Modified hyaluronic acid based materials for biomedical applications.

Hyaluronic acid (HA) is a high molecular weight, non-sulfated anionic polysaccharide from glycosamine glycan family. It is a versatile biomaterial that binds to specific cell receptor CD44 (frequently over-expressed on the tumor cell surface) and is useful in skin rejuvenation, drug delivery, tissue engineering and molecular imaging due to its biodegradable, non-toxic, biocompatible, non-immunogenic and non-inflammatory characteristics. It can be chemically modified by cross-linking, grafting, linking with hydrophobic substances and drugs, or through polyion complex formation with oppositely charged polysaccharides, proteins or surfactants. Its interpenetrating network produces self-assembled aggregates, nanoparticles and gels. The present review is aimed to provide recent updates on researches on HA, with an emphasis on different modification approaches. Various transformations in HA through covalent and non-covalent interactions and resulting applications in biomedical fields from the recent literature are described. Studies on stabilization of nanoparticles (NPs) and other colloidal carriers through layer-by-layer adsorption of HA are also highlighted. The article provides a greater visibility into the magnitude of HA application in the development of targeted drug vectors and implantable biomaterials.