Effects of gelatin conjugation and hydroxyapatite deposition on Thai silk fibroin scaffolds

Abstract

This research aimed to investigate the effects of gelatin conjugation and hydroxyapatite deposition on the physical and biological properties of Thai silk fibroin scaffolds for bone tissue engineering. Thai silk fibroin scaffolds were prepared via salt-leaching method. The morphology of scaffolds showed smooth surface and interconnected porous network. Surface of silk fibroin scaffolds were modified by gelatin conjugation and hydroxyapatite deposition by alternate soaking in calcium chloride and disodium hydrogenphosphate solutions. The different concentration of gelatin solution was found to influence the amount of gelatin conjugated onto Thai silk fibroin scaffolds, the morphology of the scaffolds and the cell proliferation on the scaffolds. After alternate soaking, hydroxyapatite was observed on the pore surface of scaffolds leading to the rough surface of porous structure and less pore volume. The scaffolds obtained from 4 cycles of alternate soaking in calcium chloride and disodium hydrogenphosphate solutions alternately with the soaking time for 30 minutes in each solution showed suitably porous morphology and compressive modulus. The results on TGA indicated that hydroxyapatite deposited after four cycles of alternate soaking in the scaffolds were about 52%. The Ca/P ratio of hydroxyapatite/Thai silk fibroin and hydroxyapatite/ conjugated gelatin/Thai silk fibroin scaffolds prepared from 4 cycles of alternate soaking were 1.71 and 1.51, respectively. The results on in vitro culture using bone-marrow derived mesenchymal stem cells showed that conjugated gelatin/Thai silk fibroin scaffold prepared from 1.0wt% gelatin concentration effectively enhanced osteogenic differentiation similar to the scaffolds containing hydroxyapatite as evaluated by alkaline phosphatase activity, calcium content and the morphology of cultured cell on the scaffold surface. The results on the physical and biological properties of hydroxyapatite/conjugated gelatin/Thai silk fibroin scaffolds markedly indicated that the scaffolds had a high potential to be applied in tissue engineering.