Synthesis and characterization of fluorescent starch using fluorescein as fluorophore: potential polymeric temperature/pH indicators

摘要

A convenient method for attaching fluorescein (via its epoxy derivate) to natural starch and its temperature/pH-sensitive qualities of fluorescence were investigated. 3-epoxypropoxy fluorescein (EPF) was first synthesized through the reaction between fluorescein and epichlorohydrin, and starch-bearing fluorescein (ST-EPF) was prepared via ring-opening reaction with EPF in dimethyl sulfoxide (DMSO) solution, in the presence of NaH as a catalyst. Both of them were characterized by the methods of H-1 NMR, MS, IR, XRD, UV-Vis, and luminescence spectra, respectively. The chemiluminescent and photophysical behaviors of the dye fluorescein derivative and the polymer-containing fluorescein were studied. The results indicated that ST-EPF could still provide temperature and pH sensitivity similar to that of fluorescein and could achieve better long-term stability and fast equilibrium response. ST-EPF had an excellent linear response between relative fluorescence intensity and temperature in the range of 0-60 degrees C and a nonlinear relationship between relative fluorescence intensity and pH in the wide range of 0.0-12.0, and so it has promise as an optical transducer for temperature and pH value determinations. Copyright (c) 2008 John Wiley & Sons, Ltd.