Vancomycin modified graphene oxide as carriers to load phthalocyanine for synergistic phototherapy of vancomycin-resistant bacteria

Overuse of antibiotics has led to the emergency of vancomycin-resistant Enterococcus (VRE), considered one of the leading causes of severe diseases and even death. The phototherapy strategy of combined photothermal therapy (PTT) and photodynamic therapy (PDT) has achieved considerable attention since it could effectively enhance synergistic efficacy and avoid new drug resistance. In this paper, a kind of hybrid nanocomposite was fabricated and applied in the phototherapy-based combination strategy against VRE pathogens, in which graphene oxide (GO) not only covalent conjugated with vancomycin (Van) but also loaded photosensitizer phthalocyanine (Pc) via pi-pi stacking interaction. Outstanding PTT and PDT effects were observed in the as-prepared nanocomposite (GO@Van@Pc), giving almost 2-3 logs of bacterial reduction in vitro. Similar data were also obtained when GO@Van@Pc was used to treat VRE-infected BALB/C mice, exhibiting obvious infection regression and accelerated wound healing with negligible damage to normal cells and major organs. Therefore, the as-prepared GO@Van@ Pc integrating PTT and PDT has great potential in the phototherapy of drug-resistant pathogens.