Institute of Environmental Sciences (IUCA), University of Zaragoza, Zaragoza, Spain.
Biosens Bioelectron. 2011 Mar 15;26(7):3254-9. doi: 10.1016/j.bios.2010.12.036. Epub 2010 Dec 30.
Ochratoxin A (OTA) is one of the most important mycotoxin contaminants of foods, particularly cereals and cereal products, with strict low regulatory levels (of ppb) in many countries worldwide. An electrochemical competitive aptamer-based biosensor for OTA is described. Paramagnetic microparticle beads (MBs) were functionalized with an aptamer specific to OTA, and were allowed to compete with a solution of the mycotoxin conjugated to the enzyme horseradish peroxidase (OTA-HRP) and free OTA. After separation and washing steps helped with magnetic separations, the modified MBs were localized on disposable screen-printed carbon electrodes (SPCEs) under a magnetic field, and the product of the enzymatic reaction with the substrate was detected with differential-pulse voltammetry. In addition to magnetic separation assays, other competitive schemes (direct/indirect aptasensors performed on the SPCEs surface or using gold nanoparticles functionalized with the aptamer) were preliminary tested, optimized and compared. The magnetic aptasensor showed a linear response to OTA in the range 0.78-8.74 ng mL(-1) and a limit of detection of 0.07±0.01 ng mL(-1), and was accurately applied to extracts of certified and spiked wheat samples with an RSD lower than about 8%.
赭曲霉毒素 A（OTA）是食品中最重要的霉菌毒素污染物之一，尤其是在许多国家，谷物及其制品中的 OTA 含量都受到严格的低监管水平（ppb）限制。本文描述了一种基于电化学竞争适配体的 OTA 生物传感器。将顺磁微球（MB）用针对 OTA 的适配体功能化，并使其与与辣根过氧化物酶（OTA-HRP）偶联的霉菌毒素溶液和游离 OTA 进行竞争。在分离和洗涤步骤（有助于磁分离）之后，修饰后的 MB 在磁场下定位于一次性丝网印刷碳电极（SPCE）上，并通过差分脉冲伏安法检测与底物的酶反应产物。除了磁分离测定法之外，还初步测试、优化并比较了其他竞争方案（直接/间接适配体传感器在 SPCE 表面上进行或使用与适配体功能化的金纳米粒子进行）。磁适配体传感器对 OTA 的线性响应范围为 0.78-8.74ngmL(-1)，检测限为 0.07±0.01ngmL(-1)，并准确应用于认证和加标小麦样品的提取物，其相对标准偏差（RSD）低于约 8%。
