Fabrication of Sensitive Glutamate Biosensor Based on Vertically Aligned CNT Nanoelectrode Array and Investigating the Effect of CNTs density on the electrode performance

Abstract

In this report, the fabrication of vertically aligned carbon nanotube nanoelectrode array (VACNT-NEA) by photolithography method is presented. Electrochemical impedance spectroscopy as well as cyclic voltammetry was performed to characterize the arrays with respect to different diffusion regimes. The fabricated array illustrated sigmoidal cyclic voltammogram with steady state current dominated by radial diffusion. The fabricated VACNT-NEA and high density VACNTs were employed as electrochemical glutamate biosensors. Glutamate dehydrogenase is covalently attached to the tip of CNTs. The voltammetric biosensor, based on high density VACNTs, exhibits a sensitivity of 0.976 mA mM(-1) cm(-2) in the range of 0.1-20 μM and 0.182 mA mM(-1) cm(-2) in the range of 20-300 μM glutamate with a low detection limit of 57 nM. Using the fabricated VACNT-NEA, the sensitivity increases approximately to a value of 2.2 Am M(-1) cm(-2) in the range of 0.01 to 20 μM and to 0.1 A mM(-1) cm(-2) in the range of 20-300 μM glutamate. Using this electrode, a record of low detection limit of 10 nM was achieved for glutamate. The results prove the efficacy of the fabricated NEA for low cost and highly sensitive enzymatic biosensor with high sensitivity well suited for voltammetric detection of a wide range of clinically important biomarkers.

Recent Advances in Electrochemiluminescence with Quantum Dots and Arrays of Nanoelectrodes

“…CNTs have been deposited on different supporting electrode materials, such as Au, ITO or glassy carbon (GC). For instance, Rusling and coworkers obtained CNTs arrays arranged in vertically aligned structures named carbon nanotubes forests, which were applied at first for electrochemical detection,, to be further developed to prepare an ECL immunosensor for immunoglobulin G (IgG) . In this sensor, capture anti‐IgG antibodies were bound onto vertically aligned single wall carbon nanotubes (SWCNTs) via amide bond formation with the carboxylic groups present on the CNTs wall.…”

Enzyme-Based Electrochemical Glutamate Biosensors

“…CNTs often significantly improve electron transfer and kinetics [75]. This is due to the electrical properties of CNTs which vary significantly and depend on the structural differences between CNTs, resulting in some CNTs being highly conductive like metals, while others act more like semiconductors [76].…”

Preparation and electroanalytical applications of vertically aligned carbon nanotubes

“…Glutamate biosensors based on glutamate dehydrogenase enzyme (GLDH) immobilised on VACNT have been developed by Gholizadeh et al 102,103 In their first work, a direct immobilisation of GLDH on a VACNT surface was carried out by covalent linkage using EDC and hydrosulfosuccinimide sodium salt (sulfo-NHS) reagents. The GLDH/VACNT electrode and DPV were used to determine glutamate concentration.…”