Abstract
The chemical stability, degradation and penetration ability of pharmaceutically active drugs in topical applications are the greatest challenges in cosmetics because of problems with the protection of actives for long times and with delivery. Therefore, the development of unique and efficient material is required for protection and for controlled drug release systems. Layered double hydroxides (LDHs), also known as hydrotalcite-like compounds, are 3D crystals formed by 2D laminates which are orderly arranged in longitudinal directions. The host LDHS layers possess positive charges due to isomorphic substitutions, which are counterbalanced by hydrated exchangeable anions located in the interlayer region. Some of the active drug molecules can be intercalated into the inner region of the LDHs host through ionic bonding, hydrogen bonding, or Van Der Waals’ interaction to form nanohybrids, which are more potent for protection and controlled-release systems. For example, aspirin, also known as acetylsalicylic acid (ASA), is a class of NSAID and is a traditional analgesic available on the market. ASA is an organic compound having easily polarizable carboxylic groups, it is therefore easily intercalated into the LDH host, to yield an LDH-ASA nanohybrid. Generally, ASA is used as a pain relief ingredient in topical skin care products. ASA is usually an unstable molecule, and easy to degrade into small fragments (salicylic acid and acetic acid) which give unwanted side effects; thus, to improve the chemical stability of ASA, the degradation behaviour of ASA is of great importance in cosmetic formulations. In this concern, LDHs nanoparticles have attracted specific attention because of their many desirable properties- particularly the protecting capacity after intercalation of drugs into LDH interlayers...
Ph.D. (Chemistry)