Multi-functional zwitterionic coating for silicone-based biomedical devices

Bacteria associated infection, blood coagulation, inflammation, tissue adhesion and weak surface lubrication are major issues challenging the biomedical application (especially long-term indwelling) of silicone rubber (SR) based catheters. Here, we report a new strategy to simultaneously address these issues by fabricating a simple zwitterionic/active ester copolymer coating via a facile two-step process. Take advantage of well-controlled reversible addition–fragmentation chain transfer polymerization (RAFT), well designed zwitterionic sulfobetaine/active ester block copolymers (pSBMA-b-pNHSMA) with different zwitterionic segment lengths (repeat units of 20 and 90) were prepared. Stable polymeric coatings were constructed on SR substrates upon covalent bonding between the active ester pendant from the copolymer and the amino residues on the activated SR surface. Robust relationship between the composition of block polymers and the ability to combat biofilm formation, blood coagulation, inflammation, cell/tissue adhesion, as well as to improve the lubricating properties of SR substrates, has been systematically established. Results showed that the polymer containing a zwitterionic sulfobetaine segment of 20 repeat units can significantly inhibit protein adsorption, platelet adhesion, bacterial adhesion, and cell adhesion for short-term (within 24 h), while the longer zwitterionic sulfobetaine segment (90 repeat units) can endow long-term antibacterial (no biofilm formation at day 21), anti-cell/tissue-adhesion (no cell adhesion at day 7), anti-inflammation (7 days) properties, as well as significantly improved surface lubrication to SR substrates. In the meantime, the surface modification didn’t compromise the mechanical property of SR substrates. The facile yet efficient surface modification process can be easily applied to SR based urinary catheters. This strategy may inspire diverse surface functionalization of SR based biomedical devices for a wide range of biomedical applications.