A molecularly imprinted polymer placed on the surface of graphene oxide and doped with Mn(II)-doped ZnS quantum dots for selective fluorometric determination of acrylamide.

A polymer imprinted with acrylamide (AM-MIP) was synthesized on the surface of graphene oxide by surface polymerization of propionamide (serving as a dummy template), methacrylic acid (as the functional monomer) and ethylene glycol dimethacrylate (the cross-linker). ZnS quantum dots (QDs) doped with Mn(II) ions were added to the AM-MIP to act as fluorescence source. The AM-MIP was characterized by infrared spectroscopy, scanning electron microscopy and X-ray powder diffraction, suggesting that the imprinted layer was successfully grafted onto graphene oxide. The fluorescence of the doped QDs is quenched when loading the AM-MIP with acrylamide (AM), and the quenching effect is much stronger than the non-imprinted polymer (AM-NIP). Quenching follows Stern-Volmer kinetics. The combination of imprinting and fluorometric detection offer AM-IIP capability to accumulate trace AM before direct determination, omitting desorption and separation or other methods. The excitation and emission spectra of AM-MIP peak at 325 nm and 601 nm, respectively. Under optimal conditions, fluorescence drops linearly in the 0.5-60 μmol·L acrylamide concentration range, and the detection limit is 0.17 μmol·L. The method has been applied to the determination of AM in spiked water samples and gave recoveries in the range from 100.2 to 104.5%, with relative standard deviations in the 1.9 to 3.9% range. In our perception, the AM-MIP presented here is a promising fluorescent probe for the detection of trace acrylamide in food. Graphical abstract Schematic of the preparation of graphene oxide coated with a molecularly imprinted polymer doped with Mn(II)-doped ZnS quantum dots. Propionamide serves as a dummy template. Acrylamide acts as a quencher of fluorescence, and this effect is used for its selective fluorometric determination.