Today more than ever, the skin-care and cosmetic formulator is being challenged to develop efficacious and clearly distinctive topical formulations. New raw materials, sometimes with profound effects on the various skin layers, are used for these preparations. The topical formulations used in cosmetics and personal-protection products that contain encapsulated active ingredient usually are one of the following delivery systems, or a combination of them: microcapsules, nanoparticles and microparticles, and porous polymeric systems. Microcapsules are small particles that contain an active agent or core material surrounded by a coating layer or shell. Sometimes each microcapsule may contain several cores, either of the same component or various components. The most important parameter in microencapsulation in general and in cosmetic products in particular is the release of the microencapsulated ingredient during storage and after its application. Several methods may be used for microencapsulation of cosmetic products, of which the in situ polymerization and phase separation methods are probably the most popular.
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