2Ivanovo State University of Chemistry and Technology, pr. F. Engelsa 7, 153000 Ivanovo, Russia
* To whom correspondence should be addressed.
Received July 18, 2008; Revision received October 23, 2008
A study of the properties of water-soluble tetrasubstituted cationic aluminum phthalocyanine (AlPcN4) revealed efficient binding of this photosensitizer to phospholipid membranes as compared with tetrasulfonated aluminum and zinc phthalocyanine complexes. This also manifested itself in enhanced photodynamic activity of AlPcN4 as measured by the photosensitized damage of gramicidin channels in a planar bilayer lipid membrane. The largest difference in the photodynamic activity of cationic and anionic phthalocyanines was observed in a membrane containing negatively charged lipids, thereby pointing to significant contribution of electrostatic interactions to the binding of photosensitizers to a membrane. Fluoride anions suppressed the photodynamic activity and binding to membrane of both tetraanionic and tetracationic aluminum phthalocyanines, which supports our hypothesis that interaction of charged metallophthalocyanines with phospholipid membranes is mostly determined by coordination of the central metal atom with the phosphate group of lipid.
KEY WORDS: planar bilayer lipid membrane, photosensitizer, phthalocyanine, singlet oxygen, ion channels, gramicidin A, liposomes, mitochondria