Poly(N-isopropylacrylamide)-Based Hydrogels for Biomedical Applications: A Review of the State-of-the-Art

Abstract

A prominent research topic in contemporary advanced functional materials science is the production of smart materials based on polymers that may independently adjust their physical and/or chemical characteristics when subjected to external stimuli. Smart hydrogels based on poly(N-isopropylacrylamide) (PNIPAM) demonstrate distinct thermoresponsive features close to a lower critical solution temperature (LCST) that enhance their capability in various biomedical applications such as drug delivery, tissue engineering, and wound dressings. Nevertheless, they have intrinsic shortcomings such as poor mechanical properties, limited loading capacity of actives, and poor biodegradability. Formulation of PNIPAM with diverse functional constituents to develop hydrogel composites is an efficient scheme to overcome these defects, which can significantly help for practicable application. This review reports on the latest developments in functional PNIPAM-based smart hydrogels for various biomedical applications. The first section describes the properties of PNIPAM-based hydrogels, followed by potential applications in diverse fields. Ultimately, this review summarizes the challenges and opportunities in this emerging area of research and development concerning this fascinating polymer-based system deep-rooted in chemistry and material science.

Modeling Tunable Fracture in Hydrogel Shell Structures for Biomedical Applications

“…These flexible sensors can better monitor subtle changes in the external environment, such as temperature [ 91 , 92 , 93 ], humidity [ 91 , 94 ], and deformation [ 95 , 96 ], and are evolving rather fast. For these kinds of sensors, various types of hydrogels are being actively developed, such as cellulose hydrogels [ 97 ], PNIPAM hydrogels [ 98 ], and double chain hydrogels [ 99 ]. These hydrogels are sensitive to mechanical signals and can be used as dynamic soft sensors that accurately detect small external forces and strains.…”

“…In recent years, research into hydrogels has made significant breakthroughs (e.g., self-healing hydrogels [ 88 , 89 , 90 , 113 ], smart hydrogels [ 98 ], cellulose hydrogels [ 97 ], double chain hydrogels [ 114 ], supramolecular hydrogels [ 115 ], etc.). However, most of the research focuses on hydrogel functionality, as for flexible wearable sensors, drug delivery, and medical engineering.…”

Alginate as a Promising Biopolymer in Drug Delivery and Wound Healing: A Review of the State-of-the-Art

“…Because hydrogels are physically comparable to biomacromolecular constituents, they are frequently biocompatible and can be administered into the body by non-invasive administration. Hydrogels are commonly formed from hydrophilic polymers by chemical and/or physical cross-linking; their physicochemical characteristics depend on the type of cross-linking, the density of the cross-linker, and the polymers’ chemical composition and molecular weight [ 58 ]. We present a review of different methods for cross-linking ALG sequences to generate gels and the effects of these methods on the hydrogel features crucial in the biomedical field.…”

Chondroitin sulfate-based composites: a tour d’horizon of their biomedical applications

“…Bone TE. Several biomaterials such as injectable hydrogels and injectable scaffolds have been developed to deliver osteoconductive growth factors, especially bone morphogenetic protein 2 (BMP-2), 155 which is necessary to initiate regeneration, and they must be given in overdose due to their short life. 156 Many in vitro and in vivo investigations have been examined and are still in the quest to find the potential biomaterial for bone tissue graft.…”