Surface-imprinted β-cyclodextrin-functionalized carbon nitride nanosheets for fluorometric determination of sterigmatomycin.

β-Cyclodextrin-functionalized carbon nitride nanosheets were modified with a molecularly imprinted polymer to obtain a fluorescent probe of type MIP@β-CD/CNNS which is shown to enable fluorometric determination of sterigmatocystin (STG). The material was characterized by transmission electron microscopy, infrared spectra, powder X-ray diffraction, X-ray photoelectron spectroscopy, and by absorption and emission spectra. The modified CNNSs have a good fluorescence quantum yield (13%), high sorption capacity for STG (86 mg·g-1), fast adsorption rate (25 min), and superior adsorption selectivity (with an imprint factor 2.56). When used as an optical probe for STG, the CNNSs act as the chromophore, while β-CD and MIP act as the recognition groups. The blue fluorescence of MIP@β-CD/CNNS (with excitation/emission maxima at 368/432 nm) is quenched by STG. Fluorescence drops linearly in the 0.15 to 3.1 μM STG concentration range. The lower detection limit is 74 nM. The method was successfully applied to the determination of STG in spiked wheat extract. Conceivably, this detection scheme based on a combination of β-CD inclusion and molecular imprinting may be extended to the detection of various other organic compounds. Graphical abstractSchematic representation of the preparation of surface-imprinted β-cyclodextrin-functionalized carbon nitride nanosheets. These are used, along with a molecularly imprinted polymer, for fluorometric determination of sterigmatomycin.