Highly Sensitive\nand Biocompatible Microsensor for\nSelective Dynamic Monitoring of Dopamine in Rat Brain

Highly selective and sensitive in vivo neurotransmitter\ndynamic\nmonitoring of the central nervous system has long been a challenging\nendeavor. Here, an implantable and biocompatible microsensor with\nexcellent performances was reported by electrodepositing poly(3,4-ethylenedioxythiophene)-electrochemically\nreduced graphene oxide (PEDOT-ERGO) nanocomposites and poly(tannic\nacid) (pTA) sequentially on the carbon fiber electrode (CFE) surface,\nand its feasibility in in vivo electrochemical sensing applications\nwere demonstrated. Due to the synergistic electrocatalytic effect\nof PEDOT-ERGO nanocomposites with the negative-charged pTA on dopamine\n(DA) redox reaction, the microsensor exhibits high detection sensitivities\nof 1.1 and 0.37 nA μM<sup>–1</sup> in the detection ranges\nof 0.02–0.5 and 0.5–20 μM with a low limit of\ndetection of 9.2 nM. Also, the microsensor shows excellent selectivity,\ngood sensing stability, repeatability, and reproducibility. In addition,\nthe highly hydrophilic and negative-charged pTA inhibits the nonspecific\nadsorption of hydrophobic proteins, which endows the microsensor with\ngood antifouling ability. Moreover, DA dynamics in rat brain were\nsuccessfully monitored in real time, and the selective sensing ability\nof the microsensor in vivo was also demonstrated. The present study\nprovides a new method for selective dynamics monitoring of DA in the\nbrain, which would help to better understand the pathological and\nphysiological functions of DA.