A Novel Choline Biosensor Based on Immobilization of Enzyme Choline Oxidase on the β-Ga2O3 Nanowires Modified Working Electrode

Abstract

This article is a report on a novel and high-stability biosensor with minor interference effects of surface modification of working electrode with β-Ga₂O₃ nanowires (NWs) on choline oxidase biosensor were investigated in an electrochemical detection system. β-Ga2O3 NWs were materialized on the silicon substrate in a catalyst-free growth mechanism. The β-Ga₂O₃ NWs were in string form with 10 μm in length and uniformly 30 nm in diameter. Then the enzyme choline oxidase (ChOx) immobilized on the β-Ga₂O₃ NW/CB arrays on the working electrode. The Cyclic voltammetry (CV), Impedance spectroscopy and differential pulse voltammetry (DPV) measurements were performed for bio-sensing detection with choline chloride as substrate. One of the most prominent features of this surface modification with Ga₂O₃ NWs /CB is that the peak intensity, which is often of the order of μA, is greatly increased and reaches about mA. Chronoamperometry amplification well confirms the performance of this surface modification. The current with the CB modified electrode is about three times more than the non-modified electrode, and Ga₂O₃ NWs/CB modified electrode twice more than the CB modified electrode. The maximum current in the DPV data is modelled linearity iap= 0.159 (C)+2.28 and R² = 0.982. The limit of detection (LOD) of the electrode for the choline measurement was reached to 8.29 μM. The Sensitivity of the electrode was around 0.0397 mA mM⁻¹ mm⁻². The stability of this biosensor has been well studied over a period of 6 months, and more than 80% of the permanency of its response has been confirmed.