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

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.