In situ detection of dopamine (DA) at single-cell level is critical for exploring neurotransmitter-related biological processes and diseases. However, the low content of DA and a variety of distractors with similar oxidation potentials as DA in cells brought great challenges. Here, a sensitive and specific electrochemical nanosensor was proposed for in situ detection of DA in single living cells based on nanodiamond (ND) and molecularly imprinted polymer (MIP)-functionalized carbon fiber nanoelectrode (ND/MIP/CFNE). Due to its excellent electrocatalytic property, ND was modified to the surface of CFNE based on amide bonding. Compared with bare CFNE, ND-modified CFNE can enhance oxidation currents of DA by about 4-fold, improving signal-to-noise ratio and detection sensitivity. MIP was further electropolymerized on the surface of nanoelectrodes to achieve specific capture and recognition of DA, which could avoid the interference of complex matrix and analogs in cells. Taking advantage of the precise positioning capability of a single-cell analyzer and micromanipulator, ND/MIP/CFNE could be precisely inserted into different locations of single cells and monitor oxidation signal of DA. The concentration of DA in the cytoplasm of single pheochromocytoma (PC12) cell was measured to be about 0.4 μM, providing a sensitive and powerful method for single-cell detection. Furthermore, the nanoelectrodes can monitor the fluctuation of intracellular DA under drug stimulation, providing new ideas and methods for new drug development and efficacy evaluation.

中文翻译：

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通过分子印迹聚合物功能化纳米电极原位检测单个活细胞中的多巴胺

单细胞水平的多巴胺（DA）原位检测对于探索神经递质相关的生物过程和疾病至关重要。然而，细胞内DA含量低以及多种与DA具有相似氧化电位的干扰物带来了巨大的挑战。在此，提出了一种基于纳米金刚石（ND）和分子印迹聚合物（MIP）功能化碳纤维纳米电极（ND/MIP/CFNE）的灵敏且特异的电化学纳米传感器，用于原位检测单个活细胞中的DA。由于ND具有优异的电催化性能，基于酰胺键对CFNE表面进行改性。与裸CFNE相比，ND修饰的CFNE可以将DA的氧化电流增强约4倍，提高信噪比和检测灵敏度。 MIP进一步电聚合在纳米电极表面，实现对DA的特异性捕获和识别，可以避免细胞内复杂基质和类似物的干扰。利用单细胞分析仪和显微操作器的精确定位能力，ND/MIP/CFNE可以精确插入单细胞的不同位置并监测DA的氧化信号。测得单个嗜铬细胞瘤（PC12）细胞胞质中DA的浓度约为0.4 μM，为单细胞检测提供了灵敏而有力的方法。此外，纳米电极可以监测药物刺激下细胞内DA的波动，为新药研发和药效评价提供新思路和方法。