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

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 ele...