Fig. 4
Rhein hydrogel performed better sustainable release and lower cytotoxicity. a In vitro release profiles of rhein hydrogel, the concentrations of rhein hydrogel were 4 mg mL−1 (14.1 mM) and 6 mg mL−1 (21.1 mM), respectively. The gels were incubated with PBS buffer solution (pH 7.4) at 37 °C. b The curve of the concentration of rhein in the cells over time. c, d Cell viability (24 h and 48 h) of BV2 cells incubated with different concentrations of rhein hydrogel and rhein, the concentrations of the samples range from 0 to 40 μM. Values are expressed as the means ± SEM (n = 3). One-way ANOVA with Tukey’s post hoc test. *p < 0.05. Error bars represent SEM
