Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, The Chinese Academy of Sciences (CAS) , Beijing 100190, People's Republic of China.
Anal Chem. 2014 May 20;86(10):5017-23. doi: 10.1021/ac500622m. Epub 2014 May 7.
The abnormal level of O2 could disturb various neurochemical processes and even induce neural injury and brain dysfunction. In order to assess critical roles of O2 in the neurochemical processes, it is essential to perform in vivo monitoring of the dynamic changes of O2. In this study, we develop a new electrochemical method for selectively monitoring O2 in vivo, using platinized vertically aligned carbon nanotube (VACNT)-sheathed carbon fibers (Pt/VACNT-CFs) as the electrodes. The VACNT-sheathed CFs (VACNT-CFs) are produced via the pyrolysis of iron phthalocyanine (FePc) on the surface of CFs, followed by electrochemical deposition of platinum nanoparticles to form Pt/VACNT-CFs. The resulting Pt/VACNT-CF microelectrodes exhibit fast overall kinetics for the O2 reduction via a four-electron reduction process without the formation of toxic H2O2 intermediate. Consequently, effective and selective electrochemical methods are developed for the measurements of O2 in rat brain with the Pt/VACNT-CF microelectrodes, even in the presence of some species at their physiological levels, such as ascorbic acid, dopamine, uric acid, 5-hydroxytryptamine, and of the O2 fluctuation in rat brain in the early stage of global cerebral ischemia/reperfusion, mild hyperoxia, and hypoxia induced by exposing the animal, for a short time, to O2 and N2, respectively, and hindfeet pinch. The use of VACNT-CF as the support for Pt effectively improves the stability of Pt, as compared with the bare CF support, while the FePc pyrolysis ensures the VACNT-CFs to be reproducibly produced. Thus, this study offers a novel and reliable strategy for preparing new microelectrodes for in vivo monitoring of O2 in various physiological processes with a high sensitivity and selectivity.
氧的异常水平可能会干扰各种神经化学过程，甚至导致神经损伤和大脑功能障碍。为了评估氧在神经化学过程中的关键作用，有必要对氧的动态变化进行体内监测。在这项研究中，我们开发了一种新的电化学方法，使用镀铂垂直排列的碳纳米管（VACNT）-碳纤维（Pt/VACNT-CFs）作为电极，用于体内选择性监测氧。VACNT 包裹碳纤维（VACNT-CFs）是通过碳纤维表面热解铁酞菁（FePc），然后电化学沉积铂纳米颗粒形成 Pt/VACNT-CFs 制备的。所得到的 Pt/VACNT-CF 微电极对氧的还原具有快速的整体动力学，通过四电子还原过程而没有形成有毒的 H2O2 中间产物。因此，即使在一些生理水平的物质（如抗坏血酸、多巴胺、尿酸、5-羟色胺）存在下，也开发了有效的、选择性的电化学方法，用于用 Pt/VACNT-CF 微电极测量大鼠脑中的氧，并且还能够测量大鼠大脑在全脑缺血再灌注早期、轻度高氧和短暂暴露于氧气和氮气引起的缺氧阶段的氧波动，以及后脚夹捏引起的氧波动。与裸碳纤维（CF）载体相比，VACNT-CF 作为 Pt 的载体，有效地提高了 Pt 的稳定性，而 FePc 的热解确保了 VACNT-CFs 能够可重复地制备。因此，这项研究为在各种生理过程中用高灵敏度和选择性对氧进行体内监测提供了一种新的、可靠的策略。
