ADSORPTION OF HEMATOPORPHYRINS ON THE PLA NAR BILAYER-MEMBRANE

Adsorption of haematoporphyrin derivatives with different hydrophobici ty of peripheral groups on planar bilayer lipid membrane (BLM) was stu died in dark and upon illumination by visible light. It was shown that haematoporphyrin molecules adsorb on BLM as anions. The adsorption ch anged the boundary potential at the membrane/water interface, in parti cular, it altered potential in the diffuse part of the double layer ou tside the membrane and increased an additional unscreenable potential drop inside of it. Illumination decreased an absolute value of the neg ative potential drop due probably to the appearence of positive charge in the haematoporphyrin macrocycle. The adsorption of haematoporphyri ns affect the BLM conductivity induced by different ionophores, which can be explained by changing the membrane structure. Haematoporphyrin derivatives with higher hydrophobicity adsorbed more deeply inside the membrane, caused more remarkable changes in its structure and display ed stronger photodynamic effect.