Electrocatalytic Performance of MWCNT on GCE for Highly Selective Dopamine and Uric Acid Sensing

A glassy carbon electrode (GCE) modified with multiwalled carbon nanotubes (MWCNTs) was fabricated using a temperature-controlled sol-gel method. The vertically aligned MWCNT structure on the electrode surface greatly enhances the modification efficiency compared to other methods. Even in complicated combinations, this MWCNT-modified GCE successfully differentiates the anodic oxidation potentials of uric acid (UA) and dopamine (DA), delivering clear peak separation. Because of this feature, it can be used as an advanced electrochemical sensor to detect DA and UA with great precision. The electrode's electroactive properties were further improved by pre-treating the MWCNT-GCE with ethanol and acetone before conducting electrochemical measurements. In contrast to other carbon nanotube-based electrodes that usually display only two redox pairs during dopamine oxidation, the ethanol and acetone-pretreated MWCNT-GCE demonstrates a unique third two-electron oxidation process, transforming 5,6-dihydroxyindole into indole-5,6-quinone. This distinctive feature underscores the exceptional electrochemical performance of the electrode for detecting dopamine and uric acid in human serum and urine samples, achieving promising recovery rates between 96% and 105%. These findings suggest that the MWCNT array-GCE holds significant potential as a highly effective platform for advancing biosensor technologies.