2022, Vol. 26 ›› Issue (22): 3550-3555

Mechanical properties of silk fibroin/type I collagen/ hydroxyapatite scaffolds based on low-temperature 3D printing

Meng Lulu1, 2, Liu Hao3, Liu Han3, 4, Zhang Jun3, Li Ruixin3, Gao Lilan1, 2   

Abstract: BACKGROUND: With the rapid development of 3D printing technology in tissue engineering, a variety of scaffold materials prepared by 3D printing are widely used in mandibular defect repair. 3D printing technology brings new possibilities for mandibular defect repair.
OBJECTIVE: The 3D bionic bone scaffold material was constructed by low-temperature 3D printing technology, and the internal structure of the scaffold was precisely controlled, and the mechanical properties of the scaffold were analyzed.
METHODS: Under the same volume, by changing the interlacing angle of the printed scaffold wire harness and the wire harness, low-temperature 3D printing technology was used to print silk fibroin/type I collagen/hydroxyapatite scaffolds with different angles (30°, 45°, 90°) and polycaprolactone/hydroxyapatite scaffolds (a total of 6 sets of scaffolds). The uniaxial compression mechanics experiment was loaded to 6 groups of scaffolds at a compression rate of 0.5%/s, compressed to 30% strain to observe the relationship between stress and strain. The stress relaxation experiment was applied to the three printing angles of silk fibroin/collagen I/hydroxyapatite scaffolds at a compression rate of 0.5%/s at 10%, 20%, and 30% strain, and the relaxation retention time was 3 hours to observe the relationship between stress and time. In the creep experiment, the silk fibroin/collagen I/hydroxyapatite scaffold with an angle of 90° was compressed and printed at a constant pressure of 2.5, 3.75, and 5 kPa, and the creep retention time was 3 hours to observe the relationship between strain and time.
RESULTS AND CONCLUSION: (1) Uniaxial compression mechanics experiment: The mechanical properties of 3D printed silk fibroin/type I collagen/hydroxyapatite scaffold and polycaprolactone/hydroxyapatite scaffold compression showed that the 90° scaffold had higher Young’s modulus than the 30° and 45° scaffolds under the same compression strain. (2) Stress relaxation experiment: When the compression rate, compression strain and compression angle were constant, the stress of silk fibroin/type I collagen/hydroxyapatite scaffold decreased rapidly with the extension of relaxation time, then slowly decreased. With the extension of relaxation time, the stress of the scaffold decreased rapidly in the beginning time (within 1 600 seconds), and in the later period (3 700 seconds). When the compression rate and compression strain were kept constant, the initial and stable stress values of silk fibroin/type I collagen/hydroxyapatite scaffolds with 90° printing angle were higher than those of scaffolds with 30° and 45° printing angle. When the compression rate and compression angle were constant, the initial and stable stress values of silk fibroin/type I collagen/hydroxyapatite scaffolds increased with the increase of compression strain. (3) Creep test: With the extension of creep time, the strain of 90° silk fibroin/type I collagen / hydroxyapatite scaffolds increased rapidly in the initial stage (within 500 seconds), then increased slowly, and finally leveled off. The strain range of the scaffolds was 35% to 55% at 2.5 kPa, and 43% to 57% at 3.75 kPa. The strain of the scaffold ranged from 45% to 57% under 5 kPa.
Key words: 3D printing, biological scaffold, silk fibroin, type I collagen, hydroxyapatite, uniaxial compression, biomechanics