Fig. 2

Equilibrium of swelling ratio of 1 or 2 % of alginate and hyaluronic acid hydrogels obtained after incubation in PBS at 37 °C. a This table represents the evolution of ESR and pore size of 1 and 2 % (w/v) alginate and HA hydrogels after incubation in PBS at 37 °C for 0.5, 1, 3 and 24 h and freeze-dried during at least 72 h. Values represent the mean ± SD. Significant differences were assessed by Student t test; p < 0.05 a alginate versus HA, b 1 versus 2 %. b–i These images show the microscopic structure of alginate (b–e) and HA (f–i) hydrogels at different concentrations (1 and 2 %) after 0.5 h (b, d, f, h) and 24 h (c, e, g, i) of incubation in PBS. Observation by SEM was done at 15 kV, 40 Pa and ×100 of magnification