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The purpose of this paper is to present possibility of fast and certain identification of bovine serum albumin (BSA) by means of ion-sensitive field effect transistor (ISFET) structures. Because BSA can cause allergic reactions in humans, it is one of reasons for development of sensitive sensors to detect residual BSA. BSA is commonly used in biochemistry and molecular biology in laboratory experiments. Therefore, to better understand the mechanism of signal transduction in simulated biological environment and to elucidate the role of adsorption of biomolecules in the generation of a signal at the interface with biological systems, the measurements of ISFET current response in the presence of BSA as a reference protein molecule were performed.

To fabricate transistors, silicon technology was used. The ISFET structures were coupled to specially designed double-side printed circuit board holder. After modification of the field effect transistor (FET) device with 3-aminopropyltriethoxysilane (APTES), a sensor with high sensitivity toward reference biomolecules was obtained. The current–voltage (I-V) characteristics of structures with and without gate modification were measured. Keithley SMU 236/237/238 measurement set was used. Deionized water solution and 0.05 per cent BSA were used.

In this research, a method of preparation of a biosensor based on a FET was developed. Sensitivity of APTES-modified FET device toward BSA as a biomolecule was investigated. I-V relationships of FET devices (with and without modification), being the effect of the interactions with the solution containing 0.05 per cent BSA, were measured and compared to the measurements performed for solutions without BSA.

Compared to SiO₂-containing ISFETs without modification or other different dielectrics, the application of APTES as the part of the membrane induced significant increase in their sensitivity to BSA.