Carbon nanotube modified microelectrode for enhanced voltammetric detection of dopamine in the presence of ascorbate

A single carbon fiber microelectrode modified with multi-wall carbon nanotubes (MWCNT) and Nation exhibits an attractive electroanalytical performance for enhanced voltammetric detection of dopamine in the presence of ascorbate at physiological pH. The fast and simple preparation protocol involves dipping a single carbon fiber microelectrode into a modification solution containing Nafion and MWCNT. The resulting surface modification couples the sensitivity improvement associated with the MWCNT with the permselectivity of Nafion films. The microsensor displays highly linear behavior over the 2 to 20 mu M dopamine range examined (R of 0.997), with a detection limit of 70 nM. A highly reproducible response was observed for 50 repetitive measurements with a RSD of 1.6%, while the effect of ascorbate upon the voltammetric signal for dopamine was negligible. In addition, some more insights are given into the electroanalytical performance of the MWCNT/Nafion modified microelectrode. Such a disposable dopamine microsensor holds great promise for convenient detection of dopamine in the presence of ascorbate at physiological concentrations in microvolume samples and at microlocations (e.g., measurement of dopamine under physiological conditions).