Scheme 1. (A) Preparation of the PSBMA/SA-Ca2+ DN hydrogel using a “one-pot” method. (B) Representation of the antifouling properties of the DN hydrogel, which resist the biological pollutants including algae (green), cells (red) and non-specific proteins (yellow). (C) The synthesis routes and formation of the SA network and the PSBMA network in the DN hydrogel.

Fig. 1. (A) Tensile curves, (B) elastic modulus, (C) fracture stress and elongation of the DN hydrogel (SBMA: 2.0 M, MBAA: 0.20 mol%) with different concentrations of SA. (D) Tensile curves, (E) elastic modulus, (F) fracture stress and elongation of the DN hydrogel with different concentrations of SBMA (SA: 0.06 g/mL, MBAA: 0.20 mol%). (G) Tensile curves, (H) elastic modulus, (I) fracture stress and elongation of the DN hydrogel (SBMA: 2.0 M, SA: 0.06 g/mL) with different concentrations of MBAA.

Fig. 2. (A) Tensile curves of the prepared hydrogel. (B) Outstanding performance of the PSBMA/SA-Ca2+ DN hydrogel (stretch, twisted stretching, knotting stretching, load bearing, compressing).

Fig. 3. (A) Digital images of the PSBMA/SA-Ca2+ DN hydrogel before and after 24 h of swelling. (B) Swelling kinetic curve of the DN hydrogel. (C) Tensile curves of the DN hydrogel before and after 24 h of swelling. (D) Retention coefficient of tensile strength, elastic modulus, fracture strain, and toughness of the swollen DN hydrogel compared with as-prepared hydrogel.

Fig. 4. (A) Loading-unloading curves of the PSBMA/SA-Ca2+ DN hydrogel under different strains (50 %-250 %). (B) The dissipated energy and dissipation coefficient of the PSBMA/SA-Ca2+ DN hydrogel during the loading-unloading tests.

Fig. 5. (A) Self-recovery behavior of the stretched PSBMA/SA-Ca2+ DN hydrogel at different time. (B) Time-dependent recovery of dissipated energy and elastic modulus of the PSBMA/SA-Ca2+ DN hydrogel.

Fig. 6. Ten successive loading-unloading cycles of: (A) as-prepared and (B) recovered (resting for 24 h at RT). (C) The corresponding dissipated energy in every cycle of the corresponding hydrogel.

Fig. 7. (A) The load-time curve and (B) stress-strain curves of fifty successive compression-relaxation cycles of PSBMA/SA-Ca2+ DN hydrogel. (C) The maximal stress and dissipated energy of the corresponding hydrogel every three cycles in 50 continuous compression-relaxation cycles.

Fig. 8. The relative HRP-conjugated IgG adsorption on the different hydrogels and TCPS. (red columns: the hydrogels were soaked in fresh PBS for 0.5 h before the addition of OPD; blue columns: the hydrogels were soaked in fresh PBS for 3 h before the addition of OPD).

Fig. 9. The fluorescence microscopic images of L929 cells attached on the PSBMA hydrogel (A), PSBMA/SA-Ca2+ DN hydrogel (B) and TCPS (C) at different time (1 d, 4 d and 7 d).

Fig. 10. The microscopic images of chlorella vulgaris and microcystis aeruginosa attached on the PSBMA/SA-Ca2+ DN hydrogel at different culture conditions.

Fig. 11. (A) Viability of L929 cells after incubated with the extraction of the PSBMA/SA-Ca2+ DN hydrogel at different concentrations for 1 d, 4 d, 7 d. (B)Viability of L929 cells after incubated with the extraction of the PSBMA/SA-Ca2+ DN hydrogel for 7 d.

Fig. 12. Micrographs of the subcutaneous implant with PSBMA/SA-Ca2+ DN hydrogel stained with H&E at 7 d and 28 d (n = 3). The red dotted rectangles indicate the boundary between the hydrogel and the tissue and magnify them.