Facile fabrication of nonswellable and biocompatible hydrogels with cartilage-comparable performances

The preparation of high-performance hydrogels from biocompatible materials via a facile process has been increasingly studied but remains challenging. Herein, a nonswellable and biocompatible hydrogel was fabricated from polyvinyl alcohol and chitosan by multiple physical interactions without harmful crosslinkers. Owing to the synergy of salting-out effect and tridentate coordination, the network uniformity and stability were improved greatly. Compared with the precursor PVA-CS hydrogel, the crosslinking density increases from 76.9 to 157.8 mmol/cm3 accompanied by an increase in the gel fraction from 58.6 to 91.5%. In contrast, the average molecular weight between adjacent knots and mesh size decrease from 1650 to 1096 g/mol and from 6.1 to 4.8 nm, respectively. Benefited from the higher cross-linking density and more homogeneous gel framework, the obtained hydrogel exhibits cartilage-equivalent mechanical properties (tensile strength = 4.5 MPa, tensile strain = 299 %, elastic modulus = 1.2 MPa, toughness = 6.5 MJ m-3 and compressive stress = 8.4 MPa), combined with a high water content of 84.3 %. Remarkably, this hydrogel demonstrates excellent anti-swelling property due to the combination of high cross-linking density, water-resistant knots and dialysis process. The hydrogel barely expands after immersion in a PBS aqueous solution at 37 degrees C for 28 days. Moreover, both the tensile and compressive stresses remain exactly the same as their initial values, which is superior to most reported swelling-resistant hydrogels. Furthermore, the hydrogel shows good creep resistance upon external loading and cytocompatibility with HeLa cells, making it an ideal material for biotechnological applications. The full-fledged starting materials and facile methods of this hydrogel show its high potential for scale up and use in industrial applications.

Automated summary

A nonswellable and biocompatible hydrogel was successfully fabricated from polyvinyl alcohol and chitosan through multiple physical interactions without harmful crosslinkers. The hydrogel demonstrated superior mechanical properties and anti-swelling property, making it an ideal material for biotechnological applications. Furthermore, the hydrogel showed good creep resistance upon external loading and cytocompatibility with HeLa cells, indicating its high potential for scale up and use in industrial applications.