Pegylated tetraarylporphyrin entrapped in liposomal membranes. A possible novel drug-carrier system for photodynamic therapy.
A system of poly(ethylene glycol) bound tetraarylporphyrin entrapped in liposomal membranes was investigated. The interactions between the 5-(4-hydroxymethylphenyl)-10,15,20-tritolylporphyrin (Po) covalently attached to the poly(ethylene glycol) chain (PEG-Po), and phosphatidylcholine liposomes in the aqueous solution were studied. The adsorption of the investigated polymer to lipid vesicles was confirmed by measurements of dynamic light scattering and zeta potential. Experimental results demonstrate that the diameter of liposomes increased and the absolute value of the zeta potential decreased after addition of PEG-Po. The binding constants (K(b)) of Po chromophores to liposome in pH range from 5.2 to 9.0 were determined using fluorescence spectroscopy. The degree of binding was found to be pH-independent and the average value was 24.6 +/- 0.9 mg ml(-1). The acid-base properties of the porphyrin chromophores and their aggregation in an aqueous solution were also studied. pK values associated with imine-N protonation of the porphyrin core were found to be 2.59 and 0.68 at the ionic strength of 0.1 M. The equilibrium constant for dimerization, K(D), was found to be 5 x 10(3) M(-1).
Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland.
Mariusz
M
Kepczyński
Kinga
K
Nawalany
Barbara
B
Jachimska
Marek
M
Romek
Maria
M
Nowakowska
D000327:Adsorption; D001665:Binding Sites; D004337:Drug Carriers; D006863:Hydrogen-Ion Concentration; D008027:Light; D008051:Lipid Bilayers / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry* / Q000627:therapeutic use*; D015394:Molecular Structure; D010713:Phosphatidylcholines / Q000737:chemistry; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D011092:Polyethylene Glycols / Q000737:chemistry*; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry* / Q000627:therapeutic use*; D011166:Porphyrins / Q000737:chemistry*; D012542:Scattering, Radiation; D012995:Solubility; D012996:Solutions / Q000737:chemistry; D013499:Surface Properties; D014867:Water / Q000737:chemistry
C512042:5-(4-hydroxymethylphenyl)-10,15,20-tritolylporphyrin; D004337:Drug Carriers; D008051:Lipid Bilayers; D008081:Liposomes; D010713:Phosphatidylcholines; D017319:Photosensitizing Agents; D011108:Polymers; D011166:Porphyrins; D012996:Solutions; D014867:Water; D011092:Polyethylene Glycols