Sol-gels doped with polymer-coated ZnS/CdSe quantum dots for the detection of organic vapors

A novel luminescent sensing material for the detection and discrimination of different organic vapors has been developed and characterized. For such purpose, colloidal polymer surface-modified ZnS/CdSe semiconductor quantum dots (QDs) were synthesized and trapped into sol-gel inorganic matrices following a simple and friendly procedure. It was observed that the QDs entrapped into the sol-gels maintain invariable optical properties. Moreover, rapid and reversible quenching of the fluorescence from the immobilized QDs upon exposure of the doped sol-gel materials to several organic vapors was observed, with the onset of the quenching process being dependent on the target gas type and on its concentration. After a necessary previous photoactivation, the luminescence of the immobilized quantum clots was found to exhibit a distinct behavior when exposed to different organic vapors at atmospheric pressure. The sensing response from the surface-modified quantum dots was also dependent upon the porous sol-gel matrix composition. Two different active materials were prepared using the same colloidal polymer-coated ZnS/CdSe QDs but changing the composition of the precursors used during the sol-gel preparation and doping process. After exposing the synthesized materials to the different organic analytes gaseous samples, the measured luminescence responses were processed, by multivariate analysis and a dynamic pattern recognition method. Results obtained demonstrated the analytical potential of ZnS/CdSe doped sol-gels as luminescent sensing materials for the rapid detection of organic vapors in contaminated atmospheres. (C) 2009 Elsevier B.V. All rights reserved.