In the present study, an aptamer-based fluorescent assay was developed to detect fipronil in liquid eggs, using a carboxyfluorescein (FAM)-labeled aptamer (FAM aptamer) and partially complementary DNA labeled with carboxytetramethylrhodamine (TAMRA cDNA). The fipronil amount in analytical samples was determined by measuring FAM fluorescence at 522 nm. In the absence of fipronil, FAM fluorescence is effectively quenched by fluorescence resonance energy transfer (FRET) phenomenon generated by the hybridized structure of the FAM aptamer and TAMRA cDNA. In contrast, in the presence of fipronil, FAM fluorescence is gradually recovered in a fipronil concentration-dependent manner because the FAM aptamer has a stronger affinity for fipronil than for TAMRA cDNA. The proposed analytical method for fipronil involves a simple one-step procedure of mixing the sample solution without any washing step, and the results can be obtained in approximately 30 min. Under optimized conditions, the developed assay showed a linear response to fipronil in the egg sample in the range of 25-300 ppb with a detection limit of 53.8 ppb (0.068 mg/kg) and recovery rates in the range of 94.7-114.4%. Additionally, the assay selectivity for fipronil was investigated against eight pesticides, and it showed good specificity for fipronil. Compared with conventional liquid chromatography-mass spectrometry (LC-MS), the proposed method provides a simple, easy, and fast method to detect fipronil in egg samples without requiring bulky and expensive instruments and complicated and laborious processes. We believe this detection method could be a promising platform for fipronil detection in real food samples.

在本研究中，开发了一种基于适体的荧光测定法，使用羧基荧光素（FAM）标记的适体（FAM适体）和用羧基四甲基罗丹明（TAMRA cDNA）标记的部分互补DNA检测液体卵中的氟虫腈。通过测量522 nm处的FAM荧光来测定分析样品中的氟虫腈含量。在没有氟虫腈的情况下，FAM荧光可通过由FAM适体和TAMRA cDNA的杂交结构产生的荧光共振能量转移（FRET）现象有效地淬灭。相反，在存在氟虫腈的情况下，FAM荧光以氟虫腈浓度依赖性的方式逐渐恢复，因为FAM适体对氟虫腈的亲和力比对TAMRA cDNA的亲和力强。拟议的氟虫腈分析方法涉及简单的一步步骤，无需任何洗涤步骤即可将样品溶液混合，结果可在约30分钟内获得。在优化的条件下，开发的测定方法显示鸡蛋样品中对氟虫腈的线性响应在25-300 ppb的范围内，检出限为53.8 ppb（0.068 mg / kg），回收率在94.7-114.4％的范围内。此外，还针对8种农药对氟虫腈的检测选择性进行了研究，结果显示对氟虫腈具有良好的特异性。与常规液相色谱-质谱法（LC-MS）相比，该方法提供了一种简单，简便，快速的方法来检测鸡蛋样品中的氟虫腈，而无需使用笨重且昂贵的仪器以及复杂而费力的过程。