Co-assembly of zwitterionic and cationic polymers for antibacterial and antithrombotic surfaces via weak...

Implantable medical device-associated infections can significantly increase the mortality rate and medical costs of patients. The construction of coatings with antibacterial and antifouling functions is an effective way to prevent bacterial infections. In this study, we construct an antimicrobial coating by means of layer-by-layer self-assembly using the zwitterionic polymer PA (poly(2-(methacryloyloxy) ethyl) dimethyl-(3-sulfopropyl) ammonium hydroxide and the cationic polymer PQ (polyquaternium). Unlike conventional strong electrostatic system of anion-cationic polymers, zwitterionic polymers can engage in weaker electrostatic interactions with cationic polymers. This "weak electrostatic interaction" provides cationic groups with more "freedom", thereby preserving their capacity to disrupt bacterial membranes. The resulting coating exhibits exceptional antibacterial performance, achieving a bactericidal efficiency exceeding 97.6% against S. aureus. Furthermore, such weak electrostatic interaction can also help retain the combination of charged groups and water molecules, facilitating the formation of a dense "hydrated protective layer" that endows the coating with outstanding antifouling performance and significantly reduces the formation of blood clots. In absorbable suture and intravascular catheter models, the coating demonstrates excellent bactericidal and antithrombotic properties. These findings not only offer a versatile surface modification strategy for implantable medical devices but also enhances the understanding of the interaction between zwitterionic polymers and cationic polymers.