Functionalized magnetic nanoparticles as chemosensors based on fluorene derivative for Cd(II) ions detection

Abstract

Chemosensor of fluorene derivative (FL) contains different conjugated aromatic rings and binding sites that indicate the maximum fluorescence spectra at 505 nm in dimethylformamide solvation. The emission color is sensitive to changes in acidity and basicity solution which explain in twisted-intramolecular charge transfer and results in a sensitivity of metal ions. At neutral solution (pH 7), these molecules are sensitive to Cd(II) ions which illustrate red-shifted fluorescence spectra and the increase of Cd(II) ions concentration results in the increases of the fluorescence intensity. The limit of detection (LOD) of Cd(II) ions is 0.289 mg/L. The presence of other metal ions in Cd(II)-complexes shows the selectivity of Cd(II) ions and was not significantly sensitive to other metal ions. The carboxylic binding sites of FL chemosensor are important to interact with Cd(II) ions in dimethylformamide solvation and the cyano moiety can withdraw the charge transfer to binding site results in fluorescence intensity increasing. In addition, superparamagnetic iron oxide nanoparticles (SPIONs) were used to improve signal fluorescence intensity for Cd(II) ions detection which lead to the lower limit of detection. The surface of SPIONs was modified with PMMA that it exhibits the decreased agglomeration of SPIONs. Then, the suspension of fluorescent magnetic nanoparticles was showed the good solubility in dimethylformamid when FL was coated on the PMMA/SPIONs.