Abnormal neurochemical signaling is often the underlying cause of brain disorders. Electrochemical microsensors are widely used to monitor neurochemicals with high spatial-temporal resolution. However, they rely on carbon fiber microelectrodes that often limit their sensing performance. In this study, we demonstrate the potential of a hybrid multiwall carbon nanotube (MWCNT) film modified boron-doped ultrananocrystalline diamond (UNCD) microelectrode (250 μm diameter) microsensor for improved detection of dopamine (DA) in the presence of common interferents. A series of modified microelectrodes with varying film thicknesses were microfabricated by electrophoretic deposition (EPD) and characterized by scanning electron microscopy, x-ray photoelectron spectroscopy, electrochemical impedance spectroscopy (EIS) and silver deposition imaging. Using cyclic voltammetry, the 100-nm “thin” film microelectrode produced the most favorable combination of DA sensitivity value of 36 ± 2% μA/μM/cm² with a linear range of 33 nM to 1 μM and a limit of detection (LOD) of 9.5 ± 1.2% nM. The EIS spectra of these microelectrodes revealed three regions with inhomogeneous pore geometry and differing impedance values and electrochemical activity, which was found to be film thickness dependent. Using differential pulse voltammetry, the modified microelectrode showed excellent selectivity by exhibiting three distinct peaks for the DA, serotonin and excess ascorbic acid in a ternary mixture. These results provide two key benefits: first, remarkable improvements in DA sensitivity (>125-fold), selectivity (>2000-fold) and LOD (>180-fold), second, these MWCNTs can be selectively coated with a simple, scalable and low cost EPD process for highly multiplexed microsensor technologies. These advances offer considerable promise for further progress in chemical neurosciences.

神经化学信号异常通常是大脑疾病的根本原因。电化学微传感器广泛用于以高时空分辨率监测神经化学物质。然而，它们依赖碳纤维微电极，这往往限制了它们的传感性能。在这项研究中，我们展示了混合多壁碳纳米管 (MWCNT) 薄膜改性硼掺杂超纳米晶金刚石 (UNCD) 微电极（直径 250 μm）微传感器在常见干扰物存在下改进多巴胺 (DA) 检测的潜力。通过电泳沉积（EPD）微加工了一系列不同膜厚的改性微电极，并通过扫描电子显微镜、X射线光电子能谱、电化学阻抗谱（EIS）和银沉积成像进行了表征。使用循环伏安法，100 nm“薄膜”微电极产生了 36 ± 2% μA/μM/cm ²的 DA 灵敏度值、33 nM 至 1 μM 的线性范围和检测限 (LOD) 的最佳组合。 ）为 9.5 ± 1.2% nM。这些微电极的 EIS 谱揭示了三个具有不均匀孔隙几何形状和不同阻抗值和电化学活性的区域，这些区域被发现与膜厚度相关。使用差分脉冲伏安法，改进的微电极表现出优异的选择性，在三元混合物中显示出 DA、血清素和过量抗坏血酸的三个不同峰。这些结果提供了两个关键优势：首先，DA 灵敏度（>125 倍）、选择性（>2000 倍）和 LOD（>180 倍）显着提高，其次，这些 MWCNT 可以选择性地涂覆简单、可扩展的涂层。以及用于高度复用微传感器技术的低成本 EPD 工艺。 这些进展为化学神经科学的进一步进步提供了巨大的希望。