Effects of gamma and e-beam sterilization on the chemical, mechanical and tribological properties of a novel hydrogel.

Hydrogels are known to possess cartilage-like mechanical and lubrication properties; however, hydrogel sterilization is challenging. Cyborgel(™), a proprietary hydrogel, is intended for use as a cartilage replacement implant. This study evaluated the effect of 30-35 kGy e-beam and gamma radiation on the polymer swell ratio, and the mechanical, chemical and tribological behavior of this hydrogel. Three different formulations were mechanically tested, and material parameters were identified using finite element analysis. FTIR spectroscopy was used to investigate chemical changes. Wear test was carried out for 2 million cycles in bovine serum, followed by 2 million cycles in distilled water. No significant difference was found in the swell ratio, mechanical and tribological properties of control hydrogel samples and those exposed to e-beam or gamma radiation; however, chemical spectra of e-beam sterilized samples revealed minor changes, which were absent in unsterilized and gamma sterilized samples.