Figure 2. Attenuated total reflection–Fourier transform infrared (ATR-FTIR) transmittance spectra of scaffolds. Silk fibroin (SF) (red line), silk fibroin-gelatin/hyaluronic acid/heparan sulfate (SF-GHHs) 2:1 (orange line), SF-GHHs 1:1 (green line), SF-GHHs 1:2 (purple line) and gelatin/hyaluronic acid/heparan sulfate (GHHs) scaffolds (blue line) in 1,800-900 cm^–1 spectral range. The numbers represent the absorption peaks of scaffolds.