Targeted photodynamic therapy using a water-soluble aggregation-Induced emission photosensitizer activated by an acidic tumor microenvironment

Aggregation-induced emission (AIE)-active photosensitizers (PSs) are considered as a kind of promising functionalized materials for photodynamic therapy of tumor. Improving the targeted ability of water-soluble AIE PSs capable of minimizing the inadvertent activation is of great significance but remains a challenging task. Herein, we report an effective synthetic strategy for preparing water-soluble AIE photosensitizer (termed WAPS) with high targeted capacity mediated by supramolecular assembly. The pillar[5]arene (WP5) can bind WAPS through host–guest interaction in neutral aqueous solution, resulting in a large change in donor–acceptor structure of WAPS and a weak photodynamic activity. Notably, the binding interface of WAPS and WP5 shifts under an acidic environment (pH 5.2), permitting the reversible control of singlet oxygen (1O2) generation and photodynamic targeting of cancer cells in cultured and tumor-bearing mice. This work provides an ingenious way to prepare water-soluble AIE PS with high selectivity for tumor treatment.