Fig. 4: The BSE strategy was generalized to different combinations of Hofmeister effect-sensitive polymers and inorganic salts.

a Hofmeister effect-sensitive polymers such as chitosan, agarose, and gelatin. b, c Mechanical properties of bionic hydrogel fibers prepared with 1 wt% chitosan, 2 wt% agarose, and 10 wt% gelatin, respectively. Data were presented as mean ± SD (n  =  3 independent samples). d Stress-strain curves of bionic hydrogel fibers with different 0.3 M cationic crosslinking and saturated Na₂SO₄-based ternary solvent treatment. e Stress-strain curves of bionic hydrogel fibers with 0.3 M Zr⁴⁺ crosslinking and different 1 M sodium salts-based ternary solvent treatment. f Modulus and (g) toughness of bionic hydrogel fibers tuned by various ions. Data were presented as mean ± SD (n = 3 independent samples). h According to the elastic modulus of bionic hydrogel fibers, the effect sequence of ions on the mechanical properties of bionic hydrogel fibers.