Development of an Aptamer-Based Field-Effect Transistor Biosensor for Rapid Detection of Boronophenylalanine (BPA) for Cancer Therapy

Abstract

Boron Neutron Capture Therapy (BNCT) relies heavily on the precise accumulation of Boronophenylalanine (BPA) in tumor cells to achieve therapeutic efficacy [1]. However, current clinical methods for monitoring BPA concentrations, such as Inductively Coupled Plasma Mass Spectrometry (ICP-MS), are limited by lengthy analysis times and complex sample pretreatment, rendering them unsuitable for real-time pharmacokinetic monitoring. Furthermore, the development of rapid electrical biosensors is often hindered by probe instability and ionic screening effects in physiological environments [2]. To address these challenges, this study presents a label-free Field-Effect Transistor (BioFET) platform [3] designed for the rapid and specific detection of BPA. A robust surface engineering strategy was employed to ensure optimal probe orientation and stability. The gold sensing gate was first coated with a silicon dioxide (SiO 2 ) layer to facilitate silanization, followed by functionalization with 3-aminopropyltriethoxysilane (APTES) and the heterobifunctional crosslinker SMCC [4, 5]. This approach enables the site-specific covalent immobilization of thiol-terminated BPA aptamers [6], significantly minimizing non-specific desorption compared to physical adsorption methods. Additionally, fluorescently labeled aptamers (FAM-modified) were utilized to visually verify the uniformity of the sensing monolayer. Experimental results in buffer solutions demonstrate that the fabricated BioFET sensor achieves a rapid response time of under 15 minutes with high sensitivity. This study successfully establishes the fundamental sensing mechanism and validates the stability of the covalent immobilization protocol. These findings provide a solid foundation for translating the technology to complex biological matrices, such as serum and whole blood, for future clinical applications in BNCT. REFERENCES Monti Hughes, A. and N. Hu, Optimizing Boron Neutron Capture Therapy (BNCT) to Treat Cancer: An Updated Review on the Latest Developments on Boron Compounds and Strategies. Cancers (Basel), 2023. 15(16). Chu, C.-H., et al., Beyond the Debye length in high ionic strength solution: direct protein detection with field-effect transistors (FETs) in human serum. Scientific reports, 2017. 7(1): p. 1-15. Vu, C.-A. and W.-Y. Chen, Field-effect transistor biosensors for biomedical applications: recent advances and future prospects. Sensors, 2019. 19(19): p. 4214. Hernandez, A. L., et al., Efficient Chemical Surface Modification Protocol on SiO2 Transducers Applied to MMP9 Biosensing. Sensors , 2021. 21(23): p. 8156. Naderlou, E., et al., Enhanced sensitivity and efficiency of detection of Staphylococcus aureus based on modified magnetic nanoparticles by photometrical method. Artificial Cells, Nanomedicine, and Biotechnology, 2020. 48(1): p. 810-817. Hayashi, H., et al., Site-specific aptamer immobilization via amine-to-thiol cross-linking on field-effect transistor biosensor for cortisol detection. Colloids and Surfaces B: Biointerfaces, 2025. 254: p. 114842. Figure 1. (A) Schematic illustration of the BioFET interface engineering. The gold gate is modified with SiO 2 /APTES/SMCC to covalently immobilize BPA-aptamers. (B) Real-time electrical response of the sensor to increasing concentrations of BPA in buffer solution, demonstrating rapid detection within 15 minutes. Figure 1