Vertical flow immunoassay for multiplex mycotoxins based on photonic nitrocellulose and SERS nanotags

Here, we report a SERS based VFA using PNC as a sensing substrate for highly sensitive multiplex mycotoxins detection. The PNC was fabricated by filtration-based self-assembled monodisperse SiO 2 NPs on a filter membrane as a template , and the obtained PNC had an ordered complementary inverse opal structure. In parallel, three kinds of Raman dyes encoding Au@ NBA Ag, Au@ 4-MBA Ag and Au@ DNTB Ag SERS nanotags were synthesized for the detection of OTA , AFB1 and ZON . In the immunoassay, because of the slow-photon effect of the PNC substrate, which facilitates the light coupling with SERS nanotags, the SERS signal was highly enhanced. The LODs of 8.2, 13.7 and 47.6 fg mL −1 were achieved for simultaneous detection of OTA , AFB1 and ZON , respectively, which were lower than the tolerable cutoff values recommended by the EC. Therefore, this proposed PNC based SERS VFA is expected to be a powerful method for multiplex mycotoxins detection.