Hitherto-Unexplored Photodynamic Therapy of Ag2S and Enhanced Regulation Based on Polydopamine In Vitro and Vivo

Graphical Ag 2 S quantum dots are shown to be capable of killing tumor cells by photodynamic therapy with near-infrared light irradiation, and after modification with polydopamine, they can induce more reactive oxygen species as a result of the regulation of polydopamine, which is demonstrated by experiments. Given their superior penetration depths, photosensitizers with longer absorption wavelengths present broader application prospects in photodynamic therapy (PDT). Herein, Ag 2 S quantum dots were discovered, for the first time, to be capable of killing tumor cells through the photodynamic route by near-infrared light irradiation, which means relatively less excitation of the probe compared with traditional photosensitizers absorbing short wavelengths. On modification with polydopamine (PDA), PDA-Ag 2 S was obtained, which showed outstanding capacity for inducing reactive oxygen species (increased by 1.69 times). With the addition of PDA, Ag 2 S had more opportunities to react with surrounding O 2 , which was demonstrated by typical triplet electron spin resonance (ESR) analysis. Furthermore, the PDT effects of Ag 2 S and PDA-Ag 2 S achieved at longer wavelengths were almost identical to the effects produced at 660 nm, which was proved by studies in vitro. PDA-Ag 2 S showed distinctly better therapeutic effects than Ag 2 S in experiments in vivo, which further validated the enhanced regulatory effect of PDA. Altogether, a new photosensitizer with longer absorption wavelength was developed by using the hitherto-unexplored photodynamic function of Ag 2 S quantum dots, which extended and enhanced the regulatory effect originating from PDA.