Synthesis and performance of novel hydrogels coatings for implantable glucose sensors

Novel hydrogel polymers were prepared, characterized, coated on implantable glucose sensors, and tested in vitro and in vivo. The effects of 2,3-dihydroxypropyl methacrylate (DHPMA) on the swelling, morphology, glass transition (T(g)), and water structure were studied. The results show that the degree of swelling increases with increasing DHPMA content. Scanning electron microscopy (SEM) studies identified uniform, porous structures in samples containing 60-90 mol % DHPMA. Glass-transition temperatures did not change significantly with DHPMA content, but the ratio of freezing to nonfreezing water tended to increase with DHPMA content. Sensors coated with different hydrogels were prepared and in vitro evaluations were performed. The 80% DHPMA hydrogels exhibited optimum sensitivity, response, and stability when coated directly onto the sensor or top of a polyurethane (PU) layer. The histology results show that 80% DHPMA samples exhibit reduced fibrosis and reduced inflammation, resulting in a longer functional life.