Osteoblast Behavior On The Nanofiber In Magnetic Field/Electric Field

Bone injuries and defects remain a significant problem in clinical therapy, which caused great pain to the patient. To overcome the shortcomings of conventional treatment methods existing in bone grafts and bone repair, bone tissue engineering offers a new and promising approach for bone repair and regeneration. Bone tissue engineering scaffolds play an important role in repairing bone defect,while a few of additional factors, such as magnetic field, electric field, etc., can also affect bone defect repair effect. In this dissertation,for the study of magnetic and electric fields on bone tissue engineering scaffolds biological properties, magnetic nanofibers and piezoelectric nanofibers were prepared by electrospinning. Then, their biological properties were evaluated under an applied magnetic and electric fields.Magnetic PLLA/Fe3O4composite nanofibers scaffolds were fabricated through the combination of in-situ co-precipitation and electrospinning methods. The magnetic PLLA/Fe3O4composite nanofiber film had good paramagnetic.The biocompatible of the magnetic composite nanofibers was determined using in vitro culture of osteoblasts (MC3T3-E1) in extracts and co-culture on nanofibrous matrixes.The results demonstrated that the PLLA/Fe3O4composite nanofibers have good compatibility.Therefore, a static magnetic field with medium strength (100mT) was applied in the osteoblasts culture on the composite nanofibers, to clarify the effects of magnetic field on osteoblasts behaviors. Characterization methods, including SEM observation, CCk-8kit, fluorescent staining, ALP activity and Ca deposition etc., were applied. The results demonstrate that cell biological behaviors on all the magnetic nanofibers were promoted in comparison with the control group, and were further enhanced in the presence of magnetic field, while the enhancement kindly depends on the contents of Fe3O4in composite nanofibers. In the case of cell attachment and proliferation, the promotion of magnetic (PLLA)/Fe3O4composite nanofibers is in the order of PLLA/Fe3O4(2.5)> PLLA/Fe3O4(5)> PLLA/Fe3O4(0). In the case of cell differentiation, the order is PLLA/Fe3O4(5)> PLLA/Fe3O4(2.5)> PLLA/Fe3O4(0). The SEM and fluorescent images show that the moderate magnetic field strength (100mT) would not change the cell morphology and orientation. The cells remain spreading along fibers according the contact guidance effect.Barium titanate nanoparticles adhered carbon nanofibrous (CNF/BTO) membranes were prepared by electrospinning and sintering a mixed solution of nitrate barium, tetra-n-butyl titanate and PAN. Crystalline structure and morphology of CNF/BTO were characterized by HRTEM, SEM, and TEM observations.The diameter of the BTO nanoparticles was in the range of20-30nm, they were well distributed on the surface of CNFs. The biocompatible of the magnetic composite nanofibers was determined using in vitro culture of osteoblasts in extracts and co-culture on nanofibrous matrixes.The results demonstrated that the CNF/BTO composite nanofibers have good compatibility.An extra pulse electric field setup was used for the application of electric field during cell culture experiments.Cell-cultured samples were analyzed qualitatively using fluorescence microscope and scanning electron microscope. It demonstrated that due to the application of electric field during the cell culture experiment, the cell proliferation and the cell spreading on the surface of the biomaterials were enhanced within an appropriate electrical stimulation. The results showed that the optimal electric field intensity of MC3T3-E1on CNF/BTO film surface was666.66mv/cm. However, the optimal electric field intensity of MC3T3-E1on CNF membrane surface was1666.66mv/cm. An extra long electrical stimulation may influenced the proliferation behavior of osteoblasts.To sum up:magnetic PLLA/Fe3O4prepared by co-precipitation and electrospinning has good paramagnetic and biocompatibility. Piezoelectric CNF/BTO by the sol-gel and electrospinning having good electrical conductivity and biocompatibility.Mean while under the influence of external factors, such as magnetic field, electric field, etc., will affect the proliferation and differentiation of osteoblasts and bone defect repairing.