Stereoisomeric engineering of aggregation-induced emission photosensitizers towards fungal killing

Fungal infections are often major causes of disease in immune compromised patients and photodynamic therapy offers and attractive treatment. Here, the authors develop stereoisomeric photosensitizers via supramolecular assembly and demonstrate aggregation-induced photodynamic action against fungi. Fungal infection poses and increased risk to human health. Photodynamic therapy (PDT) as an alternative antifungal approach garners much interest due to its minimal side effects and negligible antifungal drug resistance. Herein, we develop stereoisomeric photosensitizers ((Z)- and (E)-TPE-EPy) by harnessing different spatial configurations of one molecule. They possess aggregation-induced emission characteristics and ROS, viz. O-1(2) and O-2(-center dot) generation capabilities that enable image-guided PDT. Also, the cationization of the photosensitizers realizes the targeting of fungal mitochondria for antifungal PDT killing. Particularly, stereoisomeric engineering assisted by supramolecular assembly leads to enhanced fluorescence intensity and ROS generation efficiency of the stereoisomers due to the excited state energy flow from nonradiative decay to the fluorescence pathway and intersystem (ISC) process. As a result, the supramolecular assemblies based on (Z)- and (E)-TPE-EPy show dramatically lowered dark toxicity without sacrificing their significant phototoxicity in the photodynamic antifungal experiments. This study is a demonstration of stereoisomeric engineering of aggregation-induced emission photosensitizers based on (Z)- and (E)-configurations.

Automated summary

This study demonstrates the development of stereoisomeric photosensitizers using supramolecular assembly and their effectiveness in photodynamic therapy against fungal infections. It showcases the potential and importance of aggregation-induced photodynamic action.