Lactate, a key metabolite of the anerobic metabolic pathway serves as a biomarker for lactic acidosis in clinical diagnostics. A variety of electrochemical biosensors have been exploited for the determination of lactate. Here we describe an improved electrochemical lactic acid biosensor that utilizes self-assembled monolayers (SAMs) of cysteamine-modified gold nanoparticles (AuNPs) on flexible tungsten microwire electrode to immobilize lactate dehydrogenase (LDH) to the microwire electrode. The fabricated AuNP-cysteamine-LDH electrode showed excellent behavior towards lactic acid at pH 6 and at 35 °C at an applied potential of +0.4 V (vs Ag/AgCl reference electrode). The biosensor exhibited a linear dynamic range of $500~\mu \text{M}$ to 7 mM with a very high sensitivity of $31.40~\mu \text{A}$ /mM cm². The biosensor demonstrated good selectivity towards lactic acid, wherein a nafion layer was utilized to screen out interfering species. The AuNP-cysteamine-LDH electrode remained stable up to 18 days. The practicality of the AuNP-cysteamine-LDH electrode was assessed by determining lactic acid concentrations in sera and a sensitivity of $73.16~\mu \text{A}$ / mM cm² was observed up to 5 mM.

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基于纳米金修饰微丝电极固定乳酸脱氢酶的乳酸生物传感器

乳酸是无氧代谢途径的关键代谢物，可作为临床诊断中乳酸性酸中毒的生物标志物。多种电化学生物传感器已被用于测定乳酸。在这里，我们描述了一种改进的电化学乳酸生物传感器，它利用半胱胺修饰的金纳米粒子 (AuNPs) 在柔性钨微丝电极上的自组装单层 (SAMs) 将乳酸脱氢酶 (LDH) 固定到微丝电极上。制造的 AuNP-半胱胺-LDH 电极在 pH 6 和 35°C 下在 +0.4 V（相对于 Ag/AgCl 参比电极）的施加电位下对乳酸表现出优异的行为。生物传感器的线性动态范围为 $500~\mu \text{M}$ 至 7 mM，具有非常高的灵敏度 $31.40~\mu\text{A}$ /毫米厘米²。该生物传感器对乳酸表现出良好的选择性，其中利用 nafion 层筛选出干扰物质。AuNP-半胱胺-LDH 电极保持稳定长达 18 天。AuNP-半胱胺-LDH电极的实用性通过测定血清中的乳酸浓度和灵敏度来评估 $73.16~\mu\text{A}$ 观察到高达5mM的/mM cm ²。