Co-assembly of antimicrobial polypeptoids/carbon dots for internal-external cooperated sterilization

Bacterial infections have emerged as a significant global public health challenge that requires urgent attention. In the research of popular antimicrobial agents, antimicrobial peptide mimics with good properties have the disadvantage of high toxicity, and nanomaterials with metal-doped carbon dots as the most representative have the problems of easy agglomeration and insufficient bactericidal effect. Herein, combined therapeutic strategy was proposed to reach the best compromise and sterilization effects. We employed an electrostatic co-assembly strategy to combine nanomaterials iron-doped carbon dots (Fe-CDs) and antimicrobial polypeptoids Poly(N-allylglycine) modified with thiol-terminated amines (PNAG₆₆-NH₂), resulting in the creation of the antimicrobial composite Fe-CDs-PNAG₆₆-NH₂. Through electrostatic adsorption, the composite disrupts the electrostatic environment of the bacterial outer membrane, alters its permeability, and triggers an increase in intracellular reactive oxygen species (ROS) to rapidly kill 99.999% of Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) within 10 min. It exhibited negligible cytotoxicity to normal cells. Furthermore, in vivo experiments demonstrated that Fe-CDs-PNAG₆₆-NH₂ accelerated the healing of infected wounds, reduced inflammation. The present study demonstrates that the efficient bactericidal properties of the complexes are triggered by the synergistic action of nanomaterials and antimicrobial polypeptoids, which provides a new strategy to achieve safe and efficient broad-spectrum bactericidal activity in antimicrobial aspects.