Drug–clay nanohybrids as sustained delivery systems

Biocompatible 2-dimensional layered compounds such as clays and layered double hydroxides (anionic clays) have been explored and utilized in drug delivery system for therapeutic application because they can safely encapsulate drug molecules via intercalation reaction. Therefore, various kinds of drug molecules and bio-functional molecules with cationic or anionic charge have been incorporated into clay delivery carriers, giving rise to the heterostructured layered nanohybrids with chemo-therapeutic and gene-therapeutic functions. Recently, such inorganic delivery systems have received growing attention because their inertness and low toxicity gives rise to safety and stability in bio-systems. Furthermore, the hybridization of drug with clays offers the fascinating features such as controlled and sustained release, improved water-solubility, and even protective and targeted delivery. Unique release behaviors of drugs from the drug–clay nanohybrids are originated from molecular level incorporation, and strong interaction between drug and inorganic layers including electrostatic and hydrogen bonding interactions. In the present review, various drug–clay nanohybrids will be introduced, and their recent development will be highlighted in the viewpoint of oral administration drugs with controlled and sustained release.