Acetic acid induces osmotic imbalances in drug-resistant bacteria synergistically enhancing cobalt-doped carbon quantum dots bactericidal efficiency

When pathogenic bacteria colonise a wound, they can create an alkaline ecological niche which selects for their survival by creating an inflammatory environment which restricts healthy wound healing to proceed. To aid healing, wound acidification has been exploited to disrupt this process and stimulate fibroblast growth, increase wound oxygen concentrations, minimise proteolytic activity and re-stimulate the host immune system. Within this study, we have developed unique cobalt doped carbon quantum dot nanoparticles which work together with mild acetic acid creating a potent synergistic antimicrobial therapy. The acidic environment alters the osmotic balance of microorganisms forcing them to swell and speed up the internalisation of the ultra-small particles. The particles hyperpolarise the bacterial membranes and generate damaging peroxidase species resulting in cellular lysis. In mice, cobalt doped carbon quantum dots remove MRSA infection while allowing wounds to heal at equivalent rates to uninfected wounds. This work demonstrates how synergistic antimicrobial treatment strategies can be successfully used to combat antimicrobial resistant infections.