Gelatin hydrogel reinforced by graphene oxide grafted chitosan for cartilage tissue engineering application

Various methods, such as cross-linking and incorporation of nanoparticles, enhance hydrogels' physical and mechanical properties. Therefore, in the present research, gelatin (Gel) hydrogels cross-linked with an optimum amount of Genipin and then reinforced by the graphene oxide (GO)-grafted chitosan (CS). Gel is a derivative of collagen which can be found in cartilage tissue abundantly and shows relatively low antigenicity, GO has high tensile strength, GO raises the surface area for more interaction between cell and scaffold, CS is similar to glycosaminoglycan that can be found in the tissue ECM. For this purpose, at the first step, graphene oxide grafted chitosan (CS-g-GO) was synthesized successfully and identified by scanning electron microscope and Fourier Transform Infrared. Afterward, gelatin hydrogels with different percentages of the CS-g-GO were prepared and characterized. Results confirmed that structural and mechanical properties improved with increasing the GO concentration. Pore size increased from 244 to 287 mu m with increasing CS-g-GO content; and swelling degree increased from 800% to 1200%, however, the compressive stress rose from 40 to 65 kPa, more like healthy articular cartilage. The degradation rate also declined from 70% to 50% during 28 days. Cell viability remains more than 90% in 5 days, which indicates the biocompatibility of the samples. To conclude, hydrogels synthesized in this research are promising for cartilage tissue engineering.