Protein release kinetics for core-shell hybrid nanoparticles based on the layer-by-layer assembly of alginate and chitosan on liposomes

The present work is focused on the formulation of core-shell nanoparticles via the layer-by-layer (L-b-L) self-assembly technique for delivery of biomacromolecules such as bone growth factors. The drug encapsulation efficiency of liposomes is enhanced with the increased stability of polyelectrolyte systems achieved through the alternate adsorption of several layers of natural polymers: anionic alginate and cationic chitosan on cationic nanosized phospholipid vesicles. The resulting particles were characterized for their size, surface charge, morphology, encapsulation efficiency, loading capacity and release kinetics over an extended period of 30 days. The L-b-L deposition technique succeeded in building a spherical, monodisperse and stable hybrid nanoparticulate protein delivery system with a cumulative size of 383 +/- 11.5 nm and zeta potential surface charge of 44.61 +/- 3.31 mV for five bilayered liposomes. The system offers numerous compartments for encapsulation including the aqueous core and within the polyelectrolyte shell demonstrating good entrapment and sustained linear release of a model protein, bovine serum albumin, in vitro. Our results demonstrate that this delivery system features an extended shelf life and can be loaded immediately prior to administration, thus preventing any loss of the protein. (C) 2007 Elsevier Ltd. All rights reserved.