Assembly of stabilized dendritic magnetic ferric-silver nanocomposite with gold nanoparticles for sensitive detection of ochratoxin A using SERS aptasensor

Ochratoxin A (OTA) contamination poses a significant global threat to food security, necessitating the development of rapid and effective detection methods. A dendritic magnetic silver nanocomposite (Fe3O4@SiO2@Ag) tagged with aptamers acted as surface-enhanced Raman scattering (SERS) substrates and capture probes. Further, gold nanoparticles (AuNPs) were functionalized with cDNA and utilized as Raman-enhanced probes (cDNA-AuNPs). The SERS aptasensor which was constructed by the assembly of Apt-Fe3O4@SiO2@Ag and cDNA-AuNPs attained the accuracy quantitative and extremely sensitive detection of OTA. An inverse relationship between the concentration of OTA standard solution and Raman intensity of the characteristic peak at 1080 cm−1 was established in the range of 0.01–5 ng/mL, with an LOD of 0.0074 ng/mL. Furthermore, for positive corn samples, the coincidence rate between the established SERS aptamer sensor and HPLC was in the range of 92.67–121.10%, demonstrating tremendous promise for future practical application through other crops.