Fraunhofer USA, Inc. Center for Coatings and Diamond Technologies, East Lansing, Michigan 48824-1226, United States.
Michigan State University , Department of Chemical Engineering, East Lansing, Michigan 48824-1226, United States.
Anal Chem. 2018 Feb 6;90(3):1951-1958. doi: 10.1021/acs.analchem.7b04045. Epub 2018 Jan 23.
Boron-doped diamond (BDD) is a promising electrochemical tool that exhibits excellent chemical sensitivity and stability. These intrinsic advantages coupled with the material's vast microfabrication flexibility make BDD an attractive sensing device. In this study, two different 3-in-1 BDD electrode sensors were fabricated, characterized, and investigated for their capability to detect isatin, an anxiogenic indole that possesses anticonvulsant activity. Each device was comprised of a working, reference, and auxiliary electrode, all made of BDD. Two different working electrode geometries were studied, a 2 mm diameter macroelectrode (MAC) and a microelectrode array (MEA). The BDD quasi-reference electrode was studied by measuring its potential against a traditional Ag/AgCl reference electrode. While the potential shifted as a function of solution pH, a miniscule potential drift was observed when holding the solution pH constant. Specifically, the BDD quasi-reference electrode had a potential of -0.2 V (vs Ag/AgCl) in a pH 7 solution, and this remained stable for a 30-h time period. For the detection of isatin, solutions were analyzed using both sensors in pH 7.4 phosphate buffered saline (PBS). Using the MEA sensor, the limit of detection (LOD, (3σ)/m) for isatin was found to be 0.04 μM; an increase to 0.22 μM was observed with the MAC sensor. These results were compared to those obtained from UV-vis spectrophotometry, where a 0.57 μM LOD was observed. The feasibility for use in a complex sample matrix was also examined by completing measurements in urine simulant. The results presented herein indicate that both 3-in-1 BDD sensors are applicable at low limits of detection with potential application as an electrochemical detector for chromatographic methods.
掺硼金刚石（BDD）是一种很有前途的电化学工具，具有出色的化学灵敏度和稳定性。这些内在优势加上材料的广泛微制造灵活性，使 BDD 成为一种有吸引力的传感设备。在这项研究中，制作了两种不同的三合一 BDD 电极传感器，对其检测色胺（一种具有抗惊厥活性的致焦虑吲哚）的能力进行了表征和研究。每个器件都由工作电极、参比电极和辅助电极组成，全部由 BDD 制成。研究了两种不同的工作电极几何形状，一种是 2 毫米直径的宏观电极（MAC）和微电极阵列（MEA）。通过测量其相对于传统的 Ag/AgCl 参比电极的电位来研究 BDD 准参比电极。虽然电位随溶液 pH 值而变化，但当溶液 pH 值保持不变时，观察到微小的电位漂移。具体而言，BDD 准参比电极在 pH 为 7 的溶液中的电位为-0.2 V（相对于 Ag/AgCl），在 30 小时的时间内保持稳定。为了检测色胺，在 pH 7.4 的磷酸盐缓冲盐水（PBS）中使用两种传感器对溶液进行了分析。使用 MEA 传感器，色胺的检测限（LOD，（3σ）/m）为 0.04 μM；使用 MAC 传感器，检测限增加到 0.22 μM。将这些结果与从紫外可见分光光度法获得的结果进行了比较，观察到 0.57 μM 的 LOD。还通过在尿模拟物中完成测量来检查在复杂样品基质中使用的可行性。本文介绍的结果表明，两种三合一 BDD 传感器都可在低检测限下应用，具有作为色谱方法电化学检测器的潜在应用。
