(A) Silk gelation time decreased with increase of curcumin content. N = 5. *indicates significant difference (p < 0.05); ** indicates very significant difference (p < 0.005) (B) Silk secondary structure by FTIR. Characteristic silk I and silk II peaks in silk hydrogels were not influenced by the presence of curcumin. a, free curcumin; b-f, curcumin concentrations of 1, 0.5, 0.25, 0.1, 0 mg/mL in 4 wt% silk hydrogel, respectively. Silk gels were lyophilized prior to FTIR measurement.