywords: Adsorption; Antibiotic; Tetracycline; Zeolite beta; NMR; FTIR; Kinetic modeling;

Semiempirical PM6/SPARKLE method used to model the binding of Yb(III)-1,10-phenanthroline-5,6-dione. These studies shown that the chelating ligand selectively attaches to Yb(III) at two points in the membrane–solution interface.Display Omitted► The results of the Mopac2009 calculations show selective complexation of Yb(III) by PDO ligand that correlate quite well with experimental data. ► The proposed sensor has a very fast response time. ► This electrode was applied as an indicator electrode in potentiometric titration for determination of Yb(III) and also for fluoride ions. ► The empirical selectivity coefficients are in agreement with the PM6/SPARKLE calculations. ► Among different cations, Yb(III) has the lowest ΔHr with PDO ligand.To predict the selectivity of Yb(III)PVC membrane, the semiempirical PM6/SPARKLE method was used to investigate the binding of Yb(III) and other cations to 1,10-phenanthroline-5,6-dione (PDO). The study has shown that the chelating ligand, PDO, is selectively coordinated to Yb(III) at two coordination sites involving the pyridylic nitrogen atoms in the interface of membrane/solution. The membrane was used as a potentiometric Yb sensor, based on PDO as an ionophore, sodium tetraphenyl borate (NaTBP) as a lipophilic ionic additive, and tributyl phosphate (TBP) as a plasticizer. The electrode had a good Nernstian response for Yb(III) ions over a wide concentration range from 5 × 10−6 to 1 × 10−2  M and a detection limit of 5.7 × 10−7  M with a slope of 19.7 ± 0.2 mV/decade in a pH range of 4.0–12.0. The sensor had a very fast response time of less than 5 s over the whole concentration range and can be used over a period of 6 wk without any significant divergence in potentials.
Keywords: PVC membrane sensor; Ionophore; Ytterbium; PM6/SPARKLE; 1,10-phenanthroline-5,6-dione;

Differential capacitance transient leading to the formation of condensed film after an induction time, observed after transfer of the mercury drop (2, 3). (1) Before the transfer.Display Omitted► Adsorptive stripping voltammetry capacitance results differ from those obtained before the transfer of the drop. ► This difference decreases with the decrease of the temperature. ► Surfactants are not removed from the interface on repeated scanning. ► Reorientation of surfactants can result in condensed film. ► Adsorbed surfactants on mercury can be used as templates.The adsorption of cetyltrimethylammonium bromide (CTAB) and cetyldimethylbenzylammonium chloride (CDBACl) on a hanging mercury electrode is studied using adsorptive transfer stripping voltammetry. The surfactants are adsorbed on mercury and are then transferred in KBr or KCl under various conditions, including temperatures from 1 to 40 °C, open or closed circuits with different initial potentials, and repeated scans, etc. The results are compared with previously published results on the adsorption of CTAB or CDBACl on mercury, where condensed films were formed and are quite different than those obtained by adsorptive stripping voltammetry. In this case, an absence of condensed film is observed for CTAB. A condensed film with low capacitance value is formed in the case of CDBACl after transfer at low temperatures, or after repeated scans, resulting in reorientation of the molecules to more compact states. Capacity time curves at the potentials where the film is formed show in a few cases a nucleation and growth mechanism, with induction time and studied by the Avrami formulation, while an observed increase of the capacitance with time is attributed to the formation of hemimicelles. The results also indicate the importance of interactions between the hydrophobic chains.
Keywords: Adsorptive stripping voltammetry; Condensed film; Cetyltrimethylammonium bromide; Cetyldimethylbenzylammonium chloride;

Adsorption of phenols from aqueous solutions: Equilibria, calorimetry and kinetics of adsorption by Przemysław Podkościelny; Krzysztof Nieszporek (282-291).
The generalized Langmuir–Freundlich (GLF) isotherm equation has been applied to study the cooperative effect of the surface heterogeneity and the lateral interactions between the adjacent molecules.Display Omitted► Energetic heterogeneity plays a more essential role than lateral interaction effects. ► Utility of the SRT model for the description of adsorp. kinetics has been confirmed. ► Set of common parameters in each type of theoret. eqs (consistency of approach).The brief theoretical description of the phenols adsorption from aqueous solutions on carbonaceous adsorbents, i.e. activated carbons (ACs) and activated carbon fibers (ACFs) has been presented. The description includes adsorption equilibria, calorimetry as well as kinetics of adsorption. The generalized Langmuir–Freundlich (GLF) isotherm equation has been used to study of the cooperative effect of the surface heterogeneity and the lateral interactions between the admolecules. Theoretical isosteric heats of adsorption connected with the GLF model have been estimated too. Knowledge of both adsorption equilibria and heats of adsorption is fundamental for adequate description of any adsorption process. To correlate the kinetic data of the studied systems, the theoretical equations developed from Statistical Rate Theory (SRT) of Interfacial Transport were applied. The most advantageous of the proposed model of calculations is the set of common parameters appearing in each type of expressions, which significantly extends the possibility of their interpretation. Theoretical studies were fully reviewed using the literature experimental adsorption data. They included the data of phenols adsorption both on ACs and ACFs surfaces.
Keywords: Phenols; Activated carbons; Activated carbon fibers; Heat of adsorption; Kinetics;

Modification of montmorillonite surfaces using cationic surfactants.Display Omitted► Water purification is imperative for the welfare of a healthy population. ► Water is widely contaminated by recalcitrant organic chemicals such a pesticides, herbicides and hormones. ► One inexpensive method for purifying water from these types of molecules is through adsorption. ► One suite of materials for this adsorption is based upon organoclays. ► This paper reviews the adsorption of organics on organoclays.Water purification is imperative for the welfare of a healthy population. Water is widely contaminated by recalcitrant organic chemicals such a pesticides, herbicides and hormones. One inexpensive method for purifying water from these types of molecules is through adsorption. One suite of materials for this adsorption is based upon organoclays. This paper reviews the adsorption of organics on organoclays.
Keywords: Montmorillonite; Organoclay; High resolution thermogravimetric analysis; X-ray diffraction; Scanning electron microscopy; Transmission electron microscopy;

Characterization of acid–base properties of two gibbsite samples in the context of literature results by F. Adekola; M. Fédoroff; H. Geckeis; T. Kupcik; G. Lefèvre; J. Lützenkirchen; M. Plaschke; T. Preocanin; T. Rabung; D. Schild (306-317).
Two different gibbsite samples were extensively studied. Small and big particles yield low and high surface charge densities, respectively.Display Omitted► The titration results at 20 min waiting times refute the previous suggestion that increased waiting time causes higher charge on gibbsite particles. ► The difference in slope of literature charging curves are attributed to the titrant aliquot in terms of titrant added per surface area of gibbsite. ► We show in an interlaboratory comparison that titrations on one solid yield consistent results. ► Based on the interlaboratory comparison, it becomes clear that the discrepancies in interfacial properties of the two different gibbsite samples (in terms of their surface charging) studied are real.Two different gibbsites, one commercial and one synthesized according to a frequently applied recipe, were studied in an interlaboratory attempt to gain insight into the origin of widely differing reports on gibbsite acid–base surface properties. In addition to a thorough characterization of the two solids, several methods relevant to the interfacial charging were applied to the two samples: potentiometric titrations to obtain the “apparent” proton related surface charge density, zeta-potential measurements characterizing the potential at the plane of shear, and Attenuated Total Reflection Infrared Spectroscopy (ATR-IR) to obtain information on the variation of counter-ion adsorption with pH (using nitrate as a probe). Values of the IEP at 9–10 and 11.2–11.3 were found for the commercial and synthesized sample, respectively. The experimental observations revealed huge differences in the charging behavior between the two samples. Such differences also appeared in the titration kinetics. A detailed literature review revealed similar disparity with no apparent systematic trend. While previously the waiting time between additions had been advocated to explain such differences among synthesized samples, our results do not support such a conclusion. Instead, we find that the amount of titrant added in each aliquot appears to have a significant influence on the titration curves. While we can relate a number of observations to others, a number of open questions and contradictions remain. We suggest various processes, which can explain the observed behavior.
Keywords: Gibbsite; Surface charge; Zeta-potential; Acid–base titration; Mass titration; MUSIC model; Surface complexation; ATR-FTIR;

A single crystal silver bromide electrode (SCr–AgBr) was used to measure the inner surface potential (Ψ 0) at a silver bromide aqueous electrolyte interface in a broad temperature range. Reaction enthalpies and entropies were evaluated.Display Omitted► Bromide ions have a more pronounced tendency for binding at a silver bromide surface than silver ions K n ∘ > K p ∘ . ► The binding of bromide ions is significantly less exothermic Δ n H ∘ > Δ p H ∘ . ► The binding of silver ions is less favorable due to a significantly higher negative entropy change Δ n S ∘ < Δ p S ∘ .Dependence of surface potential (electrostatic potential at the inner Helmholtz plane, Ψ 0) at the silver bromide aqueous electrolyte interface was measured as a function of the activities of Br and Ag+ by using a single crystal silver bromide electrode (SCr–AgBr). Absolute values of surface potentials were obtained from electrode potentials of SCr–AgBr and isoelectric points. Measurements were performed at different temperatures in the range from 10 to 50 °C. Corresponding equilibrium constants of interfacial reactions were obtained using the surface complexation model and interpreted via the van’t Hoff equation. As a result of the interpretation for the binding of bromide ions leading to a negative surface charge, the thermodynamic parameters obtained were Δ n H ∘ = - 33 kJ mol - 1 and Δ n S ∘ = - 31 J mol - 1 K - 1 ; and for the binding of silver ions leading to a positive surface charge, Δ p H ∘ = - 72 kJ mol - 1 and Δ p S ∘ = - 196 J mol - 1 K - 1 . Association of counterions (CI) with oppositely charged surface sites partially compensates the surface charge. Assuming approximately the same affinities for anions ( NO 3 - ) and cations (K+) thermodynamic parameters for their binding were obtained as Δ CI H ∘ ≈ 7 kJ mol - 1 and Δ CI S ∘ ≈ 105 J mol - 1 K - 1 .
Keywords: Silver bromide; Single crystal electrode; Surface potential; Interfacial equilibrium constants; Enthalpy; Entropy;

Single-crystalline Bi5O7NO3 nanofibers were prepared and showed a high visible-light photocatalytic efficiency for the degradations of RhB..Display Omitted► Single-crystalline Bi5O7NO3 nanofibers were prepared by a facile hydrothermal method. ► Bi5O7NO3 sheets could be dissolved and transformed into nanofibers. ► Bi5O7NO3 nanofiber material exhibited a high visible-light photocatalytic activity. ► The charge carriers in the CB and VB were highly mobile.A new photocatalyst, namely single-crystalline Bi5O7NO3 nanofibers, was prepared by a facile hydrothermal method in the presence of Triton X-100 and ammonia. Bi5O7NO3 possessing a crystalline sheet morphology could be dissolved and transformed into nanofibers by controlling the reaction time. Samples were characterized by X-ray diffraction, UV–vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and high resolution transmission electron microscopy. The Bi5O7NO3 nanofiber growth mechanism is discussed in detail. The band gap energy of the as-prepared Bi5O7NO3 photocatalyst was about 2.70–2.90 eV. Results of first-principle density functional theory calculations confirmed that Bi5O7NO3 had a narrow band gap. They revealed that the conduction band bottom was predominantly composed of Bi 6s, Bi 6p, N 2p and O 2p orbitals, while the valence band (VB) top primarily consisted of Bi 6p, Bi 6s and O 2p orbitals. The as-obtained Bi5O7NO3 nanofibers showed good photocatalytic activity and stability for the degradation of Rhodamine B (RhB) under visible light irradiation, which may be ascribed to the highly mobile conduction band (CB) and VB charge carriers.
Keywords: Bismuth; Bi5O7NO3; Hydrothermal synthesis; Visible light; Photocatalytic;

Silver nanoparticles deposited on the surface of activated carbons using Tollens method significantly increase the ability of the carbons for NO2 and NO retention.Display Omitted► Introduction of silver nanoparticles, using Tollens method, significantly increases the performance of carbons as adsorbents NO2 and NO. ► The retention of NO2/NO depends on the dispersion of silver nanoparticles and their chemistry. ► Highly dispersed small silver metal particles promote the formation of complexes either with NO2 or NO. Such efficiently used catalysts are produced only when the amount of silver matches the amount of aldehyde groups and/or incompletely oxidized functionalities, which are involved in deposition of those silver nanoparticles.Wood-based activated carbon was modified by deposition of silver using Tollens method. Adsorbents with various contents of silver were used to study NO2 and NO (the product of NO2 reduction by carbon) retention. The surface of the initial and exhausted materials was characterized using adsorption of nitrogen, XRD, SEM/EDX, FTIR and TA. The results indicated that with an increasing content of silver on the surface the capacities to retain NO2 and NO increase until the plateau is reached. The performance depends on the dispersion of nanoparticles and their chemistry. Highly dispersed small silver metal particles promote formation of chelates with NO2 and/or with NO. An excess of Tollens reagent results in formation of larger silver crystals and silver oxide nanoparticles. If sufficiently dispersed, they also enhance the retention of NO2 via formation of nitrates deposited in the pore system. The surface of the carbon matrix is also active in NO2 retention, providing the small pores and edges of graphene layers, where the reductions of NO2/oxidation of carbon take place.
Keywords: Activated carbon; Silver nanoparticles; Adsorption; NO x retention; Tollens method;

Textural, structural, and morphological characterizations and catalytic activity of nanosized CeO2–MO x (M = Mg2+, Al3+, Si4+) mixed oxides for CO oxidation by Qiang Yu; Xiaoxia Wu; Changjin Tang; Lei Qi; Bin Liu; Fei Gao; Keqin Sun; Lin Dong; Yi Chen (341-352).
The CeO2–Al2O3 mixed oxides exhibited higher CO oxidation activity than corresponding CeO2–MgO and CeO2–SiO2 mixed oxides due to excellent textural/structural properties, good homogeneity, and redox abilities.Display Omitted► The textural characterizations suggested that alumina could be act as a very effective surface stabilizer for ceria-based mixed oxides. ► The structural characterizations showed the presence of CeO2 nanocrystals and amorphous oxides. ► The reducible features exhibited the reductions of surface and bulk oxygen, which was dependent upon calcination temperature. ► CO oxidation results suggested CeO2−Al2O3 exhibited the highest activity due to excellent textural/structural properties and redox properties.The present work focuses on the combination of ceria with another oxide of different ionic valences from period 3 (Mg2+, Al3+, and Si4+) using coprecipitation method, followed by calcination at 450 and 750 °C, respectively. The textural, structural, morphological and redox properties of nanosized ceria–magnesia, ceria–alumina and ceria–silica mixed oxides have been investigated by means of N2 physisorption, XRD, Raman, HRTEM, DRS, FT-IR, and H2-TPR technologies. XRD results of these mixed oxides reveal that only nanocrystalline ceria (ca. 3–6 nm for the 450 °C calcined samples) could be observed. The grain size of ceria increases with the increasing calcination temperature from 450 to 750 °C due to sintering effect. The highest specific surface area is obtained at CeO2–Al2O3 mixed oxides when calcination temperature reaches 750 °C. Raman spectra display the cubic fluorite structure of ceria and the existence of oxygen vacancies, and displacement of oxygen ions from their normal lattice positions in the ceria-based mixed oxides. DRS measurements confirm that the smaller the grain size of the ceria, the higher indirect band gap energy. H2-TPR results suggest that the reductions of surface and bulk oxygen of ceria were predominant at low and high calcination temperature, respectively. Finally, CO oxidation were performed over these ceria-based mixed oxides, and the combination of CeO2–Al2O3 exhibited highest activity irrespective of calcination temperature, which may due to excellent textural/structural properties, good homogeneity, and redox abilities.
Keywords: CeO2-based mixed oxides; Ceria–magnesia; Ceria–alumina; Ceria–silica; Ceria; CO oxidation;

Synthesis, characterization and adsorption performance of a novel post-crosslinked adsorbent by Xiaowei Zeng; Hongjie Yao; Ning Ma; Yunge Fan; Chunhong Wang; Rongfu Shi (353-358).
The N2 adsorption capacity of the post-crosslinked resin PDHT-2 is much larger than the precursor PDHT-1, which resulted from its higher specific surface area after post-crosslinking reaction.Display Omitted► Both the specific surface area and the pore volume of starting copolymer increased significantly after post-crosslinking reaction. ► Post-crosslinked adsorbent exhibited higher adsorption capacity of phenol than precursor and commercial resin XAD-4. ► The adsorption process for phenol onto the three adsorbents was proved to be exothermic and spontaneous in nature. ► Phenol uptake onto adsorbents followed the pseudo-second order model and the intraparticle diffusion process was the rate-controlling step.In this paper a post-crosslinked polymeric adsorbent PDHT-2 with high specific surface area was prepared by Friedel–Crafts reaction of the pendant vinyl groups without an externally added crosslinking agent. It was obvious that both the specific surface area and the pore volume of starting copolymer PDHT-1 increased significantly after post-crosslinking. Batch adsorption runs of phenol from aqueous solution onto adsorbent PDHT-1 and PDHT-2 were researched, and commercial macroporous resin XAD-4 was chosen for comparison purpose. Experimental results showed that the adsorption isotherms could be fitted by Langmuir model and Freundlich model and the adsorption capacity onto PDHT-2 was much larger than that onto PDHT-1 and XAD-4 with respect to phenol and phenolic compound, which possibly resulted from its larger specific surface area. The adsorption process for phenol onto the three adsorbents was proved to be exothermic and spontaneous in nature. The thermodynamic parameters such as Gibb’s free energy (ΔG), change in enthalpy (ΔH) and change in entropy (ΔS) had been calculated. The adsorption kinetic curves obeyed the pseudo-second order model and the intraparticle diffusion process was the rate-controlling step.
Keywords: Macroporous polymeric adsorbent; Post-crosslinking; Pendant vinyl groups; Phenol; Thermodynamics; Kinetics;

Landau–Levich menisci by M. Maleki; M. Reyssat; F. Restagno; D. Quéré; C. Clanet (359-363).
In this paper, we present an original experiment of reflectometry, which allows us to measure accurately the profile of the entrained film when a plate is either withdrawn or pushed into a pool of wetting liquid. A theory is also developped.Display Omitted► This article is the first experimental study on the dynamic menisci observed in dip-coating. Discussions about the theoretical shape of the dynamic meniscus in the entrainment case or in the immersion case can indeed be found in the literature (Landau–Levich and Bretherton, respectively). There were however no careful experiments on this question, and we found it useful to probe these shapes.► In addition, we specify in the immersion case, what is the validity of the Bretherton solution, and make the connection with the Jones–Wilson ripples, which were themselves very little discussed in the literature.► In the withdrawing case, we determine the validity domain of the Landau–Levich solution and provide data in the regime where gravity modifies the entrainment law.As shown by Landau, Levich and Derjaguin, a plate withdrawn out of a wetting bath at low capillary numbers deforms the very top of the liquid reservoir. At this place, a dynamic meniscus forms, whose shape and curvature select the thickness of the film entrained by the plate. In this paper, we measure accurately the thickness of the entrained film by reflectometry, and characterize the dynamic meniscus, which is found to decay exponentially towards the film. We show how this shape is modified when reversing the motion: as a plate penetrates the bath, the dynamic meniscus can “buckle” and present a stationary wavy profile, which we discuss.
Keywords: Dip coating; Dynamic meniscus; Lubrication; Wavy film; Wetting;

Gas bubbles in simulation and experiment by Peter Lakshmanan; Franz Peters; Nicolas Fries; Peter Ehrhard (364-372).
Bubbles in rotating-chamber experiment are spatially fixed. They can be subject to all kinds of long-term investigations.Display Omitted► Rotating-chamber experiment is a valuable instrument for long-term investigations of rising bubbles in liquids. ► Simulations based on the immersed-boundary formulation and a mass-conserving level-set method validate this feature in all details. ► With spatially-fixed bubble a great variety of measurements appears possible over long periods in time.An experimental setup for the examination of single bubbles, rising in a liquid, is presented. Its main part is a rotating chamber, in which the bubble is spatially stabilized by a balance of buoyancy, drag, and lift forces. This allows for long observation periods in time. Experimental results are presented for air bubbles in silicone oil. The experimental results are validated by a comparison with numerical simulations. A modified, mass-conserving level-set method is used for the representation of the free interface, while an immersed-boundary formulation is engaged for the conservation equations. The agreement between experiment and simulation, and to available correlations from literature, is found to be perfect. It is shown that the influence of the liquid shear due to the rotation is negligible. Also, for the presented liquid system, no influence by Marangoni stresses could be found, which makes the system of air and silicone oil a good choice for validation purposes.
Keywords: Rising bubbles in liquids; Rotating-chamber experiment; Numerical simulation; Level-set method; Immersed-boundary formulation;

Superhydrophilic and antireflective La(OH)3/SiO2-nanorod/nanosphere films by Ji-Ho You; Byung-Il Lee; Jinho Lee; Hongdoo Kim; Song-Ho Byeon (373-379).
La(OH)3 nanorods film self-stacked on the glass slide provided highly rough surface for SiO2 nanoparticles layer, the as-assembled La(OH)3/SiO2 film demonstrating superhydrophilicity and antireflectivity simultaneously.Display Omitted► La(OH)3 nanorods were self-stacked on the glass slide substrates. ► These thin-film coatings of La(OH)3 nanorods exhibit potentially useful single-layer antireflection property. ► La(OH)3 nanorod layer provides a sufficiently rough surface required to achieve superhydrophilicity. ► La(OH)3/SiO2-nanorod/nanosphere film shows superhydrophilicity and antireflectivity simultaneously.La(OH)3 nanorods were self-stacked on the glass slide substrates using an aqueous suspension obtained from the hydrolysis of LaOCl. The key for producing a high optical quality film of La(OH)3 lies in the preparation of an aqueous suspension in which La(OH)3 nanorods are well dispersed. These thin-film coatings of La(OH)3 nanorods led to a significantly reduced reflective losses in the visible region, exhibiting an attractive and potentially useful single-layer antireflection property. Furthermore, La(OH)3 nanorod layer provides a sufficiently porous and rough surface required to achieve superhydrophilicity. Thus, when SiO2 nanoparticles of ca. 20 nm in diameter were deposited onto La(OH)3 layer of high roughness, the resulting La(OH)3/SiO2 film demonstrated an interesting nanoporosity-derived superhydrophilicity and antifogging property with no significant loss of antireflective property.
Keywords: Hydroxide; Nanorods; Antireflection; Superhydrophilic; Antifogging;

A model for investigating the behaviour of non-spherical particles at interfaces by G. Morris; S.J. Neethling; J.J. Cilliers (380-385).
A model capable of simulating the film shape around non-spherical particles is presented with investigation into the effect of particle shape on energitically stable orientations at an interface.Display Omitted► Model for simulating many different shapes of particle at an interface introduced. ► Contact angle affects the energetically stable orientations at an interface. ► Aspect ratio of particle affects its stable orientations at an interface. ► Particle orientation can be easily defined by the user.This paper introduces a simple method for modelling non-spherical particles with a fixed contact angle at an interface whilst also providing a method to fix the particles orientation. It is shown how a wide variety of particle shapes (spherical, ellipsoidal, disc) can be created from a simple initial geometry containing only six vertices. The shapes are made from one continuous surface with edges and corners treated as smooth curves not discontinuities. As such, particles approaching cylindrical and orthorhombic shapes can be simulated but the contact angle crossing the edges will be fixed.Non-spherical particles, when attached to an interface can cause large distortions in the surface which affect the forces acting on the particle. The model presented is capable of resolving this distortion of the surface around the particle at the interface as well as allowing for the particle’s orientation to be controlled. It is shown that, when considering orthorhombic particles with rounded edges, the flatter the particle the more energetically stable it is to sit flat at the interface. However, as the particle becomes more cube like, the effects of contact angle have a greater effect on the energetically stable orientations. Results for cylindrical particles with rounded edges are also discussed. The model presented allows the user to define the shape, dimensions, contact angle and orientation of the particle at the interface allowing more in-depth investigation of the complex phenomenon of 3D film distortion around an attached particle and the forces that arise due to it.
Keywords: Non-spherical particles; Stable orientations; Simulations;

Simulations of novel nanostructures formed by capillary effects in lithography by Jiansheng Feng; Jonathan P. Rothstein (386-395).
Here we show the elevations as well as the three-dimensional profile of the menisci formed in polygonal and star-shaped capillaries.Display Omitted► At zero gravity, menisci formed in capillaries with regular polygonal or star-shaped cross sections are partial spheres. ► Analytical solutions of the height variation on the menisci formed in regular polygonal and star-shaped capillaries are presented. ► Height variation of the meniscus shows power-law dependency on the rounding radius of the corners of polygonal or star-shaped capillaries. ► High aspect ratio three-dimensional structures can be fabricated by using star-shaped capillaries in CFL.High aspect ratio three-dimensional nanostructures are of tremendous interest to a wide range of fields such as photonics, plasmonics, fluid mechanics, and biology. Recent developments in capillary force lithography (CFL) have focused on taking advantage of the formation of menisci to enhance the functionality of small size-scale structures. In this study, simulations of the three-dimensional shapes of equilibrium menisci formed in capillaries with various cross-section geometries are studied. The capillary cross sections include regular polygons and equilateral star-shapes with sharp and rounded corners. The characteristic dimension of the physical lithography systems which are simulated is on the order of 100 nm. At such size-scale, surface-tension-effects are predominant, and as a consequence, our simulations demonstrate that nanometer-sized structures with great application potentials can be fabricated. Specifically, this study demonstrates that surfaces with three-dimensional nanoscale structures can be fabricated from templates with micron or sub-micron features through the development of cusps in the corners of the polygonal capillaries. Quantitatively, the effects of contact angle, corner angle, meniscus confinement, and corner rounding radius are examined and scaling analyses are presented to describe the dependencies of the height variation across the meniscus on these parameters. These simulations serve as useful guides for extending the development and implementation of capillary force lithography.
Keywords: Capillary Force Lithography; Three-dimensional meniscus; Contact angle; Corner rounding; Star-shaped capillary;

Influence of alcohol (methanol) and anionic surfactant (SDDS) molar fraction ( X 2 s and X 1 s ) at the water–air and quartz–water interface on the spreading coefficient at the quartz–aqueous solution interface..Display Omitted► A linear dependence of adhesion and surface tension was seen with a positive slope. ► The critical surface tension of quartz wetting depends on the aqueous solution composition. ► Adhesion work of a solution to quartz can be predicted from the activities of its components.Measurements of the advancing contact angles for aqueous solutions of sodium dodecyl sulfate (SDDS) or sodium hexadecyl sulfonate (SHS) in mixtures with methanol, ethanol, or propanol on a quartz surface were carried out. On the basis of the obtained results and Young and Gibbs equations the critical surface tension of quartz wetting, the composition of the surface layer at the quartz–water interface, and the activity coefficients of the anionic surfactants and alcohols in this layer as well as the work of adhesion of aqueous solutions of anionic surfactant and alcohol mixtures to the quartz surface were determined. The analysis of the contact angle data showed that the wettability of quartz changed visibly only in the range of alcohol and anionic surfactant concentration at which these surface-active agents were present in the solution in the monomeric form. The analysis also showed that there was a linear dependence between the adhesion and the surface tension of aqueous solutions of anionic surfactant and alcohol mixtures. This dependence can be described by linear equations for which the constants depend on the anionic surfactant and alcohol concentrations. The slope of all linear dependence between adhesion and surface tension was positive. The critical surface tension of quartz wetting determined from this dependence by extrapolating the adhesion tension to the value equal to the surface tension (for contact angle equal zero) depends on the assumption whether the concentration of anionic surfactant or alcohol was constant. Its average value is equal to 29.95 mN/m and it is considerably lower than the quartz surface tension. The positive slope of the adhesion–surface tension curves was explained by the possibility of the presence of liquid vapor film beyond the solution drop which settled on the quartz surface and the adsorption of surface-active agents at the quartz/monolayer water film–water interface. This conclusion was confirmed by the work of adhesion of aqueous solutions of anionic surfactants and short-chain alcohol mixtures to the quartz surface determined on the basis of the contact angle data and molar fraction of anionic surfactants and alcohols and their activity coefficient in the surface layer.
Keywords: Quartz; Surfactants; Alcohols; Adsorption; Surface tension; Adhesion work;

TIRF microscopy as a screening method for non-specific binding on surfaces by Christy Charlton; Vladimir Gubala; Ram Prasad Gandhiraman; Julie Wiechecki; Nam Cao Hoai Le; Conor Coyle; Stephen Daniels; Brian D. MacCraith; David E. Williams (405-409).
Total internal reflection fluorescence microscopy is used for non-specific adsorption screening of nanoparticles on functionalized surfaces. Binding of fluorescent nanoparticles is observed in real-time, measuring attractive or repulsive surface properties.Display Omitted► TIRF microscopy is useful for screening of non-specific surface–particle interactions. ► Optimal surface characteristics determined result in lowest non-specific binding of particles. ► Substrate-particle charge repulsion had the strongest effect in decreasing the background. ► Charge repulsions outperformed effects of coatings based on steric hindrance and water hydration. ► COOH surfaces provide enough repulsion to antibody coated particles for low non-specific binding.We report a method for studying nanoparticle-biosensor surface interactions based on total internal reflection fluorescence (TIRF) microscopy. We demonstrate that this simple technique allows for high throughput screening of non-specific adsorption (NSA) of nanoparticles on surfaces of different chemical composition. Binding events between fluorescent nanoparticles and functionalized Zeonor® surfaces are observed in real-time, giving a measure of the attractive or repulsive properties of the surface and the kinetics of the interaction. Three types of coatings have been studied: one containing a polymerized aminosilane network with terminal –NH2 groups, a second film with a high density of –COOH surface groups and the third with sterically restraining branched poly(ethylene)glycol (PEG) functionality. TIRF microscopy revealed that the NSA of nanoparticles with negative surface charge on such modified coatings decreased in the following order –NH2  > -branched PEG > –COOH. The surface specificity of the technique also allows discrimination of the degree of NSA of the same surface at different pH.
Keywords: Total internal reflection; Fluorescence; Microscopy; Non-specific binding; Surface–particle interaction;

Hybrid Ag2S–Ag3SBr superionic conductor nanoparticles and their large-scale ordered arrays by Yuzeng Sun; Baibin Zhou; Fuhui Liao; Guobao Li (410-412).
It is the first time to synthesize the hybrid Ag2S–Ag3SBr superionic conductor nanoparticles with faceted-spherical and polyhedral morphologies, as well as their large-scale ordered arrays.Display Omitted► Synthesis of hybrid superionic–superionic conductor nanocomposites. ► Mixed ionic conductive properties. ► Fabrication of high-quality hybrid Ag2S–Ag3SBr superionic–superionic conductor nanoparticles. ► Ionic conductivity, tunable ionic conductive properties, nanoscale integrated circuits.We report a simple aqueous-solution route to synthesize hybrid Ag2S–Ag3SBr superionic conductor nanoparticles with faceted-spherical and polyhedral morphologies at low temperature. The morphological control was achieved by adjusting the H+ concentration in the presence of cetyltrimethylammonium bromide, which was used as both a Br source and a capping reagent. The hybrid nanoparticles could self-organize into large-scale ordered arrays, and have potential applications in fabricating photonic crystals, mixed superionic conductors, high energy density batteries and near-infrared photoluminescent devices.
Keywords: Hybrid; Superionic conductor; Ordered arrays; Ag2S; Ag3SBr;

Magnetic hard/soft nanocomposite ferrite aligned hollow microfibers and remanence enhancement by Fuzhan Song; Xiangqian Shen; Mingquan Liu; Jun Xiang (413-416).
Nanocomposite ferrite hollow microfibers are generally aligned and show a well exchange-coupling of hard phase (SrFe12O19) and soft phase (Ni0.5Zn0.5Fe2O4), combining a high Ms of Ni0.5Zn0.5Fe2O4 and Hc of SrFe12O19.Display Omitted► The nanocomposite ferrite aligned hollow microfibers have been prepared. ► The structure of nanocomposite ferrite aligned hollow microfibers was characterized. ► The nanocomposite ferrite hollow microfibers show enhanced magnetic properties.The nanocomposite SrFe12O19/Ni0.5Zn0.5Fe2O4 ferrite aligned hollow microfibers with the hollow diameter to the fiber diameter estimated about 3/5 have been prepared by the gel precursor transformation process. The nanocomposite binary ferrites with different mass ratios are formed after the precursor calcined at 900 °C for 2 h, fabricating from SrFe12O19 nanoparticles and Ni0.5Zn0.5Fe2O4 nanoparticles with a uniform phase distribution. These nanocomposite ferrite microfibers show a combination of magnetic characteristics for the hard (SrFe12O19) and soft (Ni0.5Zn0.5Fe2O4) phase with an enhanced remanence owing to the exchange-coupling interactions. The aligned microfibers exhibit a shape anisotropy.
Keywords: Ferrite; Nanocomposite; Hollow microfiber; Anisotropy; Exchange-coupling;

Why like-charged particles of dielectric materials can be attracted to one another by Anthony J. Stace; Adrian L. Boatwright; Armik Khachatourian; Elena Bichoutskaia (417-420).
Force calculated to exist between two positively charged particles; when this becomes negative the particles are attracted to one another.Display Omitted► Like-charged particles of dielectric materials can be attracted to one another. ► Calculations represent charged particles as having a constant, but free and dynamic surface charge. ► Mutual polarisation of the surface charge leads to attraction.Calculations of surface charge density provide evidence of the physical effects responsible for particles of a dielectric material carrying the same sign of charge being attracted to one another. The results show that attraction requires a mutual polarisation of charge leading to regions of negative and positive surface density close to the point where the particles make contact. These results emphasise the significance of using charged particle models where the surface charge is non-stationary.
Keywords: Dielectric particles; Charged; Polarisation; Attraction; Fullerenes; Droplets;

A simple model for multicomponent etching by A.C. Fowler; J.A. Ward; S.B.G. O’Brien (421-423).
Graphical abstract Snapshots of a portion of a lattice consisting of three types of molecules at three different times. In the portion illustrated, N  = 2, so there are three layers, n  = 0, 1, 2, and M  = 11 horizontal sites. It is assumed that it takes T seconds to etch a P and K molecule while S is not etched by this acid.Display Omitted► We model the acid etching of a multicomponent substrate. ► Lead crystal glass is etched using hydrofluoric and sulphuric acid. ► We obtain an estimate of the etching velocity. The wavefront simultaneously diffuses.We consider the situation where a multicomponent solid is etched using one or more acids. Of fundamental interest is the rate of surface etching but when this involves multicomponent surface reactions, it becomes unclear how the overall rate can be estimated. In this paper, we sketch a simple model designed to determine the effective etching rate by means of an atomic scale model of the etching process.
Keywords: Etching; Multicomponent; Lead glass; Interface;

A one-step process to a Janus emulsion by Hida Hasinovic; Stig E. Friberg; Guo Rong (424-426).
VO/SO: The SO forms the continuous phase. Adding water results in a double emulsion W/VO/SO, while added S gives the combination Janus emulsion (VO + SO)/W.Display Omitted► Introduction of aqueous high internal phase ratio (HIPR) (vegetable oil + silicone oil)/water Janus emulsions formed in a one-step bulk process. ► Relating the configuration of the Janus emulsions to the surfactant fraction in the aqueous phase. ► Clarifying the inversion process from the complex Janus emulsion (vegetable oil + silicone oil)/water/vegetable oil/silicone oil to the simpler HIPR (vegetable oil + silicone oil)/water Janus emulsion. ► Demonstrating the presence of surfactant in the next to innermost aqueous phase of a complex Janus emulsion, (vegetable oil + silicone oil)/water/vegetable oil/silicone oil, to bring silicone oil from the continuous phase into the Janus drops in the aqueous phase in question.Aqueous high internal phase volume ratio (O/W 90/10) Janus emulsions of a vegetable oil and a silicone fluid were prepared in a single step emulsification by the common vibrator equipment. The basis for the unique structure is discussed in relation to pair-wise interactions between the components with especial emphasis on the surfactant concentration in the aqueous phase.
Keywords: Janus emulsions; Double emulsions; High internal phase volume ratio (HIPR) emulsions; Silicone emulsions; Vegetable oil emulsions; Abnormal emulsions;

by Arthur Hubbard (427).