Asian Research Thesis Index

Abstract

A novel method was developed to synthesize switchable pH responsive hydrogel from natural and synthetic polymers. Blends of CM-chitosan and carrageenan were reacted with acrylic acid and in situ crosslinked with vinyltriethoxy silane (VTESi). This crosslinker is used for the first time for this type of blends. Three sets of polymeric hydrogels were prepared in this work. Polymerization steps involve initiation, propagation, copolymerization and crosslinking reactions. During the process of polymerization, peroxide was broken into radicals, which attack other molecules and monomers present in the reactor to convert them into radicals. These resultant radicals combine with each other to produce stable molecules which upon crosslinking through a process of condensation lead to the formation of network structure having hydrogels properties. These hydrogels are then characterized by using various techniques. Structural and thermal analysis confirmed the presence of crosslinking within hydrogel. Dynamics of water vapor sorption was also done to show the extent and rate of vapor uptake of prepared hydrogels. Similarly swelling study in water gave a clear picture about the effect of concentration of monomer and crosslinking agent on swelling ability of hydrogel. Swellings in buffered, non-buffered and ionic environment exhibited a variety of behavior. Temperature was found to be favorable for swelling but only to a specific extent. All the developed hydrogels showed switchable response against change in pH of the external media. These hydrogel showed low swelling at low and high pH and maximum swelling was observed at neutral pH. This pH response and biocompatible nature of the incorporated component made it a good candidate for drug delivery application. These hydrogels were loaded with insulin and its in-vitro release study showed very interesting results. A very low release of insulin was observed at low pH and consistent release was observed at neutral pH. Further studies on these systems will provide another biotechnological material for gastrointestinal delivery for drugs.

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