Glucose Biosensors Based on Carbon Nanotube Nanoelectrode Ensembles

Abstract

This paper describes the development of glucose biosensors based on carbon nanotube (CNT) nanoelectrode ensembles (NEEs) for the selective detection of glucose. Glucose oxidase was covalently immobilized on CNT NEEs via carbodiimide chemistry by forming amide linkages between their amine residues and carboxylic acid groups on the CNT tips. The catalytic reduction of hydrogen peroxide liberated from the enzymatic reaction of glucose oxidase upon the glucose and oxygen on CNT NEEs leads to the selective detection of glucose. The biosensor effectively performs a selective electrochemical analysis of glucose in the presence of common interferents (e.g., acetaminophen, uric and ascorbic acids), avoiding the generation of an overlapping signal from such interferers. Such an operation eliminates the need for permselective membrane barriers or artificial electron mediators, thus greatly simplifying the sensor design and fabrication.Because of the high demand for blood glucose monitoring, significant research and development efforts have been devoted to producing reliable glucose sensors for in vitro or in vivo applications. 1-2 The measurement principle of oxidase-based amperometric biosensors previously relied upon the immobilization of oxidase enzymes on the surface of various electrodes and the detection of the current associated with the redox product in the biological reaction. To increase the selectivity and sensitivity of amperometric biosensors, artificial mediators and permselective coatings are often used in biosensor fabrication. Artificial mediators are used to shuttle electrons between the enzyme and the electrode to allow operation at low potentials. 3-5 This approach can minimize interference with coexisting electroactive species, but the stability and toxicity of some mediators limit their in vivo applications. Permselective membranes are also used to eliminate interference. 6-7 Effective, but incomplete, rejection has been reported in most cases. A mediator-free and membrane-free biosensor was described by Wang's method provides a means for measuring the cathodic current of enzymatically liberated hydrogen peroxide in metal-dispersed carbon paste biosensors. The idea of a mediator-free and membrane-free biosensor based on the reduction of hydrogen peroxide has provided a new approach for biosensor development.Recently, electrochemical properties of carbon nanotubes (CNTs) have been unveiled, and their application toward electrochemical sensors and biosensors has gained interest. [10][11][12][13][14][15][16][17][18][19][20][21][22]

Nanoelectrode ensembles as recognition platform for electrochemical immunosensors

“…In typical schemes used for electrochemical biosensors, a biorecognition layer is immobilized directly on the electrode surface and the signal is produced by exchange of electrons with the underlying electrode; this was applied also to arrays of nanoelectrodes (Lin et al, 2004;Li et al, 2003;Lapierre-Devlin et al, 2005;Delvaux et al, 2005). However, for extremely miniaturized electrodes, such as NEEs, the amount of biomolecule immobilized on the nanoelectrodes can be too small to furnish useful signals (De Leo et al, 2007a).…”

High-Performance, Flexible Enzymatic Glucose Biosensor Based on ZnO Nanowires Supported on a Gold-Coated Polyester Substrate

“…In recent years, major developments have been made to increase the sensor performance by incorporating various nanostructured materials (2,(4)(5)(6)(7)(8)(9)(10). The inherently larger surface areas of nanomaterials offer a higher enzyme loading, which could dramatically improve the sensor activity.…”

Electrochemical Sensors

“…141 The CNTs were directly grown on the electrically conductive Cr-coated Si substrate, following the attachment of GOx to the tips of the CNTs by using standard the water-soluble coupling agent 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC). The new fabrication allowed them to prepare a mediator free and membrane free biosensor.…”