SMART HYDROGELS FOR ADVANCED DRUG DELIVERY

Hydrogels are three-dimensional polymeric network structures having high water content. Stimuli-responsive or smart polymers are macromolecules that show a significant physiochemical change in response to small changes in their environment. These smart hydrogels with chemical and structurally responsive moieties show excellent characteristics of reacting under different environmental conditions such as temperature, pH, light, magnetic field, ionic factors, etc. These polymers have the ability to observe a change (stimulus) in their environment, respond to it immediately, and then return to their original shape/state when the stimulus is removed. Due to the high-water content of hydrogels and more similarity with biological tissues, hydrogels provide an ideal environment for cell survival, and structure which mimics the biological tissues. More water content, soft consistency and low interfacial tension with biological fluids makes them biocompatible. Due to their superior biocompatibility and low toxicity hydrogels have a significant role in the biomedical fields. In biomedical field, these super intelligent hydrogels have gained a significant interest in tissue engineering, drug delivery, diagnostics, imaging and optics. The purpose of this review is to elaborate properties of hydrogels, their classification and their biomedical applications.