Department of Chemistry, University of Virginia, Charlottesville, VA 22901, USA.
Center for Nanophase Materials Sciences, Oak Ridge National Lab, Oak Ridge, TN, 37831, USA.
Angew Chem Int Ed Engl. 2024 Jul 22;63(30):e202405634. doi: 10.1002/anie.202405634. Epub 2024 Jun 21.
In vivo electrochemistry in small brain regions or synapses requires nanoelectrodes with long straight tips for submicron scale measurements. Nanoelectrodes can be fabricated using a Nanoscribe two-photon printer, but annealed tips curl if they are long and thin. We propose a new pulling-force strategy to fabricate a straight carbon nanoneedle structure. A micron-width bridge is printed between two blocks. The annealed structure shrinks during pyrolysis, and the blocks create a pulling force to form a long, thin, and straight carbon bridge. Parameterization study and COMSOL modeling indicate changes in the block size, bridge size and length affect the pulling force and bridge shrinkage. Electrodes were printed on niobium wires, insulated with aluminum oxide, and the bridge cut with focused ion beam (FIB) to expose the nanoneedle tip. Annealed needle diameters ranged from 400 nm to 5.25 μm and length varied from 50.5 μm to 146 μm. The electrochemical properties are similar to glassy carbon, with good performance for dopamine detection with fast-scan cyclic voltammetry. Nanoelectrodes enable biological applications, such as dopamine detection in a specific Drosophila brain region. Long and thin nanoneedles are generally useful for other applications such as cellular sensing, drug delivery, or gas sensing.
在小脑区域或突触进行活体电化学研究需要具有长直尖端的纳米电极，以实现亚微米级别的测量。纳米电极可以使用 Nanoscribe 双光子打印机来制造，但是如果电极又长又细，经过退火处理后的尖端会发生卷曲。我们提出了一种新的拉伸力策略来制造直的碳纳米针结构。在两个块体之间打印出一个微米宽度的桥。在热解过程中，退火结构会收缩，而块体则会产生拉力，从而形成长而细且直的碳桥。参数化研究和 COMSOL 建模表明，块体尺寸、桥的尺寸和长度的变化会影响拉伸力和桥的收缩。在铌丝上打印电极，用氧化铝进行绝缘，然后用聚焦离子束（FIB）切割桥，以暴露纳米针尖端。经过退火处理后的针的直径范围从 400nm 到 5.25μm，长度从 50.5μm 到 146μm 不等。电化学性能与玻璃碳相似，使用快速扫描循环伏安法对多巴胺的检测具有良好的性能。纳米电极可用于生物应用，例如在特定的果蝇大脑区域中检测多巴胺。长而细的纳米针通常也可用于其他应用，例如细胞传感、药物输送或气体传感。
