Carbohydrate Polymers (v.84, #3)
Editorial Board (CO2).
Extraction, preliminary characterization, antioxidant and anticancer activities in vitro of polysaccharides from Cyclina sinensis by Changxing Jiang; Mingchun Wang; Jun Liu; Dan Gan; Xiaoxiong Zeng (851-857).
In the present study, we investigated the extraction, purification, preliminary characterization, antioxidant and anticancer activities in vitro of polysaccharides from Cyclina sinensis (CSPS). Firstly, the optimal parameters for extraction of CSPS were obtained by using a central composite design as follows: extraction temperature, 90 °C; extraction time, 250 min; ratio of water to raw material, 29; and extraction times, two times. Then, the crude CSPS was sequentially purified by chromatography of DEAE-52 and Sephadex G-100, resulting in three purified fractions of CSPS-1, CSPS-2 and CSPS-3. We found that the composition and property of CSPS-3, having relatively higher contents of protein, uronic acid, sulfate and more complicated monosaccharide composition, were quite different from those of CSPS-1 and CSPS-2. Furthermore, we demonstrated that CSPS-3 had strong scavenging activities in vitro on superoxide radical and hydroxyl radical and strong inhibitory effect in vitro on the growth of human gastric cancer BGC-823 cells.
Keywords: Cyclina sinensis; Polysaccharide; Extraction; Characterization; Antioxidant activity; Anticancer activity;
Novel drug delivery systems: Chitosan conjugates covalently attached to steroids with potential anticancer and agrochemical activity by Javier Pérez Quiñones; Richard Szopko; Claudia Schmidt; Carlos Peniche Covas (858-864).
Chitosan (CS) was linked to diosgenin monoesters with potential anticancer and agrochemical activity employing several methods (i.e. solid phase microwave assisted synthesis with carbodiimides activation, acyl chloride approach and homogeneous reaction with carbodiimides activation in aqueous solution). The steroid contents found by elemental analysis were between 5 and 33% (w/w) and was dependent on the nature of the employed linker and the steroid–CS conjugates preparation method. Linking was confirmed by FTIR spectroscopy. Differential scanning calorimetry studies are presented. In vitro release studies performed in water at different pH indicated a drug release dependence on the dicarboxylic acid employed as linker, the steroid content and the acidity of the solution. The obtained conjugates can be potentially applied as films, microspheres or gels for delivery of plant growth regulators in agriculture and anticancer drugs.
Keywords: Steroids; Agrochemical; Chitosan conjugates; Drug delivery;
Acid and enzyme hydrolysis to convert pretreated lignocellulosic materials into glucose for ethanol production by Waleed K. El-Zawawy; Maha M. Ibrahim; Yasser R. Abdel-Fattah; Nadia A. Soliman; Morsi M. Mahmoud (865-871).
The current research investigates the use of acid and enzyme hydrolysis to produce glucose from pretreated rice straw, banana plant waste and corn cob, as a lignocellulosic materials, to be a source for ethanol production. The agricultural biomasses were first tested, then a laboratory experimental set-up was designed in order to perform the necessary conversions. The biomass materials were characterized to contain 57.46–85.28% holocellulose and 14.55–26.12% lignin. Conversion of the cellulose to glucose was achieved by pre-treatment method for the agricultural residues first applying chemical pulping and steam explosion method as well as microwave treatment then followed by two processes, namely acid hydrolysis and enzyme hydrolysis. Sulfuric acid, 5%, was used in acid hydrolysis and Trichoderma reesei cellulases in enzyme hydrolysis. These experiments demonstrated that glucose concentration differs according to the type of pre-treatment and type of hydrolysis. Conversion of the glucose to ethanol during fermentation was accomplished by the action of yeasts from Saccharomyces cerevisiae. Ethanol production in the culture sample was monitored using gas chromatography. The results indicate that ethanol can be made from the above mentioned residues in a different yield according to the pre-treatment and the glucose produced from the hydrolysis method.
Keywords: Agricultural biomass; Pre-treatment; Acid hydrolysis; Enzyme hydrolysis; Glucose concentration; Ethanol production;
Stoichiometric interpretation of thermoplastic starch water sorption and relation to mechanical behavior by Farouk Ayadi; Patrice Dole (872-880).
The characterization of glycerol plasticized starch by water sorption was interpreted in terms of interaction stoichiometry. The saturation of starch was found to correspond to a 2:1 anhydroglucose unit/glycerol stoichiometric ratio. The introduction of cellulose into the formulation of plasticized starch (TPS) decreased the quantity of bonded glycerol, due to the strong interaction between cellulose and starch. The systematic study of the TPS properties in the whole range of relative humidities showed transitions which were not connected to the “saturation transition” or to the glass transition. Breaking properties probably depended on a complex combination of different system characteristics.
Keywords: Plasticized starch; Glycerol; Interaction stoichiometry; Cellulose;
Concomitant degradation in periodate oxidation of carboxymethyl cellulose by Hongli Li; Bo Wu; Changdao Mu; Wei Lin (881-886).
Conversion of carboxymethyl cellulose (CMC) to its dialdehyde derivatives by periodate oxidization in acid solutions has been investigated as a function of pH, temperature, reaction time and periodate dosage. Our results show that the stoichiometric ratio of NaIO4 to CMC and the pH of aqueous medium are substantially responsible for the aldehyde content and yield of the product. Laser light scattering (LLS) and wide angle X-ray diffraction (WAXD) measurements demonstrate that physical and chemical degradations concomitant with the oxidization process occur, leading to the decrease in 〈R h〉 and crystallinity, respectively. The degradation mechanism for acid-catalyzed cleavage of β-1-4-glycosidic bond is proposed. Atomic force microscopy (AFM) images reveal the morphological changes of CMC with the degree of oxidization. The present study quantitatively indicates the substantial degradation in derivatization of cellulose by periodate oxidization method, and is helpful for exploring novel carboxymethyl polysaccharide derivatives.
Keywords: Carboxymethyl cellulose; Periodate; Aldehyde content; Laser light scattering (LLS); Wide angle X-ray diffraction (WAXD); Atomic force microscopy (AFM);
A novel chitosan/polyoxometalate nano-complex for anti-cancer applications by Deepthy Menon; Reny Thankam Thomas; Sreeja Narayanan; S. Maya; R. Jayakumar; Firasat Hussain; Vinoth-Kumar Lakshmanan; S.V. Nair (887-893).
Polyoxometalates (POMs) show great molecular diversity and have significant applications in material science as well as in medicine. In this study, nano-complexation of a novel europium containing polyanion [Cs⊂Eu6As6W63O218(H2O)14(OH)4]25− (EuWAs) with biocompatible chitosan was achieved through ionotropic gelation technique without the aid of any cross-linker. Thus obtained chitosan/EuWAs nano-complex was characterized using DLS and Zeta analysis, FT-IR, SEM, AFM, TG/DTA, EDAX and fluorescence spectroscopy. The cross-linking efficiency of EuWAs with chitosan was calculated to be 81% and the release profile recorded at physiological pH was slow and sustained. Cytotoxicity assays performed on a host of cancer cell lines, viz., KB, MCF-7, PC-3 and A549 proved the anticancer activity of the nanocomplex and flow cytometry studies revealed that reactive oxygen species generation can be the plausible mechanism for the apoptosis induced by this material. Our study has thus indicated the feasibility of using chitosan/EuWAs nano-complex for anticancer applications.
Keywords: Chitosan; Polyoxometalate; Ionotropic gelation; Nanocomplex; Anticancer; Flowcytometry;
Elucidation of the structure of a bioactive hydrophilic polysaccharide from Cordyceps sinensis by methylation analysis and NMR spectroscopy by Shao-Ping Nie; Steve W. Cui; Aled O. Phillips; Ming-Yong Xie; Glyn O. Phillips; Saphwan Al-Assaf; Xiao-Liang Zhang (894-899).
The structure of a bioactive hydrophilic polysaccharide fraction from Cordyceps sinensis (CBHP) was studied using methylation analysis and 2D NMR spectroscopy. Monosaccharide composition analysis revealed that it consists mainly of glucose (95.19%) with trace amounts of mannose (0.91%) and galactose (0.61%). The results of methylation analysis indicated that α-1,4 linked Glcp is the main linkage type (65.7%), followed by t-Glcp (20.7%), 1,2,3,6-Glcp (4.1%), 1,2,4,6-Glcp (3.0%), 1,3,6-Glcp (2.0%), 1,4,6-Glcp (1.6%), and 1,2-Manp (1.9%) and 1,3-Galp (1.0%). Based on 1D and 2D NMR analysis, a preliminary structure is proposed: The backbone is composed of Glcp joined by 1 → 4 linkages and 1 → 3 linkages; the branching points are located at O-2 or O-6 of Glcp with α- terminal-d-Glcp as side chain. The trace amounts of 1,2-Manp and 1, 3-Galp linkages are probably located randomly in the side chains. A schematic structure is proposed as following:Display Omitted
Keywords: Cordyceps sinensis; Hydrophilic polysaccharide; Structure; Methylation analysis; NMR;
Weathering of chitosan films in the presence of low- and high-molecular weight additives by A. Sionkowska; A. Planecka; J. Kozlowska; J. Skopinska-Wisniewska; P. Los (900-906).
The effects of artificial solar radiation from an Accelerated Weathering Chamber (Weatherometer) on thin chitosan films were studied by UV–Vis and FTIR spectroscopy, contact angle measurements, microscopy methods and mechanical properties investigation. Chitosan films were prepared through a solution casting method. Several films were prepared with low- and high-molecular weight additives, such as camphorquinone, glutathione, tyrosine, phenylalanine and collagen. It was found that UV–Vis spectra, which characterize chitosan, were significantly altered by artificial solar radiation. The thermal properties and polarity of the surface were also altered by artificial solar light. Mechanical properties such as the ultimate tensile strength, percentage elongation and Young's modulus of chitosan films were changed irregularly according to irradiation time. The deterioration of the mechanical properties of chitosan films after irradiation results mainly from photochemical changes such as cross-linking and chain scission. The contact angle and the surface free energy of chitosan films were altered by artificial solar UV irradiation. The influence of low- and high-molecular weight additives on photodegradation of chitosan has also been discussed.
Keywords: Chitosan; Weathering; Photodegradation;
Amylopectin internal molecular structure in relation to physical properties of sweetpotato starch by Fan Zhu; Harold Corke; Eric Bertoft (907-918).
Unit chain length distributions of amylopectins and their φ,β-limit dextrins (reflecting amylopectin internal part) from 11 Chinese sweetpotato genotypes were characterized by high performance anion-exchange chromatography after debranching, and were related to the thermal and pasting properties of granular starches. The weight-based unit chain length profiles of whole amylopectin and their internal parts both had three distinguishable major groups with approximate range of DP 6–36, 37–68, and >69 for amylopectins and DP 3–25, 26–55, and >55 for φ,β-limit dextrins. Among different genotypes, two different patterns of Bfp (fingerprint B-chains, DP 3–7) were observed for φ,β-limit dextrins, whereas Afp (fingerprint A-chains, DP 6–8) for whole amylopectins were consistent. Reconstruction of amylopectins from their φ,β-limit dextrins revealed that B-chains with internal DP > 20 possessed an external chain length corresponding to the average value DP 12.8. Wide genetic variations were recorded among structural parameters, of which several concerning the amylopectin internal part were highly correlated to the thermal and pasting parameters of sweetpotato starches, and suggested that the internal part of amylopectin is critical to the physical behavior of granular starch.
Keywords: Internal unit chain distribution; Sweetpotato amylopectin structure; Chain category; Structure–properties relationship;
Effect of chitosan coating in overcoming the phagocytosis of insulin loaded solid lipid nanoparticles by mononuclear phagocyte system by Bruno Sarmento; Donatella Mazzaglia; Maria Cristina Bonferoni; Ana Patrícia Neto; Maria do Céu Monteiro; Vitor Seabra (919-925).
In this work, RAW 264.7 cell line was used to investigate the macrophage internalization of insulin-loaded SLN coated with chitosan. SLN were prepared by the w/o/w double emulsion method with different lipids and two different surfactants, Pluronic and Tween 80, following chitosan coating. Witepsol 85E based SLN were suitable for dimensions, sizing between 200 and 400 nm and insulin association efficiency was around 60% for both surfactants. Fluorescence microscopy confirmed that chitosan coated SLN were neglectfully internalized within RAW 264.7 cells as compared with uncoated SLN and with polystyrene latex nanoparticles as positive control, which were fully taken up. These results were quantitatively confirmed by flow cytometry assay. Chitosan-coated SLN demonstrated to be potentially able to prolong insulin blood levels and to avoid phagocytosis by MPS after intestinal uptake.
Keywords: Solid lipid nanoparticles; Witepsol 85E; Chitosan; Insulin; Macrophage internalization;
Studies on graft copolymerization of 3-acrylamidopropyl trimethylammonium chloride on pullulan by Marieta Constantin; Ionut Mihalcea; Ionela Oanea; Valeria Harabagiu; Gheorghe Fundueanu (926-932).
Graft-polymerization of (3-acrylamidopropyl)-trimethylammonium chloride onto pullulan using potassium persulfate as an initiator was carried out in an aqueous solution. Evidence of grafting was obtained by comparing 1H NMR, FT-IR spectra, SEM and TGA analysis of pullulan and the grafted copolymer. The effects of reaction conditions on the grafting parameters (such as initiator, monomer, and pullulan concentrations, reaction time and temperature) were investigated, and the optimal conditions for the grafting reaction were established. A plausible mechanism for the free-radical grafting was suggested. The obtained graft copolymer was designed to be used in waste water treatment processes and drug delivery.
Keywords: Pullulan; 3-Acrylamidopropyl trimethylammonium chloride; Potassium persulfate; Graft polymerization;
pH responsive itaconic acid grafted alginate microspheres for the controlled release of nifedipine by Nuran Işıklan; Murat İnal; Fatma Kurşun; Gülden Ercan (933-943).
A series of pH responsive alginate-g-poly(itaconic acid) (NaAlg-g-PIA) microspheres were prepared as drug delivery matrices of nifedipine cross-linked by glutaraldehyde (GA) in the hydrochloric acid catalyst. Graft copolymers of sodium alginate with itaconic acid were synthesized using ceric ammonium nitrate. The chemical stability of the nifedipine after encapsulation into microspheres was confirmed by FTIR, DSC and X-RD analysis. The preparation conditions of the NaAlg-g-PIA microspheres such as graft yield, GA concentration, exposure time to GA and drug amount were optimized by considering the percentage entrapment efficiency, particle size, swelling capacity and their release data. The results showed that NaAlg-g-PIA microspheres are pH responsive. The release of nifedipine from grafted microspheres was slower for the pH 1.2 solution than that of the pH 7.4 buffer solution. It has been observed that an increase in exposure time, drug amount, GA and NaAlg-g-PIA concentrations causes a decrease in the nifedipine release from the microspheres, whereas an increase in graft yield leads to an increase in the nifedipine release.
Keywords: Graft copolymerization; Sodium alginate; Itaconic acid; Free radical copolymerization; Microspheres;
Xylogalactans from Lithothamnion heterocladum, a crustose member of the Corallinales (Rhodophyta) by Diego A. Navarro; Alejandra M. Ricci; María C. Rodríguez; Carlos A. Stortz (944-951).
The main polysaccharides from the red seaweed Lithothamnion heterocladum share the general characteristics of corallinans (agar-like xylogalactans), even though this seaweed is crustose, whereas those previously studied in detail were articulated seaweeds. After fractionation by cetrimide precipitation, several fractions were separated and characterized by sugar composition, other components, methylation, ethylation, desulfation–methylation, and NMR analyses. The main group of fractions carry the agaran disaccharidic repeating unit [→3)-β-d-Galp-(1 → 4)-α-l-Gal-(1→] substituted mainly on O-6 of the β-d-Gal unit by β-xylosyl side stubs, and less with sulfate or methoxyl groups, and also on O-2 of the α-l-Gal unit with methoxyl or sulfate, or less on O-3 of the same unit with methoxyl groups. These features are common to those of the polysaccharides of the four members of the order Corallinales already studied. However, a sugar not very common to the order appears in substantial proportions: 2,3-di-O-methyl-d-galactose, which acts as a side stub. Another peculiar issue is the presence of significant amounts of 4-linked α-l-Gal units glycosylated on O-6 or O-3. These results confirm that within a common pattern of corallinean xylogalactans, each species has minor characteristics of their own.
Keywords: Rhodophyta; Corallinales; Xylogalactans; Lithothamnion; 2,3-Di-O-methylgalactose; Agaran;
Preparation and characterization of novel curdlan/chitosan blending membranes for antibacterial applications by Yan Sun; Yong Liu; Yongzhen Li; Mingzhe Lv; Puwang Li; Hanglong Xu; Lei Wang (952-959).
Antibacterial membranes were prepared from a mixture of hydrolyzed curdlan and chitosan. The elongation-at-break and water vapor transmission rate of curdlan/chitosan blended membranes were substantially improved when the temperature was high (90 °C) due to curdlan gel formation and the interaction between the hydroxyl groups of curdlan and the amino groups of chitosan. This was confirmed by Fourier transform infrared spectroscopy. The membranes were further investigated for their miscibility between the two components using differential scanning calorimetric measurements, dynamic mechanical analysis, optical microscopy, and scanning electron microscopy. High reaction temperatures (90 °C) and low curdlan contents caused better interactions between components, and allowed membranes to be prepared with higher storage moduli and lower water absorption rates. The 4 bacteria strains were chosen as target bacteria using the optical density method to prove the antibacterial activity of the membranes obtained. The resulting curdlan/chitosan membranes exhibited outstanding antibacterial activity.
Keywords: Curdlan/chitosan; Blending membranes; Miscibility; Antibacterial activity;
Enzymatic degradation of poly-l-lysine-polygalacturonic acid multilayers by Marta Westwood; Dorota Roberts; Roger Parker (960-969).
The action of polygalacturonase on layer-by-layer deposited multilayer films composed of poly-l-lysine and polygalacturonic acid was examined using a quartz crystal microbalance with dissipation monitoring (QCMD), dual polarisation interferometry (DPI) and atomic force microscopy. These techniques were used to determine changes in polymer mass, density, thickness, morphology and hydration of the multilayers in response to enzymatic degradation.The degradation of the multilayer films by polygalacturonase was studied in the range 0.01–1.0 activity units mL−1 (U mL−1). The QCMD and DPI results show that addition of polygalacturonase solution with an activity of 1 U mL−1 led to an almost complete disintegration (over 80% mass loss) of the PLL–PGA structure within 20 min, whilst a polygalacturonase solution with the lowest activity had negligible effect on PLL–PGA films. It was found that the multilayer film with PLL uppermost slows the degradation, an effect which persisted throughout the course of the degradation.
Keywords: Enzymatic degradation; Polyelectrolyte; Multilayers; Layer-by-layer;
Slowly digestible starch prepared from rice starches by temperature-cycled retrogradation by Lulu Zhang; Xiuting Hu; Xueming Xu; Zhengyu Jin; Yaoqi Tian (970-974).
The temperature-cycled retrogradation of rice starch used to prepare slowly digestible starch was investigated in this study. Our results showed that a maximum slowly digestible starch content of 51.62% was obtained from waxy rice starch at the optimal tested conditions: temperature cycles of 4/25 °C, at intervals of 24 h, and 7 days of storage. The results also indicated that there was a higher onset temperature (T o), a narrower melting temperature range (T c − T o), and a higher ratio (1047 cm−1/1022 cm−1) of the slowly digestible starch products prepared under the temperature-cycled condition than that under the isothermal retrogradation. Furthermore, it was evident that the in vitro glycemic index of slowly digestible starch products with temperature-cycled retrogradation was reduced more than that with isothermal storage. These results suggest that the temperature-cycled retrogradation is applicable to prepare the high yield of slowly digestible starch from waxy rice starch.
Keywords: Slowly digestible starch; Cycled temperature; Preparation; Starch retrogradation; Waxy rice starch;
Nanofibrillated cellulose from TEMPO-oxidized eucalyptus fibres: Effect of the carboxyl content by Iskander Besbes; Sabrine Alila; Sami Boufi (975-983).
In the present work the effect of the carboxyl content on the high pressure defibrillation of oxidized eucalyptus from micro to nanoscale size was investigated. It has been shown that TEMPO-mediated oxidation of dried softwood pulp not only facilitates the defibrillation process, but also reduces the number of passes necessary to get the gel, as well as preventing the clogging of the homogenizer. In fact, these effects became apparent up to a carboxyl content about 300 μmol/g, and over 500 μmol/g, the yield in the nanofibrillated cellulose exceeded 90%, at a defibrillation pressure of 600 bar. The morphology of the ensuing nanofibrillated cellulose (NFC) and its crystalline degree were characterised by FE-SEM and DRX measurement, respectively. The evolution of the transparency degree and the viscosity according to the oxidation degree and defibrillation pressure were also analysed by UV–vis transmittance and rheological measurement.The reinforcing potential of the ensuing NFC was explored by means of dynamic mechanical analysis (DMA) carried on nanocomposite film prepared from a suspension of NFC as the reinforcing phase and an acrylic latex dispersion as the matrix.
Keywords: Nanofibrillated cellulose; Cellulose; Eucalyptus; Nanocomposite;
Stress relaxation in synergistically associated polysaccharides: Galactomananns and a non-pectic polysaccharide fraction from yellow mustard mucilage by Y. Wu; W. Cui; N.A.M. Eskin; H.D. Goff (984-989).
In the current study, stress relaxation test and dynamic temperature sweep test were performed to study a non-pectic polysaccharide (NPP) fraction from yellow mustard mucilage and its synergistic interactions with galactomannans (GMs). All solutions were prepared at the total polysaccharide concentration of 1% (w/v). NPP and GM were mixed at the blending ratio of 7/3. Prior to measuring the behaviour of the mixed solutions, the effects of temperature and pH on 1% NPP solution were studied. The results showed that both acidic condition and increased temperature led to stronger NPP gels due to hydrophobic interactions along the NPP backbones. When NPP was mixed with either fenugreek gum (FG) or locust bean gum (LBG) at pH 8, synergistic interactions were observed at all examined temperatures. The relaxation modulus (G(t)) increased at higher temperatures. The difference in relaxation curves between the two mixed solutions, NPP/FG and NPP/LBG, at increased temperatures further confirmed the difference in their synergy mechanism: the breakdown of “hyperentanglements” in NPP/FG solution started at a lower temperature (50 °C) while the breakdown of “junction zones” via hydrogen bonding in NPP/LBG solution occurred at a higher temperature (70 °C). This paper provides further evidence for our previously proposed mechanisms of the synergistic interactions in NPP/FG and NPP/LBG mixed systems.
Keywords: Synergistic interactions; Non-pectic polysacchrides; Galactomannan; Stress relaxation; Temperature; pH;
The mineralization of electrospun chitosan/poly(vinyl alcohol) nanofibrous membranes by Dongzhi Yang; Kun Yu; Yufei Ai; Hongpeng Zhen; Jun Nie; John F. Kennedy (990-996).
Based on the principles of biomineralization, a calcium carbonate (CaCO3) and chitosan composite membrane was prepared by mineralized of calcium carbonate on chitosan/poly(vinyl alcohol) nanofibers under dynamic condition. The morphology and structure of membranes were characterized by scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. The results showed that the chitosan/poly(vinyl alcohol) nanofibers produced thin CaCO3 island crystals, which interlaced with the chitosan fiber not only on the surface of the membrane but also within the membrane. The crystals could develop into a continuous CaCO3 membrane on the fibers at latter stage of mineralization, the obtained crystals was mainly calcite type of CaCO3, and with small quantity of vaterite. MTT test and SEM imaging indicated that the attachment and growth of mouse fibroblast were well on the surface of CaCO3/chitosan/PVA composite membrane, and this composite has a good application prospect in the field of biomedical materials.
Keywords: Mineralization; Chitosan; Electrospinning; Calcium carbonate;
Production, preliminary characterization and antitumor activity in vitro of polysaccharides from the mycelium of Pholiota dinghuensis Bi by Dan Gan; Liping Ma; Changxing Jiang; Renjie Xu; Xiaoxiong Zeng (997-1003).
The production, preliminary characterization and antitumor activity in vitro of mycelial polysaccharides from Pholiota dinghuensis Bi (PDP) were investigated in the present study. Firstly, crude PDP was prepared from the mycelia of P. dinghuensis Bi by submerged culture. Then, the crude PDP was purified by chromatography of DEAE-52 cellulose and Sephadex G-100, resulting three purified fractions of PDP-1, PDP-2 and PDP-3. We found that the monosaccharide composition of PDP-3 was greatly different from that of PDP-1 or PDP-2. In addition, it contained the highest contents of protein, sulfate and uronic acid among the polysaccharides tested. Furthermore, PDP-3 exhibited higher antiproliferative activity against human gastric cancer BGC-823 cells in vitro than crude PDP, PDP-1 or PDP-2. At a concentration of 400 mg/L and an exposure time of 72 h, the inhibition rates for crude PDP, PDP-2 and PDP-3 were 69.36%, 73.65% and 85.78%, respectively.
Keywords: Pholiota dinghuensis Bi; Polysaccharide; Production; Preliminary characterization; Antitumor activity;
Chemical modification of cotton-based natural materials: Products from carboxymethylation by H.N. Cheng; Atanu Biswas (1004-1010).
The processing of cotton generates a number of byproducts, two of which are cotton burr and cottonseed hull. A proximate analysis indicates that they contain about 30–32% cellulose, 17–19% lignin and lesser amounts of protein and oil. They differ in level of hemicellulose with burr containing ∼6% and hull containing ∼20%. Both materials can swell in aqueous NaOH–isopropanol solutions in which state they become susceptible to reaction with monochloroacetic acid. The products of this reaction consist of a water-soluble fraction (observed weight yields ranging from 28% to 55%) and a water-insoluble residue. The water-soluble fractions produce clear films that dissolve slowly in water with viscosities that are somewhat lower than for carboxymethyl products generated from purified cellulose. The products were characterized by NMR and IR and were found to consist mostly of carboxymethyl derivatives of cellulose and hemicellulose.
Keywords: Burr; Hull; Cotton; Carboxymethyl derivatives; Cellulose; Hemicellulose; Xylan;
Preparation of biodegradable nanoporous microspherical aerogel based on alginate by M. Alnaief; M.A. Alzaitoun; C.A. García-González; I. Smirnova (1011-1018).
Supercritical extraction of the solvent from organic gels, like polysaccharides, enables the production of highly porous biodegradable aerogel with a high surface area. The structural properties of the produced aerogel depend mainly on the preparation methods and the composition of the gel phase. This work presents a new method to produce biodegradable microspherical alginate aerogels particles using an emulsion technique. Water in oil (W/O) emulsion was produced by mixing a Na–alginate solution (dispersed phase) with oil (continuous phase) followed by cross-linking the dispersed phase to form the gel particles. The gelation parameters as well as the emulsion process parameters were investigated in order to control the form and the structural properties of the produced alginate aerogel. Alginate aerogel microspherical particles with a high surface area up to 680 m2/g and relatively large pore volume up to 4.0 cm3/g and different mean particle diameters ranging from 25 μm to few hundred microns were produced using the presented method.
Keywords: Spherical aerogel microparticles; Biodegradable nanoporous materials; Supercritical CO2 extraction; Polysaccharides; Alginate aerogels;
Isolation and characterization of exopolysaccharides from seaweed associated bacteria Bacillus licheniformis by Ravindra Pal Singh; Mahendra K. Shukla; Avinash Mishra; Puja Kumari; C.R.K. Reddy; Bhavanath Jha (1019-1026).
In the present study, EPS secreted by the endophytic bacterium Bacillus licheniformis was isolated and characterized. The molecular masses of the EPS were 1540 and 44,565 kDa and 1H NMR, FT-IR and UV–Vis spectral analyses revealed prevalence of characteristic primary amine-group, aromatic-compound, halide and aliphatic alkyl-group in addition to Na, P, Ca, C, O, Cl and S as inferred from EDX analysis. XRD and DSC analysis confirmed the amorphous nature of EPS, showing an average particle size of 24.977 μm (d 0.5) with 191 nm average roughness. The positive ion reflector mode of MALDI TOF-TOF MS exhibited a series of low and high mass peaks corresponding to various oligosaccharides and polysaccharides respectively. Further, GC–MS analysis revealed its four monosaccharide constituents glucose, galactose, mannose and arabinose. The potential heterogeneous properties of EPS as revealed in the present study may be explored in various biotechnological and industrial applications.
Keywords: Exopolysaccharide; MALDI-TOF-TOF MS; Bacillus licheniformis; Seaweed; Atomic force microscopy; X-ray diffraction;
Photoactive antibacterial cotton fabrics treated by 3,3′,4,4′-benzophenonetetracarboxylic dianhydride by Kyung Hwa Hong; Gang Sun (1027-1032).
Photoactive antimicrobial cotton fabrics were produced by chemically incorporating 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BPTCD) onto the fibers through a pad-dry-cure finishing process. An esterification reaction between anhydride group of BPTCD and hydroxyl group of cotton cellulose was promoted by a catalyst under elevated temperature. The structural features and functional properties of the BPTCD treated cotton fabrics were investigated by FTIR, XRD, SEM, TGA and antimicrobial testing. Results showed that the BPTCD treated cotton fabrics display excellent antimicrobial functions under UVA (365 nm) light, and also the treatment does not damage the mechanical properties of the cotton fabric.
Keywords: Photoactive antimicrobial function; Cotton fabrics; Benzophenone; 3,3′,4,4′-Benzophenonetetracarboxylic dianhydride;
A comparative study of Eucalyptus and Pinus radiata pulp fibres as raw materials for production of cellulose nanofibrils by Kristin Syverud; Gary Chinga-Carrasco; Juan Toledo; Pedro G. Toledo (1033-1038).
This work comprises a comparison between Eucalyptus and Pinus radiata pulp fibres, as raw materials for producing nanofibrils. The cellulose nanofibrils were produced mechanically and chemi-mechanically. Series of the fibres were subjected to a TEMPO mediated oxidation to facilitate the homogenization. The contents of carboxyl acids after the pre-treatment indicated a favourable situation for producing nanofibrils using Eucalyptus pulp fibres as raw material. However, films made of P. radiata-based nanofibrils evidenced less shrinkage and higher transparency levels, which were related to a higher fibrillation of the pulp fibres. The energy consumption during homogenization was quantified. The results demonstrated that for a given number of passes through the homogenizator, TEMPO pre-treatment will facilitate the homogeneous fibrillation of a given fibre. This implies that less energy is required for producing nanofibrils with homogeneous sizes.
Keywords: Microfibrillated cellulose (MFC); Computerized image analysis; Microscopy; Metrology; Nanotechnology;
Free radical graft copolymerization of nanofibrillated cellulose with acrylic monomers by Kuisma Littunen; Ulla Hippi; Leena-Sisko Johansson; Monika Österberg; Tekla Tammelin; Janne Laine; Jukka Seppälä (1039-1047).
Nanofibrillated cellulose (NFC) was graft copolymerized in aqueous suspension by a redox-initiated free radical method. Cerium ammonium nitrate was used as initiator. Acrylic monomers used in the grafting were glycidyl methacrylate, ethyl acrylate, methyl methacrylate, butyl acrylate, and 2-hydroxyethyl methacrylate. Effects of monomer type and concentration, initiator concentration and polymerization time on grafting from NFC were studied. Grafting was verified by several chemical characterizations and the synthesis method was found to be both efficient and selective for grafting. Overall, graft yields were higher than those reported in studies with macroscopic cellulose but surprisingly independent of the water solubility of each monomer. All modifications made NFC more hydrophobic, and some also improved its heat resistance. The structures formed by the grafted polymer varied from a thin coating to a matrix completely surrounding the nanofibrils. By performing the grafting in aqueous suspension, the nanofibrillar structure was retained.
Keywords: Nanofibrillated cellulose; Copolymerization; Grafting from; Acrylates; Methacrylates;
In vitro characterization, and in vivo studies of crosslinked lactosaminated carboxymethyl chitosan nanoparticles by Hua Zheng; Xueqiong Zhang; Yihua Yin; Fuliang Xiong; Xiaoyu Gong; Zhongjia Zhu; Bo Lu; Peihu Xu (1048-1053).
The liver targeting and controlled release nanoparticles based on carboxymethyl chitosan derivatives were prepared: firstly, novel thiolated lactosaminated carboxymethyl chitosan (LAC-CMC) was synthesized, its chemical structure was characterized by 1H NMR spectroscopy. Then, glycyrrhizic acid was chosen as model drug and encapsulated within thiolated LAC-CMC nanoparticles through ionic gelification. The crosslinked glycyrrhizic acid-loaded nanoparticles dissociated to release drug in the presence of glutathione (GSH) at a concentration comparable to the intracellular environment, featuring the potential ability of this system for intracellular delivery. Crosslinked nanoparticles modify the tissue distribution profile of the glycyrrhizic acid solution, the kidney excretion rate is reduced and the drug accumulation in the liver is increased. According to these results, the nanoparticles have the potential to be used as drug delivery system with hepatic targeting and controlled release properties.
Keywords: Carboxymethyl chitosan; Galactose group; Thiol; Pharmacokinetic; Biodistribution;
Characteristics of amine-crosslinked wheat straw and its adsorption mechanisms for phosphate and chromium (VI) removal from aqueous solution by Xing Xu; Bao-Yu Gao; Xin Tan; Qin-Yan Yue; Qian-Qian Zhong; Qian Li (1054-1060).
A new adsorbent was prepared from wheat straw (WS) after the crosslinking of amine groups. Its adsorption characteristics and operating parameters for phosphate and chromium (VI) removal were studied. BET surface area, elemental content and zeta potential analysis illustrated the physicochemical change between amine-crosslinked wheat straw (AC-WS) and WS. Significant variation in Raman shift of phosphate/chromium (VI)-loaded AC-WS was observed, and the results suggested the differential adsorption mechanisms for phosphate and chromate (VI) removal by AC-WS. The adverse effect of ionic strength on phosphate and chromate (VI) uptake suggests the possibility of ion exchange mechanisms being active in the adsorption process. The regeneration capacities for phosphate-loaded AC-WS and chromium (VI)-loaded AC-WS were 98.1% and 74.8%, respectively, which validated a potential chemical bonding between chromium (VI) and AC-WS. In addition, the adsorption capacities of AC-WS for phosphate and chromate (VI) were 1.71 and 5.68 mmol/g, respectively, providing a potential application of AC-WS for toxic heavy metals and nutrient substances removal from aqueous solutions.
Keywords: Phosphate; Chromate (VI); Wheat straw; Raman shift; Adsorption;
Optimisation of extraction procedure for black fungus polysaccharides and effect of the polysaccharides on blood lipid and myocardium antioxidant enzymes activities by Ma Jiangwei; Qiao Zengyong; Xiang Xia (1061-1068).
Optimal conditions for the extraction of black fungus polysaccharides were 350 W, 5, 35 min and 90 °C, for ultrasonic power, ratio of water to sample, extraction time and extraction temperature, respectively. Gas chromatography (GC) analysis showed that black fungus polysaccharides contained glucose, xylose, mannose and ribose. Their molar percentages were 6.8%, 34.2%, 50.7% and 8.9%, respectively. FT-IR and NMR analysis showed typical chemical structure of black fungus polysaccharides. In animal experiment, high fat diet feeding for 29 days markedly reduced myocardium and blood antioxidant enzyme activities and enhanced lipid peroxidation level. Administration of black fungus polysaccharides had significantly enhanced myocardium and blood antioxidant enzyme activities and reduced lipid peroxidation level in high fat mice. Our results indicated that black fungus polysaccharides could be beneficial for protection against cardiovascular diseases and its complications.
Keywords: Black fungus polysaccharides; Antitumour activities; Blood lipid; High fat diet; Cardiovascular diseases;
Understanding starch organisation in gluten-free pasta from rice flour by Alessandra Marti; Maria Ambrogina Pagani; Koushik Seetharaman (1069-1074).
Starches extracted from parboiled rice flour and pasta samples produced by two extrusion processes – a conventional method carried out at 50 °C and an extrusion-cooking process at 115 °C – were evaluated by differential scanning calorimetry (DSC) and size exclusion chromatography (SEC) analysis. Molecular changes induced by both pasta-making process and following cooking in boiling water were also investigated using iodine absorption properties of samples expressed as the ratio of absorption to scattering spectra (K/S) and X-ray diffraction. A decrease in polymer chain mobility and iodine binding capacity were observed after pasta-making process. While the characteristic A-type crystalline pattern remained, the exposure to iodine vapor changed the peak intensity of starch samples, especially at 0.97 aw. The higher melting temperature of pasta samples in comparison with parboiled rice flour reflected the decrease in mobility of the amorphous regions detected by K/S spectral analysis. The pasta making-process also affected the molecular size distribution of starch samples. In particular, the elution peak shifted toward lower fraction numbers with increasing extrusion temperature, showing a higher molecular size for starch after the extrusion-cooking. All the differences detected between starch samples according to extrusion conditions were deleted during cooking. Compared to the uncooked samples, starch from cooked pasta showed higher K/S value at all wavelengths, highlighting the increase in mobility of the amorphous region. Moreover, beside the increase in melting temperature, a decrease in endothermic enthalpy was detected, confirming the loss of order observed by X-ray diffraction.
Keywords: Milled rice; Starch; Iodine; Pasta-making;
Cell wall polysaccharides of Chinese Wolfberry (Lycium barbarum): Part 2. Characterisation of arabinogalactan-proteins by Robert J. Redgwell; Delphine Curti; Juankuan Wang; Justyna M. Dobruchowska; Gerrit J. Gerwig; Johannis P. Kamerling; Peter Bucheli (1075-1083).
Arabinogalactan-proteins (AGPs) were isolated from Wolfberry fruit (Lycium barbarum) and purified by anion-exchange chromatography and precipitation with Yariv reagent. Linkage and NMR analysis established the structure of Wolfberry AGP as typical of AGP reported from other sources. The data were consistent with a backbone of (1 → 3)-linked β-d-galactopyranosyl residues, many of which were substituted at O-6 with side chains of mainly 5-substituted α-l-arabinofuranosyl residues, terminated with α-(and β-)l-arabinofuranosyl, α-l-rhamnopyranosyl and β-d-glucopyranosyluronic acid residues. An unusual structural feature of the AGP was the occurrence of 4-substituted β-d-glucopyranosyluronic acid residues in the side chains. The AGP, which had a MW average of between 50 and 60 kDa, displayed heterogeneity with regard to both galactose/arabinose ratio and degree of branching. Protein accounted for ∼6% of the AGP and was rich in hydroxyproline. Evidence for an interaction between some of the AGP and hydrophobic moieties is presented.
Keywords: Wolfberry; Goji berries; Lycium barbarum; Cell wall polysaccharides; Arabinogalactan-proteins;
Structures of acidic polysaccharides from Basella rubra L. and their antiviral effects by Cai-Xia Dong; Kyoko Hayashi; Yusuke Mizukoshi; Jung-Bum Lee; Toshimitsu Hayashi (1084-1092).
In this study four acidic polysaccharides (BRP-1, BRP-2, BPR-3 and BRP-4) were isolated from the aerial part of Basella rubra L. Sugar composition and methylation analyses indicated that both BRP-2 and BRP-4 were native pectins containing dominant homogalacturonan regions and minor ramified rhamnogalacturonan type I regions branched with arabinogalactan type II neutral side chains. They exhibited antiviral activity against herpes simplex virus type 2 by interfering with absorption and penetration of virus to host cells. The most abundant component, BRP-4, showed a high therapeutic efficacy in the mouse model infected intravaginally with herpes simplex virus type 2. Moreover, orally administered BRP-4 resulted in moderate therapeutic efficacy in the mice infected intranasally with influenza A virus, and was shown to stimulate the production of neutralizing antibody and the secretion of mucosal IgA in influenza virus-infected mice.
Keywords: Basella rubra L.; Pectic polysaccharides; Antiviral effect; Herpes simplex virus type 2; Influenza A virus;
Nanofibers based on polysaccharides from the green seaweed Ulva Rigida by Georgios Toskas; Rolf-Dieter Hund; Ezzedine Laourine; Chokri Cherif; Vangelis Smyrniotopoulos; Vassilios Roussis (1093-1102).
The nanofiber ability of an ulvan-rich extract, originated from the low cost biomass of the alga Ulva rigida, has been achieved for the first time via electrospinning. Ulvan-based uniform nanofibers were produced by being blended with poly(vinyl alcohol) (PVA). The nanofibers have an average diameter controllable down to 84 nm and present a highly ordered crystalline structure under transmission electron microscopy (TEM). A new complex fiber is created, which results from ulvan-rich extract and PVA ionic assembly and involves borate esters and divalent cations. The spinnability of this anionic sulfated polysaccharide-rich extract in combination with its interesting biological and physicochemical properties can lead to new biomedical applications such as drug release systems.
Keywords: Polysaccharide ulvan; Nanofibers; Electrospinning; Ulvan/poly(vinyl alcohol) fibers; Crystallinity; Biomaterial;
Evaluation of pretreatment methods in improving the enzymatic saccharification of cellulosic materials by Rishi Gupta; Yogender Pal Khasa; Ramesh Chander Kuhad (1103-1109).
The effectiveness of alkali, acid and chlorite pretreatment of lignocellulosic feedstocks for improving the enzymatic saccharification of cellulose has been evaluated. The feedstocks such as Corncob, Prosopis juliflora and Lantana camara were pretreated with varied concentration of sulfuric acid, sodium hydroxide and sodium chlorite at 121 °C for 15–60 min. Among different methods used, chlorite pretreatment removed maximum lignin with ∼90% (w/w) residual holocellulose content in all the substrates tested. Moreover, irrespective of the substrates used, the chlorite treated substrates were enzymatically saccharified from 86.4% to 92.5% (w/w). While, the alkali treated substrates containing 66.0–76.0% (w/w) holocellulose could be enzymatically saccharified up to 55% (w/w). The acid pretreated substrates were found to contain almost 54–62% (w/w) holocellulose, which on enzymatic hydrolysis could result in 39.5–48% (w/w) saccharification.
Keywords: Cellulosic feedstocks; Pretreatment; Acid; Alkali; Chlorite; Enzymatic hydrolysis;
Hydrophobically modified inulin from alkenyl succinic anhydride in aqueous media by Jordi Morros; Bart Levecke; M. Rosa Infante (1110-1116).
Medium and long chain esters of inulin have been prepared by reaction of alkenyl succinic anhydrides (ASA) such as 2-octen-1-ylsuccinic anhydride (OSA), and 2-dodecen-1-ylsuccinic anhydride (DDSA) in aqueous media and aqueous surfactant media, respectively. The design of the chemical process was based on the study of the influence of several reaction parameters on reaction efficiency (estimated by 1H NMR analysis of the pure end product) and reaction time. Inulin concentration, pH range, temperature, and the addition of a cationic surfactant such as dodecyltrimethylammonium bromide (DTAB) to the reaction media were evaluated for both OSA and DDSA anhydrides.Inulin slurry aqueous systems were found the best reaction media to carry out the esterification with OSA. In case of DDSA, the addition of a cationic surfactant such as DTAB was required to convert 65% of anhydride. Inulin precipitation was prevented at pH range 8.5–9.0 by the addition of DTAB. The reaction time for the synthesis of dodecenyl succinic esters of inulin, estimated as the total time required to consume all DDSA, was reduced dramatically from 24 h (without DTAB) to less than 1 h in presence of cationic surfactant. The use of micellar basic catalysis resulted in a useful way to obtain long chain alkenyl succinic esters of inulin.
Keywords: Inulin; Hydrophobic polysaccharides; Synthesis; Hydrophobic modification; Esterification; Micellar catalysis;
Rheological properties of aqueous solution of new exopolysaccharide secreted by a deep-sea mesophilic bacterium by Hai-ping Li; Wan-guo Hou; Yu-zhong Zhang (1117-1125).
The rheological properties, such as shear flow behavior, thixotropy and viscoelasticity, of aqueous solution of a new type of exopolysaccharide (SM-A87 EPS) secreted by a deep-sea mesophilic bacterium were investigated using shear flow and dynamic rheological measurements. For the SM-A87 EPS solutions, the overlapping concentration C * and crossover concentration C ** were confirmed to be 0.95 g/L and 4.99 g/L respectively by the concentration-dependences of rheological parameters, such as equilibrium viscosity, thixotropic strength, static and dynamic stress, critical shear rate, and storage modulus in the linear viscoelastic region besides the zero-shear viscosity of solutions. At concentrations higher than C *, the solutions exhibited a static stress, a dominant elastic behavior and a stronger absolute positive thixotropic strength. Otherwise, at concentrations lower than C *, no static stress, a dominant viscous behavior and a weaker absolute positive thixotropic strength were exhibited. The SM-A87 EPS solutions may be used as enhanced oil recovery system.
Keywords: Rheology; Oscillatory test; Thixotropy; Creep and recovery test; Critical concentration; SM-A87 EPS;
Chitosan rods reinforced by aligned multiwalled carbon nanotubes via magnetic-field-assistant in situ precipitation by Zhengke Wang; Hui Zhao; Li Fan; Jun Lin; Pengyu Zhuang; Wang Zhang Yuan; Qiaoling Hu; Jing Zhi Sun; Ben Zhong Tang (1126-1132).
Chitosan (CS) rods are a good candidate as temporary mechanical supports in bone regeneration, however the bending strength and bending modulus should be improved to match commercially available devices used for bone fracture internal fixation. Poly(p-amino-phenylacetylene)/multi-walled carbon nanotubes (PaPA/MWCNTs) hybrids with superparamagnetic Fe3O4 nanoparticles (Fe3O4@PaPA/MWCNTs) are applied to reinforce the CS rods. Fe3O4@PaPA/MWCNTs could be uniformly dispersed in CS solution and aligned by an external magnetic field, in the direction parallel to the axis of CS rod. This greatly helped to resist the bending stress, thus the bending strength and modulus of the reinforced CS rods are 124.6 MPa and 5.3 GPa, respectively; which are 34.8% and 29.3% stronger than pure CS rods. As a result, the magnetic-field-assisted in situ precipitation method offers one feasible route for the reinforcement of CS-based devices with nano-scaled one-dimensional additives such as MWCNTs. In addition, CS-based biomaterials containing Fe3O4@PaPA/MWCNTs could obviously promote MG63 cells proliferation, so CS rods modified with Fe3O4@PaPA/MWCNTs are good candidates for bone fracture internal fixation.
Keywords: Chitosan; Multiwalled carbon nanotubes; Poly(p-amino-phenylacetylene); Magnetism; Alignment; Biomaterials;
Cryo-milling of starch granules leads to differential effects on molecular size and conformation by Sushil Dhital; Ashok K. Shrestha; Bernadine M. Flanagan; Jovin Hasjim; Michael J. Gidley (1133-1140).
Milling of starch granules is important for many food applications and involves a combination of mechanical and thermal energy. In order to understand the effects of mechanical force alone, four commercial starches including maize starch (MS), potato starch (PS), and two high amylose maize starches (HAMS) (Gelose 50 and Gelose 80) were cryo-milled for 20 min under the same conditions. The structural and conformational changes of the starches after cryo-milling were evaluated using X-ray diffraction, NMR spectroscopy, IR and Raman spectroscopy, and size exclusion chromatography (SEC). The cryo-milled starches had less crystallinity (15–35%) and 35–50% less ordered structure (double and single helices) than the native starch counterparts. The gelatinisation temperatures of the starches were not significantly altered by cryo-milling, but the gelatinisation enthalpies were significantly reduced in line with the reductions in the amount of double helices. Although, all four starches showed similar extent of degradation of crystalline/ordered structure, SEC results showed a greater degradation of amylopectin molecule in MS and PS than in HAMS. Increased amylose content in starch seemed to reduce the molecular degradation during milling, which is consistent with a role for amylose as a mechanical plasticiser in starch granules. It is concluded that (i) cryo-milling has differential effects on molecular size and conformation depending on starch granule type, and (ii) deterioration of starch crystalline and molecular order by mechanical treatment is not necessarily linked with the reduction in molecular size. The implication from the results is that the mechanical forces acting during cryo-milling are capable of disrupting helical and crystalline structures without breaking covalent bonds of starch molecules.
Keywords: Starch granules; Cryo-milling; Granule; Amylose; Amylopectin; Crystallinity; Molecular size;
In situ SAXS under shear unveils the gelation of aqueous starch suspensions and the impact of added amylose–lipid complexes by J.A. Putseys; C.J. Gommes; P. Van Puyvelde; J.A. Delcour; B. Goderis (1141-1150).
The gelation of heat-treated, aqueous starch suspensions has been explained either in terms of a nanoscopic amylose aggregation or a fractal-like phase separation. These concepts, as well as the supporting experimental evidence, at first sight seem incompatible. The present study exploits rheometry in combination with in situ small angle X-ray scattering and clearly points to creation of finely dispersed, elongated nano-objects when a starch gel is formed in the presence of shear forces. These objects are interpreted as aggregated amylose double helices that provide the system with physical, intermolecular crosslinks. Increasing the aggregate size and concentration increases the gel storage modulus. The gelation process is enhanced in the presence of amylose–lipid complexes as, during heating, short amylose fragments are liberated from these complexes that, upon cooling, promote amylose aggregation and thus gel formation. When shearing is stopped, the aggregates promptly grow and agglomerate into larger fractal objects resulting in an increased gel stiffness. The present work thus suggests that small scale amylose aggregation and the formation of fractal phases have to be considered as subsequent events rather than as mutually exclusive concepts. Finally, it is argued that size-induced polymorphic changes may also contribute to the starch gel stiffness.
Keywords: Starch; Rheology; Small angle X-ray scattering; Gelation;
Physicochemical properties, structure and in vitro digestion of resistant starch from waxy rice starch by Miao-miao Shi; Qun-yu Gao (1151-1157).
Physicochemical properties, structure and in vitro digestibility of resistant starch (RS) from debranched waxy rice starch were investigated. Compared to native starch, all RS products have higher apparent amylose content. All RS products displayed a mixture of B and V-type X-ray diffraction (XRD) pattern while native starch showed A-type X-ray diffraction pattern. With increasing the RS content, the relative crystallinity was increased. RS products had a higher peak melting temperature and enthalpy than that of native starch in differential scanning calorimetry (DSC). The in vitro digestibility of products was decreased. The total carbohydrate digestion products and the average rate of digestion of resistant starches were decreased with increasing RS content.
Keywords: Waxy rice starch; Resistant starch; In vitro digestibility;
Preparation, characterization, in vitro drug release and biological studies of curcumin loaded dextran sulphate–chitosan nanoparticles by A. Anitha; V.G. Deepagan; V.V. Divya Rani; Deepthy Menon; S.V. Nair; R. Jayakumar (1158-1164).
Nanoformulation of curcumin, (a low molecular weight hydrophobic drug) was prepared by using dextran sulphate and chitosan. The developed nanoparticles were characterized by Dynamic Light Scattering measurements (DLS), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD) and Differential Thermal Analysis (DTA). The prepared system showed an average size of 200–220 nm with a zeta potential value of −30 mV and showed ∼74% drug entrapment efficiency. In vitro drug release studies showed a controlled and pH dependent curcumin release over a period of one week. The cytocompatibility of bare nanoparticles was verified by MTT assay; cellular internalisation of curcumin loaded nanoparticles was confirmed by fluorescent imaging and quantified spectrophotometrically, anticancer activity of curcumin loaded nanoparticles was proved by MTT assay and reconfirmed by apoptosis assay (FACS). The results showed preferential killing of cancer cells compared to normal cells by the curcumin-loaded nanoparticles. Thus the developed curcumin loaded nanoformulation could be a promising candidate in cancer therapy.
Keywords: Chitosan; Dextran sulphate; Nanoparticles; Curcumin; Controlled delivery; Cytotoxicity; Cell uptake studies;
Starch retrogradation studied by thermogravimetric analysis (TGA) by Yaoqi Tian; Yin Li; Xueming Xu; Zhengyu Jin (1165-1168).
Thermogravimetric analysis (TGA) as an analytical method to follow retrogradation properties of rice starch was investigated in this study. Our results showed that the bound water content (Mb) of retrograded starch samples was significantly increased with the increasing of storage time. Based on the measurement of bound water, degree of starch retrogradation was determined, and it was consistent with the data obtained from differential scanning calorimetry (DSC). The degree of starch retrogradation determined from the TGA was further employed to study starch recrystallization kinetics, indicating that the recrystallization data were well suited to Avrami theory (R > 0.98). The results also found that the absorbed water content (Ma) was significantly reduced for the retrograded starch (P ≤ 0.05). These findings suggest that the TGA as well as the DSC is able to provide potential data for evaluating starch retrogradation.
Keywords: Thermogravimetric analysis; Bound water; Starch recrystallization; Retrogradation degree; Avrami theory;
Preparation of ethylenediamine-modified magnetic chitosan complex for adsorption of uranyl ions by Jing-song Wang; Rui-ting Peng; Jin-hui Yang; Yao-chi Liu; Xin-jiang Hu (1169-1175).
Ethylenediamine-modified magnetic chitosan (EMMC) complex was developed as a novel magnetic adsorbent for the removal of uranyl ions. XRD spectrum indicated that the magnetic particles were pure Fe3O4 with a spinel structure, and the binding of chitosan did not result in a phase change. IR analysis demonstrated that Fe3O4 particles were successfully bounded by chitosan and more amino groups appeared in the EMMC samples. EMMC was found to be quite efficient to adsorb uranyl ions at pH 2–7. Equilibrium was established within 30 min, and the kinetic experimental data properly correlated with the pseudo-second-order kinetic model, indicating that the chemical sorption is the rate-limiting step. The adsorption data could be best interpreted by the Sips model with a maximum adsorption capacity of 82.83 mg U g−1. The EMMC can be regenerated with high efficiency, suggesting that this adsorbent is satisfactory to reuse uranyl ions.
Keywords: Chitosan; Magnetic; Modified; Uranyl ions; Adsorption;
Phosphorylated polysaccharides. 3. Synthesis of phosphorylated curdlan and its polyelectrolyte behaviour compared with other phosphorylated polysaccharides by Dana M. Suflet; Alina Nicolescu; Irina Popescu; Gabrielle C. Chitanu (1176-1181).
A water-soluble phosphorylated curdlan (PCurd) was synthesized by reaction of curdlan with phosphorous acid in molten urea. The structure of PCurd was investigated by FTIR and NMR spectroscopy and the substitution degree was calculated from potentiometric titration. It was found that the obtained curdlan derivative is a monobasic curdlan phosphate with –HP(O)(OH) groups. The polyelectrolyte behaviour of PCurd, studied by electrochemical methods and by viscometry, was compared with other phosphorylated polysaccharides. A slight influence of the polysaccharide chain flexibility on the polyelectrolyte dissociation was observed.
Keywords: Polysaccharide derivatives; Curdlan; Phosphorylation; Polyelectrolyte behaviour;
Characterization of hyaluronate lyase from Streptococcus pyogenes bacteriophage H4489A by Nermeen S. El-Safory; Guan-Chiun Lee; Cheng-Kang Lee (1182-1191).
Hyaluronate (HA) lyase of Streptococcus pyogenes bacteriophage H4489A, was expressed in Escherichia coli, purified, and characterized. The purified homogeneous preparation of HA lyase had a molecular mass of 40 kDa. The optimum enzymatic activity was achieved at pH ∼ 5.5 and 37 °C, and the enzyme was stable at pH profile from 4 to 7 and temperature range from 25 to 45 °C. The enzymatic activity was vaguely enhanced by Mg2+, slightly inhibited by Ca2+, triton X-100, and Tween 80, strongly inhibited by Zn2+, and completely inhibited by Cu2+, Ni2+, Co2+ and sodium dodecyl sulfate. Kinetic measurements give Michaelis constant of 0.44 mg/ml, maximal velocity of 0.20 μmol ml−1 min−1, and showed that bacteriophage HA lyase degraded the HA efficiently. Light scattering dynamic measurements determined the denaturation temperate of HA lyase of about 46 °C. Circular dichromism and UV–visible absorption spectroscopy estimated the changes in secondary structure of native and denatureated HA lyase.
Keywords: Hyaluronate lyase; Purification; Characterization; Kinetics; Structure;
Preparation and characterizations of a novel deoxycholic acid–O-carboxymethylated chitosan–folic acid conjugates and self-aggregates by Feihu Wang; Dianrui Zhang; Cunxian Duan; Lejiao Jia; Feifei Feng; Yue Liu; Yancai Wang; Leilei Hao; Qiang Zhang (1192-1200).
O-carboxymethylated chitosan (OCMC) was firstly hydrophobically modified with various deoxycholic acid (DOCA) to obtain a novel kind of amphiphilic polymer, and then covalently bound with folic acid (FA) to develop a new potential cancer-targeted drug delivery system. Structural characterizations of the conjugates were investigated using FTIR, 1H NMR and XRD. The physicochemical properties of self-aggregates in aqueous media were studied by 1H NMR, zetasizer, zeta potential, fluorescence spectroscopy, and transmission electron microscopy (TEM). The mean diameter of self-aggregates in PBS solution (pH 7.4) decreased with the degree of substitution (DS) of DOCA increasing. Zeta potential of self-aggregates exhibited near −20 mV in PBS solution (pH 7.4), indicating these nanoparticles were covered with negatively charged OCMC shells. The critical aggregation concentrations (cac) of the conjugates were dependent on the DS of DOCA and were significantly lower than those of low molecular weight surfactants. TEM images demonstrated that the shape of self-aggregates was spherical.
Keywords: O-carboxymethylated chitosan; Deoxycholic acid; Folic acid; Self-aggregates;
A carotenoid-free mutant strain of Sphingomonas paucimobilis ATCC 31461 for the commercial production of gellan by Xuechang Wu; Ou Li; Yamin Chen; Liang Zhu; Chaodong Qian; Yi Teng; Xianglin Tao (1201-1207).
Gellan, an exopolysaccharide produced by Sphingomonas paucimobilis ATCC 31461, is used in the food, pharmaceutical, and other industries. During the fermentative production of gellan, strain ATCC 31461 also accumulates large amounts of yellow carotenoid pigments, thereby increasing processing costs. A carotenoid-free mutant strain of ATCC 31461 was isolated by ethyl methanesulfonate mutagenesis combined with ultraviolet irradiation. A new gellan purification method which reduced the consumption of isopropanol was developed based on this mutant strain. The final gellan production of the mutant strain was 13% higher than that of the parent strain. The glycerate and acetate substituents of gellan produced by the mutant strain were 17% and 65% higher than those produced by gellan from ATCC 31461, respectively. Stability tests suggested that the broth produced by the mutant strain was more stable during storage at room temperature compared with that produced by the parent strain. The mutant strain seems to be an ideal strain for use in the commercial production of gellan.
Keywords: Sphingomonas paucimobilis ATCC 31461; Gellan; Carotenoid-free mutant strain; Purification;
Effect of sodium fluorescein on release characteristics of a macromolecule from calcium alginate gel beads by Pornsak Sriamornsak; Ross A. Kennedy (1208-1212).
This study describes a detailed investigation of swelling and release behavior of a macromolecule from calcium alginate gel (CAG) beads in the presence of a small molecule, sodium fluorescein (SF). Blue dextran (BD) was used as a model macromolecule. The bead diameter was slightly different after soaking in various concentrations of SF although the SF uptake into calcium gel beads is markedly different. The swelling kinetics of CAG beads showed the rapid hydration and reached a maximum within 6 h. It is thought that the effect of SF, which is predominant in the swelling of CAG beads without BD, was hindered by the entanglement of BD. It appeared that the SF concentration has an effect on the BD release; the higher the SF concentration, the higher amount of BD released from the CAG beads. The release from this system basically follows Fick's law (Higuchi's expression). The increase in SF concentration decreased the Higuchi release coefficient. It was observed that the effect of small molecule is quite obvious, since the difference in Higuchi release coefficients of the CAG beads soaked in 1000-μg SF is less than non-soaked beads, about 25%.
Keywords: Alginate; Polysaccharide; Gel beads; Release; Swelling; Macromolecule;