G-CSF loaded biodegradable PLGA nanoparticles prepared by a single oil-in-water emulsion method

A new formulation method was developed for preparing poly(d,l-lactic-co-glycolic acid) (PLGA) nanoparticles loaded with recombinant human granulocyte colony-stimulating factor (rhG-CSF). Lyophilized rhG-CSF powder and PLGA polymer were directly co-dissolved in a single organic phase, and the resulting solution was dispersed into an aqueous solution. PLGA nanoparticles encapsulating rhG-CSF were produced by a spontaneous emulsion/solvent diffusion method. In this manner, rhG-CSF was molecularly dissolved in the polymer phase. Release profile of rhG-CSF from PLGA nanoparticles was compared with those from two kinds of PLGA microparticles which were separately prepared by either single oil-in-water (O/W) or double water-in-oil-in-water (W/O/W) emulsion technique. The sizes of rhG-CSF loaded nanoparticles, O/W microparticles, and W/O/W microparticles were about 257 nm, 4.7 μm, and 4.3 μm, respectively. For rhG-CSF nanoparticles, about 90% of encapsulated rhG-CSF was released out in a sustained manner from PLGA nanoparticles over a 1 week period, but for rhG-CSF microparticles, only about 20% of rhG-CSF could be released out during the same period. Reversed phase and size exclusion chromatograms revealed that the structural integrity of released rhG-CSF from nanoparticles was nearly intact, compared to that of native rhG-CSF.