A new water-soluble photocatalyst for singlet oxygen generation is presented. Its absorption extends to the red part of the spectrum, showing activity up to irradiation at 660 nm. Its efficiency has been compared to that of a commercial analogue (Rose Bengal) for the oxidation of L-methionine. The quantitative and selective oxidation was promising enough to encapsulate the photocatalyst in polymersomes. The singlet oxygen generated in this way can diffuse and remain active for the oxidation of L-methionine outside the polymeric compartment. These results made us consider the use of these polymersomes for antimicrobial applications. E. coli colonies were subjected to oxidative stress using the photocatalyst-polymersome conjugates and nearly all the colonies were damaged upon extensive irradiation while under the same red LED light irradiation, liquid cultures in the absence of porphyrin or porphyrin-loaded polymersomes were unharmed.
Keywords: Methionine; Photosensitizer; Polymersomes; Porphyrin; Singlet oxygen.