| As the development of tissue engineering, it's more and more interested in usingbiomedical materials to make bone graft to treat large area of bone tissue damage. When usingcommon bone graft material for bone repair, it always causes nonunion of bone and stressshielding at the ends of the injured bone. Shape memory polyurethane (SMPU) is a kind of"smart" functional material. When employed for bone repair, it can overcome the difficultiesof nonunion of bone and stress shielding using typical materials to repair bone.Electrospinning is an efficient approach to prepare micro/nano-fibers with mesh structure andhigh specific surface area and porosity. So to a certain extent electrospinning fiber film canmimic the structure and even the biological function of extracellular matrix and provides idealmicroenvironment of cell growth, proliferation and differentiation. Successful elcstrospinningrequires the solution exbiting the desired spinnability. Moreover the prepared electrospinningfilm can be further crosslinked under temperature lower than its phase transition point.Because of the limits of above-mentioned condition, the preparation of SMPU film withstability or reversibility micro/nano-fiber structure and its influence on the cell behavior haverarely been reported at present.In the research, SMPU electrospinning film with micro/nano-fibers was successfullyprepared. Firstly, the stability of the microtopography and shape memory effect of the SMPUelectrospinning film were characterized. Moreover, the shape recovery difference of the samesize SMPU electrospinning and bulk film was also observed. At last, the osteoblasts wereseeded on the SMPU electrospinning and bulk film, respectively. And the difference of cellgrowth behavior of osteoblasts on the two films was evaluated.From the experiments, the following results were obtained:1. Precursor-ASPU was prepared by solution polymerization method and its possiblemolecular structure was analysised by FTIR and NMR. The SEM shows that the SMPU bulkfilm is dense with a comparatively smooth surface. The hand-operated tensile tests and DMAapprove that the SMPU bulk film has good shape memory property and the Rfand Rrare allnearly100%. Through the DSC analysis of the two films, we know that the crystallization ofPCL phase is affected by the formation of the blcok polymer. 2. SMPU electrospinning film has also good shape memory effect. The SMPUelectrospinning film has the micro/nano-fibers structure morphology, and the structure can bemaintained at least three cycles of shape memory test. Compared to the SMPU bulk film, theSMPU electrospinning film affords much shaper and quicker shape recovey property whenheated. It considered due to the higher surface area of the SMPU electrospinning film.3. The osteoblasts were seeded on the SMPU electrospinning and bulk films, respectively.And the cell adhedion, spread and proliferation of osteoblasts on the two films wereresearched. The results show that the osteoblasts were all labeled by DiI which can be used asa good method to observe the cells seeded on the scaffold. Cell adhedion, spread andproliferation of osteoblasts on the SMPU electrospinning film are better than that on theSMPU bulk film. It indicats the SMPU electrospinning film has better biocompatibility thanthe bulk film.We overcome the difficulties of the electrospinning technology and successfully preparedthe SMPU electrospinning film with mico/nano-fibers structure. Compared to the SMPU bulkfilm, the SMPU electrospinning film has greatly advantages in shape recovery property andearly growth of osteoblasts. Moreover, it will provide theoretical basis and first-phasepreparation for using SMPU against bone injury. Othervise, it opens the way to thedevelopment of using other shape memory materials to cure bone injury. |
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