ZnS:Mn nanoparticles functionalized by PAMAM-OH dendrimer based fluorescence ratiometric probe for cadmium.

We report a nanocomposite of ZnS:Mn quantum dots and a third generation PAMAM-OH dendrimer (ZnS:Mn@PAMAM-OH(G=3)) which was rationalized to be used as ratiometric nanosensor for Cd(2+) in aqueous solution. The nanoparticles exhibited a bright yellow-orange emission with peaks at 448 and 595 nm. The structure of ZnS:Mn was not changed after coupling with PAMAM-OH, which was evidenced by the analysis of the emission spectra of the compounds. The results confirm that the prepared fluorescence nanoparticles could selectively detect Cd(2+) in aqueous solution with a limit of detection of 24.34 μM and RSD 4.07%, obtained by using the ratio I448/I595. The method was applied to different water samples.