| Constructing polymer liquid crystal composite materials with excellent biocompatibility through simulating the liquid crystal structure of biomembrane in vito is a new direction in the field of biological material from the biomimetic point in 21st century. In this study, thermal cholesteric crystal hydroxy propyl cellulose (HPC) macromolecule was first derived to obtain a series of cholesteric liquid crystal molecules which exhibited liquid crystalline phase at physiological temperature. Then it was complexed with polymer. The influence of molecular structure, content and aggregative states of liquid crystal in composite membrane to protein adsorption and cell adhesion growth were studied systematically. This can provide experimental and theoretical basis for the development of high-performance liquid crystal biological materials.Hydroxypropyl cellulose propionate (PPC) and hydroxypropyl cellulose octanate (OPC) were successfully synthesized by the esterification using hydroxypropyl cellulose (HPC) as crude material. The chemical structures and properties of the PPC and OPC were characterized by infrared spectrum (IR), nuclear magnetic resonance (NMR) and polarizing optical microscopy (POM) etc. Results show that the introducing of flexible acyl long-chain can reduce the liquid crystal temperature area of HPC. Under a certain condition, cholesteric liquid crystal macromoleculars of PPC and OPC displaying liquid crystal state can be obtained both at room temperature and the body temperature. In addition, the length of carbon chain of acyl had large effect on the liquid crystal transition temperature and the liquid crystal state performance of HPC ester.A series of polymer/liquid crystal composite membranes with different liquid crystal content, such as (PVC)/PPC,(PU)/PPC,PVC/OPC,PU/OPC, were prepared by solution deposition technique using polyvinyl chloride and polyurethane respectively. Their morphology and hydrophilicity were investigated by polarization microscope (POM) and scanning electron microscopy (SEM). The surface morphology of different composite membranes was investigated, such as different degree of phase separation, liquid crystal domain shapes and liquid crystal domains distribution. And also the theoretical mechanisms and the relationship of the surface morphology with the liquid crystal content were studied. The results show that polymer and liquid crystal in four kinds of composite membranes showed phase separation with the gradually increase of the liquid crystal content. And PPC and OPC forming liquid crystal domains dispersed in polymer matrix. Moreover, with the liquid crystal content increased, the liquid crystal domain size was also growing and exhibited strip distribution in composite films. And then gradually interweaved into network structure, which can cause the increase of the membrane surface roughness. In addition, the composite membrane contact angle test showed that the hydrophilcity of composite membranes can be related to the content of liquid crystal. The contact angle of composite membrane reduced with the increase of the content of liquid crystal.Bovine serum albumin (BSA) adsorption of kinds of polymer/liquid crystal composite membranes was measured by coomassie brilliant blue. Results show that the protein adsorption amount on the surface of composite membranes reduced with the increase of the content of liquid crystal. The protein adsorption of polymericmatrix could significant reduced by the adding of PPC liquid crystal, which may provide a promising alternative strategy for improving the anti-protein adhesion of polymeric materials. The results of the contact angle experiment showed that the contact angle of the composite film decreases with the liquid content increased, that is to say the hydrophility of composite membrane can be affected by the liquid crystal content. The cell-compatibility of the polymer/liquid crystal composite membranes was investigated by using mouse embryonic fibrocyte (3T3) as cell model. Results showed that that the cytotoxicity of all polymer/liquid crystal composite membranes was 1 and the following, which satisfied the evaluation criteria of biological materials. Cells on the surface of liquid crystal composite membranes have good adhesion and growth. Moreover, the cell-compatibility of OPC was better than PPC.All researches mentioned above showed that hydroxypropyl cellulose ester liquid crystal and its composite materials with polymer with good cell-compatibility will be hopeful applied as a new biological materials. |
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