<scp>pH</scp>‐sensitive size/surface charge‐adaptive quaternary ammonium salt copolymer micelles for antibiofilm activity against <scp><i>Staphylococcus aureus</i></scp>

Abstract The low penetration of antibacterial materials within biofilms results in a 1000‐fold decrease in bactericidal efficiency, complicating the complete removal of biofilms and potentially leading to persistent and recurrent bacterial infections that significantly impact human health. In this study, we present a multifunctional pH‐responsive antibacterial material based on random copolymers poly(dimethylaminoethyl methacrylate decyl ammonium bromide‐ co ‐polyethylene glycol methacrylate) copolymer (PQACs 10 ‐ co ‐PEGMA 10 ). The PQACs 10 ‐ co ‐PEGMA 10 copolymers could self‐assemble into micelles in selective solvent water. With the stealth function of polyethylene glycol (PEG), the PQACs 10 ‐ co ‐PEGMA 10 micelles can rapidly penetrate biofilms in a physiological environment and exhibit excellent antibacterial activity by exposing the quaternary ammonium salt (QACs) in an acidic microenvironment to eliminate biofilm. Furthermore, PQACs 10 ‐ co ‐PEGMA 10 micelles were applied as coatings using a dropwise method. The PEG chain formed hydration layer and the QACs chain for sterilization can hinders bacterial adhesion and proliferation, thereby preventing biofilm formation. The results show that the minimal inhibit concentration values and minimum biofilm eradication concentrations of the PQACs 10 ‐ co ‐PEGMA 10 micelles against Gram‐positive Staphylococcus aureus were 64 and 128 μg/mL, respectively. The antifouling and antibacterial rates of micelle coating against S. aureus were more than 99.99%. Taken together, the pH‐responsive PQACs 10 ‐ co ‐PEGMA 10 micelles demonstrate a good ability to clear and prevent biofilms, holding promise for complete biofilm removal and a reduction in biofilm‐related infections.