Electrochemical detection of dopamine (DA) usually depends on electrochemical oxidation of DA. This conventional method can hardly provide sufficient sensitivity and selectivity in the determination of the cerebral DA down to nanomolar level, because the ability of DA to be electrochemically oxidized is limited and many electroactive interferents are also oxidized at a similar potential with DA. Here, an electrochemical assay based on a double molecular recognition strategy has been proposed and proved to be of high sensitivity and selectivity for DA measurement in the cerebral system. 3,3'-Dithiodipropionic acid di(N-hydroxysuccinimide ester) (DSP) was anchored on the electrode surface to capture DA target through the specific reaction between N-hydroxysuccinimide (NHS) ester and amine. The captured DA endowed the electrode with a layer of diol groups, which further reacted with the boronic acid to trap of 4-mercaptophenylboronic acid (MBA) molecules, thus leading to the conjunction of electroactive thionine (Th) molecules on the electrode for signal readout. In addition, an Au nanostructure was employed to enhance signal amplification and facilitate the double molecular recognition process. As a consequence, this method was able to quantify DA from 1 to 300 nM with a detection limit of 0.74 nM, which exhibited a high specificity against cerebral interferents. Furthermore, the practicability of this platform was successfully demonstrated through determination of the dynamics of cerebral DA in the events of high K+ and nomifensine retromicrodialysis. Graphical abstract.
Keywords: Cerebral; Dopamine; Double molecular recognition; Microdialysis.