Faculty of Science and Engineering, Manchester Metropolitan University, Chester Street, Manchester, M1 5GD, UK.
Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, SP, 13566-590, Brazil.
Mikrochim Acta. 2019 Feb 22;186(3):200. doi: 10.1007/s00604-019-3315-y.
The electroanalytical detection of the neurotransmitter dopamine (DA) in the presence of uric acid (UA) is explored for the first time using commercially procured nanodiamonds (NDs). These are electrically wired via surface modification upon screen-printed graphite macroelectrodes (SPEs). The surface coverage of the NDs on the SPEs was explored in order to optimize electroanalytical outputs to result in well-resolved signals and in low limits of detection. The (electro)analytical outputs are observed to be more sensitive than those achieved at bare (unmodified) SPEs. Such responses, previously reported in the academic literature have been reported to be electrocatalytic and have been previously attributed to the presence of surface sp carbon and oxygenated species on the surface of the NDs. However, XPS analysis reveals the commercial NDs to be solely composed of nonconductive sp carbon. The low/negligible electroconductivity of the NDs was further confirmed when ND paste electrodes were fabricated and found to exhibit no electrochemical activity. The electroanalytical enhancement, when using NDs electronically wired upon SPEs, is attributed not to the NDs themselves being electrocatalytic, as reported previously, but rather changes in mass transport where the inert NDs block the underlying electroactive SPEs and create a random array of graphite microelectrodes. The electrode was applied to simultaneous sensing of DA and UA at pH 5.5. Figures of merit include (a) low working potentials of around 0.27 and 0.35 V (vs. Ag/AgCl); and (b) detection limits of 5.7 × 10 and 8.9 × 10 M for DA and UA, respectively. Graphical abstract The electroanalytical enhancement of screen-printed electrodes modified with inert/non-conductive nanodiamonds is due to a change in mass transfer where the inert nanodiamonds facilitate the production of a random microelectrode array.
首次使用商业采购的纳米金刚石（NDs）探索了在尿酸（UA）存在下神经递质多巴胺（DA）的电分析检测。这些通过在丝网印刷石墨宏观电极（SPEs）上进行表面修饰来进行电连接。探索了 NDs 在 SPEs 上的表面覆盖率，以优化电分析输出，从而产生分辨率良好的信号和低检测限。与裸（未修饰）SPEs 相比，观察到（电）分析输出更灵敏。之前在学术文献中报道的此类响应被认为是电催化的，并且以前归因于 NDs 表面存在表面 sp 碳和含氧物种。然而，XPS 分析表明商业 NDs 仅由非导电 sp 碳组成。当制备 ND 糊电极并发现其没有电化学活性时，进一步证实了 ND 的低/可忽略的电导率。当使用电子连接在 SPE 上的 NDs 时，电分析增强归因于 ND 本身不是之前报道的电催化，而是质量传输的变化，其中惰性 ND 阻止了下面的电活性 SPE 并创建了随机的石墨微电极阵列。该电极用于在 pH 5.5 下同时感应 DA 和 UA。优点包括（a）约 0.27 和 0.35 V（相对于 Ag/AgCl）的低工作电位；和（b）DA 和 UA 的检测限分别为 5.7×10 和 8.9×10 M。
