Chitosan-based hydrogel: synthesis and its application in loadig and release of nile blue

Hydrogels are hydrophilic polymers with a three-dimensional network which is capable of absorption and desorption hydrophilic solutions. In general, the rate of release of trapped material inside the hydrogel network is directly related to the rate of diffusion of water into the hydrogel network. That is, the higher the rate of water diffusion into the network, the faster release of the trapped material. The high rate of water diffusion into the hydrogel network causes the flow of water in to the network to be fast and, therefore, the trapped material is release more rapidly from the hydrogel. Chitosan hydrogel is soluble in water and has a positive charge, and this feature is technically important. Because it enables polymers to interact with negatively charged polymers, coarse molecules, and even with some poly-anions in an aqueous medium. A gel is created from these interactions and states of transition [1-3]. PH-sensitive hydrogels were synthesized by grafting acrylic acid monomers onto chitosan in the presence of the cross-linking agent methylene-bis-acrylamide and the thermal primer of ammonium persulfate for controlled release of nile blue. In this research, a pH-sensitive hydrogel was used as carrier of electro-active substance nile blue. The concentration of released nile blue was evaluated utilizing DPV as a sensitive electrochemical method at different pH levels. The synthesized material was inserted at a pH 1 to 12 for a specified period, then the calibration curve was plotted to measure the concentrations of the solutions. The results showed that in acidic PHs the nile blue concentration was higher, indicating that the nile blue release rate was higher in acidic pHs.