基于碳量子点过氧化物模拟酶的肌氨酸比色测定

以果皮为原料制备了水溶性碳量子点(CQDs), 透射电子显微镜分析表明其平均粒径为2.4 nm; 红外光谱分析证实CQDs表面富含含氧官能团. 所得CQDs可催化H₂O₂氧化3,3',5,5'-四甲基联苯胺(TMB)生成蓝色氧化产物(ox-TMB). 基于上述反应, 建立了测定H₂O₂的分析方法, 在pH=3.5, 温度40 ℃, TMB浓度为1.0 mmol/L及孵育时间15 min的条件下, 当H₂O₂浓度在5.0~100 μmol/L范围时, ox-TMB的吸光度随H₂O₂浓度的升高而线 性增强, 方法的检出限为3.0 μmol/L. 鉴于H₂O₂是肌氨酸氧化酶催化肌氨酸氧化的产物之一, 建立了CQDs催化H₂O₂氧化TMB间接测定肌氨酸的分析方法. 结果表明, 当肌氨酸浓度在0.5~350 μmol/L范围内时, 吸光度 与其浓度呈良好的线性关系, 方法的检出限为0.3 μmol/L; 将该方法应用于人体尿样的测定, 回收率为94%~99%.

Colorimetric Determination of Sarcosine with Carbon Quantum Dots as Mimetic Peroxidase

Water soluble carbon quantum dots（CQDs） were prepared from fruit skin. Transmission electron microscopy（TEM） analysis showed that the average particle size of the CQDs was 2.4 nm. Fourier transform infrared spectroscopy（FTIR） revealed that the surface of CQDs was predominated in oxygen-containing functional groups. The obtained CQDs could catalyze the H₂O₂-mediated oxidation of 3，3'，5，5'-tetramethylbenzidine（TMB） to produce the corresponding blue oxidized product（ox-TMB）. Thus， a simple method for the detection of H₂O₂ was established. Under the conditions of pH=3.5， temperature of 40 °C， 1.0 mmol/L TMB and incubation time of 15 min， the absorbance of ox-TMB increased linearly with the increase of H₂O₂ concentration in the range of 5.0—100 μmol/L， and the detection limit（3σ/k） for H₂O₂ was 3.0 μmol/L. Given the fact that H₂O₂ was one of the products of sarcosine oxidase（SOX）-catalyzed sarcosine oxidation， a method for the indirect detection of sarcosine based on CQDs-catalyzed and H₂O₂-mediated TMB oxidation was also deve-loped. The increase of ox-TMB absorbance enabled the sensitive determination of sarcosine in the range of 0.5—350 μmol/L， and the detection limit sarcosine was calculated to be 0.3 μmol/L. The method exhibited its potential application in the detection of sarcosine in human urine samples with the recovery of 94%—99%.