Department of Chemistry , University of Cincinnati , Cincinnati , Ohio 45221 , United States.
ACS Sens. 2019 Feb 22;4(2):479-487. doi: 10.1021/acssensors.8b01504. Epub 2019 Jan 30.
Purine detection in the brain with fast-scan cyclic voltammetry (FSCV) at carbon-fiber microelectrodes (CFME) has become increasingly popular over the past decade; despite the growing interest, an in-depth analysis of how purines interact with the CFME at fast-scan rates has not been investigated. Here, we show how the functional group type and placement in the purine ring modulate sensitivity, electron transfer kinetics, and adsorption on the carbon-fiber surface. Similar investigations of catecholamine interaction at CFME with FSCV have informed the development of novel catecholamine-based sensors and is needed for purine-based sensors. We tested purine bases with either amino, carbonyl, or both functional groups substituted at different positions on the ring and an unsubstituted purine. Unsubstituted purine showed very little to no interaction with the electrode surface, indicating that functional groups are important for interaction at the CFME. Purine nucleosides and nucleotides, like adenosine, guanosine, and adenosine triphosphate, are most often probed using FSCV due to their rich extracellular signaling modalities in the brain. Because of this, the extent to which the ribose and triphosphate groups affect the purine-CFME interaction was also evaluated. Amino functional groups facilitated the interaction of purine analogues with CFME more than carbonyl groups, permitting strong adsorption and high surface coverage. Ribose and triphosphate groups decreased the oxidative current and slowed the interaction at the electrode which is likely due to steric effects and electrostatic repulsion. This work provides insight into the factors that affect purine-CFME interaction and conditions to consider when developing purine-targeted sensors for FSCV.
在过去十年中，使用碳纤维微电极（CFME）的快速扫描循环伏安法（FSCV）检测大脑中的嘌呤已变得越来越流行；尽管人们对此越来越感兴趣，但尚未深入分析嘌呤如何在快速扫描速率下与 CFME 相互作用。在这里，我们展示了嘌呤环中的官能团类型和位置如何调节灵敏度、电子转移动力学以及在碳纤维表面的吸附。对 CFME 上儿茶酚胺与 FSCV 相互作用的类似研究为新型儿茶酚胺基传感器的发展提供了信息，并且是嘌呤基传感器所必需的。我们测试了嘌呤碱基，其中嘌呤环上的不同位置取代有氨基、羰基或两者的官能团，以及未取代的嘌呤。未取代的嘌呤与电极表面几乎没有相互作用，这表明官能团对于 CFME 上的相互作用很重要。由于其在大脑中丰富的细胞外信号转导方式，嘌呤核苷和核苷酸（如腺苷、鸟苷和三磷酸腺苷）通常使用 FSCV 进行探测。因此，还评估了核糖和三磷酸基团对嘌呤-CFME 相互作用的影响程度。与羰基相比，氨基官能团更有利于嘌呤类似物与 CFME 的相互作用，从而允许强吸附和高表面覆盖。核糖和三磷酸基团降低了氧化电流并减缓了电极上的相互作用，这可能是由于空间位阻和静电排斥所致。这项工作深入了解了影响嘌呤-CFME 相互作用的因素，以及在开发用于 FSCV 的嘌呤靶向传感器时需要考虑的条件。
