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

• Purification method employed here use cheap and green oxidants.
• The method does not disrupt the electronic structure of nanotubes.
• This method removes nearly < 2% metallic impurities.
• Increases the sensitivity and performance of glassy carbon electrode
• This system can detect as low as 0.066 μM of H2O2 and 0.2633 μM of glucose.

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 (1.0 mg/ml SWCNT in 1.0 mg/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 0.7 V versus Ag/AgCl. The GCE/(SWCNT–PEI, PEG, PPY) gave a detection limit of 0.2633 μM, 0.434 μM, and 0.9617 μM, and sensitivities of 0.2411 ± 0.0033 μA mM− 1, r2 = 0.9984, 0.08164 ± 0.001129 μA mM− 1, r2 = 0.9975, 0.04189 ± 0.00087 μA mM− 1, and r2 = 0.9944 respectively and a response time of less than 5 s. 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.