Magnetic molecularly imprinted polymers for the fluorescent detection of trace 17β-estradiol in environmental water

A novel core-shell structured composite of Fe3O4 nanoparticles and molecularly imprinted polymers (MIPs), namely, magnetic MIPs (M-MIPs), was synthesized by surface imprinting technique combined with precipitation polymerization for the selective and sensitive fluorescent detection of 17 beta-estradiol (17 beta-E-2) based on the competitive desorption of fluorescein as a fluorescent indicator from the M-MIPs. The resulting M-MIPs were well characterized, and they showed ideal spherical morphology and magnetic property. Competitive rebinding of 17 beta-E-2, to the corresponding recognition sites regulated the release of fluorescein and resulted in an enhanced fluorescence signal. The fluorescence increase linearly coincided with the concentration of 17 beta-E-2 within the range of 0.10-70 mu M with a detection limit of 0.03 mu M. The recovery of 17 beta-E-2 from spiked lake and river water samples ranged from 98.2 to 103.8% with relative standard deviations between 1.1 and 3.8%. This study successfully integrated surface imprinting, competitive adsorption, magnetic separation and fluorescent detection, and also demonstrated fast binding kinetics, easy separation and reusability, and sensitive determination of template molecules. Thus, the MMIP-based method may provide a simple, rapid, convenient, cost-effective and environmentally friendly way for the highly selective and sensitive recognition and detection of non-fluorescent molecules at trace levels. (C) 2016 Elsevier B.V. All rights reserved.