| Electrospinning technology has been widely used in various areas, due to the unique properties of obtained fiber such as high specific surface area, high porosity and nano scale diameter. Because of these merits, electrospinning is applied in tissue engineering to fabricate materials with similar fibrous network structures to exracellular matrix (ECM).In this study, electrospinning technology was used to manufacture poly(L-lactic acid)(PLLA)/gelatin composite fibrous mats with different weight ratios. Various methods, including hydrophilicity determination, SEM and TEM observation, XPS analysis, degradation experiment, and selective removal, the microphase strucutures of PLLA/gelatin composite fibers and its relationship with the hydrophilicity were indentidied and investigated. An interesting phenomenon was that the water contact angles of PLLA/gelatin mats were decreased to zero when the weight ratios of PLLA to gelatin were 1:1 and 1:3, while the water contact angle of pure gelatin fibrous mat remained at 42°. PLLA/gelatin mat with weight ratio of 3:1 had similar water contact angle to pure PLLA fibrous mat which was about 123°. These phenomena demonstrated that phase separation had happened between the PLLA and gelatin component during the electrospinning procedure and different microstructures resulted with different PLLA to gelatin weight ratios. Selective removal of one component, TEM images and the degradation experiments revealed that the two polymers appeared a kind of co-continuous phase morphologies when the weight ratio of PLLA to gelatin was 1:1. However, when the content of PLLA or gelatin in fibers was lower than 50%wt, the low-content polymer would be interspersed in the high-content polymer matrix, and the high content component would form the fiber surface. The results of crosslinking treatment and cell culture suggested the composite fibrous mats with PLLA/gelatin weight ratio of 1:1 turned out to be the suitable system for tissue engineering application.Biomineralization of pure gelatin, PLLA and PLLA/gelatin (weight ratio was 1:1) mats was investigated. Two 5 times simulated body fluid were made which named as traditional 5SBF (t-5SBF) and improved 5SBF (i-5SBF), respectively. The pH value of the former increased continuously while the pH value of the latter remained constant during the whole experiment. Comparing the results of the three samples after being incubated in the two SBF solutions for certain time, the morphology of apatite obtained from i-5SBF incubation was similar to that of apatite in human body. The mineralization rate in t-5SBF incubation didn't change too much during the whole procedure; on the contrary, the mineralization rate in i-5SBF incubation was slow at the initial stage but increased with prolonged incubation time. XRD results indicated that the apatite obtained from t-5SBF treatment was mainly hydroxyaptite (HA), while the apatite obtained by i-5SBF treatment was mainly brushite (DCPD) at first and subsequently changed into HA. PLLA/gelatin mat's biomineralization result appeared the best one among these three materials.In order to provide materials for the study on the guided tissue which was perfomed by other people in our lab, electropsun PLLA nanofibrous mats with different topological morphologies, such as non-woven, parallel-aligned and lattice-patterened, were produced by using aluminum plate, roller or lattice mesh as the receiver. And the parallel-aligned fibrous mats were further hot-stretched to make fiber thinner and mechnical properties higher. The lattice-patterened mats had a kind of framework, in which fibers were parallel-aligned, and nonwoven regions between the frames. The hot-stretched mat showed the highest hydrophilicity among all the samples probably owing to capillarial effect. DSC analysis demonstrated that electrospinning had little influence on the crystallinity of PLLA.
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