The formation of aggregate always limits the reactive oxygen species generation efficacy of photosensitizer (PS). Developing PS with high performance under physiological environment is essential for the widespread application of photodynamic therapy (PDT) in clinic. In this work, platinum-based photosensitizers with adaptive confinement effect are designed and prepared for enhanced tumor PDT treatments. By introducing pyridinothiadiazole with sp 2 nitrogen hybridization and strong electron-withdrawing properties as the ligand, spin-orbit coupling (SOC) could be efficiently enhanced, accelerati...