New amphiphilic conjugates of mono- and bis(carboxy)-PEG(2,000) polymers with lipoamino acids as surface modifiers of colloidal drug carriers

Linking PEG(2,000) polymers ending in 1 or 2 carboxylic groups to lipoamino acids (LAAs) gives mono- and homo-disubstituted PEG-LAA conjugates. They show an identical solubility to parent PEGs in water and organic solvents. By DSC the degree and depth of interaction of these conjugates with a biomembrane model is studied, gaining information about their future incorporation in drug-loaded nanocarriers. The ability of PEG-LAA conjugates to adopt an ordinate arrangement on the surface of particles and efficiently cover them is demonstrated, compared to DSPE-PEG, by measuring the zeta potential values of negatively charged liposomes prepared in their presence.