Probing internal environment of sol–gel bulk and thin films using multiple fluorescent probes

The selection of sol compositions, conditions of preparation and storage of gels are an important aspects for encapsulating biomolecules in gel matrix for applications in biosensor. In the present investigation, fluorescence spectroscopic measurements (emission and fluorescence lifetimes) were carried out in bulk gel and thin films prepared from sols with water and tetraethyl-orthosilicate (TEOS) containing different fluorescent probes viz Hoechst 33258 (H258), Pyranine (Py), and 7-Azaindole (7-AI) in different sols. Sols were prepared with addition of water, HCl and surfactant Triton X-100, and stored at room temperature (RT) and low temperature (4 °C). The spectral characteristics have been compared for two different storage conditions as a function of aging. The results of the present study clearly suggested that the internal environment of gels specifically the content of water inside the pores of the sol–gel matrix can be controlled by storage at 4 °C as compared to RT.