Construction and optimization of a versatile bioFET platform for detecting nucleic acids and protein using the biotin–neutravidin affinity system

A biosensor based on a field-effect transistor (bioFET) is a promising system for point-of-care testing due to its portability and high sensitivity. A bioFET uses a linker platform to connect capture molecules to the FET, which detects electrical changes when targets bind to the capture molecules. This study presents the development and optimization of a versatile, highly sensitive bioFET platform utilizing a biotin–neutravidin affinity system capable of detecting both DNA and proteins. The bioFET was constructed using an extended-gate field-effect transistor (EGFET) with an aluminum gate functionalized with (3-aminopropyl)triethoxysilane (APTES)–biotin–neutravidin. We optimized the concentrations and molar ratio of biotin and neutravidin using fluorescence imaging and biosensing benchmarks. We found that 0.1 μg/mL biotin paired with 30 μg/mL neutravidin, approximately 1:1 in molarity, achieved optimal sensitivity. The optimized bioFET system demonstrated good sensitivity, with lower detection limits of 3.5 copies for Escherichia coli genomic DNA and 0.3 fg/mL for p-Tau217, an Alzheimer's disease biomarker. In summary, this study establishes the ideal conditions for constructing a bioFET system using an APTES–biotin–neutravidin linker capable of detecting DNA and proteins, with potential for convenient and sensitive point-of-care diagnostics.