Structural characterization of organized systems of polysaccharides and phospholipids by light scattering spectroscopy and electron microscopy

Biovectors are recently developed nanoparticles intended to be used as drug carriers and in the formulation of vaccines. The Biovectors are composed of a polysaccharide core to which phospholipids and cholesterol can be added. The cores are prepared by disruption of a gel of cross-linked maltodextrins, and can have a positive, neutral or negative charge depending on the grafting ionic ligands used. In this study static and dynamic light scattering measurements were combined to characterize the structure of these Biovectors. Transmission electron microscopy was also used. The present work, carried out with positively charged Biovectors in PBS (phosphate buffer saline) and phosphate buffer, points towards a microgel like structure to the polysaccharide fragments of these Biovectors and a spherical geometry with radius ≈ 50 nm. The influence of lipid composition on Biovectors size and density was also studied. The use of transmission electron microscopy gives first evidence for a structure consisting of several phospholipid bilayers surrounding a polysaccharide core. This organized lipidic environment is suitable for hydrophobic drug interaction and membrane proteins insertion. The formulation of a stable, highly controlled drug delivery system or vaccine formulation is implicated.