3.3 Morphological analysis
The SEM micrographs of a representative 3D printed A-SA-Gel hydrogel scaffolds are shown in Figure 2E-2M, where surface and cross-sectional morphologies of the scaffolds and filament structural features were investigated. It was found that the mesh-like structural features were obvious and they are structurally intact well. In addition, the SEM analysis revealed the porous nature of the printed scaffolds with rectangular architecture (Figure 2E-2F). It is noteworthy that the intersections of adjacent layers of filaments were tightly intact and connected (Figure 2G). In addition, the filaments of different layers were aligned, and the interlayer structure is clearly visible (Figure 2H-2I). The uneven rough surface morphology was observed (Figure 2J). The surface morphology of single filament was also analyzed and the results are shown in Figure 2K-2M. The wavy micro rough surfaces were noticed from the high-resolution images of the scaffold. The average diameter of the filament was found to be 385μm, which is distinctly smaller than the 22G nozzle’s inner diameter of 410μm.
To further verify the printability and self-standing ability of the A-SA-Gel hydrogel suitable to use as a scaffolding system, various structures were printed out as a model and the results are presented in Figure 3. A thick cube scaffold structure is shown Figure 3A. A blood vessel structure can be seen from Figure 3B. The abbreviations of Shanghai University (SHU) and Vellore Institute of Technology (VIT) were printed out as pictured in Figure 3C. Importantly, human ear-like structures were also fabricated without any noticeable deformation and the results are presented in Figure 3D. All these are the experimental examples serve as a proof that the multi-material hydrogel developed in this study can be utilized for 3D printing of various structures and shapes with high fidelity.