Utilization of highly purified single wall carbon nanotubes dispersed in polymer thin films for an improved performance of an electrochemical glucose sensor

Abstract

In this work we report the improved performance an electrochemical glucose sensor based on a glassy carbon electrode (GCE) that has been modified with highly purified single wall carbon nanotubes (SWCNTs) dispersed in polyethyleneimine (PEI), polyethylene glycol (PEG) and polypyrrole (PPy). The single wall carbon nanotubes were purified by both thermal and chemical oxidation to achieve maximum purity of ~98% with no damage to the tubes. The SWCNTs were then dispersed by sonication in three different organic polymers (1.0mg/ml SWCNT in 1.0mg/ml of organic polymer). The stable suspension was coated onto the GCE and electrochemical characterization was performed by Cyclic Voltammetry (CV) and Amperometry. The electroactive enzyme glucose oxidase (GOx) was immobilized on the surface of the GCE/(organic polymer–SWCNT) electrode. The amperometric detection of glucose was carried out at 0.7V versus Ag/AgCl. The GCE/(SWCNT–PEI, PEG, PPY) gave a detection limit of 0.2633μM, 0.434μM, and 0.9617μM, and sensitivities of 0.2411±0.0033μAmM−1, r2=0.9984, 0.08164±0.001129μAmM−1, r2=0.9975, 0.04189±0.00087μAmM−1, and r2=0.9944 respectively and a response time of less than 5s. The use of purified SWCNTs has several advantages, including fast electron transfer rate and stability in the immobilized enzyme. The significant enhancement of the SWCNT modified electrode as a glucose sensor can be attributed to the superior conductivity and large surface area of the well dispersed purified SWCNTs.