Immobilization of biomolecules on polyurethane membrane surfaces.

Lipophilic polymer membranes incorporating binding sites are widely used in various potentiometric, amperometric, and optical sensors. Here, we report on the biofunctional modification of the surface of a Ca(2+)-selective membrane. A photoactivatable biotin derivative was synthesized and covalently immobilized on a soft polyurethane membrane. The modified polymer was characterized by X-ray photoelectron spectroscopy (XPS) as well as by potentiometric measurements. The selective binding of streptavidin by the photo-cross-linked biotin derivative was demonstrated. The surface coverage obtained with different experimental protocols was analyzed by autoradiography using [(35)S]-streptavidin. The new approach may significantly extend the scope of applicability of potentiometric sensors.