Enhancing the ROS Generation via Polypyridine for Bacteria Imaging and Photodynamic Therapy
Bacterial infections impose a substantial clinical burden, with antibiotic resistance diminishing the efficacy of conventional therapeutics. Photodynamic therapy (PDT) offers a noninvasive antibacterial modality, yet existing photosensitizers suffer from insufficient free radical generation and limited functionality. This study reports a π-conjugated viologen derivative, 3TPhDPyMeOTf, incorporating multiple thiophene units to extend visible-light absorption and multiple pyridine structures to promote radical formation. Experimental and theoretical analyses confirm broad-spectrum antibacterial activity in vitro and in vivo. At 0.5 μM, the photosensitizer achieves over 60% eradication of Escherichia coli, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus (MRSA). In an MRSA-infected wound model, it accelerates healing with 93% efficacy within 12 days, significantly exceeding controls. The compound also exhibits excellent bacterial membrane staining, enabling bacterial imaging. This molecular design addresses the dual bottlenecks of weak visible-light absorption and inefficient radical generation in viologen-based photosensitizers, providing a promising strategy for potent PDT agents.