Review: smart and active hydrogels in biotechnology—synthetic techniques and applications

Hydrogels have been extensively utilized in biomedical applications for multiple decades and because of their distinct engineering potential they have been growing with discoveries in biology and chemistry. Distinct properties involving excellent biocompatibility, versatility, efficient stimuli responsiveness, great flexibility, softness, degradability, and high water content make them competent for various applications ranging from industrial to biological fields. Hydrogels can easily be synthesized by physical and chemical cross-linking of either natural or synthetic polymers and further modification with required functionalities may lead to the desired applications as well. Natural and synthetic hydrophilic polymers can be physically or chemically cross-linked in order to produce hydrogels. However, this review mainly focuses on synthesis as well as discrete biomedical applications like contact lenses, tissues engineering, drug delivery, diagnostic imaging, and immunoregulation.