Fully physically crosslinked pectin-based hydrogel with high stretchability and toughness for biomedical application.

Hydrogels derived from natural polymers have been extensively investigated in the biomedical field, while inherent brittleness and poor stability limit their applications. In this study, a tough pectin-Fe/poly (acrylamide-co-stearyl methacrylate) (P(AAm-co-SMA)) double physical crosslinking (DPC) network hydrogel is prepared using a three-step method. The first HPAAm network is formed via hydrophobic associations among the PSMA segment in P(AAm-co-SMA), and trivalent ions (Fe) crosslinked pectin network as the second network. Due to the reversibility of dual physical cross-linking structures, the pectin-Fe/HPAAm hydrogel exhibit excellent toughness (1.04-11.20 MJ m). In addition, the pectin-Fe/HPAAm DPC hydrogels have tunable mechanical properties (tensile strength: 0.97-1.61 MPa, elongation: 133-1346%, elastic modulus: 0.30-2.20 MPa) via adjusting the ratio of pectin network and HPAAm network. To explore their potential application in tissue engineering, ATDC5 chondrocytes were seeded on the prepared DPC hydrogels. Results suggest that the pectin-Fe/HPAAm DPC hydrogels can support the adhesion and proliferation of ATDC5, moreover, the ATDC5 cells can penetrate into the hydrogel. It is concluded that the prepared hydrogels exhibit potential application in the load-bearing tissue repair field.