An Ion-Sensitive Field-Effect Transistor Biosensor Based on SWCNT and Aligned MWCNTs for Detection of ABTS
Soheila Ebrahimi, Zahra Ebrahim Nataj, Shima Khodaverdian, Anousha Khamsavi, Yaser Abdi, Khosro Khajeh
Abstract
The perfect combination of biomolecules and nanomaterials is critical to achieve a biosensor with high sensitivity and selectivity. In this study, ion sensitive field effect transistor (ISFET) biosensors were fabricated based on carbon nanotube (CNT) with two different structures as the enzyme immobilization support. Laccase was immobilized over two kinds of CNT including: drop-casted single wall carbon nanotubes (SWCNTs) and forest-like multi-walled carbon nanotubes (MWCNTs) grown via Plasma-Enhanced Chemical Vapor Deposition (PECVD). The immobilization was non-covalent without any coupling agent and direct detection of 2, 2-azino-bis 3-ethylbenzothiazoline-6-sulphonic acid (ABTS) was carried out. Hydrogen and oxygen plasma treatments were performed on both types of devices to assess their effect on the enzyme immobilization. To investigate CNT-laccase interaction, the fourier transform infrared (FTIR)-attenuated total reflection (ATR) analysis was performed before and after the laccase immobilization for pristine and plasma treated CNTs. Results showed that drop-casted SWCNT-based sensor with oxygen treatment has the highest sensitivity as high as 3.66 A. M <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> .cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> , limit of detection (LOD) of 3 μM and linear range up to 300 μM .