Hydrogel Beads of Natural Polymers as a Potential Vehicle for Colon-Targeted Drug Delivery.

Polysaccharides are excellent candidates for drug delivery applications as they are available in abundance from natural sources. Polysaccharides such as starch, cellulose, lignin, chitosan, alginate, and tragacanth gum are used to make hydrogels beads. Hydrogels beads are three-dimensional, cross-linked networks of hydrophilic polymers formed in spherical shape and sized in the range of 0.5-1.0 mm of diameter. Beads are formed by various cross-linking methods such as chemical and irradiation methods. Natural polymer-based hydrogels are biocompatible and biodegradable and have inherently low immunogenicity, which makes them suitable for physiological drug delivery approaches. The cross-linked polysaccharide-based hydrogels are environment-sensitive polymers that can potentially be used for the development of "smart" delivery systems, which are capable of control release of the encapsulated drug at a targeted colon site. This topic focuses on various aspects of fabricating and optimizing the cross-linking of polysaccharides, either by a single polysaccharide or mixtures and also natural-synthetic hybrids to produce polymer-based hydrogel vehicles for colon-targeted drug delivery.