New amphiphilic conjugates of amino-poly(ethylene glycols) with lipoamino acids as surface modifiers of colloidal drug carriers

Poly(ethylene glycol) (PEG2000) polymers containing one or two amine residues are linked to α-lipoamino acids (LAA) to produce mono- and homo-disubstituted PEG-LAA conjugates as new materials for the surface coating of colloidal drug carriers. Conjugates are characterized by FT-IR, 1H-NMR, and MALDI-TOF mass spectrometry. Differential scanning calorimetry studies are performed to assess the interaction of PEG2000-LAAs with a biomembrane model (dipalmitoylphosphatidylcholine multilamellar liposomes). Whereas the parent PEGs affect only the superficial structure of the bilayers, the amphiphilic PEG-LAA conjugates exert a modulated perturbing effect on the thermotropic profile of liposomes. A molar concentration between 5% and 10% is individuated as the more suitable to produce stable vesicles. Amphiphilic conjugates of amino-PEG and α-lipoamino acids (LAA) were synthetized and characterized. These polymers are planned as alternative surface coating materials than phospholipid-PEGs, to produce stealth polymer and lipid nanocarriers. The interaction of PEG-LAA conjugates with DPPC liposomes (biomembrane model) was studied by DSC.