Anionic or Mixed-Charge Copolypeptides with Potent Antibiofilm Activities

Bacterial biofilm-associated infections (BBAIs) and antibiotic resistance constantly threaten human health and life. Herein, we report a series of anionic or mixed-charge copolypeptides that can simultaneously prevent and eradicate Pseudomonas aeruginosa and Staphylococcus aureus biofilms without the development of bacterial resistance. The copolypeptides composed of anionic l-glutamic acid (E), hydrophobic l-phenylalanine (F), and/or cationic l-lysine (K) residues were readily synthesized by ring-opening polymerization and side-chain modifications. Anionic or mixed-charge copolypeptides with moderate hydrophobic F residues exhibited potent antibiofilm activity by a nonbactericidal mechanism. Typically, the inhibition efficacy of P. aeruginosa biofilm formation was 93.6% for F₂₇E₁₀₈ and 96.6% for F₁₅E₆₀K₆₀, respectively. F₂₇E₁₀₈ also exhibited 98.8% and 91.6% eradication efficacies of P. aeruginosa and S. aureus biofilms, respectively. F₂₇E₁₀₈ was able to efficiently bind to the bacterial surface, leading to inhibition of biofilm formation. It can disrupt extracellular polymeric substances of biofilms, modulate bacterial motilities, and bind to bacterial virulence factors, leading to a potent biofilm eradication property. In addition, F₂₇E₁₀₈ exhibited potent in vivo antibacterial effect and reduced inflammatory responses in an acute P. aeruginosa lung infection of a mouse model. This work provides a new nonbactericidal antibiofilm material to efficiently treat BBAIs.