Abstract:

The effects of lanthanide ions and their complexes of citrate and DTPA ligands on the fluldity of dipalmitoylphosphatidylethanolamine (DPPE) bilayers have been studied by FT-Raman spectroscopy. The results show that lanthanide ions of lower concentration decrease the fluidity of acyl chains of DPPE bilayers and change the conformation of C-C-C backbone from gauche to the trans lanthanide ions of higher concentration, however, increase the fluidity of acyl chains and increase the gauche population of C-C-C backbone. Lanthanide complex of citrate have no effect on the fluidity of acyl chains of DPPE bilayers in the region of experimental concentration, but La-DTPA complex increase slightly the fluidity of acyl chains. The results also indicated that lanthanide ion of lower concentration changed the lattice packing of hydrocarbon chains from hexagonal form to orthorhombic form, but it is still in hexagonal or distorted hexagonal lattice cell in the gel state in the presence of metal ions and lanthanide complexes of higher concentration.

Key words: Lanthanide ion, Lanthanide complex, FT-Raman spectroscopy Dipalmitoylphosphatidylethanolamine