Acceptor engineering of metallacycles with high phototoxicity indices for safe and effective photodynamic therapy.

Abstract

Although metallacycle-based photosensitizers have attracted increasing attention in biomedicine, their clinical application has been hindered by their inherent dark toxicity and unsatisfactory phototherapeutic efficiency. Herein, we employ a π-expansion strategy for ruthenium acceptors to develop a series of Ru(ii) metallacycles (Ru1-Ru4), while simultaneously reducing dark toxicity and enhancing phototoxicity, thus obtaining a high phototoxicity index (PI). These metallacycles enable deep-tissue (∼7 mm) fluorescence imaging and reactive oxygen species (ROS) production and exhibit remarkable anti-tumor activity even under hypoxic conditions. Notably, Ru4 has the lowest dark toxicity, highest ROS generation ability and an optimal PI (∼146). Theoretical calculations verify that Ru4 exhibits the largest steric bulk and the lowest singlet-triplet energy gap (ΔE ST, 0.62 eV). In vivo studies confirm that Ru4 allows for effective and safe phototherapy against A549 tumors. This work thus is expected to open a new avenue for the design of high-performance metal-based photosensitizers for potential clinical applications.

• Authors: Chonglu Li, Le Tu, Jingfang Yang, Chang Liu, Yuling Xu, Junrong Li, Wei Tuo, Bogdan Olenyuk, Yan Sun, Peter J Stang, Yao Sun
• Journal: Chemical science (Chem Sci) Vol. 14 Issue 11 Pg. 2901-2909 (Mar 15 2023) ISSN: 2041-6520 [Print] England
• PMID: 36937588 (Publication Type: Journal Article)
• Copyright: This journal is © The Royal Society of Chemistry.