Polysaccharide-covered nanoparticles prepared by nanoprecipitation

Dextran-covered poly(lactic acid) (PLA) nanoparticles were prepared using the nanoprecipitation process. Two alternative procedures were compared. On the one hand, PLA was nanoprecipitated in the presence of dextran-based polymeric stabilizer. On the other hand, a PLA-grafted dextran copolymer was nanoprecipitated without the addition of any external stabilizer. The characteristics of particles (yield, size, colloidal stability in the presence of salt) were correlated to the properties of initial polymers. PLA-grafted dextran led to small particles, with high yield and improved colloidal stability even without any stabilizer in the aqueous phase. Viscometric experiments in organic solvent/water mixtures indicated that PLA-grafted dextran self-organized upon mutual diffusion of water and organic solvent spontaneously, providing nanoparticles with a PLA core and a dextran-enriched surface. These nanoparticles exhibited good colloidal stability in water even at high ionic strengths (4 mol/L).