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Participants/Project AbstractsSummer 2006 Bioanalytical Science REU Participants
Katherine Wentz, Benedictine College ULTRATHIN POYMER FILMS AS FLUORESCENT SENSORS Katherine M. Wentz and Christopher J. Bardeen, Department of Chemistry, University of California-Riverside, UCR 92521 and Benedictine College, Atchison, Kansas, 66002. We present a study on ultrathin perylene red-doped poly(methyl methacrylate) (PMMA) films which act as solid-liquid phase sensors. The sensing mechanism is based on Förster Resonance Energy Transfer (FRET) between perylene red and malachite green molecules. The perylene red/PMMA films were spin-cast onto a glass substrate and thermally annealed at 100 O C for 48 hours to increase adhesion. The thickness of the films was determined by both absorbance measurements and by using an atomic force microscopy (AFM) instrument. Ultrathin spin-cast films had thicknesses of roughly 9 nm. An aqueous solution of malachite green (1 mM) was placed on top of the polymer-doped slide in order to quench the fluorescence which was detected using a fluorimeter. The fluorimeter was custom designed to decrease fluctuations in fluorescence signal and to make sample placement easier. We found that using toluene as the solvent for both the PMMA solution and the perylene red/PMMA solution created reproducible thin films. We also found that the adhesion of the films to the glass substrate was poor without thermally annealing the slides. It was shown that there is reversible fluorescence quenching of the ultrathin perylene red/PMMA films due to the presence of malachite green solution. The mechanism of the quenching was investigated by fluorescence lifetime analysis, the results of which will be discussed. << Back to Participants/Project Abstracts Main Page
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