ENVIRONMENTAL RESPONSIVE HYDROGELS: A NOVEL APPROACH IN DRUG DELIVERY SYSTEM

Abstract

Hydrogels are three dimensional crosslinked hydrophilic polymeric networks which has the capability to imbibewater or biological fluids. Environmentally responsive hydrogels have the ability to respond to change in theirexternal environment. They can exhibit dramatic changes in their swelling behaviour, network structure,permeability and mechanical strength in response to change in pH or ionic strength of the surrounding fluid ortemperature. Other hydrogels have the ability to respond to applied electric or magnetic field or to change inconcentration of glucose. Environmental responsive hydrogels for drug delivery application also requiresbiocompatibility. The chemical structure of the polymer may also affect the swelling ratio of hydrogels. Hydrogelscontaining hydrophilic groups swell to a higher degree compared to those containing hydrophobic groups.Swelling of environmentally responsive hydrogels can be affected by changes in the temperature of the swellingmedia, ionic strength and pH