Recent advances in high-strength and elastic hydrogels for 3D printing in biomedical applications

Abstract

Three-dimensional (3D) printing enables the production of personalized tissue-engineered products with high tunability and complexity. It is thus an attractive and promising technology in the pharmaceutical and medical fields. Printable and biocompatible hydrogels are attractive materials for 3D printing applications because they offer favorable biomimetic environments for live cells, such as high water content, porous structure, bioactive molecule incorporation, and tunable mechanical properties and degradation rates. However, most conventional hydrogel materials are brittle and mechanically weak and hence cannot meet the mechanical needs for handling and soft and elastic tissue use. Thus, the development of printable, high strength, and elastic hydrogel materials for 3D printing in tissue repair and regeneration is critical and interesting. In this review, we summarized the recent reports on high strength and elastic hydrogels for printing use and categorized them into three groups, namely double-network hydrogels, nanocomposite hydrogels, and single-network hydrogels. The reinforcing mechanisms of these high strength hydrogels and the strategies to improve their printability and biocompatibility were further discussed. These high-strength and elastic hydrogels may offer opportunities to accelerate the development of 3D printing technology and provide new insights for 3D-printed product design in biomedicine.