Stimuli-Responsive Polysaccharide-Based Smart Hydrogels and Their Emerging Applications

Hydrogels are a soft material that undergoes cross-linking between polymers to form a hydrophilic three-dimensional network. In fact, similarity to body tissue, soft consistency, biocompatibility, and elasticity, impart a protagonic role of hydrogel to be applied as a biomaterial. In response to external cues, stimuli-responsive hydrogels are particularly impactful, enabling remarkable levels of control over material properties. They can endure changes in swelling behavior, permeability, network structure, and mechanical strength. Nevertheless, such changes induce single-cycle or reversible transitions, so hydrogels can regain their initial state once the trigger is removed. Recently, polysaccharide-based hydrogels with stimuli-responsive properties resulted in developing biomimetic structures for a widespread biotechnological application owing to their excellent biodegradability, biocompatibility, nonimmunogenicity, functional properties, ease of gelation, and derivatization. This review will initially highlight recent advances in cross-linking methods and chemistry for preparing stimuli-responsive hydrogels. Subsequently, state-of-the-art techniques to understand the structural, chemical, and rheological behavior of polysaccharide-based stimuli-responsive hydrogel will be discussed. Additionally, the responsiveness of polysaccharide hydrogel toward diverse stimuli such as redox, temperature, light, pH, magnetism, electricity, etc., with a broad spectrum of applications will be described in detail. This review also attempts to address the lacunae of existing stimuli-responsive hydrogel and their future perspectives.