A comparative study of electrochemical and biointerfacial properties of acid- and plasma-treated single-walled carbon-nanotube-film electrode systems for use in biosensors

The electrocatalytic and biointerfacial properties of acid- and O₂-plasma-treated single-walled carbon nanotube (SWCNT) electrodes were investigated. The SWCNT-modified electrodes were characterized using scanning electron microscopy and X-ray photoelectron spectroscopy. The electrochemical performance of these electrodes was analyzed by cyclic voltammetry and chronoamperometry. Glucose oxidase was covalently immobilized on the surface of the treated SWCNTs, and the analytical characteristics of the integrated glucose sensor were investigated using glucose as a target analyte. The plasma-activated SWCNT electrode exhibited a much higher sensitivity to the glucose and a lower detection limit than the acid-treated electrode, indicating that a larger amount of enzyme was immobilized on the plasma-treated SWCNT electrode than on the acid-treated electrode. This is due to the fact that the oxygenated functional groups are mainly located at the ends of the tubes in the acid-treated SWCNTs, while the plasma-treated SWCNTs have an even larger surface area available for enzyme immobilization owing to the functional groups covering the entire surface of the SWCNTs.