Layered double hydroxides: A brief review from fundamentals to application as evolving biomaterials

Layered double hydroxides (LDH) which are one type of layered materials and are also known as anionic clays, are promising layered materials due to some of their interesting properties, such as ease of synthesis, unique structure, uniform distribution of different metal cations in the brucite layer, surface hydroxyl groups, flexible tunability, intercalated anions with interlayer spaces, swelling properties, oxo-bridged linkage, and high chemical and thermal stability, ability to intercalate different type of anions (inorganic, organic, biomolecules, and even genes), delivery of intercalated anions in a sustained manner and also high biocompatibility. Considering the previous work on LDH as novel biomaterials, research on this particular materials has become one of the most interesting topic of today's research. LDH has become an important class of layered materials having prospects in the field of biomaterials, wherein great attention has been paid to the biocompatibility nature, exchange of the existing anion with the target anion, holding of guest species in between the interlayer space and its controlled release of the anion in a particular medium. This article, after deliberating the recent significant evolution in the structure and different methods of synthesis of different LDH materials and its applications in various extents especially its biological applications through their structural and functional properties, considers many typical examples. In particular, recent progress on the emerging strategies of LDH to improve their antimicrobial activity is also presented.