ABSTRACT
Hydrophilic polymeric networks that are capable of imbibing huge volumes of water and undergoing swelling and shrinkage suitably to facilitate controlled drug-release are called hydrogels. Hydrogels are promising, trendy, intelligent, and “smart” drug delivery vehicles that cater to the specific requirements for targeting drugs to the specific sites and controlling drug release. The attractive physical properties of hydrogels, especially their porosity, offer tremendous advantages in drug delivery applications such as sustained release of the loaded drug. Diffusion-controlled drug delivery with hydrogels uses reservoir or matrix devices that allow diffusion-based drug release through a hydrogel mesh or pores filled with water. The swelling-controlled drug release from hydrogels uses drugs dispersed within a glassy polymer which when in contact with a biofluid begins swelling. The supramolecular hydrogel system is composed of intermolecular interactions that are non-covalent and has two or more molecular entities held together. A newer variety of hydrogels used for drug delivery applications are the bioinspired hydrogels.
