Enzyme-modified Pt nanoelectrodes for glutamate detection

IF 3.3 3区化学 Q2 CHEMISTRY, PHYSICAL

Faraday Discussions Pub Date : 2024-07-30 DOI:10.1039/d4fd00138a

Peibo Xu, Henry David Jetmore, Ran Chen, Mei Shen

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Abstract

We present here a glutamate oxidase (GluOx)-modified platinum (Pt) nanoelectrode with a planar geometry for glutamate detection. The Pt nanoelectrode was characterized using electrochemistry and scanning electron microscopy (SEM). The radius of the Pt nanoelectrode measured using SEM is ~210 nm. GluOx-modified Pt nanoelectrodes were generated by dip coating GluOx on the Pt nanoelectrode in a solution of 0.9% (wt%) bovine serum albumin (BSA), 0.126% (wt%) glutaraldehyde, and 100 U/mL GluOx. An increase in current was observed at +0.7 V vs. Ag/AgCl/1M KCl with adding increasing concentrations of glutamate. A two-sample t-test results showed that there is a significant difference for current at +0.7 V between the blank and the added lowest glutamate concentration, as well as between adjacent glutamate concentrations, confirming that the increase in current is related to the increased glutamate concentration. The experimental current-concentration curve of glutamate detection fitted well to the theoretical Michaelis-Menten curve. At the low concentration range (50 μM to 200 μM), a linear relationship between the current and glutamate concentration was observed. The Michaelis-Menten constants of Imax and Km were calculated to be 1.093 pA and 0.227 mM, respectively. Biosensor efficiency (the ratio of glutamate sensitivity to H2O2 sensitivity) is calculated to be 57.9%. Enzact (Imax /H2O2 sensitivity, an indicator of the amount of enzyme loaded on the electrode) of the GluOx-modified Pt nanoelectrode is 0.243 mM. We further compared the sensitivity of a GluOx-modified Pt nanoelectrode with a GluOx-modified carbon fiber microelectrode (7-μm diameter and a sensing length of ~350 μm). Glutamate detection on the GluOx-modified carbon fiber microelectrode fitted well to a Michaelis-Menten like response. Based on the fitting, the GluOx-modified carbon fiber microelectrode exhibited an Imax of 0.689 nA and a Km of 301.2 μM towards glutamate detection. The best linear range of glutamate detection on the GluOx-modified carbon fiber microelectrode is from 50 μM to 150 μM Glutamate. GluOx-modified carbon fiber microelectrode exhibited a higher potential requirement for glutamate detection comparing to the GluOx-modified Pt nanoelectrode.

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用于谷氨酸检测的酶修饰铂纳米电极

我们在此介绍一种具有平面几何形状的谷氨酸氧化酶（GluOx）修饰铂（Pt）纳米电极，用于谷氨酸检测。我们利用电化学和扫描电子显微镜（SEM）对铂纳米电极进行了表征。利用扫描电子显微镜测量的铂纳米电极半径约为 210 纳米。在 0.9% (wt%) 牛血清白蛋白 (BSA)、0.126% (wt%) 戊二醛和 100 U/mL GluOx 的溶液中，通过在铂纳米电极上浸涂 GluOx 生成了 GluOx 修饰的铂纳米电极。随着谷氨酸浓度的增加，在 +0.7 V 与 Ag/AgCl/1M KCl 的对比中观察到电流增加。双样本 t 检验结果表明，在 +0.7 V 处，空白与添加的最低谷氨酸浓度之间以及相邻谷氨酸浓度之间的电流差异显著，这证实了电流的增加与谷氨酸浓度的增加有关。谷氨酸检测的实验电流-浓度曲线与理论 Michaelis-Menten 曲线非常吻合。在低浓度范围内（50 μM 至 200 μM），电流与谷氨酸浓度之间呈线性关系。经计算，Imax 和 Km 的 Michaelis-Menten 常数分别为 1.093 pA 和 0.227 mM。生物传感器效率（谷氨酸敏感度与 H2O2 敏感度之比）计算值为 57.9%。GluOx 改性铂纳米电极的 Enzact（Imax /H2O2 灵敏度，电极上负载酶量的指标）为 0.243 mM。我们进一步比较了 GluOx 改性铂纳米电极与 GluOx 改性碳纤维微电极（直径 7 微米，传感长度约 350 微米）的灵敏度。GluOx 改性碳纤维微电极上的谷氨酸检测与类似 Michaelis-Menten 的反应非常吻合。根据拟合结果，GluOx 改性碳纤维微电极在谷氨酸检测方面的 Imax 为 0.689 nA，Km 为 301.2 μM。GluOx 改性碳纤维微电极检测谷氨酸的最佳线性范围为 50 μM 至 150 μM。与 GluOx 改性铂纳米电极相比，GluOx 改性碳纤维微电极检测谷氨酸的电位要求更高。

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来源期刊

Faraday Discussions 化学-物理化学

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259

期刊介绍： Discussion summary and research papers from discussion meetings that focus on rapidly developing areas of physical chemistry and its interfaces