Antimicrobial/antifouling polycarbonate coatings: Role of block copolymer architecture

The high prevalence of catheter-associated infections accounts for more than 3 billion dollars annually in hospitals, and antimicrobial polymer coatings on catheter surface may serve as an attractive weapon to mitigate infections. Triblock polycarbonate polymers consisting of three critical components including antifouling poly(ethylene glycol) (PEG), antimicrobial cationic polycarbonate, and a tethering or adhesive functional block were synthesized. In this study, the block topology or placement of the distinctive blocks was varied and their efficacy as antimicrobial and antifouling agents investigated on coated surfaces. The individual blocks were designed to have comparable lengths that were subsequently grafted onto a prefunctionalized catheter surface through covalent bonding under mild conditions. The anchoring/adhesive functional moiety based on a maleimide functional carbonate was positioned at either the center or end of the polymer block and subsequently tethered to the surface via Michael addition chemistry. The placement of the adhesive block was investigated in terms of its effect on antimicrobial and antifouling properties. The surface coated with the polymer containing the center-positioned tethering block (2.4k-V) was unable to prevent bacteria fouling, even though demonstrated higher bacteria killing efficacy in solution as compared to the surface coated with the polymer containing the end-positioned tethering block (2.4k-S). In contrast, the 2.4k-S coating resisted fouling of both Gram-positive S. aureus and Gram-negative E. coli effectively under conditions that simulate the device lifetime (1 week). Moreover, the coating prevented protein fouling and platelet adhesion without inducing significant hemolysis. Consequently, this antibacterial and antifouling polymer coating is an interesting candidate to prevent catheter-associated bloodstream infections.