Aflatoxin B1 (AFB1) is a carcinogenic substance produced by fungi of genus Aspergillus, especially Aspergillus flavus. Few nanograms of AFB1 that permeated through the skin is sufficient to cause liver cancer and stunted growth. In this study, a rapid aptamer-based assay for AFB1 was developed using the fluorescence quenching property of graphene oxide (GO) and a fluorescein amidite (FAM)-modified aptamer specific to AFB1. The aptamer, modified with the fluorescence dye FAM on its 5'-end, was used as a probe. Once bound by AFB1, a conformational change of the aptamer was caused that led to its interaction with the well-known fluorescence quencher GO, resulting in a decrease of the fluorescence intensity of the system. In the absence of AFB1, the fluorescence intensity remained unchanged. The aptamer-based AFB1 assay process was conducted through 3 steps within 40min. The aptamer was incubated with AFB1 before the addition of GO. The amount of AFB1 present was measured by the change in fluorescence intensity. The detection system was evaluated with standard solutions of AFB1 of various concentrations. The results showed that the fluorescence intensity decreased linearly as the concentration of AFB1 gradually increased. Although the assay was specific to AFB1, there was slight interference by other types of aflatoxin. When the assay was applied to a real sample, the limit of detection was 4.5 ppb, which was within the wide detection range of up to 300ppb with good linearity. Thus, this biosensor is considered to be competitive with the conventional detection methods in the field owing to its wide detection range and assay rapidity.

中文翻译：

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基于使用氧化石墨烯猝灭剂的宽范围荧光检测的黄曲霉毒素B1适体传感器的开发。

黄曲霉毒素B1（AFB1）是由曲霉属，尤其是黄曲霉属真菌产生的致癌物质。几毫微克的AFB1渗透通过皮肤足以引起肝癌和发育不良。在这项研究中，利用氧化石墨烯（GO）的荧光猝灭特性和针对AFB1的荧光素亚酰胺（FAM）修饰的适体，开发了一种基于适体的AFB1快速测定方法。将在其5'端用荧光染料FAM修饰的适体用作探针。一旦与AFB1结合，就会引起适体的构象变化，从而导致其与众所周知的荧光猝灭剂GO相互作用，从而导致系统的荧光强度降低。在没有AFB1的情况下，荧光强度保持不变。基于适体的AFB1分析过程在40分钟内通过3个步骤进行。在加入GO之前，将适体与AFB1一起温育。通过荧光强度的变化测量存在的AFB1的量。用各种浓度的AFB1的标准溶液评估检测系统。结果表明，随着AFB1浓度的逐渐增加，荧光强度呈线性下降。尽管该测定法对AFB1具有特异性，但其他类型的黄曲霉毒素也有轻微的干扰。当将分析应用于真实样品时，检出限为4.5 ppb，在高达300 ppb的宽检测范围内，具有良好的线性。因此，由于其广泛的检测范围和测定速度，该生物传感器被认为与本领域的常规检测方法竞争。