A core-shell surface magnetic molecularly imprinted polymers with fluorescence for λ-cyhalothrin selective recognition

In this study, we report here a general protocol for making core-shell magnetic Fe 3 O 4 /SiO 2 -MPS/MIPs (MPS = 3-(methacryloxyl) propyl trimethoxysilane, MIPs = molecularly imprinted polymers, Fe 3 O 4 /SiO 2 -MPS as core, MIPs as shell) via a surface molecular imprinting technique for optical detection of trace λ -cyhalothrin. The fluorescent molecularly imprinted polymer shell was first prepared by copolymerization of acrylamide with a small quantity of allyl fluorescein in the presence of λ -cyhalothrin to form recognition sites without doping. The magnetic Fe 3 O 4 /SiO 2 -MPS/MIPs exhibited paramagnetism, high fluorescence intensity, and highly selective recognition. Using fluorescence quenching as a detecting tool, Fe 3 O 4 /SiO 2 -MPS/MIPs were successfully applied to selectively and sensitively detect λ -cyhalothrin, and a linear relationship could be obtained covering a wide concentration range of 0–50 nM with a correlation coefficient of 0.9962 described by the Stern-Volmer equation. The experimental results of practical detection revealed that magnetic Fe 3 O 4 /SiO 2 -MPS/MIPs as an attractive recognition element was satisfactory for determination of trace λ -cyhalothrin in honey samples. This study, therefore, demonstrated the potential of MIPs for detection of λ -cyhalothrin in food.