Study On The Preparation Tissue Engineering Composite Fiber Scaffolds Of PLLA/PCL, PLLA/PHBV By Electrospinning

Scaffold plays an important role in tissue engineering strategies. The scaffolds were widely applied for different tissue engineering via an electrospinning technique at present.The paper gives a systematic study of the preparation of tissue engineering scaffolds by electrospining. The results showed that the electrospinning nanoscaffolds mimicked Extrocelluar Matrix (ECM) well, with high porosity, well interconnected, and high surface-to-volume ratio that was suitable for cell growth.The PLLA, PCL, PHBV, hyaluronic acid (HA) were choosed as tissue engineering scaffold materials. The composite nanoscaffolds were prepared by electrospining and plasma technique. The structure, morphology, storage modulus and loss factor properties, crystallization property and hydrophilicity of the electrospun fibers were characterized by scanning electron microscopy(SEM), dynamic mechanical properties(DMA), thermal analysis (DSC), wide angle X-ray diffraction(WAXD) and contact angle. Degradation behaviors were investigated during the enzymatic degradation in PBS aqueous for different time. Dermal fibroblasts were seeded on the electrospun scaffold and the cells in material growth situation were evaluated by SEM. The fiber mats were tested for tissue engineering scaffold applications. The main results wered listed as follows:1. PHBV, PLLA, PLLA/PHBV electrospun ultra-fine fibers were prepared by using dichloroethane/DMF (60:40) as solvent systems. PLLA, PCL, PLLA/PCL electrospun fibers were prepared by chloroform/DMF(60:40) . The result indicated that the fibers were smooth and uniform with the interwoven and porous morphology. All of them were suitable for the solvent of PLLA, PHBV, PCL and the mixture for electrospining.2. Although the electrospining process results in alignment and orientation of the polymer chains within the fiber to a great extent, crystallation structure can not be developed very well due to the quick solidification of the fibers. Thus, the crystallinity of PCL and PLLA fibrous mats was lower than that of the corresponding films according to DSC and WXAD results. The phenomenon of the blocked crystallization did not occur because of the fast crystallization rate in the process of electrospinning. So the crystallinity of PHBV was increased after electrospinning.3. Degradation velocity of different proportion of PLLA/PCL and PLLA/PHBV fibrous membrane were greatly accelerated with the addition of enzyme, which were far faster than that of PCL and PHBV fibrous membrane without enzyme. With an increase in the proportion of polylactic acid (PLLA), the degradation speed was obviously speeded up. It is because small molecule acid produced in the course of PCL and PHBV degradation had indirectly catalyzed the degradation of polylactic acid. Weight-loss ratio and water absorption rate of the fibrous membrane were proportionally increased with the degradation time.4. The PLLA/PCL (60:40) nanofibers were treated by three different gases in the low-temperature plasma. The results showed,water contact angle of the films reduced significantly after plasma treatments, and the hydrophilic of composite scaffolds were enhanced. PLLA/PCL (60:40) nanofibers were prepared by electrospining technology and haluronic acid was grafted on the surface ultra-thin fibers after the low-tempature plasma treatment.Dermal fibroblasts were seeded on the electrospun scaffold and the cell proliferation was also evaluated by MTT method and SEM. It can be concluded that the cell affinity of the PLLA/PCL (60:40) fibers were greatly improved by haluronic acid grafting. And it may have great potential applications of tissue engineering scaffold.