| The liquid crystal state is a ubiquitous material state in the living body,and is also the basis for the formation of many tissues and structures in the body.It is very important for maintaining the normal function of living systems.Cholesterol is an important component of cell membranes,and is a key factor in maintaining cell membrane stability and liquid crystal structure.Its derivatives are liquid crystal(LC)materials with good biocompatibility,especially cholesteryl ester liquid crystals are widely used in tissue engineering fields such as cell sensors and tissue engineering scaffolds due to their good biocompatibility.Therefore,the construction of liquid crystal biomaterials from a bionic perspective,combining cholesteryl ester liquid crystals with similar life structure and characteristics with Poly(l-lactide)(PLLA)lacking biocompatibility,will become a promising new bionic material in the field of bone tissue engineering.In order to better simulate the microenvironment of tissue culture in vivo,based on the concept of bionic design of biological materials,this study used cholesterol oleyl carbonate(COC)and cholesterol pelargonate(CP)as raw materials through two-phase blending.Different concentration gradients of thermally induced cholesteryl ester binary blended liquid crystal COC / CP were obtained.The results show that when the CP concentration is less than 60 %(wt),COC / CP is in the liquid crystal state at the physiological temperature of the human body.This overcomes the shortcoming that the single liquid crystal cannot be in the liquid crystal state at the physiological temperature of the human body,and more realistically simulates the human tissue culture microenvironment.The liquid crystal texture and phase transition temperature of COC / CP change with the concentration of CP.When the CP concentration increases,the liquid crystal phase transition temperature of COC / CP gradually increases,and the cholesteric spiral texture becomes more and more obvious.When the CP concentration is 30 %(wt),COC / CP is in a liquid crystal state at 37 ?,which is particularly sensitive to changes in ambient temperature and has thermal responsiveness.Cell experiment in vitro results show that,compared with cell slides,COC / CP can significantly promote the adhesion,migration and proliferation of Pre-osteoblast(MC3T3-E1),indicating that the liquid crystal matrix better mimics the microenvironment of tissue culture in vivo.The lack of active functional groups on the surface of PLLA results in poor cell compatibility.In order to improve the cell compatibility of the PLLA and find a material carrier with good mechanical properties for the COC / CP liquid crystal,a PLLA / liquid crystal(LC)composite film with a liquid crystal substrate is produced by a solution casting method.The results show that the liquid crystal distribution on the surface of the PLLA / LC composite film is uniform,and there is no obvious phase separation structure.The liquid crystal substrate of the PLLA / LC composite film is in a liquid crystal state at 37 ° C and has thermal responsiveness to external signals.The surface of the PLLA / LC composite membrane is dense,with a uniformly connected void structure in the middle,which is similar to the natural bone tissue material in physical structure.LC-30 % CP liquid crystal can significantly improve the cell compatibility of PLLA and improve the interaction between MC3T3-E1 and materials.The cell compatibility of PLLA-30%LC composite membrane is better than other composite membranes.In order to explore the feasibility of PLLA / LC composite membrane as a repair material for bone tissue,this study explored the promoting effect of PLLA / LC composite membrane on osteogenic differentiation of murine mesenchymal stem cells(BMSCs).Then,the SD rat cranial defect model was used to study the effect of PLLA / LC composite membrane on promoting cranial repair and regeneration.The results show that,compared with PLLA,PLLA-30%LC composite membrane can significantly promote the differentiation of BMSCs into osteoblasts and the repair and regeneration of cranial.In summary,this article prepared a COC / CP binary blended liquid crystal in the liquid crystal state at the physiological temperature of the human body,and combined it with PLLA to prepare a thermally responsive PLLA / LC composite film.The physical structure and chemical properties of the composite membrane are highly similar to those of natural bone tissue materials,which can better simulate the tissue culture microenvironment in vivo.It will have good application prospects in the field of biomedical engineering because of its significant role in promoting bone tissue repair and regeneration... |
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