Hydrotalcite-like compounds: Versatile layered hosts of molecular anions with biological activity

This paper reviews a systematic work, mainly performed in our laboratories, on the intercalation into hydrotalcite-like compounds (HTlc) of anti-inflammatory drugs, sunscreen and antimicrobials species. The paper is divided in three parts, the first part being addressed to the synthesis, structural aspects and intercalation properties of HTlc, the second part to the properties of the intercalation compounds with biologically active molecular anions, the third part to the preparation of polymeric nanocomposites for biomedical applications. Ion exchange procedures have been used to obtain the intercalation compounds of MgAl-HTlc with ibuprofen, diclofenac, indomethacin, ketoprofen and tiaprofenic acid and to study their release in solutions simulating biological fluids. Some of these intercalation compounds have been tested to improve the solubility of poorly water-soluble drugs such as indomethacin, ketoprofen, tiaprofenic acid and flurbiprofen. MgAl-HTlc and ZnAl-HTlc have been used as starting materials to prepare new sunscreen products, in which organic filters are entrapped between HTlc lamellae, in order to improve “solar product” effectiveness and safety. The preparation of polymeric composites constituted by HTlc exchanged with the anti-inflammatory diclofenac or the antimicrobial drugs and polycaprolactone are also described.