Figure 1.

(a) The two-step chemical synthesis process for cross-linking matrices: (1) the cross-linking agent, EDC, linked HA with another organic molecule to form the activated intermediate acid anhydride. (2) The carboxyl groups of the activated intermediated product reacted with the amino group of Col or Gel to complete the cross-linking reaction. (b) FTIR spectra absorbance vs. wavenumber (cm⁻¹) data: HA (black), Col (green), Gel (blue), HA-L (yellow), and HA-H (red); absorbance (A.U.) and wavenumber (cm⁻¹). The molecules overlapped at ~1700 cm⁻¹, indicating an amide bond for the C=O stretching vibration. (c) The swelling ratio of testing samples: HA-L/HA-H/non-cross-linking. The white and blue bars represented HA-L and HA-H implant matrices, respectively. Without cross-linking, the scaffold was not formed in the water phase solution. Each value was represented as the mean values ± standard deviation (SD) (n = 3). The level of significance was designated as ^∗p < 0.05 and ^∗∗p < 0.01.