Molecularly imprinted polymers hydrogel for the rapid risk-category-specific screening of food using SPE followed by fluorescence spectrometric detection

In fluorescence measurement, one pressing concern today is to construct sensors that can withstand various disturbances for highly selective and sensitive detection of trace analytes in complicated samples. Molecularly imprinted polymers (MIPs) with tailored binding sites are preferred to be recognition elements in sensors for effective target detection. Here, MIPs combined with solid-phase extraction (SPE), followed by direct fluorescence detection on the same extraction medium, was proposed for rapid onsite selective screening for risk categories in food safety without sample pretreatment. A novel surface solid-phase fluorescence substrate with special adsorption property for rhodamine B (RhB) or sulfamethoxazole (SMX) was synthesized by wrapping the MIPs in the deformable hydrogel prepared by polyvinyl alcohol (PVA). Parameters that affected the extraction capacity of the analytes were explored. MIPs-PVA hydrogel showed a good selectivity (imprinting factor α = 2.95 with RhB-MIPs-PVA hydrogel), reproducibility (RSD ≤ 16.5% with 5 ppm RhB) and sensitivity (0.1 ppm to RhB) with a short analysis time of less than 5 min including sampling. The proposed method is very promising as a rapid, onsite screening protocol for food safety.