A large Raman scattering cross-section molecular embedded SERS aptasensor for ultrasensitive Aflatoxin B1 detection...

With growing concern on oil safety problems, developing a simple and sensitive method to detect Aflatoxin B1 (AFB1), a common mycotoxin in peanut oil, is very necessary. In this study, Surface-enhanced Raman Scattering (SERS) aptasensor was developed for ultrasensitive AFB1 detection using the amino-terminal AFB1 aptamer (NH₂-DNA1); and thiol-terminal AFB1 complementary aptamer (SH-DNA2) conjugated magnetic-beads (CS-Fe₃O₄) as enrichment nanoprobe and AuNR@DNTB@Ag nanorods (ADANRs) as reporter nanoprobe respectively. 5,5'-Dithiobis(2-nitrobenzoicacid) (DNTB) with large Raman scattering cross-section and no fluorescence interference was embedded in Au and Ag core/shell nanorods as Raman reporter molecules. CS-Fe₃O₄ possessed excellent biocompatibility and superparamagnetism for rapid signal enrichment. Therefore, NH₂-DNA1-CS-Fe₃O₄ and SH-DNA2-ADANRs were fabricated via the hybrid reaction between aptamers and complementary aptamers. When there is AFB1, AFB1 would competitively combine with the NH₂-DNA1-CS-Fe₃O₄ inducing the dissociation of SH-DNA2-ADANRs from CS-Fe₃O₄ and further decreasing the SERS signal. Based on this developed SERS aptasensor, a low limit of 0.0036ng/mL and an effective linear detection range from 0.01 to 100ng/mL with the correlation coefficient up to 0.986 for AFB1 detection were obtained. Moreover, the specificity of this SERS aptasensor was demonstrated by detecting other two mycotoxins and its accuracy for AFB1 detection in real peanut oil was further confirmed by standard addition recovery test.