A dual-mode lateral flow immunoassay by ultrahigh signal-to background ratio SERS probes for nitrofurazone metabolites ultrasensitive detection.

In this work, an ultra-sensitive lateral flow immunoassay (LFIA) with SERS/colorimetric dual signal mode was constructed for the detection of nitrofurazone metabolites, an antibiotic prohibited in animal-origin foods. Au@4-MBN@AgNRs nano-sandwich structural signal tag integrates the unique advantages of high signal-to-background ratio and anti-matrix interference through geometric control of SERS tag and nanoengineering adjustment of chemical composition. Under the optimal conditions, the detection limits of nitrofurazone metabolites by SERS/colorimetric dual-mode LFIA were 20 pg/mL (colorimetric mode) and 0.08 pg/mL (SERS mode). Excitingly, the vLOD of the colorimetric signal improved by a factor of 100 compared to Au NPs-based LFIA. In this study, the proposed dual-mode LFIA was successfully applied to the on-site real-time detection of honey, milk powder, and chicken. It is anticipated that with low background interference and anti-matrix interference output signal, our proposed dual-mode strategy can pave an innovative pathway for the fabrication of a powerful biosensor.