Carboxymethyl chitosan crosslinked ꞵ-cyclodextrin containing hydrogen bonded NC QDs nanocomposites to design fluorescence probes for manganese ion (II) sensing

The direct determination Mn 2+ using carboxymethyl chitosan crosslinked with cyclodextrin containing hydrogen-bonded N C QDs (N C QD/CCSCD nanocomposites). The probable mechanism of the N C QD/CCSCD nanocomposites' fluorescence was quenched by Mn 2+ could be interpreted as acyclic crown ether chelation. Mn 2+ induced the N C QD/CCSCD clusters assembly to form large aggregates, which resulted in aggregation-caused quenching. The linear detection ( I  = 479.93–15.94C (R 2  = 0.9954)) can be established at Mn 2+ concentrations from 0 to 21.11 × 10 −6  mol/L. Common metal ions, except iron and magnesium, showed minimal effect on detection. It could satisfy the standard range of Mn 2+ in actual water samples. The method which using chelating assembly mechanism to build a novel sensor would provide a new model for the application of polymer materials in this field, but the precise assembly of polymer is an unsolved challenge.