STIMULI SENSITIVE HYDROGELS IN DRUG DELIVERY SYSTEMS

Hydrogels are the 3 dimensional cross linked polymeric networks which absorb the water 10-20 times of its molecular weight. Hydrogels are sensitive to different environmental stimuli like pH, temperature, ion, electric signals, light, pressure, antigen specific, enzyme sensitive, and glucose levels. When the environment is get change they get swell, and swelling is the most important characteristics for release of drug through hydrogel devices, and release by either diffusion or swelling or chemically controlled. These stimuli sensitive hydrogel used in delivery of drug through various routs like oral, ophthalmic parenteral drug, nasal TDDS, and also in novel drug delivery like in nanoparticles. Now a day's stimuli sensitive hydrogels are also used in administration of DNA. Most widely stimuli sensitive hydrogels used are pH and temperature sensitive hydrogels because in body wide pH range available so it is used for targeted drug delivery. Hydrogels that are responsive to specific molecules, such as glucose or antigens, can be used as biosensors as well as drug delivery systems.