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Photophysics of anthracene–indole systems in unilamellar vesicles of DMPC and POPC: Exciplex formation and temperature effects

Paper ID Volume ID Publish Year Pages File Format Full-Text
30566 44487 2006 7 PDF Available
Title
Photophysics of anthracene–indole systems in unilamellar vesicles of DMPC and POPC: Exciplex formation and temperature effects
Abstract

The quenching of anthracene fluorescence by indole (IN), 1,2-dimethylindole (DMI), tryptophan (Trp) and indole 3-acetic acid (IAA) in dimiristoylphophatidylcholine (DMPC) and palmitoyloleoylphosphatidylcholine (POPC) lipid bilayers was investigated. The studies were carried out at 25 °C in POPC vesicles and below (15 °C) and above (35 °C) the phase transition temperature (24 °C) of DMPC. A very efficient quenching of the anthracene fluorescence by IN and DMI in the lipid membrane is observed in all cases. It is less efficient in the case of Trp and IAA. Stern–Volmer plots are linear for DMI but present a downward curvature for the other quenchers. This was interpreted as an indication of the presence of an inaccessible fraction of anthracene molecules. By a modified Stern–Volmer analysis the fraction accessible to the quenchers and the quenching constant were determined. Partition constants of the quenchers were obtained from the changes in the fluorescence emission of the indole moiety caused by the presence of the phospholipid. Using the partition constants bimolecular quenching rate constants were determined in terms of the local concentration of quencher in the lipid bilayer. These corrected rate constants are lower than those in homogeneous solvents. In the case of DMPC values the gel phase are higher than in the liquid-crystalline phase. In the quenching by IN and DMI a new, red shifted, emission band appears which could be assigned to an exciplex emission. The exciplex band is absent in the quenching by IAA and Trp.

Keywords
Vesicles; Fluorescence quenching; Anthracene; Indoles; Exciplex; DMPC; POPC
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Photophysics of anthracene–indole systems in unilamellar vesicles of DMPC and POPC: Exciplex formation and temperature effects
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology B: Biology - Volume 85, Issue 2, 1 November 2006, Pages 102–108
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
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Any Questions? feel free to contact us