A magnetic-fluorescent integrated platform for three-in-one sensing of doxycycline in food with enhanced sensitivity and specificity

A magnetic-fluorescent integrated platform (Fe 3 O 4 -COOH@MIL-101(Cr)@MIPs/b-BCDs), designed for the magnetic separation, biomimetic recognition, and fluorescence detection of doxycycline, was proposed. In this proposal, Fe 3 O 4 -COOH@MIL-101(Cr)@MIPs were synthesized through layer-by-layer self-assembly modification of MIL-101(Cr) onto the surface of Fe 3 O 4 -COOH and coupling with MIPs. The introduction of MIL-101(Cr) endowed Fe 3 O 4 -COOH@MIL-101(Cr)@MIPs with superior binding capacity and mass-transfer rate. High-affinity imprinting layer boosted the precise identification of Fe 3 O 4 -COOH@MIL-101(Cr)@MIPS towards doxycycline in complex environments. Benefiting from inherent merits, Fe 3 O 4 -COOH@MIL-101(Cr)@MIPs demonstrated an appealing adsorption capacity ( Q e  = 13.19 mg g −1 ), favorable mass-transfer rates ( h =  9.22 mg g −1  min −1 ), and specificity. Biomass-based carbon dots (b-BCDs) were introduced to construct Fe 3 O 4 -COOH@MIL-101(Cr)@MIPs/b-BCDs-based sensing platform, which demonstrated satisfactory analytical performance, with a linear range of 0.05–2 mg/L, a limit of detection of 3.86 ng/mL, and recoveries of 90.24–98.85% in water, milk, and chicken samples. The platform offers high accessibility for ultrasensitive and selective doxycycline measurement in samples and a novel perspective for three-in-one detection method development.