Proofs of the structure of lipid coated nanoparticles (SMBV (TM)) used as drug carriers

Purpose. Supramolecular Biovectors (SMBV(TM)) consist of cross-linked catio nic nanoparticles surrounded by a lipid membrane. The purpose was to study the structure of the lipid membrane and to characterise its interaction wit h the nanoparticles in order to differentiate SMBV(TM) from other polymer/l ipid associations. Methods. The interaction of lipids with the nanoparticle surface was studie d using zeta potential, Fluorescence Energy Transfer (FET) and Fluorescence Microscopy. SMBV(TM) were compared to liposomes and mixtures nanoparticles /liposomes. Finally the structure of SMBV(TM) was visualised by Electron Mi croscopy. Results. Zeta potential measurements showed that lipids on SMBV(TM) had a p ronounced shielding effect on the surface charge. This was not the case for mixtures of nanoparticles and liposomes. FET experiments confirmed these r esults indicating that, for SMBV(TM), the lipids are much closer to the nan oparticle surface. SMBV(TM) Fluorescence microscopy on model microparticles showed a lipid crown on SMBV(TM) that was confirmed by electron microscopy on SMBV(TM) nanoparticles. Conclusions. Results show that in case of SMBV(TM) lipids are strongly adso rbed on the polysaccharide core surface probably due to ionic/hydrophobic i nteractions. The resulting supramolecular structure is a spherical cationic polysaccharide particle surrounded by a phospholipid/cholesterol layer.