Fast-scan cyclic voltammetry (FSCV) is a widely used technique for detecting neurotransmitters. However, electrode fouling can negatively impact its accuracy and sensitivity. Fouling refers to the accumulation of unwanted materials on the electrode surface, which can alter its electrochemical properties and reduce its sensitivity and selectivity. Fouling mechanisms can be broad and may include biofouling, the accumulation of biomolecules on the electrode surface, and chemical fouling, the deposition of unwanted chemical species. Despite individual studies discussing fouling effects on either the working electrode or the reference electrode, no comprehensive study has been conducted to compare the overall fouling effects on both electrodes in the context of FSCV. Here, we examined the effects of biofouling and chemical fouling on the carbon fiber micro-electrode (CFME) as the working electrode and the Ag/AgCl reference electrode with FSCV. Both fouling mechanisms significantly decreased the sensitivity and caused peak voltage shifts in the FSCV signal with the CFME, but not with the Ag/AgCl reference electrode. Interestingly, previous studies have reported peak voltage shifts in FSCV signals due to the fouling of Ag/AgCl electrodes after implantation in the brain. We noticed in a previous study that energy-dispersive spectroscopy (EDS) spectra showed increased sulfide ion concentration after implantation. We hypothesized that sulfide ions may be responsible for the peak voltage shift. To test this hypothesis, we added sulfide ions to the buffer solution, which decreased the open circuit potential of the Ag/AgCl electrode and caused a peak voltage shift in the FSCV voltammograms. Also, EDS analysis showed that sulfide ion concentration increased on the surface of the Ag/AgCl electrodes after 3 weeks of chronic implantation, necessitating consideration of sulfide ions as the fouling agent for the reference electrodes. Overall, our study provides important insights into the mechanisms of electrode fouling and its impact on FSCV measurements. These findings could inform the design of FSCV experiments, with the development of new strategies for improving the accuracy and reliability of FSCV measurements in vivo.

中文翻译：

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了解神经递质检测的快速扫描循环伏安法中结垢机制对工作电极和参比电极的不同影响

快速扫描循环伏安法（FSCV）是一种广泛使用的检测神经递质的技术。然而，电极污垢会对其准确性和灵敏度产生负面影响。污垢是指电极表面上不需要的材料的积累，这会改变其电化学性能并降低其灵敏度和选择性。结垢机制可能很广泛，可能包括生物结垢（生物分子在电极表面上的积累）和化学结垢（不需要的化学物质的沉积）。尽管个别研究讨论了工作电极或参比电极上的污垢影响，但尚未进行全面的研究来比较 FSCV 背景下两个电极的总体污垢影响。在这里，我们研究了生物污垢和化学污垢对作为工作电极的碳纤维微电极 (CFME) 和具有 FSCV 的 Ag/AgCl 参比电极的影响。两种结垢机制均显着降低了灵敏度，并导致 CFME 的 FSCV 信号峰值电压发生变化，但 Ag/AgCl 参比电极则不然。有趣的是，之前的研究报告称，由于 Ag/AgCl 电极植入大脑后发生污垢，导致 FSCV 信号的峰值电压发生变化。我们在之前的研究中注意到，能量色散光谱（EDS）光谱显示注入后硫化物离子浓度增加。我们假设硫离子可能是造成峰值电压偏移的原因。为了检验这一假设，我们在缓冲溶液中添加了硫离子，这降低了 Ag/AgCl 电极的开路电位，并导致 FSCV 伏安图中的峰值电压发生变化。此外，EDS 分析表明，慢性植入 3 周后，Ag/AgCl 电极表面的硫离子浓度增加，因此需要考虑将硫离子作为参比电极的污染剂。总的来说，我们的研究为电极污垢的机制及其对 FSCV 测量的影响提供了重要的见解。这些发现可以为 FSCV 实验的设计提供信息，并开发新策略来提高 FSCV体内测量的准确性和可靠性。