Despite the high ability of bone tissue in the process of repairing bone defects on a large scale, the body cannot completely repair it naturally. Therefore, among different treatment options such as autograft and allograft, bone tissue engineering is the best method in bone regeneration and preservation. Nanocomposite polymer-based scaffolds with good mechanical properties and favorable bioactivity are promising for bone tissue engineering. In this research, dense alginate/gelatin scaffolds with homogeneous nanoapatite coating were developed using 3D printing and in situ mineralization. The addition of chitin nanofibers in this structure can improve the mechanical and antibacterial properties. In addition, nanoapatite coating and nanofiber reinforcement can significantly stimulate the proliferation and osteogenic differentiation of bone marrow stem cells. In addition, the nanoapatite coating increases the protein adsorption on the surface of the scaffolds. Fabricated biomimetic apatite/hydrogel nanocomposite scaffolds can be potential candidates for bone tissue engineering. In this research, preparation of hydrogel scaffolds based on gelatin-alginate, reinforced with chitin nanofibers and coated with hydroxyapatite was done with 3D printing. According to the investigations carried out in terms of mechanical properties, it was found that the scaffold containing 1% chitin nanofibers showed the best Young's modulus of 0.678 MPa. FTIR spectroscopic investigations confirmed the existence of all three materials and the formation of strong hydrogen interactions between them and the formation of hydroxyapatite on the surface of the scaffold. It was also observed from the FESEM analysis that the diameter of the pores decreased and their amount increased with the addition of gelatin and finally chitin nanofibers to the alginate matrix. The swelling rate of alginate-gelatin hydrogels, coated alginate-gelatin and hydrogel containing chitin nanofibers by immersion in distilled water after 24 hours were equal to 671.43, 595.3 and 580.06%, respectively. Also, eva‎luation of the in vitro biodegradability of the desired hydrogels by immersion in SBF solution at 37°C showed that after 40 days Al-Gel/U hydrogel 93%, Al-Gel 9-1, 91% And the hydrogel containing chitin nanofibers had lost 89% of their weight. In the next step, human fibroblast cells were planted on hydrogel structures and cell characterization was done after 7 days. FESEM results showed that cell adhesion was the highest in Al-Gel-NCHF hydrogel and the lowest in alginate-gelatin hydrogel. Also, by examining the MTT test, it was observed that the addition of chitin nanofibers to the alginate-gelatin matrix increased the cell density in the sample to its highest level compared to the control group on the seventh day. . According to the results obtained from this thesis, it can be said that the constructed scaffold is considered a desirable and efficient structure in bone tissue engineering.

طيبه بهزاد , افسانه فخار

محمد ديناري

سعيد نوري خراساني , صديقه برهاني