Thick polystyrene-coated quartz crystal microbalance as a basis of a cost effective immunosensor

The use of a commercial quartz crystal microbalance for a disposable low co st and reliable immunosensor is presented. Thick polystyrene coating provid es a physical adsorption scheme to immobilise antigens or antibodies and av oids the oxidation of the commercial quartz crystal electrodes. The coating does not contribute significantly to the damping of quartz crystal. The po lystyrene-coated quartz also shows a smoother surface than the non-coated o ne. This is important for applications in liquids. Using the polystyrene-co ated quartz, the physical adsorption of protein is well-achieved. The frequ ency decrease caused by specific reactions between insulin, anti-insulin an tibody, and anti-mouse IgG antibody is presented as an example. A frequency shift caused by non-specific reactions is not detected. (C) 1999 Elsevier Science S.A. All rights reserved.