Construction Of Cell Model Of Liquid-crystal Base And Study On Guiding The Behavior Of Macrophages

Immune response plays an important role in the tissue repair process mediated by biomaterials,and biomaterials with immunomodulatory properties can obtain beneficial tissue regeneration effects.Macrophages have a continuous influence on the tissue repair process in response to the properties of biomaterials,and the mechanical properties play a key role in guiding this response.In order to systematically explore the influence of matrix mechanical stimulation on the behavior and function of immune cells,this study is based on the principle of bionic design,simulating the mechanical microenvironment of cells in the body,and designing and constructing a series of hydroxypropyl cellulose esters with adjustable elastic modulus Liquid crystal material is used as a cell substrate model to understand the impact of mechanical stimulation caused by the mechanical properties of the liquid crystal soft material substrate on the behavior and function of immune cells.In this paper,through the esterification reaction of hydroxypropyl cellulose（HPC）and acid chloride,the number of methylene units（octyl,hexyl,butanyl）and the adjustment of substitution are introduced into the side groups of the rigid backbone of HPC.A series of liquid crystal materials（C_nPC）with a gradient of elastic modulus are prepared to form a series of liquid crystal substrate models.Advanced testing technology is used to characterize the physical and chemical properties of the liquid crystal substrate;the macrophage RAW264.7 is used as the research object to systematically study the changes in cell behavior and function of RAW264.7 in response to C_nPC viscoelastic mechanical stimulation,including the initial cell adhesion,Cell proliferation,cell apoptosis,etc.Cytoskeleton staining,inflammatory-related gene expression and inflammatory-related cytokine expression revealed the mechanical stimulation induced by the viscoelasticity of the liquid crystal substrate on the induction of M1/M2 phenotypic transformation of macrophages.The results show that the C_nPC designed and prepared in this paper has a unique fingerprint texture of cholesteric liquid crystals.The length of the side chain soft segment and the degree of substitution of the side groups have a significant effect on the order of the molecular arrangement of the C_nPC,and the hydrophilicity and mechanical properties of the C_nPC..The cell culture results show that C_nPC has excellent cell compatibility and provides a favorable microenvironment for maintaining the viability of RAW264.7 cells.In addition,the viscoelastic mechanics stimulation of C_nPC can trigger a series of responses to the behavior of RAW264.7 cells.The low elastic modulus liquid crystal substrate C₄PC-2 promotes the expression of M1 anti-inflammatory genes and the secretion of pro-inflammatory factor TNF-αin RAW264.7;The liquid crystal substrate of the C₈PC group with a higher modulus significantly increased the spreading degree of RAW264.7 cells and contributed to the elongated pseudopodia;at the same time,the C₈PC-1 liquid crystal substrate with a high elastic modulus can enhance the expression of M2 anti-inflammatory genes and inhibit M1 related The expression of genes and pro-inflammatory cytokines regulates the phenotypic transformation of RAW264.7 from M1 to M2.The C_nPC liquid crystal cell substrate model constructed in this study provides a reference for exploring the mechanism of the mechanical stimulation of viscoelastic soft material substrate to regulate the transformation between M1/M2 macrophages,and provides a reference for the establishment of cell culture model-based immune microenvironment regulation in vitro New ideas.