Wang Yuanmo, Gupta Pankaj, Pradhan Ajay, Trouillon Raphaël, Hanrieder Jörg, Zetterberg Henrik, Cans Ann-Sofie
Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Kemigården 4, Gothenburg 412 96, Sweden.
Department of Psychiatry and Neurochemistry, Institute of Neuroscience & Physiology, The Sahlgrenska Academy at the University of Gothenburg, Mölndal 431 80, Sweden.
ACS Electrochem. 2025 Jun 16;1(9):1698-1709. doi: 10.1021/acselectrochem.5c00135. eCollection 2025 Sep 4.
Carbon fiber nanotip electrodes (CFNEs) are crucial for electrochemical recordings of neurotransmission release in confined spaces, such as synapses and intracellular measurements. However, fabricating CFNEs with small surface area to minimize noise remains challenging due to inconsistent tip size control, low reproducibility, and low fabrication success rate. Here, we present a reliable, user-friendly method with high reproducibility and success rate for precise CFNE fabrication using microscopy-guided electrochemical etching of cylindrical carbon fiber microelectrodes in a potassium hydroxide droplet. The electrode positioning at the droplet's liquid-air interface determines the etched region, while manually applied time- and amplitude-controlled voltage pulses regulate material removal. Hence, real-time adjustments to electrode positioning and incremental voltage pulses enable precise sculpturing, akin to woodcarving with a knife. Using this method, we demonstrate successful fabrication of short (10 μm) CFNEs with tip diameters of 100 nm, with excellent electrochemical properties and sculptured into cone- and needle-shaped electrodes. Employing these CFNEs for low-noise amperometric dopamine (DA) detection from individual 200 nm DA-loaded liposomes, combined with simulations, revealed that electrode shape influences detection efficiency based on vesicle size. These findings highlight the critical role of electrode geometry in vesicle-based electroanalysis.
碳纤维纳米尖端电极（CFNEs）对于在诸如突触和细胞内测量等受限空间中进行神经递质释放的电化学记录至关重要。然而，由于尖端尺寸控制不一致、重现性低和制造成功率低，制造具有小表面积以最小化噪声的CFNEs仍然具有挑战性。在此，我们提出一种可靠、用户友好的方法，该方法具有高重现性和成功率，用于在氢氧化钾液滴中通过显微镜引导的圆柱形碳纤维微电极电化学蚀刻来精确制造CFNEs。电极在液滴的液 - 气界面处的定位决定了蚀刻区域，而手动施加的时间和幅度控制的电压脉冲调节材料去除。因此，对电极定位的实时调整和增量电压脉冲能够实现精确雕刻，类似于用刀进行木雕。使用这种方法，我们展示了成功制造出尖端直径为100 nm的短（10μm）CFNEs，其具有优异的电化学性能，并雕刻成锥形和针形电极。将这些CFNEs用于从单个200 nm载多巴胺（DA）的脂质体中进行低噪声安培法检测多巴胺（DA），并结合模拟，揭示了电极形状基于囊泡大小影响检测效率。这些发现突出了电极几何形状在基于囊泡的电分析中的关键作用。
