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 protein-loaded 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).

Uniform encapsulation of stable protein nanoparticles produced by spray freezing for the reduction of burst release.

Stable protein nanostructured particles, produced by spray freezing into liquid (SFL) nitrogen, were encapsulated uniformly into microspheres to reduce the burst release over the first 24 h. The denaturation and aggregation of these bovine serum albumin (BSA) high-surface area particles were minimal due to ultra-rapid freezing and the absence of a liquid-air interface. Upon sonication, these friable highly porous, solid protein particle aggregates broke up into submicron particles.