An Oxygen-Independent Photodynamic Therapy Nanoplatform for Combating Anaerobic Infection

Anaerobic bacteria infections remain a major threat to humans. Oxidative stress mediated by photodynamic therapy (PDT) has shown great potential in antimicrobial applications, attributing to its controllability and non-resistance. However, the hypoxic infection microenvironment severely compromises the therapeutic outcomes. Here, we designed a nanoplatform comprising the initiator of alkyl radicals(R·), 2,2′-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (AIPH) -loaded oxidized mesoporous carbon nanoparticles (OMCN) and then coated with a phase change material (PCM) nanoparticle for oxygen-independent PDT to combat anaerobic infections. Upon near-infrared (NIR) light irradiation, OMCN mediates the generation of heat to melt PCM, which could trigger the liberation and decomposition of AIPH to produce R· and further induce the oxidative damage to bacteria, and cooperate with optothermal effects to eradicate anaerobic bacteria. As results, the nanoplatform displays strong synergistic antibacterial behavior, effectively eliminating anaerobic Propionibacterium acnes(P. acnes) in vitro under hypoxic conditions, and successfully treating P. acnes-infected cutaneous abscess in mice models. Moreover, no distinct toxicity appears through the entire course of treatment. Collectively, this light-activated oxygen-independent PDT offers a novel approach to combat anaerobic bacteria infections.