Construction Of Cell Model Based On Viscoelastic Liquid Crystal And The Investigation Of Their Influence On RBMSCs Behaviors

In this study,based on the principle of bionic construction,hydroxypropyl cellulose ester liquid crystal,which is similar to the viscoelastic characteristics of cell membrane,was selected as the basic material of cell model system.A liquid crystal cell substrate model with good cell affinity and mechanical properties similar to ECM was designed and constructed to induce stem cells to differentiate into osteoblasts.Through the systematic exploration of the interaction between liquid crystal substrate and stem cells,to understand the effects of the changes of substrate viscoelasticity and surface properties on the behavior and function of stem cells.In this paper,a series of liquid crystal substrate?Cn PC?,with adjustable elastic modulus were prepared by changing the rigid/flexible structure of liquid crystal compound structure,and the physicochemical properties of liquid crystal substrate were characterized,and then a series of responses induced by viscoelastic stimulation of liquid crystal substrate induced by r BMSCs were systematically studied,including cell adhesion,proliferation,polarization and skeleton formation.Through the localization and activation of YAP protein nucleus and the qualitative/quantitative analysis of osteogenic differentiation related markers ALP and calcium nodules,the effect of osteogenic differentiation of r BMSCs in response to mechanical stimulation caused by the change of basal elastic modulus was revealed.In order to expand the application range of viscoelastic liquid crystal cell substrate model,collagen with excellent biological activity was selected to modify the liquid crystal substrate surface,and the effects of liquid crystal/Type I collagen composite membrane on the proliferation,cytoskeleton formation and cell differentiation of r BMSCs were studied.The results show that the hydroxypropyl cellulose butyrate/caproate/caprylic ester liquid crystal materials prepared in this paper show the color texture of cholesteric liquid crystal phase.the length and degree of substitution of the soft segment of the side chain have a significant effect on the degree of order and elastic modulus of the liquid crystal materials.Liquid crystal compounds as a cell model can affect the series of cell behaviors of r BMSCs through mechanical stimulation induced by viscoelastic properties of the substrate,in which the cells cultured on the substrate whose elastic modulus is higher than that of 1000Pa liquid crystal show stable nuclear localization and continuous activation of YAP protein in the early stage of osteogenic differentiation.The expression levels of ALP and calcium nodules in C₈PC-2 and C₈PC-1substrates with higher elastic modulus increased rapidly in the middle and later stage of osteogenesis,indicating that the mechanical response of r BMSCs to liquid crystal substrates with higher elastic modulus can maintain a continuous process.The C₈PC-1/Col composite liquid crystal substrate prepared by the combination of hydroxypropyl cellulose octanoate liquid crystal and collagen changed the surface activity,surface microstructure and elastic modulus of simple Cn PC liquid crystal substrate.The synergistic effect of biochemical and biophysical signals on the surface of C₈PC-1/Col composite substrate created a good microenvironment for cell growth and promoted cell proliferation,skeleton formation and differentiation.The Cn PC liquid crystal substrate and C₈PC-1/Col composite liquid crystal substrate constructed in this paper provide a reference for exploring the mechanism of liquid crystal viscoelasticity and surface properties affecting cell behavior,and provide guidance for understanding the interaction between soft matter cell model and cell,as well as the contribution of substrate liquid crystal microdomain and collagen biological activity to cell behavior.