Protein Pretreatment of Microelectrodes Enables in Vivo Electrochemical Measurements with Easy Precalibration and Interference-Free from Proteins

Abstract

In vivo electrochemistry is one powerful strategy for probing brain chemistry. However, the decreases in sensitivity mainly caused by the adsorption of proteins onto electrode surface in short-term in vivo measurements unfortunately render great challenges in both electrode calibration and selectivity against the alternation of proteins. In this study, we observe that the pretreatment of carbon fiber microelectrodes (CFEs) with bovine serum albumin (BSA) would offer a simple but effective strategy to the challenges mentioned above. We verify our strategy for dopamine (DA) with conventionally used CFEs and for ascorbate with our previously developed carbon nanotube-modified CFEs. We find that, in artificial cerebral spinal fluid (aCSF) solution containing BSA, the current responses of the microelectrodes equilibrate shortly and the results for precalibration carried out in this solution are found to be almost the same as those for the postcalibration in pure aCSF. This observation offers a new solution to electrode calibration for in vivo measurements with a technical simplicity. Furthermore, we find that the use of BSA pretreated CFEs to replace bare CFEs would minimize the interference from the alternation of proteins in the brain. This study offers a new general and effective approach to in vivo electrochemistry with a high reliability and a simplified procedure.

Long Term Amperometric Recordings in the Brain Extracellular Fluid of Freely Moving Immunocompromised NOD SCID Mice

“…It is imperative that the sensor demonstrates efficient stability for continuous long term recordings. The potential benefits of pre-treating microelectrodes with lipids [29,38] and proteins [39] has been investigated by research groups to permit more accurate pre-calibration techniques by mitigating this sensitivity decrease observed upon implantation. These studies have established that exposing the electrodes to fouling agents in vitro may serve as a good model of the behaviour of implanted sensors in brain tissue.…”

O2 Plasma Etching and Antistatic Gun Surface Modifications for CNT Yarn Microelectrode Improve Sensitivity and Antifouling Properties

“…3 The enhanced electrochemical properties of CNTYMEs are attributed to the alignment of the CNTs, which exposes the ends of the tubes that contain more oxygen functional groups known to promote adsorption of neurotransmitters such as dopamine. 4–8 Moreover, the ability to fabricate CNT yarns directly into electrodes in a manner similar to CFMEs dramatically simplifies the electrode fabrication process and improves the reproducibility. 9,10 One main advantage of CNTYMEs is that the dopamine signal is independent of the repetition rate of the applied voltage waveform for FSCV, a stark contrast to traditional CFMEs which dramatically lose sensitivity with increasing repetition rate.…”

Ultrathin Cell‐Membrane‐Mimic Phosphorylcholine Polymer Film Coating Enables Large Improvements for In Vivo Electrochemical Detection

“…These results demonstrate that the coating of PEDOT‐PC membrane does not affect the electrode sensitivity toward DA. This is a step forward from electrode coatings with conventional antifouling membranes or BSA that compromise current responses of DA . Furthermore, the current recorded at the PEDOT‐PC/CFE was stable compared to that at bare CFE (Figure C and the Supporting Information, Figure S5), suggesting that PEDOT did not adsorb the product of DA oxidation, which was frequently observed at carbon electrodes…”

“…Towards the goal of minimizing the protein adsorption on the brain‐implanted microelectrodes, we previously found that pre‐treatment of CFEs with bovine serum albumin (BSA) can minimize further adsorption of proteins when the electrodes are implanted into the rat brain; however, this also causes significant sensitivity drop of CFEs to neurochemicals, including DA …”

“…To further study the antifouling properties of PEDOT‐PC/CFE against proteins, we performed in vitro electrochemical studies with BSA, a model protein commonly used in antifouling researches . As a starting point, we continuously recorded the amperometric response of the PEDOT‐PC/CFE toward DA followed by the addition of BSA into solution.…”