A wide array of effective functional ingredients is available for topical application via different cosmetic products. However, the effects and benefits of these ingredients can be observed only if they reach their target sites at an effective concentration and for a sufficient exposure time. Most conventional rinse-off products, such as body washes, leave a very small amount of functional ingredient on the skin after rinsing. For these products to be efficacious, the functional ingredients that remain on the body should be at an effective level for an extended period of time.
An ideal delivery system for water-based skin products would enable a product that is completely washable with water, yet the functional ingredients remain in contact with the skin to perform their pharmacological action. These two completely opposite performance criteria can be achieved by applying a delivery system that incorporates bio-adhesive nanospheres. The nanospheres are incorporated in a water base and all the ingredients of the base are completely removed by water through rinsing while the nanospheres are made bio-adhesive so that they stick to tissue surfaces and slowly release their contents.
Roughly spherical particles smaller than one micron are commonly called nanospheres. Small uni- or multi-lamellar liposomes and a variety of lipid structures are broadly classified as nanospheres. However, the application of these latter lipid structures in personal care products is limited by their instability and by their limited ability to encapsulate functional ingredients at practical levels in the presence of surfactants.
An alternative approach to the use of liposomes is to use solid nanospheres. Their solid hydrophobic structure encapsulates the functional ingredients to retain them during the shelf life of the product in a water-soluble base. Furthermore, the nanospheres can be surface modified to promote adhesion and hence deposition on body surfaces in rinse-off products.
Excerpt Only This is a shortened version or summary of the article that appeared in the July 1, 2004 issue of Cosmetics & Toiletries magazine. The full content is not currently available online.