Porphyrin-assembled nano-photosensitizer with near-infrared response for highly efficient type I photodynamic and photothermal therapy
Type II photosensitizers (PSs) activated by 660 nm light suffer from high oxygen consumption, limiting efficacy in hypoxic microenvironments. Type I PSs triggered by 808 nm near-infrared (NIR) light enable electron transfer to generate superoxide anions (O2•−) with lower oxygen dependence. However, developing type I PSs remains challenging due to the low energy of NIR light and the intrinsic preference for type II processes under matched energy levels. Here, co-assembly of 5,10,15,20-tetrakis-(4-aminophenyl)-porphyrin (TAPP) with N-carbobenzyloxy-L-leucine (Cbz-Leu) yields a supramolecular nano-PS (TAPP@Cbz-Leu). Under 808 nm irradiation, TAPP@Cbz-Leu significantly produces O2•−. Noncovalent tight binding between TAPP and Cbz-Leu enhances photoinduced electron transfer from Cbz-Leu to triplet TAPP, generating TAPP•− and promoting O2•− formation. TAPP@Cbz-Leu also exhibits excellent photothermal properties under 808 nm irradiation, with a photothermal conversion efficiency of 32.7%. In vivo studies demonstrate effective antibacterial activity against MRSA-infected wound models and accelerated wound healing. This work represents the first example of converting a type II PS into a type I PS via a simple co-assembly strategy, offering a new paradigm for NIR-triggered supramolecular type I photosensitizers.