A GSH-responsive Ru(II) complex: Mitochondria-targeted cell imaging and photodynamic therapy.

Glutathione (GSH) is a critical intracellular antioxidant. In cancer cells, the overexpression of GSH scavenges reactive oxygen species (ROS) produced during photodynamic therapy (PDT), thereby compromising therapeutic efficacy. To address this limitation, we designed and synthesized a GSH-responsive Ru(II) complex (Ru(phen)2(bpy-nap)(PF6)2) for simultaneous GSH imaging and enhanced PDT. This probe exhibits excellent GSH-sensing performance, including a significant phosphorescence turn-on response and a low detection limit (0.05 μM). It was successfully employed for visualizing both endogenous and exogenous GSH in HepG2 cells by imaging. Furthermore, under 450 nm bandpass xenon lamp irradiation, it demonstrates remarkable photostability and generates both Type I and Type II ROS, leading to potent phototoxicity against cancer cells. Notably, the probe selectively localizes in mitochondria, further enhancing its therapeutic potential. Given these advantages, Ru(phen)2(bpy-nap)(PF6)2 represents a promising dual-functional phosphorescence probe for GSH detection and PDT applications.