Ultrasensitive magnetic SERS aptasensor utilizing NiFe2O4@TiO2@Au composite for acetamiprid detection in leafy vegetables.

A magnetic NiFe2O4@TiO2@Au composite was successfully synthesized via layer-by-layer assembly approach and exhibited excellent SERS performance. The composite was functionalized with an aptamer modified with Cy3, serving as the Raman signal reporter, and was hybridized with complementary DNA oligonucleotides (cDNA) to construct the NiFe2O4@TiO2@Au@ssDNA SERS aptasensor. This aptasensor enabled the development of a sensitive, specific, and straightforward SERS assay for acetamiprid detection, exhibiting good accuracy. Under optimized conditions, an inverse correlation was established between the acetamiprid concentration and the Raman intensity at the characteristic peak of 1132 cm-1, spanning a range of 10-1-104 nmol/L with a LOD of 8.4 × 10-1 pmol/L. Standard addition experiments to three types of leafy vegetables samples yielded recoveries ranging from 94.30 % to 111.83 %, with a relative standard deviation of <5.56 %. This method shows potential for detecting other hazardous substances in food and environmental samples by simply changing the corresponding aptamers and cDNA.