Two-Electron Oxidation of Dopamine Controlled by Surface Modification of Few-Layer Graphene

Oxidation of dopamine (DA) at classical electrodes is suggested to go through three steps and then form melanin-like compounds, which would inhibit electron transfer and result in the fouling of electrode. In addition, the selective oxidation of DA in the presence of ascorbate (VC) should also be considered for the design of electrode. Here, graphenes modified with different surface groups are used to investigate the oxidation behaviour of DA. Compared with classical electrodes, negatively charged few-layer graphene (AA-GN) shows a good performance in selective oxidation of DA and can also control the oxidation of DA in the first step, which would further prevent the fouling of electrode. The rate constant and number of electron transfer are calculated to be about 7.38 s−1 and 2, respectively, which further indicates that the oxidation of DA was controlled in the first step. Furthermore, AA-GN-modified electrode is used to selectively detect DA with a detection limit of 10 nM in the prescence of excess VC. At last, AA-GN-modified macro-electrode is used to monitor DA release from living cells for the first time.