Chapter 6 - Graft copolymers of polysaccharides: Synthesis techniques and pharmaceutical applications

Abstract

In recent years, polymer grafting has created an innovative pathway to develop new and improved polymers having desired functional properties for use in different pharmaceutical formulations. The modification of the polymers used to take place with the help of those techniques, such as grafting, cross-linking, blending, composite formation, etc. In recent times, the polymer grafting process has gained an extensive interest than the other techniques employed in the modifications of the polymers. Polymer grafting may be accomplished by means of the covalent bonding of the monomer to the polymer. Choice of appropriate polymer system is a crucial stage implicated in the development of pharmaceutical dosage forms. Different types of polymer(s) are included in pharmaceutical dosage forms, which majorly determine the stability of formulation as well as an active ingredient itself, mechanism of action, as well as the release rate of drugs from the formulations. Recently, natural polysaccharides have accepted additional consideration in the drug delivery field owing to their outstanding merits. However, natural polysaccharides usually fail to meet several basic requirements, such as solubility, colloidal properties, mechanical behavior, degradability, etc. The copolymerization method assists in the advancement of natural polysaccharides by providing them with desirable physicochemical and functional characteristics. On grafting, the host biopolymer achieves a number of desired characteristics of monomers utilized in the grafting process. Polysaccharide-based graft copolymers are possessing immense significance as they can be employed in the production of different stimuli-dependent controlled release systems. The present review contends with a variety of techniques engaged in the synthesis of grafted polysaccharides in addition to the up-to-date developments for the designing of novel drug delivery systems. Grafting can be attained by the methods explained herein and can be analyzed by various modern analytical technologies, including infrared (IR), nuclear magnetic resonance (NMR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), etc. Due to their modified physicochemical and functional characteristics, these grafted polysaccharides tender many applications in terms of site-specific drugs and biological delivery capacity.