Hydrophobic CdSe/ZnS quantum dots (QDs) coated with a molecularly imprinted polymer (MIP) sensitized with graphene (Gra-QDs@MIP) were prepared through a one-pot reverse microemulsion polymerization at room temperature. Gra-QDs@MIP was used as a molecular recognition element to construct a N(ε)-carboxymethyllysine (CML) optosensor. Graphene was used as a polymerization platform to increase the stability and kinetic binding properties of the system. Reverse microemulsion polymerization can anchor silica spheres on the surface of the QDs. This provides functional groups on the surface of Gra-QDs@MIP, which can bind CML and improve the fluorescence stability. Selective and sensitive optosensing of CML is possible at concentrations down to 3.0 μg L(-1) using Gra-QDs@MIP. Gra-QDs@MIP can be applied to dairy samples, as a recognition and response element for determining CML concentrations. The optosensing method was validated by high-performance liquid chromatography-mass spectrometry. The optosensor is economically and easily prepared, and the method is simple, fast, accurate, and reproducible.
Keywords: Nε-carboxymethyllysine; dairy product; graphene; molecularly imprinted polymer; quantum dot.