Ir(Ⅲ) complexes specifically recognize cancer cells by photoluminescence measurements of glutathione and pH

Compared to normal cells, cancer cells possess elevated levels of glutathione (GSH) and are characterized by a more acidic microenvironment. Taking advantage of this property, a GSH-sensitive probe Ir-dt, and a pH-sensitive probe Ir-OH, were designed and synthesized in this work. Due to the reducibility of GSH, the diketone part of the Ir-dt ligand was first changed to OH. After that, OH was oxidized to COOH by oxygen in the air due to its instability, resulting in enhanced photoluminescence (PL) of the solution after the reaction with GSH. Ir-dt had good specificity in response to GSH, and was not interfered by thiols such as Hcy and Cys. With the change of acid-base environment, the OH group in Ir-OH easily gained or lost protons, which led to the change of electron cloud distribution in the molecule. When the pH of the solution changed from acidic to alkaline, the PL color of the solution shifted progressively from red to green. Based on the changes of PL wavelength and intensity before and after the reaction, a ratio PL detection method for GSH and pH was designed. The PL of their mixed solutions was green when the GSH content was low and the pH was alkaline, and gradually became red with the GSH content increases and the pH decreases. After the verification of cell experiments, this method was expected to realize the specific detection of cancer cells.