Enhancing the Efficacy of Photodynamic Therapy through a Porphyrin/POSS Alternating Copolymer.

Aggregation-induced quenching (AIQ) of photosensitizers greatly reduces the quantum yield of singlet oxygen generation and mitigates the efficacy of photodynamic therapy (PDT). We have prepared an alternating copolymer starting from 4-vinylbenzyl-terminated tetraphenylporphyrin (VBTPP) and maleimide isobutyl polyhedral oligomeric silsesquioxane (MIPOSS), via alternating reversible addition-fragmentation chain transfer (RAFT) polymerization. Porphyrin and POSS are installed on the amphiphilic block copolymers backbone in an alternating fashion and POSS completely inhibits the aggregation of porphyrin units via stacking. The amphiphilic block copolymer can self-assemble into nanoparticles and its application in PDT treatment was tested. These porphyrin-containing polymeric nanoparticles display high photochemical yield and phototoxicity in vitro and in vivo, providing a novel strategy to enhance the PDT efficacy.