Scheme 1. Scheme depicts the procedure for synthesizing Au@BSA-CuPpIX and the mechanism of eliminating the core pathogenic bacteria in CRC in order to boost the therapeutic effect of SDT together with reduced skin photosensitivity. (a) Schematic description of the Au@BSA-CuPpIX synthesizing process. (b) Au@BSA-CuPpIX reduces the level of apoptosis-inhibiting proteins by inhibiting F. nucleatum to advance the efficacy of SDT for orthotopic CRC with lung metastasis restriction. (c) Au@BSA-CuPpIX effectively reduces the phototoxicity of metalloporphyrin accumulated in the skin during tumor treatment, preventing severe inflammation and damage to the skin.