Department of Analytical Chemistry, Institute of Fine Chemistry and Nanochemistry (IAQFN), University of Córdoba, Campus of Rabanales, E-14071 Córdoba, Spain.
Anal Chim Acta. 2012 Feb 3;713:1-6. doi: 10.1016/j.aca.2011.11.049. Epub 2011 Dec 1.
An enzymatic fluorimetric method for the determination of polyphenol compounds in beverages is described, which is based on the temporal inhibition caused by these compounds on the oxidation of the long wavelength fluorophor indocyanine green (λ(ex) 764 nm, λ(em) 806 nm), in the presence of the enzyme laccase and positively charged gold nanoparticles (AuNPs). The oxidation of the dye gives rise to a fast decrease in its fluorescence, but it is delayed by the polyphenol, obtaining a time period directly proportional to its concentration, which has been used as the analytical parameter. The behaviour of several benzenediols and benzenetriols in the system and the modification of the activity of the enzyme by its interaction with AuNPs have been studied. The system has been optimized using gallic acid as a polyphenol model, but the dynamic ranges of the calibration graphs and the detection limits for several of the polyphenols assayed were obtained (μmol L(-1)): gallic acid (0.13-5, 0.04), catechol (0.08-5, 0.01), hydroquinone (0.05-2, 0.01), hydroxyhydroquinone (0.09-5, 0.03), pyrogallol (0.17-5, 0.04). Most of the values of the regression coefficients were 0.999 and the precision of the method, expressed as RSD% and checked at two concentration levels of each analyte, ranged between 1.8 and 5.6%. The method has been applied to the determination of polyphenol content in several foodstuff samples and the results compared with those obtained with the standard Folin-Ciocalteu method.
一种用于测定饮料中多酚化合物的酶促荧光法，该方法基于这些化合物在酶漆酶和带正电荷的金纳米粒子（AuNPs）存在下对长波长荧光染料吲哚菁绿（λ（ex）764nm，λ（em）806nm）氧化的时间抑制。染料的氧化会导致其荧光迅速下降，但被多酚延迟，获得一个与浓度直接成正比的时间段，该时间段被用作分析参数。研究了几种苯二酚和苯三醇在该体系中的行为以及多酚与 AuNPs 相互作用对酶活性的修饰。使用没食子酸作为多酚模型对该体系进行了优化，但获得了几种多酚的校准曲线的动态范围和检测限（μmol L（-1））：没食子酸（0.13-5，0.04）、儿茶酚（0.08-5，0.01）、对苯二酚（0.05-2，0.01）、邻苯二酚（0.09-5，0.03）、焦儿茶酚（0.17-5，0.04）。大多数回归系数的值为 0.999，方法的精密度，以相对标准偏差（RSD%）表示，并在每个分析物的两个浓度水平进行检查，范围在 1.8 到 5.6%之间。该方法已应用于几种食品样品中多酚含量的测定，并将结果与标准福林-酚法进行了比较。
