Analytical Chemistry Department, Faculty of Sciences, Aragón Institute of Nanoscience (INA-ICMA), University of Zaragoza, E-50009, Zaragoza, Spain.
Mikrochim Acta. 2020 Feb 18;187(3):174. doi: 10.1007/s00604-020-4141-y.
In this paper, it has been demonstrated that Au(III) is able to act instead of O in the oxidase enzymatic reaction, so that it becomes reduced to purple gold nanoparticles (AuNPs). The plasmon band (at 540 nm) can be used as the analytical signal. Tyramine has been determined using its enzymatic reaction with tyramine oxidase (TAO). The kinetic of the AuNP formation has been studied in the light of both the Avrami equation for crystallization and the Finke-Watsy mechanism for AuNP nucleation and growth. The effects of the Au(III), TAO and tyramine concentrations on the corresponding kinetic constants have been investigated. Working at room temperature, under optimal conditions (phosphate buffer pH 7.0, TAO 0.5 U.mL Au(III) 1 mM), the linear response ranges from 2.5 × 10 M to 3.3 × 10 M Tyramine (5.6% RSD) and the LOD is 2.9 × 10 M. Under these conditions, the signal is measured after 30 min reaction (to obtain the highest sensitivity), but this time can be significantly reduced by increasing the temperature (the reaction is finished after 4 min when working at 50 °C). The method has been applied to tyramine determination in a cheese sample with good results. The new scheme proposed in this paper can be extended, in principle, to other enzymatic methods based on oxidase enzymes. Graphical abstractTyramine is determined by measuring the plasmon band of the gold nanoparticles formed during its enzymatic reaction with Tyramine oxidase. Moreover, a mathematical model has been developed to explain the formation of the gold nanoparticles during the reaction.
在本文中，已经证明 Au(III) 能够在氧化酶酶促反应中代替 O 作用，从而被还原为紫色金纳米颗粒 (AuNPs)。等离子体带（在 540nm 处）可用作分析信号。通过使用酪氨酸氧化酶 (TAO) 与其进行的酶促反应来测定酪氨酸。根据结晶的 Avrami 方程和 AuNP 成核和生长的 Finke-Watsy 机制研究了 AuNP 形成的动力学。研究了 Au(III)、TAO 和酪氨酸浓度对相应动力学常数的影响。在室温下，在最佳条件下（磷酸盐缓冲液 pH 7.0、TAO 0.5 U.mL Au(III) 1 mM），线性响应范围为 2.5×10-6 M 至 3.3×10-6 M 酪氨酸（5.6% RSD），检出限为 2.9×10-6 M。在这些条件下，在 30 分钟反应后测量信号（以获得最高灵敏度），但通过升高温度可以显著缩短反应时间（在 50°C 下反应在 4 分钟后结束）。该方法已成功应用于奶酪样品中酪氨酸的测定。本文提出的新方案原则上可以扩展到其他基于氧化酶的酶促方法。
