Hydrogels: Properties and Applications in Biomedicine

Abstract

Hydrogels are crosslinked polymer chains with three-dimensional (3D) network structures, which can absorb relatively large amounts of fluid. Because of the high water content, soft structure, and porosity of hydrogels, they closely resemble living tissues. Research in recent years shows that hydrogels have been applied in various fields, such as agriculture, biomaterials, the food industry, drug delivery, tissue engineering, and regenerative medicine. Along with the underlying technology improvements of hydrogel development, hydrogels can be expected to be applied in more fields. Although not all hydrogels have good biodegradability and biocompatibility, such as synthetic hydrogels (polyvinyl alcohol, polyacrylamide, polyethylene glycol hydrogels, etc.), their biodegradability and biocompatibility can be adjusted by modification of their functional group or incorporation of natural polymers. Hence, scientists are still interested in the biomedical applications of hydrogels due to their creative adjustability for different uses. In this review, we first introduce the basic information of hydrogels, such as structure, classification, and synthesis. Then, we further describe the recent applications of hydrogels in 3D cell cultures, drug delivery, wound dressing, and tissue engineering.

Keywords: 3D cell culture; drug delivery; hydrogel; medical application; tissue engineering; wound dressing.

Figure 1

The number of publications related to hydrogels in the biomedical field in the past five years. The data was obtained from the biomedical database PubMed, using the search term “hydrogel”.

Figure 2

Classification of hydrogels.

Figure 3

Simple diagram of homopolymer hydrogels, copolymer hydrogels, semi-IPNs, and IPN hydrogels.

Figure 4

The structure of hydrogels (chemical linking and physical junctions).

Figure 5

Methods of chemical and physical crosslinking for hydrogels preparation.