Photolysis of methicillin-resistant Staphylococcus aureus using Cu-doped carbon spheres

Developing alternative treatment strategies against methicillin-resistant Staphylococcus aureus (MRSA) infections is a challenge but could have many potential applications. In this paper, we developed a novel approach to eradicate MRSA through photolysis of the staphyloxanthin (STX) pigment found within the MRSA membranes and intracellular molecules (e.g. genomic DNA and proteins). Specifically, Cu-doped hollow carbon spheres (Cu-HCSs) were employed here for antibacterial treatment. Unlike blue-light treatment alone, which only "injured" MRSA, Cu-HCSs in combination with blue-light irradiation promoted photobleaching of STX to destroy membrane integrity, and further caused oxidative cleavage of DNA and proteins inside MRSA, working as a nuclease/protease mimicking nanozyme, resulting in efficient killing of MRSA. Mechanism analysis showed that the cleavage activity resulted from the elevated levels of singlet oxygen (1O2) generated from the photosensitized oxidation of Cu-HCSs. Further animal studies demonstrated that the photolysis activity of Cu-HCSs could be used to treat subcutaneous abscesses and bacteremia caused by MRSA. Thus, this photolysis-based antibacterial platform may help avoid bacterial resistance, with the potential to kill multidrug resistant bacteria.