Location of mesoporphyrin in liposomes determined by site-selective fluorescence spectroscopy.
Binding of photosensitizers to target cells is a crucial step during the photodynamic effect. Sensitizer distribution is a good indication of whether the chemical is a good candidate for perturbing cell membrane integrity. Hence, the photophysical properties of porphyrinoid sensitizers in microheterogeneous systems such as liposomes are of outstanding interest. Here we present a site-selective fluorescence study of liposome systems. Monocomponent, small unilamellar vesicles formed of different phosphatidylcholines with incorporated mesoporphyrin were investigated. The size distribution of liposomes was measured by dynamic light scattering after each step of the experiment. On the basis of fluorescence line narrowing spectra of mesoporphyrin, the inhomogeneous distribution function was determined in order to characterize the photosensitizer location. The dual character of the functions revealed two different locations. Decomposition of the inhomogeneous distribution functions into Gaussians and the analysis of the fit results suggest that one of the locations for mesoporphyrin is between the two lipid layers, and the other one is between the hydrocarbon chains of the lipid molecules.
Herenyi
Levente
L
Department of Biophysics and Radiation Biology, Semmelweis University, P. O. Box 263, H-1444 Budapest, Hungary. levente.herenyi@eok.sote.hu
Veres
Dániel
D
Békási
Sándor
S
Voszka
István
I
Módos
Károly
K
Csík
Gabriella
G
Kaposi
András D
AD
Fidy
Judit
J
D008027:Light; D008051:Lipid Bilayers / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry*; D008652:Mesoporphyrins / Q000737:chemistry*; D008956:Models, Chemical; D010777:Photochemistry; D017319:Photosensitizing Agents / Q000737:chemistry*; D012542:Scattering, Radiation; D013050:Spectrometry, Fluorescence
D008051:Lipid Bilayers; D008081:Liposomes; D008652:Mesoporphyrins; D017319:Photosensitizing Agents; C031468:mesoporphyrin IX