Development of immunosensors based on commercially available surface acoustic wave (SAW) devices

Abstract

In the present paper we report about the development of immunosensors based on commercially available surface acoustic wave (SAW) devices. The SAW devices applied were originally developed for use in modern telecommunications and are thus available as series products at low costs. For biosensing applications the devices must be coated with a shielding layer to prevent corrosion of the aluminum structures in aqueous media. Thin films of polyimide and parylene, respectively, show good shielding properties and were used as a basis for immobilization of receptor molecules. Various approaches to coating the shielded surfaces with receptive biomolecules are presented briefly and discussed. Finally, covalent binding of dextran as an intermediate layer on SAW devices is described. Dextran bonding is achieved by a photoimmobilization process. The aryldiazirine-functionalized bovine serum albumin (T-BSA) serves as a multifunctional light-activated linking agent (photolinker polymer). Dextran and the photolinker are mixed and photobonded to the sensor surface. Essential parameters of the coating procedure are optimized. Immobilization of proteins to the dextran layer via carbodiimide chemistry is demonstrated. The feasibility of specific immunosensing is investigated using SAW sensors connected to a fluid handling system.