Microelectrodes with gold nanoparticles and self-assembled monolayers for in vivo recording of striatal dopamine

Abstract

Electrochemical determination of in vivo dopamine (DA) using implantable microelectrodes is essential for monitoring the DA depletion of an animal model of Parkinson's disease (PD), but faces substantial interference from ascorbic acid (AA) in the brain area due to similar electroactive characteristics. This study utilizes gold nanoparticles (Au-NPs) and self-assembled monolayers (SAMs) to modify platinum microelectrodes for improving sensitivity and specificity to DA and alleviating AA interference. With appropriate choice of ω-mercaptoalkane carboxylic acid chain length, our results show that a platinum microelectrode coated with Au-NPs and 3-mercaptopropionic acid (MPA) has approximately an 881-fold specificity to AA. During amperometric measurements, Au-NP/MPA reveals that the responsive current is linearly dependent on DA over the range of 0.01-5 μM with a correlation coefficient of 0.99 and the sensitivity is 2.7-fold that of a conventional Nafion-coated electrode. Other important features observed include fast response time (below 2 s), resistance to albumin adhesion and low detection limit (7 nM) at a signal to noise ratio of 3. Feasibility of in vivo DA recording with the modified microelectrodes is verified by real-time monitoring of electrically stimulated DA release in the striatum of anesthetized rats with various stimulation parameters and administration of a DA uptake inhibitor. The developed microelectrodes present an attractive alternative to the traditional options for continuous electrochemical in vivo DA monitoring.

New trends in the electrochemical sensing of dopamine

“…Gold has the beneficial properties of adsorbing and preconcentrating catecholamines on its surface, thus increasing the sensitivity of gold electrodes to these compounds. The gold surface can, moreover, be easily modified by covalent bonding with thiol groups, enabling formation of self-assembled monolayers (SAMs) with different functionality facing the external solution [161]. Miniature gold electrodes prepared in this way have been used to characterize a variety of neurotransmitters (including dopamine) and interfering agents, and the results have been compared with analogous results obtained by use of carbon fiber microelectrodes [120].…”

Microelectrode Arrays Modified with Nafion/Nanoporous AuPt Nanoparticles for in vivo Detection of Dopamine

“…Therefore, it was believed that the increased responsive currents and slow decline of peak currents upon nomifensine administration were mainly due to the accumulation of DA concentration in fluids outside of cells, which is consistent with previous reports. (2,7,37) In a word, the above results indicated that amperometry coupled with Nafion/AuPt-alloy-nanoparticle-modified Au sites possessed sufficient feasibility for enabling in vivo recording of DA concentration in the brain of anesthetized rats.…”

“…In order to clarify that the observed responsive currents were not mainly due to stimulus artifacts, a DA uptake inhibitor (nomifensine, 7 mg/kg) was injected intraperitoneally. (37) As shown in Fig. 8(c), in contrast with the responsive current of the control condition (without nomifensine), the DA reuptake inhibitor could greatly enhance DA responsive currents.…”

“…To verify in vivo detection of DA, nomifensine, a DA uptake inhibitor, was injected intraperitoneally (7 mg/kg). (37) …”

Desenvolvimento de uma superfície bifuncional Pt/Au modificada com glicose oxidase para determinação de glicose em amostras alimentícias

“…Muitos alcanotióis já foram estudados devido à sua alta interação com alguns substratos, como o ouro, por exemplo 35 . Tsai et al 36 apresentam um estudo utilizando-se microeletrodos compostos por nanopartículas de ouro imobilizando-se uma camada auto-organizada de ácido mercaptooctanoico para detecção analítica de dopamina.…”