Nanosecond dynamics of charged fluorescent probes at the polar interface of a membrane phospholipid bilayer.
Molecular relaxation fluorescence methods were applied to analyze the nature and characteristic times of motions of amphiphilic molecules absorbed in the polar region of a phospholipid bilayer. The fluorescence probes 2-toluidinonaphthalene-6-sulfonate and 1-anilinonaphthalene-8-sulfonate in egg phosphatidylcholine vesicles were studied. The methods of edge excitation fluorescence red shifts, nanosecond time-resolved spectroscopy, fluorescence quenching by hydrophilic and hydrophobic quenchers and emission wavelength dependence of polarization were used. The structural (dipolar) relaxation is shown to be a very rapid (subnanosecond) process. The observed nanosecond phenomena are related to translational movement of the chromophore itself towards a more polar environment and its rotation. The polar surface area of the phospholipid membrane appears to be a highly mobile liquid-like system.
D004530:Egg Yolk; D005456:Fluorescent Dyes; D007700:Kinetics; D008051:Lipid Bilayers; D008954:Models, Biological; D010713:Phosphatidylcholines; D013050:Spectrometry, Fluorescence / Q000379:methods; D013329:Structure-Activity Relationship; D013997:Time Factors
D005456:Fluorescent Dyes; D008051:Lipid Bilayers; D010713:Phosphatidylcholines