Dopamine-Chelated Metal–Organic Framework Nanostructure-Based Coatings as a Photodynamic Therapy Amplifier

In recent years, photodynamic therapy (PDT) has been frequently applied in the treatment of bacterial infections. However, reactive oxygen species (ROS) produced by PDT have a short lifetime and operating distance, resulting in a generally inadequate therapeutic efficacy. Herein, we report the fabrication of a nanostructure-based PDT amplifier composite coating via self-assembly between MIL-96 (Ga) particles, dopamine (DA), and methylene blue (MB). The coatings exhibited a bacterial inhibition rate of over 99% after 5 min of red light exposure. Based on the chelation between Ga3+ and DA, these metal–organic frameworks (MOFs) can stably adhere to surfaces of various substrates, such as polyurethane (PU), nonwoven, and titanium (Ti) alloy. The Ga-MOF can slowly and consistently release Ga3+, avoiding the rapid hydration of Ga3+. Furthermore, after loading MB, the nanostructure-based Ga-MOF composite coating exhibits PDT capability triggered by red light (660 nm). By blocking of bacterial iron metabolism through Ga3+, the coating disrupts bacterial antioxidant systems and significantly enhances PDT efficacy. In addition, the iron block antibacterial therapy (IBAT)/PDT coating also shows excellent in vitro biocompatibility. This work provides an innovative antibacterial strategy for medical device surfaces.