Fourier Transform Infrared Spectrovoltammetry and Quantitative Modeling of Analytes in Kinetically Constrained Redox Mixtures
Fourier Transform Infrared Spectrovoltammetry and Quantitative Modeling of Analytes in Kinetically Constrained Redox Mixtures
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DOI：
10.1021/acs.analchem.9b00859
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发表时间：
2019-08-06
影响因子：
7.4
通讯作者：
Proshlyakov, Denis A.
中科院分区：
文献类型：
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作者：
John, Christopher W.;Proshlyakov, Denis A.
不支持电极上的直接电子转移的氧化还原活性分析物，如具有掩埋氧化还原中心的蛋白质，对表征其结构和热力学性质提出了挑战。复杂的氧化还原混合物支持的分析物中的间接转换的调查需要从介质的动力学限制和光谱干扰之间的仔细平衡。使用亚甲基绿色和噻托溴铵醋酸盐作为氧化还原介质和肌红蛋白作为分析物，我们证明，正常脉冲光谱伏安法（NPSV）与傅里叶变换红外（FT-IR）检测和随后的全球光谱回归分析，可以解决结构和热力学性质，同时很少的先验信息。无论是E-1/2和无偏氧化还原差FT-IR光谱的Fe（II）/Fe（III）的还原和氧化NPSV模式的肌红蛋白的氧化还原对是在良好的协议与先前报道的独立技术。介质/分析物相互作用的热力学和动力学限制进行了研究，使用全面的半经验动力学模拟模型。这种建模工作产生了一个灵活的计算工具，能够定量预测介导的电化学研究中的氧化还原反应，并定义其局限性，从而大大扩展了正式的介质/分析物浓度比规则的范围和精度。
Redox-active analytes that do not support direct electron transfer on the electrode, such as proteins with buried redox centers, pose challenges to characterization of their structural and thermodynamic properties. Investigations of indirect transitions in analytes supported by complex redox mixtures require a careful balance between kinetic limitations and spectral interference from the mediators. Using methylene green and thionine acetate as redox mediators and myoglobin as the analyte, we demonstrate that normal pulse spectrovoltammetry (NPSV) with Fourier transform infrared (FT-IR) detection and subsequent global spectral regression analysis can resolve structural and thermodynamic properties simultaneously with little a priori information. Both the E-1/2 and unbiased redox difference FT-IR spectra of the Fe(II)/Fe(III) redox couple of myoglobin in reduction and oxidation NPSV modes were in good agreement with those reported earlier by independent techniques. The thermodynamic and kinetic limitations of mediators/analyte interactions were investigated using comprehensive semiempirical kinetic simulation models. This modeling effort yielded a flexible computational tool capable of quantitatively predicting the redox response in mediated electrochemical studies and defining its limitations, thus greatly expanding the range and precision of the formal mediator/analyte concentration ratio rule.