Charge-Switchable Polymeric Coating Kills Bacteria and Prevents Biofilm Formation In vivo

Preventing bacterial biofilm formation on medical devices and implants in vivo still remains a daunting task. Current antibacterial coatings to combat implant-associated infections are generally composed of toxic metals or nondegradable polymers and involve multistep surface modifications. Here, we present a charge-switchable antibacterial and antibiofilm coating based on water-insoluble cationic hydrophobic polymers that are soluble in organic solvents and can be noncovalently coated onto different surfaces. Toward this, a library of quaternary polyethylenimine (QPEI) polymers with an amide or ester group in their pendant alkyl chain was developed. These QPEIs are shown to hydrolyze from active cationic to nontoxic zwitterionic polymers under acidic or enzymatic conditions. Notably, polymers with both zwitterionic and cationic groups, obtained upon partial hydrolysis of QPEIs, are shown to retain their antibacterial activity with much lower toxicity toward mammalian cells. Furthermore, the zwitterionic p...