Abstract：
In this work, a sensitive colorimetric bioassay method based on a poly(adenine) aptamer (polyA apt) and gold nanoparticles (AuNPs) was developed for the determination of aflatoxin B1 (AFB1). The polyA apt, adsorbed on the AuNPs, especially can bind to the analyte while deterring non-specific interactions. This nano aptasensor uses cationic polymer poly(diallyl dimethyl ammonium chloride) (PDDA), as an aggregating agent, to aggregate gold nanoparticles. PolyA apt-decorated gold nanoparticles (AuNPs/polyA apt) show resistance to PDDA-induced aggregation and maintains their dispersed state (red color) with the optical absorbance signal at λ = 520 nm. However, in the presence of AFB1 in the assay solution, the specific aptamer reacts with high affinity and folds into its three-dimensional form. Aggregation of AuNPs induced by PDDA caused their optical signal shift to λ = 620 nm (blue color). AFB1 concentration in the bioassay solution determines the amount of optical signal shift. Therefore, optical density ratio in two wavelengths (A620/520) can be used as a sturdy colorimetric signal to detect the concentration of aflatoxin B1. AFB1 was linearly detected between 0.5 and 20 ng mL-1, with a detection limit of 0.09 ng mL-1 (S/N = 3). The fabricated aptasensor was applied to the detection of AFB1 in real corn samples.
摘要：
在这项工作中,开发了一种基于聚（腺嘌呤）适体（polyAapt）和金纳米颗粒（AuNPs）的灵敏比色生物测定方法，用于测定黄曲霉毒素B1（AFB1）。PolyAapt，吸附在AuNPs上，特别是可以结合到分析物，同时阻止非特异性相互作用。这种纳米aptasensor使用阳离子聚合物聚（二烯丙基二甲基氯化铵）（PDDA），作为聚合代理，聚集金纳米颗粒。PolyAapt修饰的金纳米颗粒（AuNP/polyAapt）显示出对PDDA诱导的聚集的抵抗力，并保持其分散状态（红色），在λ=520nm处具有光吸收信号。然而,在测定溶液中存在AFB1的情况下，特定的适体以高亲和力反应并折叠成其三维形式。由PDDA诱导的AuNP的聚集导致它们的光信号偏移到λ=620nm(蓝色)。生物测定溶液中的AFB1浓度决定了光信号移位的量。因此,光密度比在两个波长(A620/520)可以作为一个坚固的比色信号来检测黄曲霉毒素B1的浓度。AFB1在0.5至20ngmL-1之间线性检测，检出限为0.09ngmL-1（S/N=3）。将制作的aptasensor应用于实际玉米样品中AFB1的检测。
