Enhanced SERS-based vertical flow assay for high sensitivity multiplex analysis of antibiotics

Vertical flow assay (VFA) is of great significance in food safety and environmental monitoring for rapid and highly sensitive detection of a variety of antibiotics. Herein, an enhanced surface-enhanced Raman scattering (SERS)-based VFA (eSERS-VFA) was proposed for multiplex determination of avermectin (AVM) and streptomycin (STR) through SERS nanotag recognition, and gold-core silver-shell nanocube was employed as the enhanced substrate of nanotag. A polyethylene terephthalate (PET) membrane with the hydrophobic property was inserted into the interface of nitrocellulose (NC) membrane and absorbent pad to increase immunoreaction time of SERS nanotags and antigens fixed on the NC membrane. The experimental results indicate that the as-developed eSERS-VFA possessed extraordinary properties for antibiotics analysis with excellent sensitivity, wide quantitative detection range, and short analysis time less than 15 min. The limits of detection (LODs) for AVM and STR reached 38.9 and 29.1 fg mL⁻¹, respectively, and the linear dynamic detection ranges (LDRs) were all from 1 pg mL⁻¹ to 100 ng mL⁻¹. We believe that this eSERS-VFA will open a bright window for VFA-based scheme design, and support potential application prospects in the detection of trace antibiotics.