Investigation On Stem Cell Adhesion And Intracellular Calcium Contents On Polydopamine-modified Poly (Vinylidene Fluoride) Membranes

Biomaterials with piezoelectric properties have attracted extensive attention in the development of bone tissue engineering and regeneration applications.Unlike the usually used methods that induce controllable piezoelectric stimulation to cells according to external loading,cell adhesion-mediated piezoelectric stimulation provides a self-stimualtion method for in situ electrical regulation of cell behavior.Paricullaly,the surface potential is mainly influenced by inherent piezoelectric properties of biological material and the dynamic cell adhesion state.Systematically investigation of cell piezoelectric self-stimualtion during cell-material interaction will benefit the rational design of smart materials and understanding of cell regulation mechanisam.In this paper,we modified the surface of poled poly(vinylidene fluoride)(PVDF)membranes through polymerization of dopamine and investigated their influence on cell adhesion and electromechanical self-stimulation.The chemical structure and composition of the films were characterized by attenuated total reflection fourier-transform infrared spectrometer,X-ray diffraction and X-ray photoelectron spectroscopy.The surface morphology of the films were characterized by atomic force microscopy and scanning electron microscopy,and the hydrophilic property was evaluated by water contact angle test.Mesenchymal stem cells(MSC)were seeded on the surface of hydrophilicity modified piezoelectric PVDF membrane,and cell adhesion morphology and intracellular calcium concentration were analyzed to investigate the effects of cell adhesion and on electromechanical self-stimulation.Meanwhile,the piezoelectric output of cell adhesion mediated piezoelectric PVDF membrane was simulated by three-dimensional finite element method,and the regulation mechanism of cell adhesion-calcium signaling pathway was analyzed in combination with experiments.The results showed that the surface modification of polydopamine significantly improved the hydrophilicity of the samples,and MSC seeded on the modified poled PVDF membrane exhibited stronger cell spreading and adhesion,demonstrating that surface modification contributed to the formation of cellular actin bundles and the maturation of focal adhesions,which then futher positively regulated the cell piezoelectric self-stimulation and intracellular calcium transients.Combined with the finite element simulation,we found that the increase of piezoelectric self-stimulation effect is mainly due to the increase of adhesion position sites and adhesion force.These results provide new ideas for exploring the cell piezoelectric self-stimulation mechanism and offer more opportunities for the rational design of piezoelectric biomaterial interfaces in biomedical engineering.