Anodized gold surface enables mediator-free and low-overpotential electrochemical oxidation of NADH: A facile method for the development of an NAD+-dependent enzyme biosensor
Anodized gold surface enables mediator-free and low-overpotential electrochemical oxidation of NADH: A facile method for the development of an NAD+-dependent enzyme biosensor
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DOI：
10.1016/j.snb.2019.03.039
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发表时间：
2019-06-01
影响因子：
8.4
通讯作者：
Tamura, Tomohiro
中科院分区：
文献类型：
--
作者：
Mie, Yasuhiro;Yasutake, Yoshiaki;Tamura, Tomohiro
烟酰胺腺嘌呤二核苷酸（nicotinamide adenine dinucleotide，NADH）的还原形式需要一种有效的电化学氧化策略来开发NAD（+）依赖的酶基生物传感器。然而，在常规电极上氧化NADH需要高的过电位。在这里，我们报告说，纳米多孔金（NPG）表面制备的一个简单的方法，通过阳极氧化的传统的多晶金电极，使“直接”电化学氧化的NADH在极低的过电位。在伏安图中，在pH 7.5下，在-0.075 V处观察到氧化峰电流，相对于Ag垂直棒AgCl，而不使用介体。该电位比在常规金电极处获得的电位（0.6V）负得多。该活性可以用NPG表面的晶面来解释。由于检测电位低，抗坏血酸的干扰可忽略不计。我们使用来自巨大芽孢杆菌的NAD（+）依赖性D-葡萄糖1-脱氢酶（BmGDH-IV）在NPG评估D-葡萄糖传感。野生型和G259 A突变体的BmGDH-IV在D-葡萄糖的存在下表现出明确的生物电催化信号，根据其固有的特性。该突变体没有表现出可检测的信号，除了D-葡萄糖以外，证实了高度特异性的检测。因此，NPG的优异的NADH氧化活性允许开发NAD（+）依赖的基于酶的生物传感。
An efficient electrochemical oxidation strategy for the reduced form of nicotinamide adenine dinucleotide (NADH) is required to develop NAD(+)-dependent enzyme-based biosensors. However, oxidation of NADH at conventional electrodes requires high overpotentials. Here, we report that a nanoporous gold (NPG) surface prepared by a facile method via anodization of a conventional polycrystalline gold electrode enables "direct" electrochemical oxidation of NADH at an extremely low overpotential. In the voltammogram, the oxidation peak current was observed at -0.075 V vs. Ag vertical bar AgCl at pH 7.5 without the use of mediators. The potential was substantially more negative than that obtained at a conventional gold electrode (0.6 V). The activity could be explained in terms of the crystal planes at the NPG surface. Because of the low detection potential, interference by ascorbic acid was negligible. We evaluated D-glucose sensing using NAD(+)-dependent D-glucose 1-dehydrogenase from Bacillus megaterium (BmGDH-IV) at the NPG. Wild-type and a G259A mutant of BmGDH-IV exhibited clear bioelectrocatalytic signals in the presence of D-glucose, in accordance with their inherent properties. The mutant did not exhibit detectable signals for saccharides other than D-glucose, confirming the highly specific detection. Thus, the excellent NADH oxidation activity of NPG allows the development of NAD(+)-dependent enzyme-based biosensing.