Preparation and characterization of aligned carbon nanotube sheet for electrochemical detection of dopamine

Abstract

A sensitive, flexible and convenient electrochemical method for the determination of dopamine (DA) was developed using an aligned carbon nanotube (CNT) sheet electrode. The electrochemical behaviour of DA at the aligned CNT sheet electrode was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) with three parameters which are the scan rate of CV, the pH values of phosphate buffer solution (PBS) solution and the concentration of DA. The results of cyclic and differential pulse voltammetric investigations showed that the aligned CNT sheet electrode has an efficient electrocatalytic activity for the electrochemical oxidation of DA. The aligned CNT sheet displays linear behaviour with the square root of scan rates over the 0.01 to 0.5 V/s range. With an increase in pH value, the DA oxidation peak potential shifted negatively. In addition, the aligned CNT sheet was observed to show higher sensitivity to lower concentration compared to higher concentration of DA. The oxidation peak current of DA at the modified electrode was linear to the lower and higher concentration of DA from 1 to 120 μM, with correlation coefficient of 0.998 for both and detection limit of 0.1 μM. A reproducible response was observed for repetitive measurements with a RSD of less than 5%. The aligned CNT sheet electrode also showed flexibility and pre-treatment was not required. These studies show that aligned CNT sheet electrodes can be used with fast scanning techniques and are advantageous due to their good sensitivity, reproducibility, conductivity, flexibility and convenience.