A universal SERS aptasensor based on DTNB labeled GNTs/Ag core-shell nanotriangle and CS-Fe3O4 magnetic-bead trace detection of Aflatoxin B1.

A novel universal Surface-enhanced Raman Spectroscopy (SERS) based aptasensor platform for the trace detection of Aflatoxin B1 (AFB1), a common food contaminating mycotoxin, has been constructed, with the aid of the specific interaction between AFB1 and aptamers. The amino-terminal aptamer conjugated magnetic-bead (CS-Fe3O4) and the gold nanotriangles (GNTs)-DTNB@Ag-DTNB nanotriangles (GDADNTs) were used as the capturer and the reporter of AFB1, respectively. Under the optimized assay condition, the platform shows a distinguished sensitivity with the LOD as low as 0.54 pg/mL and the linear range from 0.001 to 10 ng/mL, a high stability of the SERS substrate activity remained three months at least, a decent reproducibility with RSD of ca. 5%, and a good selectivity to the general coexisted interferences. The distinguished sensitivity and selectivity for trace AFB1 detection has been achieved mainly due to the strong Raman enhancement effect of GNTs as the kernel for GDADNTs from the double-layer of the reporter molecules, the specificity of aptamer and superparamagnetic CS-Fe3O4 respectively. Furthermore, the proposed SERS aptasensor is universal to other trace molecules detection with the specific aptamers.