Synthesis of hydrotalcite-like nanocompounds for novel biological application

Abstract

Hydrotalcite-like compounds (HTlcs, also known as layered-double hydroxides, LDHs) stand for an important class of layered materials with host-guest structure. With increasing interest developed recently in the field of organic-inorganic nanocomposites, biomolecular-inorganic nanohybrids and other nanostructured materials, the research on layered hydroxide compounds has received much attention, due to their unique intercalation properties. The purpose of intercalating drugs into the layered structure of LDHs is to achieve sustained release and to diminish the negative physicochemical effects of the drugs. To achieve success in such applications, the crystalline and morphological properties of the materials need to be controlled and optimized, along with their chemical compositions. In this project, we have investigated the influence of experimental parameters at various stages on the properties of the formed drug-LDHs, which have then been correlated with their drug release behaviours. In particular, wet-chemical synthesis methods are used and the effects of solvent systems and synthesis conditions (e.g., temperature and pressure) have been studied in detail. The types of drug are varied widely from anti-inflammatory, anti-cancer, to metabolic drugs. It has been found that the size, size uniformity and dispersity of the formed drug-LDH composites in solution determine the inter-particle interactions upon drying. Two distinctive interactions are identified, face-to-face and edge-to-face among the plate-like particles. The former results in compact and oriented packing of individual platelets, therefore leading to a sustained drug release in general due to diffusion resistance. In contrast, the latter causes inter particle pores and a losing packing, which results in faster drug release from the solid matrix. Besides platelet-like morphology, we have also successfully fabricated unique coral-like LDH microspheres containing high drug loadings (ca. 30-50 wt%) in organic solvent/surfactant system. These microspheres are nonaggregated and can be potentially applied for intravenous drug injection. We have also developed a new method based on template-assisted route for the fabrication of LDH hollow nanospheres. Furthermore, drugs can be intercalated into these hollow nanospheres effectively for potential medical applications.