Contact-killing antibacterial mechanisms of polycationic coatings: A review

Antibacterial coatings play an important role in combating bacterial infections. Compared with release-killing strategy, contact-killing gains a strong advantage in avoiding antibiotic resistance through utilization of physical approaches, such as electrostatic action and nanostructures to damage bacterial cell walls. Considerable amount of attention has been paid to polycationic coatings utilized to eradicate pathogenic bacteria upon contact. However, the related contact-killing mechanisms have not been systematically summarized. Herein, the essential antibacterial mechanisms of polycationic coatings for contact-killing were reviewed, including penetration, ion-exchange, and anion sponge. The involved key factors were also discussed, including positive charge, hydrophobic/hydrophilic composition, coulombic force, counter anion, and surface structure. In addition, bacterial responses to polycationic coatings were introduced, such as bacterial conditions and self-rescue. This review will benefit the rational design of efficient antibacterial surfaces via contact-killing strategy for fighting bacterial infections.