College of Food and Biological Engineering, Jimei University, Xiamen, 361021, China.
Fujian Provincial Key Laboratory of Food Microbiology and Enzyme Engineering, Xiamen, 361021, Fujian Province, China.
Mikrochim Acta. 2019 May 2;186(5):322. doi: 10.1007/s00604-019-3436-3.
A specific and sensitive colorimetric aptasensor is described for the determination of Malachite Green (MG). It is exploiting the inhibition of the peroxidase-like activity of gold nanoparticles (AuNPs). The AuNPs act as enzyme mimics that catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by HO to yield a dark blue solution. The catalytic activity is inhibited by hexadecyl trimethyl ammonium ion, specifically by cetyltrimethylammonium bromide (CTAB), which causes the aggregation of AuNPs. If a (negatively charged) RNA-aptamer against MG is added, it binds to the positively charged CTAB and prevents aggregation. This enhances the enzyme mimicking activity of the AuNPs and leads to the formation of a dark blue solution. However, in the presence of MG, the aptamer binds to MG, and leads to the aggregation of AuNPs again. The aggregated AuNPs possess a light blue color. A colorimetric method (best performed at 650 nm) was work out that can detect MG in a concentration range from 10 to 500 nmol L. The detection limit based on 3σ/k criterion is 1.8 nmol L. The assay is highly specific and accurate. Recoveries from spiked real samples (aquaculture water) ranged from 80% to 120%. Graphical abstract Based on the inhibition of cetyltrimethyal ammonium ion and the enhancement of RNA-aptamer, the differences of the peroxidase-like activities of AuNPs can be greatly enlarged with and without MG, by which a colorimetric aptasensor can be constructed for the detection of Malachite Green (MG).
一种用于测定孔雀石绿（MG）的特异性和灵敏的比色适体传感器。它利用了金纳米粒子（AuNPs）过氧化物酶样活性的抑制作用。AuNPs 作为酶模拟物，催化 HO 对 3,3',5,5'-四甲基联苯胺（TMB）的氧化，生成深蓝色溶液。催化活性被十六烷基三甲基铵离子（特别是十六烷基三甲基溴化铵（CTAB））抑制，导致 AuNPs 聚集。如果添加针对 MG 的（带负电荷）RNA 适体，它将与带正电荷的 CTAB 结合，从而阻止聚集。这增强了 AuNPs 的酶模拟活性，并导致深蓝色溶液的形成。然而，在存在 MG 的情况下，适体与 MG 结合，导致 AuNPs 再次聚集。聚集的 AuNPs 具有浅蓝色。制定了一种比色法（最佳在 650nm 下进行），可在 10 至 500nmol·L 范围内检测 MG。基于 3σ/k 准则的检测限为 1.8nmol·L。该测定法具有高度特异性和准确性。从加标实际样品（水产养殖水）中的回收率在 80%至 120%之间。摘要基于十六烷基三甲基铵离子的抑制作用和 RNA-适体的增强作用，可以大大放大有无 MG 时 AuNPs 的过氧化物酶样活性的差异，从而可以构建用于检测孔雀石绿（MG）的比色适体传感器。
