Detection of fipronil in eggs by an aptasensor based on the Au@Ag NPs Raman enhanced substrate

Fipronil, a phenylpyrazole insecticide, is widely used but raises concerns regarding potential human health risks. This study introduces an aptasensor that utilizes Au@Ag nanoparticles (NPs) as a Raman-enhanced substrate for detecting fipronil residues in eggs. In this system, 4-mercaptobenzoic acid (4-MBA) serves as the Raman signaling molecule, anchored to Au@Ag NPs via Ag-S bonds. The presence of an aptamer initially reduces the 4-MBA Raman signal, which is subsequently restored to varying extents when different concentrations of fipronil are introduced. Thus, fipronil is indirectly quantified by measuring the intensity of the 4-MBA Raman signal. Under optimized conditions, the sensor demonstrates a linear detection range for fipronil between 50 and 400 nM with a coefficient of determination (R²) of 0.9968, and a detection limit of 15.68 nM. It also exhibits excellent selectivity and sensitivity towards fipronil. Furthermore, recovery rates for fipronil detection in egg samples ranged from 90 to 100%, with a relative standard deviation (RSD) below 5%, underscoring the method’s strong potential for practical applications.