Thiolated DAB dendrimers and CdSe quantum dots nanocomposites for Cd(II) or Pb(II) sensing

Four different generation of thiol-DAB dendrimers were synthesized, S-DAB-G(x) (x = 1, 2, 3 and 5), and coupled with CdSe quantum dots, to obtain fluorescent nanocomposites as metal ions sensing. Cd(II) and Pb(II) showed the higher enhancement and quenching effects respectively towards the fluorescence of S-DAB-G(5)-CdSe nanocomposite. The fluorescence enhancement provoked by Cd(II) can be linearized using a Henderson-Hasselbalch type equation and the quenching provoked by Pb(II) can be linearized by a Stern-Volmer equation. The sensor responds to Cd(II) ion in the 0.05-0.7 mu M concentration range and to Pb(II) ion in the 0.01-0.15 mM concentration range with a LOD of 0.06 mM. The sensor has selectivity limitations but its dendrimer configuration has analytical advantages. (C) 2011 Elsevier B.V. All rights reserved.