Energy interactions and phospholipid vesicles
Luminescence quenching studies of unilamellar phosphatidylcholine vesicles containing a surfactant sensitizer derived from tris(2,2'-bipyridine)ruthenium(II) have shown that only a fraction of these sensitizers is quenchable when ferricyanide is added to the continuous aqueous phase, and that this fraction is made up exclusively of the sensitizers located in the outer monolayer. The size of this fraction is independent of the sensitizer concentration. In contrast to this, the quenching rate constant increases with sensitizer concentration. From these observations, one can conclude that energy transfer occurs among sensitizers located on the same surface of a vesicle, but energy transfer between these sensitizers is not long range enough to reach efficiently across the membrane from inside to outside (and vice versa). The existence of this energy transfer in the first case has important implications on the kinetic scheme for photosensitized electron transport reactions through vesicle walls. The size of the vesicles studied was determined to be approx. 500 angstroms in diameter by /sup 14/C-sucrose entrapment. This experimental finding in addition to the fixed fraction of quenchable fluorescence of 0.67 +- 0.02 implies that the surfactant ruthenium molecules extend a considerable distance out of the vesicle into the aqueous phase, and/or they are asymmetrically distributed between inner and outer vesicle surfaces.
- Research Organization:
- Lawrence Berkeley Lab., CA (USA)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 5113936
- Report Number(s):
- LBL-14673; ON: DE82019301
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
400500* -- Photochemistry
AQUEOUS SOLUTIONS
AZINES
BIPYRIDINES
CHEMICAL REACTIONS
COMPLEXES
DATA
DISPERSIONS
ELECTRON TRANSFER
EMISSION SPECTROSCOPY
ENERGY TRANSFER
ESTERS
EXPERIMENTAL DATA
FERRICYANIDES
FLUORESCENCE SPECTROSCOPY
HETEROCYCLIC COMPOUNDS
INFORMATION
IRON COMPLEXES
LIPIDS
LUMINESCENCE
MIXTURES
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PHOSPHOLIPIDS
PHOTOCHEMICAL REACTIONS
PYRIDINES
REAGENTS
RUTHENIUM COMPLEXES
SCINTILLATION QUENCHING
SENSITIZERS
SOLUTIONS
SPECTROSCOPY
SURFACTANTS
TRANSITION ELEMENT COMPLEXES