Fabrication, Characterization And Biocompatibility Of Liquid-Electrospinning Novel Three-Dimensional Scaffolds

Bone has important function on supporting, protection of organ and hemopoiesis. Large bone defects are one of ticklish problem faced with bone surgery. Tissue engineering has emerged as a promising approach for restoration of function in damaged or diseased skeletal tissue. Scaffold, cell and grow factor are the three elements of tissue engineering. The basic strategy of making a bone scaffolds is to biomimic the structure and mechanical behavior of cancellous bone. The extracellular matrix (ECM) of the bone is composed of organic phase of collagen and inorganic phase of hydroxyapatite (HA).In consideration of ECM plays an important role in the function of cell proliferation, it is a key technique to design and engineer a scaffold with structure, composition similar to the bone ECM.In this study, two kinds of scaffolds were fabricated by modified liquid-electrospinning. The main study contents are as follows:Novel nanoyarns three-dimensional scaffold of P(LLA-CL) and P(LLA-CL)/Silk fibroin (SF) were fabricated by modified liquid-electrospinning. To mimic the component of natural bone, they were further to coat with a mineral surface by an alternate calcium and phosphate (Ca-P) solution dipping method. Scanning electron microscope (SEM), Fourier transform infrared spectrum (FTIR) and X-ray diffraction (XRD) were used into this study to determine morphology, chemical component and crystal structure before and after biomineralization. The results showed nanoyarns were consisted of nanofibers and average diameter of P(LLA-CL) nanofibers was larger than that of P(LLA-CL)/SF. FTIR and XRD analysis showed that SF of P(LLA-CL)/SF had transformed from random coil toβ-sheet structure when collecting and the mineral phase of two scaffolds was made of HA. ME3T3-E1 cells were used to evaluate the effects of pre-osteoblast cell proliferation and differentiation on them. P(LLA-CL)/SF, P(LLA-CL)-HA and P(LLA-CL)/SF-HA scaffold significantly increased cell proliferation (t-test, P<0.05).In hematoxylin-eosin staining experiment, cells were observed to align on to nanoyarns and infiltrate into the whole scaffolds. The results suggested that modified liquid-electrospinning is an effective method to form porous 3D scaffold that allows cell infiltration and these novel scaffolds exhibit good potential for bone repair.Modified electrospinning P(LLA-CL) and P(LLA-CL)/SF nano-yarns were respectively combined with SF to give a fiber reinforced sponge by freeze-drying. They were exposed to 75% ethanol vapor to transfer the water soluble SF into water insoluble SF. These samples were further to coat with a mineral surface by submersion in 10 X simulated body fluid (SBF).The result suggested that nanoyarns as reinforcement are effective to prepare porous scaffold with certain strength. It showed that fiber reinforcement increases the compressive modulus of the scaffolds from 0.9792±0.2269 MPa for the non-reinforced SF scaffold to 1.17017±0.1619 MPa for the PLCL-R-SF scaffolds.The compressive strength of P(LLA-CL)/(SF) nano-yarns reinforced scaffold were increased to 1.7265±0.5042 MPa with porosity of 82.8%. Morphology and distribution of the ceramic phase on these scaffolds were examined by SEM. The Energy dispersive spectrometer (EDS) analysis showed apatite deposited on the scaffolds was consisted of a Ca/P ratio of about 1.56, which is similar to the ratio of 1.67 seen in stoichiometric hydroxyapatite. FTIR and XRD data confirmed the mineral phase was made of HA. In vitro biological evaluation showed that HA coated PLCL-R-SF-HA and PLCL/SF-R-SF-HA scaffolds provided higher cell proliferation efficiency (t-test, P< 0.05) compared to uncoated ones, suggesting that the apatite surface could decrease osteoblast-like cells proliferation on early period but contribute to cell proliferation on later period. The results suggested that nanoyarns as reinforcement is a promising alternative for prepare porous scaffold with certain strength and the mineralized nanoyarns reinforced scaffolds with calcium phosphate coatings exhibit good potential and biocompatibility for bone repair.