Engineering of Tripeptide-Stabilized Gold Nanoclusters with Inherent Photosensitizing Property for Bioimaging and Photodynamic Therapy

Abstract

Gold nanoclusters have the characteristics of small size, unique optical properties, and eco-friendly synthesis that make them promising candidates for biomedical applications, especially for bioimaging. However, their inherent photochemical activity and therapeutic efficiency are largely unknown and remain unexplored. Here, we report a simple one-step green synthesis procedure for the preparation of two tripeptide-stabilized silver-doped gold nanoclusters (TPGNCs) and their photodynamic therapeutic effect on cancer cells and simultaneous imaging. The custom-designed tripeptides were used for the preparation of silver-doped gold nanoclusters with enhanced fluorescence emission. These TPGNCs exhibited strong red fluorescence with high quantum yield, large Stokes shift, good photostability, and excellent biocompatibility toward normal cells. TPGNCs imparted minimum dark toxicity toward breast cancer cells. These TPGNCs exhibited appreciable photosensitization to generate ROS within the cancer cells triggering loss of mitochondrial membrane potential, leading to apoptotic cell death. The photosensitizing ability of TPGNCs will be a new avenue in the area of photoinduced cancer therapy with negligible side effects.