2.3 Characterization of DP
The surface morphology of DP scaffolds was analyzed by scanning electron
microscopy (SEM; Model: JSM-6700F, JEOL, Japan) and atomic force
microscopy (AFM; Model: Multimode & Dimension 3100, Varian, USA).
Additionally, the scaffolds were stained with Picrosirius Red (Solarbio,
China) and viewed under a polarizing microscopy (Leica, Germany) for
observation of the collagen structure. DP samples were also
histologically examined using Masson trichrome staining and
safranin-O/fast green staining. Immunohistochemical analysis was
performed using antibody against type I collagen (dilution: 1:200,
Abcam, USA). The surface hydrophilicity was evaluated by measuring the
water contact angle with a contact angle goniometer (Dataphysics OCA 35,
Germany) using the sessile drop method. The mechanical properties of the
DP scaffolds were tested using a universal testing machine (Model: AG-IC
50KN, SHIMADZU, Japan). Dumbbell-shaped samples measuring 4 mm × 50 mm
were prepared for mechanical testing, and the crosshead speed was set at
15 mm/min with a load capacity of 50 N. The yield stress, failure
strain, and modulus data were obtained.