Fig. 3

a Schematic illustration showing an oxidised polypyrrole/sodium dodecyl sulphate-modified multi-walled carbon nanotube (OPPy/SDS-CNT) electrode for the detection of DA. b DPV graphs of the OPPy/SDS-CNT electrode with several concentrations of DA (5 nM–10 µM). c Regression analysis of the current peaks obtained from b. d Amperometric currents of DA were released from cells using the OPPy/SDS-CNT electrode. e Cytotoxicity test of the OPPy/SDS-CNT electrode using the MTT assay. With permission from [54], Copyright 2019 Elsevier B.V