Surface fixation of hydrogels. Heparin and glucose oxidase hydrogelated surfaces

The authors report a new photochemical technique for the fixation of hydrogels onto the surface of fabricated devices and sensors. The preparative method is based on two different types of photochemistry: photocross-linking due to intermolecular photodimerization of cinnamoyl groups, and photoinduced covalent bonding due to the photoreactivity of azido groups. The immobilization of heparin, useful as a thromboresistant coating, onto poly(ethylene terephthalate), and the immobilization of glucose oxidase onto the surface of a carbon fiber electrode, were demonstrated. In the former, immobilized heparin was found to be continuously released from the hydrogel, and the release rate was effectively controlled by the thickness of the hydrogel. In the latter, upon the addition of glucose, a spontaneous electrical response was observed to function as a glucose sensor. No delamination was found for either system after vigorous washing with water. Thus, durable surface hydrogelation, simultaneous immobilization of bioactive substances, and functioning of the systems were demonstrated.