Page 38 - Development of Functional Scaffolds for Bone Tissue Engineering Using 3D-Bioprinting of Cells and Biomaterials - Yasaman Zamani

Surface modification using 3 M NaOH resulted in visibly more collagenous matrix deposition compared to modification with 1 or 5 M NaOH (Fig. 1b). For further experiments, we used 3 M NaOH for chemical surface modification, since it provided highest cell proliferation and matrix deposition compared to other concentrations tested.
Characterization of surface-modified and unmodified PCL scaffolds
In this study, 3D-printed poly(ɛ-caprolactone) scaffolds were surface-modified by either chemical modification using 3 M sodium hydroxide (NaOH) for 24 or 72 h, or by RGD-immobilization. The chemical reaction mechanism of RGD immobilization is presented in figure 2a. RGD was immobilized on the surface of aminated PCL scaffold using sulfo-SMCC crosslinker. Density of immobilized RGD on the surface was 0.011 ± 0.001 μg/mg scaffold (Fig. 2b). To study the surface composition changes as a result of both NaOH treatment and RGD immobilization, FTIR analysis was performed (Fig. 3). Representative peaks of PCL were observed at 2939 cm-1 (asymmetric CH2 stretching), 2865 cm-1 (symmetric CH2), 1718 cm-1 (carbonyl C=O stretching), 1188 cm-1 (C- O-H stretching), and 1163 cm-1 (C-O-C stretching). Treatment of PCL scaffolds with 3 M NaOH for 24 and 72 h increased the intensity of the C-O-H (carboxyl and hydroxyl) peak compared to the intensity of the C-O-C (ester) peak. This intensity increase was more significant for 72 h NaOH-treated than 24 h NaOH-treated scaffolds. For the RGD-immobilized scaffolds, three additional peaks at 3338 cm-1 (N-H stretching), 1635 cm-1 (amide I) and 1588 cm-1 (amide II) were observed. These peaks are major bands that appear in the FTIR spectrum of proteins [34].
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