Protoporphyrin-dimethylester (PP) is an amphiphilic porphyrin which shows a fast clearance and is therefore of interest for photodynamic therapy. The localization of the sensitizer is one point of interest, since it has a strong influence on the phototoxic effect. Localization of PP in fibrosarcoma cells was probed by time resolved and steady state spectroscopy. Dioleoyl L- (alpha) -phosphatidylcholine (DOPC) liposomes were used as a carrier system for the amphiphilic sensitizer with a molar ratio of PP/DMSO equals 1/200. Since intermembrane exchange is responsible for the uptake of PP we expected a membrane bound localization. Therefore the characterization of the microenvironment was based on the comparison of the spectroscopic properties of PP in organic solvents, artificial membranes and in cells. Based on this comparison we suggest that PP is bound within the amphiphilic part of the membranes i.e. between the polar headgroups and the fatty acyl chains of the cytoplasm membrane.

Date Published: 1 March 1994
PDF: 8 pages
Proc. SPIE 2078, Photodynamic Therapy of Cancer, (1 March 1994); doi: 10.1117/12.168676

Published in SPIE Proceedings Vol. 2078:
Photodynamic Therapy of Cancer
Giulio Jori; Johan Moan; Willem M. Star, Editor(s)