Preparation And Performance Study Of Composite Nanofibers With Core-Shell/Island Structure

Currently, electrospinning technology has developed into one of most optimized methods for preparation of nano/micro-sized composite fiberous materials with specific functions. This technique was simple?used widely and functionalized easily. The products possessed high porosity and large specific surface area, which could be universally used in the fields of biology?medicine? environmental conservation?energy storage?clothing?insulation and sensors. In the field of biomedicine, the 3D structure obtained by electrospinning could successfully imitate the extracellular matrix (ECM) structure, thus electrospinning technology was used as a processing method for tissue engineering scaffold extensively. In this research, a kind of ideal composite nanofibrous material with core-shell/island structure based on synthetic polyester polylactic acid (PLA) and natural polysaccharides chitosan (CS) was prepared by the automatic phase separation mechnism of incompatible two-component in the process of electrospining. This nanofibrous material with CS on the surface exihitited excellent biocompatible interface. On the basis of the structure and morphology characterizations of the scaffold, the formation mechanism of this structure was discussed and the cell adhesion and growth on the surface was also mainly studied. In addition, the protein adsorption capacity was an important factor for the cell adhesion and growth on the scaffold. By adding graphene oxide (GO) with the excellent mechanical property-. favourable hydrophily and particular protein adsorption function into the above system, PLA/CS/GO ternary composite fibrous scaffold was also prepared. Both CS and GO migrated to the outer via hydrogen bond and electrostatic interaction in the process of electrospinning. The changes of protein adsorption and the cell adhesion and growth on the surface of the fiberous membrane were preliminary studied. The main contents and conclusions of this subject were as follows:1?For the PLA and CS blending homogeneous solution, the solvent evaporation speed was affected by controlling electrospinning temperature from 25? to 60? in the process of forming fibers, thus changed the phase separation process of PLA and CS to obtain fiberous scaffolds with mooth core-shell structure or island protuberance structure.2?By a variety of characterization methods such as transmission electron microscopy(TEM)?contact angle meter(WAC)?X-ray photoelectron energy spectrum (XPS)?confocal laser scanning microscope (CLSM), the appearent morphology?internal structure?interaction?hydrophilic-hydrophobic propty? crystallization?thermo-dynamics and mechanical performance of PLA/CS nanofibers were observed and analysised in detail. The mechanism of incompatible two-component automatic phase separation as the main reason for the formation of core-shell and island structure was determine. Meanwhile, CS was the main component on the surface because of characteristics of polyelectrolyte by charge repulsion.3?In vitro biomineralization experimental results showed that the CS on the surface could effectively promote the hydroxyapatite mineralization on the PLA/CS fibrous scaffold; MTT test results instructed that there was no obvious biological toxicity for this fibrous scaffold; MC3T3-E1 cell adhesion and growth experimental results proved that the composite fiberous scaffold with island structure possessed the better compatibility and more cells could be adhered to the surface.4?The apparent morphology?internal structure and property of a series of PLA/CS/GO three composite fibers with different GO contents were characterized. Compared to the PLA/CS fibers, the hydrophily of PLA/CS/GO fiberous membrane was increased and the contact angle decreased from 88°to 68°. Respectively choosing negative bovine serum albumin and positive lysozyme as models, the amount of protein adsorbed on the fibrous scaffold separatedly from 0.28 mg/mg,0.007 mg/mg increased to 1.12 mg/mg,0.22 mg/mg at the same time. Moreover, the existence of a small amount of GO (0.2 wt.%) made it more conducive to cell attachment and growth.