Overcoming the Oxygen Dilemma in Photoredox Catalysis: Near-Infrared (NIR) Light-Triggered Peroxynitrite Generation for Antibacterial Applications

The peroxynitrite anion (ONOO-) is closely associated with many diseases and the creation of ONOO- donors is an essential means of understanding its pathophysiological functions. However, it is challenging to develop ONOO- donors due to the difficulties in simultaneously producing highly reactive and short-lived nitric oxide (NO) and superoxide anion (O-2(center dot)). Here, we report a novel strategy for constructing ONOO- donors by combining near-infrared (NIR)-mediated type I photosensitization and photoredox catalysis. The key design using a Nile blue analogue that can serve as both a type I photosensitizer and a metal-free photocatalyst. Intriguingly, the formation of O-2(center dot-) via type I photosensitization avoids oxygen interference and instead activates nitrobenzofurazan-based NO donors via oxygen-tolerant NIR photoredox catalysis. The simultaneous release of O-2(center dot-) and NO leads to ONOO- release, showing both antibacterial and antibiofilm activities.