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 cost and reliable immunosensor is presented. Thick polystyrene coating provides a physical adsorption scheme to immobilise antigens or antibodies and avoids the oxidation of the commercial quartz crystal electrodes. The coating does not contribute significantly to the damping of quartz crystal. The polystyrene-coated quartz also shows a smoother surface than the non-coated one. This is important for applications in liquids. Using the polystyrene-coated quartz, the physical adsorption of protein is well-achieved. The frequency decrease caused by specific reactions between insulin, anti-insulin antibody, and anti-mouse IgG antibody is presented as an example. A frequency shift caused by non-specific reactions is not detected.