2.4. Thrombin Loading

A TB solution was prepared with a concentration of 250 U/mL, the PCL and PCL–PDA fibrous membranes were soaked in the TB solution for 12 h, washed with deionized water three times, and freeze-dried to obtain a PCL-TB and PCL–PDA–TB fibrous membranes. The TB loaded on the fiber scaffold was observed by SEM. The surface chemical elements of PCL–PDA–TB fiber membranes were analyzed by energy dispersive spectrometry (EDS) and element diagram.

In order to evaluate the distribution of TB on the membranes, fluorescein isothiocyanate-labeled bovine serum albumin (FITC-BSA) (Solarbio, Beijing, China) was applied as a model drug for TB according to the procedure described above. After FITC-BSA loading, the membranes were harvested, washed with deionized water, and observed using a confocal laser scanning microscope (CLSM) (TCS-SP8, Leica, Wetzlar, Germany). Image-Pro Plus 6.0 software was used to compare the fluorescence intensity of FITC-BSA on the membranes. Six independent fields of view were selected for each group of samples.