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

Authors

  • Xiaolin Guan,

    1. Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, People's Republic of China
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  • Zhixing Su

    Corresponding author
    1. Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, People's Republic of China
    • Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, People's Republic of China.
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Abstract

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 1H 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°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 © 2008 John Wiley & Sons, Ltd.

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