Thermosensitive Hydrogels and Advances in Their Application in Disease Therapy

Abstract

Thermosensitive hydrogels, having unique sol–gel transition properties, have recently received special research attention. These hydrogels exhibit a phase transition near body temperature. This feature is the key to their applications in human medicine. In addition, hydrogels can quickly gel at the application site with simple temperature stimulation and without additional organic solvents, cross-linking agents, or external equipment, and the loaded drugs can be retained locally to improve the local drug concentration and avoid unexpected toxicity or side effects caused by systemic administration. All of these features have led to thermosensitive hydrogels being some of the most promising and practical drug delivery systems. In this paper, we review thermosensitive hydrogel materials with biomedical application potential, including natural and synthetic materials. We describe their structural characteristics and gelation mechanism and briefly summarize the mechanism of drug release from thermosensitive hydrogels. Our focus in this review was to summarize the application of thermosensitive hydrogels in disease treatment, including the postoperative recurrence of tumors, the delivery of vaccines, the prevention of postoperative adhesions, the treatment of nervous system diseases via nasal brain targeting, wound healing, and osteoarthritis treatment.

Preparation and Evaluation of a Sulfadimethoxine‐Conjugated Hydrogel Based on N‐isopropylacrylamide as a Sustained Release Drug Delivery System

“…Compared to pure NIPAAm hydrogel, the LCST of the P[NIPAAm‐co‐NMSDMO]‐3 hydrogel shifted to be a higher temperature. A carboxylic acid group with high polarity was introduced to the hydrogel matrix when the NMSDMO monomer was grafted to the NIPAAm, which could be the significant reason of the increase in the LCST value [10,35] . Moreover, conjugating the SDMO as massive molecule to the hydrogel backbone makes shrinkage complicated, so chain association occurs at higher temperatures.…”

Developments on the Smart Hydrogel-Based Drug Delivery System for Oral Tumor Therapy

“…The network structure contracts, reflecting the overall impact, which causes water molecules to extrude, medications to be released from their capsules, and the gel to constrict. The hydrogel drainage shrinkage makes the structure compact, and the gel state can be formed at physiological temperature in situ [ 39 , 40 , 41 , 42 ]. For oral tumor treatment, the hydrogel can sustainably release the medications that have been encapsulated.…”

Hyaluronic Acid Scaffolds for Loco-Regional Therapy in Nervous System Related Disorders

“…The selection of either strategy is dependent on the application. For example, to fill a superficial cavity, thermosensitive soluble components would be easier to deposit with a subsequent instantaneous reaction upon a change in temperature, whereas the endoscopic delivery of thermosensitive compounds may not be suited for long distances that could result in the gelation of the solution in the tubing system [ 80 , 81 , 82 ]. On the contrary, the injection of a consolidated hydrogel may be limited to the rheological behavior and nature of the components.…”

“…On the contrary, the injection of a consolidated hydrogel may be limited to the rheological behavior and nature of the components. For instance, changes in structure or properties after injection and degradation due to hydrolysis are variables that could constrain their application [ 81 , 83 , 84 , 85 ].…”

“…When hydrogels are developed by covalent crosslinking, they form chemical or permanent gels. On the other hand, when physical bonding between molecules produces hydrogels, they form physical gels and they are usually reversible [ 81 , 85 , 130 ]. Hydrogels are polymeric mesh networks that have the ability to bind a high amount of water [ 77 , 118 , 131 ].…”