3D printing of alginate/thymoquinone/halloysite nanotube bio-scaffolds for cartilage repairs: experimental and numerical study

One of the newest advances in 3D printing is the printing process of bio-scaffolds. The 3D printing of true materials for cartilage repairs accelerates cell growth and proliferation. In this study, a novel biomaterial was developed for the 3D printing of cartilage scaffolds composed of alginate, thymoquinone and halloysite nanotube. Calcium chloride was used as a cross-linker to form hydrogels. Experimental and numerical studies such as scanning electron microscopy, experimental tensile tests, and compression tests, chondrocyte cell seed, and MTT assay were also done. According to the results, alginate and halloysite nanotube increased the printing quality and mechanical performance of biomaterials. Tensile strength in bio-ink with the 30 mg/ml of alginate, 40 mg/ml of halloysite nanotube with 5% of thymoquinone increased up to 372 +/- 42 kPa, while compressive stress reached 894 +/- 39 kPa. Numerical results indicated that tensile and compressive properties of the scaffold structure depend on the space between printed rows. The best structure was obtained when the distance of rows was chosen at 0.4 mm, and the nozzle diameter was 0.3 mm. Finally, the biomaterial with the 30 mg/ml of alginate, 40 mg/ml of halloysite nanotube with 5% of thymoquinone showed a high mechanical and biological performance, compared to pure alginate bio-scaffolds.