Selective biomolecular sensing is of great importance in biomedical applications. Yet, due to the countless number of contaminants in real bio-systems, realization of selective sensing, especially of small biomolecules, remains a great challenge. Herein, we propose a novel biosensing platform based on an extended-gate field-effect transistor (EG-FET) biosensor of which sensor surface is modified by filterly-designed polymeric membrane. FET biosensors can sensitively detect small molecules by the induced change of gate surface charges within the range of electric double layer. Particularly, extended Au gate enables ultra-sensitive detection of various biomolecules based on the electrochemical reactions. Thus, our sensor is designed so that the polymeric membrane works as a filter, capturing various contaminants, and only the target biomolecule reaches the sensing area. For a fundamental investigation, in this study, we use dopamine, a well-known neurotransmitter, and phenylboronic acid (PBA) as a receptor, to show the impact of filtering effect and thus the possibility of building selective biosensing platform.<br/>To investigate the filtering effect, we prepared FET sensors with its sensing surface modified by polymer with and without PBA. Polymerization was carried out using visible light mediated atom transfer radical polymerization (ATRP). First, Au electrode was modified by ATRP initiator using diazonium salt chemistry. Then, co-polymerization of methacrylic acid, 2-hydroxyethyl methacrylate, and N,N’-methylenebisacrylamide with an optimized ratio was carried out. Finally, PBA was introduced into the polymeric structure through carboxyl-amino chemical reaction between methacrylic acid and m-aminophenylboronic acid.<br/>The gate surface potential was monitored using FET real-time monitoring system in aqueous buffer solution while continuously increasing the concentration of dopamine. While the detection limit of the sensor without PBA was as low as in nM order, sensitivity of the sensor with PBA polymer decreased significantly to a µM order, indicating dopamine being captured by PBA-based polymer membrane. Thus, the result showed succession of both an ultra-sensitive detection and a filtering effect, which opens a possibility of building selective biosensing platform.

Towards selective molecular biosensing: Fundamental investigation of polymeric filtering effect on field-effect transistor biosensor

254th National Meeting (2017)

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