Sergey Borisov and his team at Graz University of Technology in Austria have developed strongly phosphorescent porphyrin complexes of iridium(III) that can act as optical oxygen-sensing materials. The amount of oxygen in living tissues accurately is a valuable tool in biomedical research, the team says, because it allows scientists to follow metabolic processes, spot anomalies and even detect diseased tissues. The use of these metal complexes highlights just how well they absorb and emit light, which makes them particularly good materials for optical sensor applications. While iridium complexes have been little studied previously, they do have the advantage of a broader absorption that is also shifted to lower wavelengths compared to platinum and palladium. The team adds that their sensor complexes can be tuned for particular applications. They demonstrated proof of principle with a water-soluble oxygen probe stained using bovine serum albumin and a trace oxygen sensor that is coupled to amino-modified silica gel.
An optical sense of oxygen