Porphyrin as\nPhotosensitizers for Controlling Marine\nBiodegradation of Polymer Composites

Biodegradable polymer–photosensitizer composites\nwere developed,\nwhich is suppressed biodegradation due to bactericidal activity under\nlight irradiation but proceeds under dark conditions. The composites\nexhibited antibacterial activity under light irradiation, which was\nattributed to the generation of singlet oxygen (<sup>1</sup>O<sub>2</sub>). Biodegradation was evaluated in seawater using the biochemical\noxygen demand (BOD) method. In the dark, the composite and base polymer\nbiodegraded to a similar degree. However, under light irradiation,\nthe biodegradation of the composite was suppressed. In field tests,\nthe rate of volume reduction of the composites decreased under illumination.\nThe main cause of the suppression of biodegradation is suggested to\nbe due to the decrease in the number of bacteria on the surface of\nthe material and the inactivation of exoenzymes. The findings are\nexpected to contribute to the development of biodegradable polymers\nthat do not biodegrade during use but only when disposed of in the\nenvironment, thereby achieving on-demand degradation.