(668a) Durability and Lubricity of Photografted Zwitterionic Hydrogel Coatings

Zwitterionic hydrogel coatings have shown promise in inhibiting the foreign body response and scarring surrounding medical implants. By employing simultaneous photografting and photopolymerization, a durable crosslinked coating can be produced which is covalently attached to the desired surface. With incorporation of adequate amounts of crosslinker, zwitterionic monomer, and photoinitiator, the hydrated coating remains attached and viable under significant normal forces (up to 15 N) and bending (up to a 2mm diameter). Failure of loosely crosslinked films due to normal force only begins to occur after drying in ambient conditions for 80 minutes or 60 minutes under bending forces. Successful coatings have been formed with both sulfobetaine methacrylate (SBMA) and carboxybetaine methacrylate (CBMA) zwitterionic monomers, using polyethylene glycol dimethacrylate (PEGDMA) as non-zwitterionic crosslinker. The crosslinker ratio allows for tuning of the hydrogel properties, including compressive modulus and equilibrium swelling. Additionally, zwitterionic coatings impart significant lubricity with reductions of up to 95% in the coefficient of friction relative to uncoated polydimethylsiloxane (PDMS). These results illustrate the durability and tunability of photografted/photopolymerized zwitterionic hydrogels for use as biomedical implant coatings.