Swamy B E Kumara, Venton B Jill
Dept. of Chemistry, University of Virginia, P.O. Box 400319, Charlottesville, VA 22904-4319, USA.
Analyst. 2007 Sep;132(9):876-84. doi: 10.1039/b705552h. Epub 2007 Jul 5.
Dopamine and serotonin are important neurotransmitters that interact in the brain. While dopamine is easily detected with electrochemical sensors, the detection of serotonin is more difficult because reactive species formed after oxidation can adsorb to the electrode, reducing sensitivity. Carbon nanotube treatments of electrodes have been used to increase the sensitivity, promote electron transfer, and reduce fouling. Most methods have focused on nanotube coatings of large electrodes and slower electrochemical techniques that are not conducive to measurements in vivo. In this study, we investigated carbon-fiber microelectrodes modified with single-walled carbon nanotubes for the co-detection of dopamine and serotonin in vivo. Using fast-scan cyclic voltammetry, S/N ratios for the neurotransmitters increased after nanotube coating. Electrocatalytic effects of nanotubes were not apparent at fast scan rates but faster kinetics were observed with slower scanning. Nanotube-modified microelectrodes showed significantly less fouling after exposure to serotonin than bare electrodes. The nanotube-modified electrodes were used to monitor stimulated dopamine and serotonin changes simultaneously in the striatum of anesthetized rat after administration of a serotonin synthetic precursor. These studies show that nanotube-coated microelectrodes can be used with fast scanning techniques and are advantageous for in vivo measurements of neurotransmitters because of their greater sensitivity and resistance to fouling.
多巴胺和血清素是在大脑中相互作用的重要神经递质。虽然多巴胺可以很容易地用电化学传感器检测到，但血清素的检测则更为困难，因为氧化后形成的反应性物质会吸附到电极上，从而降低灵敏度。电极的碳纳米管处理已被用于提高灵敏度、促进电子转移并减少污垢。大多数方法都集中在大电极的纳米管涂层以及不利于体内测量的较慢电化学技术上。在本研究中，我们研究了用单壁碳纳米管修饰的碳纤维微电极用于体内多巴胺和血清素的共同检测。使用快速扫描循环伏安法，纳米管涂层后神经递质的信噪比增加。在快速扫描速率下，纳米管的电催化作用不明显，但在较慢扫描时观察到更快的动力学。与裸电极相比，纳米管修饰的微电极在暴露于血清素后显示出明显更少的污垢。纳米管修饰的电极用于在给予血清素合成前体后监测麻醉大鼠纹状体中刺激引起的多巴胺和血清素变化。这些研究表明，纳米管涂层微电极可与快速扫描技术一起使用，并且由于其更高的灵敏度和抗污垢能力，有利于神经递质的体内测量。
