Effects of chemical crosslinking and hydroxyapatite on the properties of Thai silk fibroin/gelatin scaffolds

Abstract

This research aimed to investigate the effects of chemical crosslinking and hydroxyapatite on the properties of Thai silk fibroin/gelatin scaffolds. Crosslinked Thai silk fibroin/gelatin scaffolds were prepared by directly adding EDC/NHS in blended solution and subsequently fabricating via freeze-drying method. The effect of the weight blending ratios of Thai silk fibroin/gelatin was examined. It was found that all Thai silk fibroin/gelatin scaffolds possessed uniform porous structure. Crosslinked Thai silk fibroin/gelatin scaffolds showed lower weight loss (%) and higher compressive modulus than those of non-crosslinked scaffolds. Interestingly, non-crosslinked Thai silk fibroin/gelatin scaffold at the weight blending ratio of 50/50 showed the lowest weight loss (%) with excellent mechanical strength as good as the crosslinked scaffold due to the suitable electrostatic interactions between silk fibroin and gelatin. The results on in vitro biodegradability using collagenase solution revealed that Thai silk fibroin and crosslinking could delay the biodegradability of scaffolds. XRD results proved that all Thai silk fibroin/gelatin scaffolds before and after biodegradation possessed similar amorphous structure. The results on in vitro cell culture using bone marrow-derived stem cells showed that Thai silk fibroin/gelatin scaffolds containing high amount of gelatin were more effective to promote cell proliferation. Furthermore, in the study of the effect of hydroxyapatite adding, Thai silk fibroin/gelatin scaffolds were added with hydroxyapatite using homogenization method. Homogeneous distribution of hydroxyapatite granules in the scaffolds was observed. Homogenized Thai silk fibroin/gelatin scaffolds with and without hydroxyapatite incorporation did not support proliferation. This might be the result of mass transfer limit and the toxicity of chloroform residue in scaffolds. The result of osteogenic differentiation suggested that osteoconductive potential of both scaffolds was similar. However, these should be investigated and clarified in further study to obtain suitable scaffolds for tissue engineering application.