Continuous and surfactant-free preparation of nanocapsulized proteins

In this study, we demonstrate the preparation of nanocapsules using the self-assembly of preformed polymers at the interface of a three-way controlled laminated stream flow in a microchannel. The production process occurs without the use of surfactants and allows the regulation of nanocapsule size with solvent recycling. Problems associated with nanocapsule attachment to the channel surface disturbing the lamination flow and producing nanocapsules of poor quality were overcome by altering the microchannel aspect ratio. The aspect ratio was altered by considering the mixing ratio and velocity distribution on the cross section along the microchannel. Modeling and practical experiment identified the aspect ratio of the microchannel of 1.6 as producing clear lamination flow. Ovalbumin-encapsulated nanocapsules were produced with a narrow size distribution of <200 nm, allowing standard bacterial filtration processes to be used to sterilize the nanocapsules. To obtain a concentrated preparation of protein nanocapsules with minimal solvent contamination, a three-outlet separation system was developed. Using a diffuser with a diverging angle on the outlet collection port, we were able to focus 95% of the nanocapsules into the central collection channel with the PLGA acetone fraction into the side channels from which they could be collected and the components recycled. Liquid phase 1H NMR analysis indicated that the lyophilized nanocapsules do not contain detectable acetone.