Carbon fiber microelectrode array loaded with the diazonium salt-single-walled carbon nanotubes composites for the simultaneous monitoring of dopamine and serotonin in vivo

Highlights: • Diazonium salt-single-walled carbon nanotubes composites coated carbon fiber microelectrode array has been prepared. • The synergistic effect of DS and SWCNT improves the sensitivity and selectivity for the determination of DA and 5-HT. • The prepared microsensor can monitor the concentration change of DA and 5-HT in the mouse brain striatum over time. • The provided method proved the pharmacological effects of Uncaria alkaloid extract on DA and 5-HT in the mouse brain striatum. Carbon fiber microelectrode arrays based on diazonium salt and single-walled carbon nanotubes composites (DS-SWCNT/CFMEA) have been fabricated, and it developed for the simultaneous monitoring of dopamine (DA) and serotonin (5-HT) with differential pulse voltammary (DPV). The diazonium salt can improve the water-solubility of single-walled carbon nanotubes and show good selectivity to DA, thus DS-SWCNT/CFMEA exhibits enhanced electrocatalytic activity for the oxidation of DA and 5-HT, and well antifouling ability to the other biomolecules. Moreover, DS-SWCNT/CFMEA shows the wider liner range, and the good performance of precision, reproducibility and biocompatibility. The excellent characteristics of the prepared microsensor array make it to be used to monitor the release of DA and 5-HT in the mouse brain striatum of different group over time. Meanwhile, the results of in vivo on line assay further confirmed the pharmacological effects of Uncaria alkaloid extract solution on DA and 5-HT. This research may provide a new method for monitoring the release of neurobiomolecules, and the microsensor array are expected to be a tool for the study of pharmacological and physiological processes on line in vivo.