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Critical Reviews™ in Therapeutic Drug Carrier Systems
IF: 2.414 5-Year IF: 3.324 SJR: 0.573 SNIP: 0.551 CiteScore™: 2.43

ISSN Print: 0743-4863
ISSN Online: 2162-660X

Critical Reviews™ in Therapeutic Drug Carrier Systems

DOI: 10.1615/CritRevTherDrugCarrierSyst.2013007259
pages 369-409

Stimuli-Sensitive Hydrogels: An Excellent Carrier for Drug and Cell Delivery

Tarun Garg
Department of Pharmaceutics, ISF College of Pharmacy, Moga, Punjab, India
Simranjit Singh
Department of Pharmaceutics, ISF College of Pharmacy, Moga (Punjab), India
Amit Kumar Goyal
Department of Pharmaceutics, ISF College of Pharmacy, Moga (Punjab), India; Punjab Technical University, Kapurthala, Punjab, India


The stimuli-sensitive hydrogel is an injectable formulation that is used to deliver drugs, cells, and genes into the body. Hydrogels are available in various physical forms such as solid molded, pressed powder matrix, microparticle, coating, or membrane forms. The network structure of hydrogels can be macroporous, microporous, or nonporous. Different categories of biomaterials, such as natural, synthetic, and combinations (e.g., semisynthetic such as natural-natural, natural-synthetic, and synthetic-synthetic polymers), are commonly used in hydrogel preparation. Classification of hydrogels mainly depends upon physical stimuli (temperature, electric fields, solvent composition, light, pressure, sound, and magnetic fields) and chemical or biochemical stimuli (pH, ions, and specific molecular recognition events). Several approaches for the synthesis of hydrogels have been reported, including emulsification, micromolding, photolithography, isostatic ultra high pressure, and microfluidic techniques. Hydrogels provide structural integrity and cellular organization, serve as tissue barriers, act as bioadhesive and drug depots, deliver bioactive agents and cells, and possess unique swelling properties and structures. This review provides a detailed account of the need for development of hydrogels, along with the materials used and techniques adopted to manufacture scaffolds for tissue engineering and for prolonged drug, cell, and gene delivery.