A fluorescent sensor array based on ion imprinted mesoporous silica

We report an ion imprinted mesoporous silica based fluorescence turn-on sensor array for discrimination of metal ions. A novel fluorescent functional monomer containing an 8-hydroxyquinoline (8-HQ) moiety in combination with one-pot co-condensation method was employed to prepare fluorescent ion imprinted mesoporous silica. The imprinted materials for Zn2+ and Cd2+ as well as a control blank non-imprinted material (NIM) were synthesized. With the covalently anchored organic fluorophore in the inorganic mesoporous silica matrix, the binding of metal ions to the imprinting site was directly transformed into fluorescence signals. Both the imprinted materials displayed faster binding kinetics toward metal ions than NIM. Apparent binding constants (adsorption constants) for the materials with the metal ions in water were determined by a Langmuir-type analysis of the spectrofluorimetric titration data. The sensor array composed of the three materials allows discriminating the two template metal ions (Zn2+ and Cd2+) plus three non-template metal ions (Mg2+, Ca2+ and Al3+) at two different concentrations. This work proves that using a simple fluorescent receptor can provide a pattern based fluorescent sensing system by taking advantage of the imprinting effect. (C) 2009 Elsevier B.V. All rights reserved.