Poly(ethylene glycol) (PEG2000) polymers containing one or two amine residues are linked to a-lipoamino acids (LAA) to produce mono- and homo-disubstituted PEGLAA conjugates as new materials for the surface coating of colloidal drug carriers. Conjugates are characterized by FT-IR, 1H-NMR, and MALDITOF mass spectrometry. Differential scanning calorimetry studies are performed to assess the interaction of PEG2000LAAs with a biomembrane model (dipalmitoylphosphatidylcholine multilamellar liposomes). Whereas the parent PEGs affect only the superficial structure of the bilayers, the amphiphilic PEGLAA 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.