Electric-Field-Induced Changes in Absorption and Fluorescence of the Green Fluorescent Protein Chromophore in a PMMA Film

Abstract

External electric field effects on absorption, fluorescence, and fluorescence decay of p-HBDI that is a model compound of the chromophore of GFP have been examined in a poly(methyl methacrylate) film. The electroabsorption spectrum is similar in shape to the first derivative of the absorption spectrum, which results from the difference in molecular polarizability between the ground state and the Franck-Condon excited state. The electrophotoluminescence spectrum is dominated by the corresponding fluorescence spectrum, indicating the enhancement of the fluorescence intensity in the presence of external electric fields. The direct measurements of the electric field effect on the fluorescence decay profile suggest that the field-induced deceleration of the nonradiative process contributes to the increase in the fluorescence intensity in the presence of electric fields.

Electric Field Effects on Photoluminescence of CdSe Nanoparticles in a PMMA Film

“…E-PL spectra and E-A spectra were measured by the same system and procedures as reported elsewhere [13][14][15][16][17][18][19][20][21][22]. PMMA (MW = 120,000) was obtained from Aldrich and purified by a precipitation with a mixture of benzene and methanol.…”

“…We measured the so-called electroabsorption and electrophotoluminescence spectra (plots of the electric-field-induced change in absorption and PL intensity as a function of wavelength or wavenumber) to investigate molecular properties including intramolecular and intermolecular electron transfer [13][14][15], excimer formation [16], photoisomerization [17], and electrostatic interaction in protein [18]. Measurements of these spectra provide unique information about the differences in electric dipole moment (μ) and molecular polarizability (α) between the ground state and excited states.…”

The key to the yellow-to-cyan tuning in the green fluorescent protein family is polarisation

“…Recently, a renewed interest in the measurement of local electrostatic fields in complex molecular environments has led to the development and calibration of different techniques 11,56,[58][59][60] . One such technique 60 is based on the first-order Stark effect and relates changes in excitation energy (∆∆E 01 ) in different GFP mutants to changes in the electrostatic field ∆ F as…”

Electric field effect on the ground state proton transfer in the H-bonded HBDI complex: an implication of the green fluorescent protein

“…23,24 When the isolated neutral HBDI is placed on a poly(methyl methacrylate) (PMMA) lm, electric elds can increase the uorescence lifetime arising from the deenhancement of the non-radiative process caused by the steric hindrance of the polymer lm. 25 In the meantime, it has been found that an electric eld can affect the absorption spectra of HBDI. However, the electric eld, with a strength of only 1 MV cm À1 , was applied without any information about eld orientation, which could not adequately simulate the electrostatic environment inside the GFP cavity.…”