|Tropical Journal of Pharmaceutical Research|
|Official Journal of Pharmacotherapy Group|
African Journals Online
Life is based on a combination of
Tropical Journal of Pharmaceutical Research 2007; 6(2): 685-686
A long time ago, it was nothing. Then, a big bang dispersed energy over the universe. Some of this energy compacted to form atoms, which combined to form molecules. The molecules became more and more complex, resulting in biochemistry, but life was still not there.
Somebody, let us call Him God, said, let’s try a new thing. Let’s put a microcapsule (membrane) around this biochemistry. Then, life started! Biological cells multiplied, and colonized the earth. They organized themselves to give pluricellular organisms, which evolved to finally become an exceptional structure of more than 1012 microcapsules called a human being.
Bioencapsulation essentially mimicks this very ancient process, i.e.
· immobilizing bioactive material (‘actives’), thus avoiding its dispersion in water.
· protecting it (against pH, oxygen, etc,.
· controlling mass transfer (exchange with the surrounding).
· structuring it (change from liquid state to an apparent solid form), and
· creating new functions (such as ATP production over mitochondrial membrane).
The challenge of bioencapsulation researchers and engineers is to obtain microcapsules presenting powerful properties and functions like biological cells.
The initial microcapsule concept referred to a liquid core surrounded by a membrane; however, biocapsules may take many different forms such as solid beads, hydrogel beads, liposomes, etc. The core could be a solid, a liquid, an emulsion, or a liquid dispersion in a solid matrix. Some companies even develop small capsules integrated inside larger capsules.
There are a number of methods (and combinations of methods) for producing microcapsules. One simple approach is to classify them as shown in Table 1 based on the assumption that an encapsulation process comprises of three steps:
1. Incorporation of the ‘actives’ in the future core of the capsules; if the core is liquid, the ‘actives’ may be dissolved, dispersed, or emulsified in this liquid. If the core is solid (particles), the ‘actives’ may be incorporated by absorption during or after production of the core particles.
2. Dispersion of the core; either by production of air droplets or liquid dispersion (in the case of a liquid core) or by agitation of a powder and deposition of the coating material on it.
3. Stabilisation of the capsules; liquid droplets or particles surrounded by a liquid are stabilized by solidifying the external surface (membrane) or the core (beads) via solidification, gellation, polymerization, precipitation, drying or any other physical, physicochemical or chemical process.
Table 1: Classification of the microencapsulation methods
Biocapsules may be used for many purposes; specifically, in the medical domain, one could cite:
This is only a short list of potential applications. The domain of applicability is very broad and is likely to expand in the next few years. For additional information, you may connect to the Bioencapsulation Research Group website (http://bioencapsulation.net) where you will find listed relevant books and reviews.
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|Last updated: June 12, 2007|