Selective determination of dopamine with an amperometric biosensor using electrochemically pretreated and activated carbon/tyrosinase/Nafion®-modified glassy carbon electrode

Dopamine, the most important neurotransmitter in the human brain, controls various functions. Dopamine deficiency causes fatal neurological disorders such as Parkinson’s disease. Even though various types of electrochemical sensors have been studied to measure dopamine levels, they often have poor selectivity for dopamine due to co-existence of interfering substances (e.g. ascorbic acid). Herein, we aimed to develop a highly sensitive dopamine detection method in the co-existence of ascorbic acid, a major interfering substance in real sample by designing an electrochemically pretreated and activated carbon/tyrosinase/Nafion®-modified GCE as an amperometric dopamine biosensor. To maximize the biosensor performance, pH, volume of Nafion®, and scan rate were optimized. This electrochemically pretreated and activated carbon/tyrosinase/ Nafion®-modified GCE could detect as low as 50 μM of dopamine with a wide linear range (50 ~ 1,000 μM) within a few seconds. In addition, it had a sensitivity of 103mAM/cm², which was higher than all previously reported tyrosinasebased dopamine biosensors. In addition, interference effect caused by 4 mM of ascorbic acid was negligible in the co-existence of 1 mM of dopamine. Consequently, this electrochemically pretreated and activated carbon/tyrosinase/ Nafion®-modified GCE might be applicable as amperometric biosensor for selective detection of dopamine in real samples with interfering substances.