Abstract: BACKGROUND: Electrical stimulation has been shown to promote bone regeneration and piezoelectric materials with bioelectrical activity can be used in bone tissue engineering.
OBJECTIVE: To prepare an ideal piezoelectric film material, which can promote bone regeneration and characterize its effects on the adhesion, proliferation, and osteogenic differentiation of MC3T3-E1 cells. 
METHODS: Barium titanate/polylactic acid composite film was prepared by solution casting with polylactic acid as raw material and a certain proportion (0%, 5%, 10%, 20%, 30%, and 40%) of piezoelectric ceramic barium titanate was added and methylene chloride was selected as the organic solvent. After corona polarization treatment, the surface morphology, crystal phase composition, hydrophilic and piezoelectric properties of films were investigated to select materials with better physical and chemical properties. The 0% and 20% barium titanate/polylactic acid composite film materials before and after polarization treatment were separately co-cultured with MC3T3-E1 cells to test the ability of cell adhesion, proliferation, and osteogenic differentiation. 
RESULTS AND CONCLUSION: (1) The scanning electron microscope, X-ray diffraction, water contact angle experiment, and pressure point constant test results showed that when the mass ratio of barium titanate to composite film was 20%, the polarized composite film material had good physical and chemical properties. The piezoelectric constant d33 after polarization reached (7.03±0.26) pC/N, which was in the normal piezoelectric range of bone tissue. (2) CCK-8 assay results showed that on the 4th day of culture, the proliferation activity of the cells in the polarized 20% group was higher than that in the unpolarized 20% group (P < 0.05). On the 7th day of culture, the proliferation activity of the cells in the polarized 20% group was higher than that of the blank control group, the unpolarized 0% group, and the unpolarized 20% group (P < 0.05). (3) The fluorescence microscope and scanning electron microscope exhibited that the cells in the polarized 20% group were polygonal and had obvious pseudopodia. Compared with the unpolarized 20% group, polarized 0% group and unpolarized 0% group showed better cell adhesion ability. (4) The alkaline phosphatase activity detection results showed that on the 4th day of culture, the alkaline phosphatase activity of the polarized 20% group was higher than that in the unpolarized 0% group and the unpolarized 20% group (P < 0.05). On the 7th day of culture, the alkaline phosphatase activity of the polarized 20% group was higher than that of the unpolarized 0% group, the unpolarized 20% group, and polarized 0% group (P < 0.05). (5) The barium titanate/polylactic acid composite piezoelectric film material has good piezoelectric properties and cytocompatibility.

Key words: conductive bone tissue regeneration, piezoelectric material, barium titanate, polylactic acid, solution-casting, composite film material, corona polarization, piezoelectric properties, osteogenic differentiation