The widespread use of antibiotics has caused the rapid emergence of antibiotic-resistant
bacterial strains and antibiotic resistance genes in the past few decades. Photocatalytic
inactivation, a promising approach for the killing of pathogens, efficiently avoids
the problems induced by antimicrobial drugs. However, traditional photocatalysts usually
have some disadvantages, such as high costs of raw materials, ultraviolet ray excitation,
and potential leaching of toxic metals. Here, a metal-free heterojunction photocatalyst,
denoted as CQDs/g-C3N4, is synthesized through incorporating carbon quantum dots (CQDs)
on graphitic carbon nitride (g-C3N4), which significantly enhances photocatalytic
inactivation of Staphylococcus aureus (S. aureus) compared with pure g-C3N4 in vitro.
CQDs/g-C3N4 causes a rapid increase of intracellular reactive oxygen species levels
and destruction of cell membranes under visible light, eventually leading to death
of bacteria. The efficacy of CQDs/g-C3N4 is further examined by a mouse cutaneous
infection model of S. aureus. CQDs/g-C3N4 markedly reduces the bacterial loads and
prompts lesion recovery in mice, as compared with g-C3N4-treated group. In vivo and
in vitro toxicity analyses show that the side effects of CQDs/g-C3N4 are negligible.
Considering the efficient photocatalytic inactivation and nontoxicity of CQDs/g-C3N4,
this visible-light-driven photocatalyst paves a brand new avenue for the treatment
of S. aureus infection.