We examine lanthanide-lipid interactions using Langmuir monolayers of DPPC and a new double-chain malonamide. Contrary to the popular belief that these interactions are strong, we find them weaker than expected and strongly dependent on the anion of the lanthanide salt. Pressure-area isotherms, Brewster-angle microscopy, grazing incidence X-ray diffraction and IRRAS have been used to study the monolayers. Bulk water studies (ITC, SAXS and fluorescence) involving dodecyl phosphocholine micelles corroborate that the anion of the lanthanide salt has a strong effect on lanthanide-lipid interactions, something which has not been recognized in the literature. Thus, nitrate and sulfate salts have a much stronger interaction with the lipids than chloride salts, and the presence of additional “neutral” electrolytes provides additional strong modifications of the interactions. Such many-tiered effects appear to be general enough for highly charged cations and may be used to change the affinities between ions and interfaces in controlled ways.
References:
[1] E. Leontidis, M. Christoforou, C. Georgiou, T. Delclos , Cur. Opin. Colloid Int. Sci. 2014, 19, 2-8, DOI 10.1016/j.cocis.2014.02.003.
psleon@ucy.ac.cy
