Durable Zwitterionic Hydrogel Coating Reinforced with Chitosan Microspheres for Bone Fracture Fixation Devices

The bone fixation implants in the clinic are prone to inflammation and thrombosis that result in efficacy and patient health risks. This paper introduces chitosan microsphere-enhanced poly(sulfobetaine) (CSM/PSBMA) zwitterionic hydrogel coated on the surface of polylactic acid (PLA) fracture fixation devices through interfacial autocatalytic polymerization and in situ gelation. CSM as a disperse phase improves both the mechanical strength and swelling resistance of the PSBMA matrix of the continuous phase. The CSM/PSBMA hydrogel coating keeps the superhydrophilicity and excellent antifouling properties of the pure PSBMA hydrogel coating. In particular, the CSM/PSBMA hydrogel coating still exhibits good stability after 30 days of PBS immersion, 7 days of PBS shearing, 30 min of PBS ultrasonication, and 30 min of water flushing. Furthermore, the CSM/PSBMA hydrogel-coated PLA implants can alleviate foreign body reaction and accelerate the bone repair in the rat femoral fracture model. This brings a promising path for devising zwitterionic hydrogel coatings for implantable medical devices.