A highly sensitive electrochemical biosensor for dopamine and uric acid in the presence of a high concentration of ascorbic acid

Applying zein nanoparticles in addition to MWCNTs, a bio-nanocomposite has been produced to modify glass carbon electrodes. The modified electrode has been used as an economically affordable electrochemical biosensor to be simple, selective, and sensitive for determining dopamine and uric acid in biological samples (such as blood serum and human urine). Not only the morphology but also the electrode's electrochemical behavior has been characterized. Such characterization has also been conducted for the nanocomposite. Transmission electron microscopy (TEM), field emission-scanning electron microscopy (FE-SEM), cyclic voltammetry (CV), and differential pulse voltammetry (DPV) were used for the characterizations. DPV demonstrated response over concentration ranges regarding dopamine (DA), from 0.098 to 200.0 mu M, with a limit of detection (LOD) of 0.02 mu M. The same manner of response was also manifested for uric acid (UA), from 0.1 to 908 mu M, with a LOD of 0.08 mu M. This electrode was also studied to gauge dopamine and uric acid in the presence of interfering substances including ascorbic acid, citric acid, tartaric acid, urea, maleic acid, Cu2+, Al3+, Ca2+, Mg2+, NH4+, and F-. As a result, the electrode emanated an appropriate amplitude of selectivity. Operational stability studies have revealed a decrease in the DPV primary response on the part of the biosensor for purposes of determining dopamine and uric acid levels after three days of being held at a temperature of 4 degrees C. This decrease amounted to 91.02%.