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The Dispersion Cell membrane emulsification technique was used for the production of w/o emulsions with controlled droplet size and narrow size distribution. The influence of the operating parameters of the process was investigated. Varying the dispersed phase flux (10–1250 L h −1 m −2) and the shear stress (2–59 Pa), droplets between 30 and 280 μm were produced with CV ’s as low as 18%. Nickel and stainless steel membranes were used for the membrane emulsification. Pore geometry influenced the droplet size as well as uniformity and a normally hydrophilic stainless steel membrane with sharp pore openings produced more uniform and smaller drops compared to a PTFE coated hydrophobic nickel membrane with a conical pore surface. For the dispersed phase 15 wt.% PVA or 1–3 wt.% chitosan as well as their blends in water were used. Surfactants PGPR and ABIL EM90 were tested to determine their capability to form stable emulsions in Miglyol 840. PGPR could not be used to stabilize the emulsion with chitosan as the dispersed phase, probably due to the chemical interference between the carboxyl group present in the PGPR and chitosan. Solid microparticles were obtained by chemical crosslinking with glutaraldehyde (GA) at different concentrations (1–50 vol.%). Particles crosslinked using less than 10 vol.% GA were able to swell and release encapsulated compounds. Acid sensitive particles were produced by blending the PVA and chitosan. Up to 80% of Cu 2+ and 20% of sodium salicylate was released from the particles under acidic conditions. No significant release was determined under neutral conditions. [ABSTRACT FROM AUTHOR]

Abstract: Particles for subcutaneous depot use encapsulating a model water-soluble drug have been produced from poly(lactic–glycolic acid) (PLGA) using a membrane emulsification—solvent evaporation technique. The release behaviour, mainly the change in size and inner morphology are reported. During release, the particles initially swelled in size, then reduced. A diffusion based model, taking in to account the change in particle size, is presented. Surface erosion is evident from the particle size and image evidence, and the diffusion model provides a fit to the data even during the surface erosion period, suggesting that the model drug diffuses before the particle degrades. [Copyright &y& Elsevier]

Co-encapsulation of drugs in the same carrier, as well as the development of microencapsulation processes for biomolecules using mild operating conditions, and the production of particles with tailored size and uniformity are major challenges for encapsulation technologies. In the present work, a suitable method consisting of the combination of membrane emulsification with solvent diffusion is reported for the production of multi-core matrix particles with tailored size and potential application in multi-therapies. In the emulsification step, the production of a W/O/W emulsion was carried out using a batch Dispersion Cell for formulation testing and subsequently a continuous azimuthally oscillating membrane emulsification system for the scaling-up of the process to higher capacities. In both cases precise and gentle control of droplet size and uniformity of the W/O/W emulsion was achieved, preserving the encapsulation of the drug model within the droplet. Multi-core matrix particles were produced in a post emulsification step using solvent diffusion. The compartmentalized structure of the multicore-matrix particle combined with the different chemical properties of polycaprolactone (matrix material) and fish gelatin (core material) was tested for the simultaneous encapsulation of hydrophilic (copper ions) and hydrophobic (α-tocopherol) test components. The best operating conditions for the solidification of the particles to achieve the highest encapsulation efficiency of copper ions and α-tocopherol of 99 (±4)% and 93(±6)% respectively were found. The multi-core matrix particle produced in this work demonstrates good potential as a co-loaded delivery system. [ABSTRACT FROM AUTHOR]