Electrofluorochromic imaging analysis of dopamine release from living PC12 cells with bipolar nanoelectrodes array

The coupling of bipolar electrode (BPE) arrays and electrofluorochromic (EFC) imaging has exhibited great abilities in bioanalysis. However, the imaging resolution and analytical performance are hampered by the large size of the electrode and the rapid diffusion of EFC molecules on the electrode surface. Here, to address the challenges, bipolar nanoelectrodes (BPnE) array and in situ immobilization strategy of EFC molecules were proposed. Anodized aluminum oxide (AAO) template-assisted Au nanoelectrodes array with high density was fabricated as BPnE array for high spatial imaging resolution. By electrically polymerizing EFC molecules on the surface of single Au nanoelectrode, the rapid diffusion of EFC molecules on the electrode surface was not only avoided, but also realizing electrofluorescent imaging on an individual nanoelectrode. Using dopamine (DA) released from living PC12 cells as a model, the proposed strategy exhibited an ultra-high sensitivity for DA analysis with a detection limit of 0.45 nmol/L and the DA release amount from a single cell was calculated to be 0.13 pmol/L. Moreover, the dynamic change of DA release under the drug stimulation from living PC12 cells could also be monitored.