Nanocrystalline boron-doped diamond nanoelectrode arrays for ultrasensitive dopamine detection

Highlights: • BDD-NEAs for low-level dopamine detection without selective membrane are presented. • DA detection at O-terminated BDD shows a signal largely independent of AA. • Differential pulse voltammetry is employed to improve the DA sensitivity. • Detection limit less than 100 nM under physiological conditions is achieved. - Abstract: In this paper we present nanocrystalline boron-doped diamond nanoelectrode arrays (BDD-NEAs) for the low-level detection of biogenic substances such as dopamine (DA) without the need for a selective membrane. We achieved a sensitive and reproducible detection of dopamine in the presence of ascorbic acid (AA) with oxygen (O-) terminated BDD-NEAs. To improve the peak separation between dopamine and ascorbic acid, differential pulse voltammetry (DPV) was employed. Therewith, it was possible to measure dopamine with a sensitivity of 57.9 nA μM⁻¹ cm⁻². The detection limit was less than 100 nM with a linear behavior up to a concentration of 20 μM. The choice of the appropriate termination, the combination of the advantages of nanoelectrode arrays together with the outstanding electrochemical properties of boron-doped diamond and the right measurement method allowed successful measurement of dopamine in physiological concentrations in the presence of ascorbic acid.