Hydrogen peroxide (H₂O₂) and ascorbic acid (AA), acting as two significant indicative species, correlate with the oxidative stress status in living brains, which have historically been considered to be involved mainly in neurodegenerative disorders such as Alzheimer’s disease, Huntington’s disease, and Parkinson’s disease (PD). The development of efficient biosensors for the simultaneous measurement of their levels in living brains is vital to understand their roles played in the brain and their interactive relationship in the progress of these diseases. Herein, a robust ratiometric electrochemical microsensor was rationally designed to realize the determination of H₂O₂ and AA simultaneously. Therefore, a specific probe was designed and synthesized with both recognition units responsible for reacting with H₂O₂ to produce a detectable signal on the microsensor and linkage units helping the probe modify onto the carbon substrate. A topping ingredient, single-walled carbon nanotubes (SWCNTs) was added on the surface of the electrode, with the purpose of not only facilitating the oxidation of AA but also absorbing methylene blue (MB), prompting to read out the inner reference signal. This proposed electrochemical microsensor exhibited a robust ability to real-time track H₂O₂ and AA in linear ranges of 0.5–900 and 10–1000 μM with high selectivity and accuracy, respectively. Eventually, the efficient electrochemical microsensor was successfully applied to the simultaneous measurement of H₂O₂ and AA in the rat brain, followed by microinjection, and in the PD mouse brain.

中文翻译：

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用于同时测量活体大脑中过氧化氢和抗坏血酸的高效电化学微传感器

过氧化氢 (H ₂ O ₂ ) 和抗坏血酸 (AA) 作为两种重要的指示物质，与活体大脑中的氧化应激状态相关，历来认为这主要与神经退行性疾病有关，例如阿尔茨海默氏病、亨廷顿氏舞蹈症病和帕金森病（PD）。开发有效的生物传感器来同时测量它们在活体大脑中的水平对于了解它们在大脑中的作用以及它们在这些疾病进展中的相互作用关系至关重要。本文合理设计了一种稳健的比率电化学微传感器，以实现H ₂ O ₂和AA的同时测定。因此，设计并合成了一种特定的探针，其具有负责与H ₂ O ₂反应以在微传感器上产生可检测信号的识别单元和帮助探针修饰到碳基底上的连接单元。电极表面添加了一种配料——单壁碳纳米管（SWCNT），目的不仅可以促进AA的氧化，还可以吸收亚甲基蓝（MB），促使读出内部参考信号。这种电化学微传感器表现出强大的能力，可以分别在0.5-900和10-1000μM的线性范围内实时跟踪H ₂ O ₂和AA，并具有高选择性和准确性。最终，高效电化学微传感器成功应用于大鼠脑中H ₂ O _{2和AA的同步测量，随后显微注射以及PD小鼠脑中。}