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A novel pH sensor with application to milk based on electrochemical oxidative quinone-functionalization of tryptophan residues
Journal of Electroanalytical Chemistry ( IF 4.1 ) Pub Date : 2020-02-01 , DOI: 10.1016/j.jelechem.2020.113871
Gengxin Hu , Nanxi Li , Yuwei Zhang , Hong Li

Abstract The electrochemical oxidative quinone-functionalization of tryptophan (Trp) residues, and the proton-coupled electron transfer properties between quinonized Trp (Trp=O) and its re-reduced species (Trp-OH) are investigated for potentiometric pH sensors. The Trp=O/Trp-OH couples are assembled on a graphite electrode using multiple cyclic voltammetry, and exhibit a pair of well-defined redox peaks at redox potential of 0.090 V (vs. SCE) at pH 7.0 and 298 K. The proton-coupled electron transfer properties of Trp=O/Trp-OH couples are dependent on electrode substrate material, incubation temperature and pH values, and Trp residue sources including amino acid, peptide and protein. The Trp=O/Trp-OH-based surface-confined exothermic electrode reaction rates show a decrease with increasing incubation temperature from 283 to 323 K at pH 5.0. Both of redox peak potential and open-circuit potential under optimum conditions have a good linear pH dependence between 1.0 and 12.0 with sensitivity of more than 52 mV pH −1 and relative standard derivation of 1.5%. The proposed potentiometric pH sensor has significant advantages of low cost, good stability and reproducibility, and strong anti-interference ability. The present study shows a new approach to endow Trp, Trp-containing peptides and non-conjugated proteins with analogous proton-coupled electron transfer performance to prosthetic groups of quinoproteins for monitoring pH changes in milk samples.

中文翻译:

基于色氨酸残基电化学氧化醌功能化的应用于牛奶的新型 pH 传感器

摘要 针对电位 pH 传感器,研究了色氨酸 (Trp) 残基的电化学氧化醌功能化,以及醌化 Trp (Trp=O) 与其再还原物质 (Trp-OH) 之间的质子耦合电子转移特性。使用多重循环伏安法将 Trp=O/Trp-OH 对组装在石墨电极上,并在 pH 7.0 和 298 K 下,在 0.090 V(相对于 SCE)的氧化还原电位下显示出一对明确的氧化还原峰。质子Trp=O/Trp-OH 对的耦合电子转移特性取决于电极基底材料、孵育温度和 pH 值,以及包括氨基酸、肽和蛋白质在内的 Trp 残基来源。在 pH 5.0 时,Trp=O/Trp-OH 基于表面限制的放热电极反应速率随着孵育温度从 283 K 增加到 323 K 而降低。最佳条件下的氧化还原峰电位和开路电位均在 1.0 和 12.0 之间具有良好的线性 pH 依赖性,灵敏度超过 52 mV pH -1,相对标准导数为 1.5%。所提出的电位pH传感器具有成本低、稳定性和重现性好、抗干扰能力强等显着优点。本研究展示了一种新方法,可赋予 Trp、含 Trp 的肽和非共轭蛋白质类似的质子耦合电子转移性能,以监测牛奶样品中的 pH 值变化。所提出的电位pH传感器具有成本低、稳定性和重现性好、抗干扰能力强等显着优点。本研究展示了一种新方法,可赋予 Trp、含 Trp 的肽和非共轭蛋白质类似的质子耦合电子转移性能,以监测牛奶样品中的 pH 值变化。所提出的电位pH传感器具有成本低、稳定性和重现性好、抗干扰能力强等显着优点。本研究展示了一种新方法,可赋予 Trp、含 Trp 的肽和非共轭蛋白质类似的质子耦合电子转移性能,以监测牛奶样品中的 pH 值变化。
更新日期:2020-02-01
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