Encapsulation, particle microspheres

In encapsulation process, microspheres and microcapsules can be obtained. Microspheres are microbeads composed of a biopolymer gel network entrapping an active, whereas microcapsules are constituted by an active ingredient (small droplets of liquid or particles) that is inside a hollow and involved by thin walls(s) (Madene et al 2006 Umer et al 2011). The simplest of the microcapsules may have a core surrounded by a wall of uniform or nonuniform thickness. The core material may have one or several different types of ingredients. The wall may be single or multilayered (Madene et al., 2006). 

Li et al., 2011). Solidified IFNa-2b was then encapsulated into microspheres made of PEGT/PBT-PLGA (poly(ethylene glycal/butylenes terephthalate)-poly(D,L-lactide-co-glycolide)). The protein was found to release from the microspheres following zero-order kinetics. These particles were administered to rats and a steady release of lFNa-2b was observed for 13 days. 

Microcarrier particles Can encapsulate antigen and be carried across the mucosal epithelium Biodegradable microspheres, liposomes, vims-hke particles, stimulating complexes (ISCOMM... 

Few works on proteins encapsulation have been presented. A recent study by Young et al. [60] deals with the encapsulation of lysozyme in biodegradable polymer microspheres. A 1-10 pm lysozyme particle suspension in a polymer solution was sprayed into a CO2 vapour phase through a capillary nozzle. The droplets solidified after falling into the liquid phase. By delaying the precipitation in the vapour phase, the larger microparticles obtained were able to encapsulate the suspended lysozyme. The final capsules were in the range of 5 - 70 pm. This work is a nice example of protein encapsulation for microparticle delivery systems. 

Costantino, H. R., Johnson, O. L., and Zale, S. F. (2004), Relationship between encapsulated drug particle size and initial release of recombinant human growth hormone from biodegradable microspheres,/. Pharm. Sci., 93, 2624-2634. 

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