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AAPS PharmSciTech. 2005 December; 6(4): E605–E617.
Published online 2005 December 6. doi:  10.1208/pt060475
PMCID: PMC2750608

Encapsulation of protein nanoparticles into uniform-sized microspheres formed in a spinning oil film


A new spinning oil film (SOF) solid-in-oil-in-oil emulsion process was developed to produce uniform-sized proteinloaded biodegradable microspheres. A thin SOF on a cylindrical rotor was used to shear droplets from a nozzle tip to control droplet size. The resulting microspheres with low polydispersity (6%) produced a low burst (6%–11%) release even at high loadings (13%–18% encapsulated solids, 8%–12% protein). The SOF process had a high yield and did not require the presence of water, which can cause protein denaturation, or surfactants, which may be unwanted in the final product. Amorphous protein and crystalline excipient solids were encapsulated into 3 different polymers, giving a homogenous drug distribution throughout the microspheres, and an essentially complete protein encapsulation efficiency (average=99%). In contrast, large burst release was observed for polydisperse microspheres produced by a conventional emulsification technique, particularly for microspheres smaller than 25 μm in diameter, which gave 93% burst at 15% loading. The uniform encapsulation of high loadings of proteins into microspheres with low polydispersity in an anhydrous process is of practical interest in the development of controlled-release protein therapeutics.

Keywords: microsphere size control, monodisperse emulsions, spray freezing into liquid process, bovine serum albumin, solid-in-oil-in-oil processing, PLGA, initial burst

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.
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