Study On The Preparation And Properties Of PLGA/Gelatin Fibers With Core-shell Structure

Coaxial electrospinning method is widely used in the preparation of special structure of nanofibers. The fibers with large surface to volume ratio, high porosity and core-shell structure have great application value in the biomedical field, especially as drug carrier. In this paper, poly(lactic-co-glycolic acid) PLGA/gelatin coaxial electrospun fibers were prepared with PLGA as core layer and the mixture of PLGA and gelatin as shell layer. And PLGA/gelatin drug-loaded coaxial electrospun fibers with voltaren as a model drug were also produced. The effects of different parameters on the surface morphology, diameter distribution, degradation in vitro and drug release properties of coaxial electrospun fibers were investigated. The main content includes three parts as follows.Firstly, PLGA/gelatin coaxial electrospun fibers were prepared. The surface morphology, internal structure, chemical composition and hydrophilicity of PLGA/gelatin nanofibers were revealed by scanning electron microscope (SEM), transmission electron microscopy (TEM), infrared spectroscopy (FTIR), water absorption and contact angle test. It was found that with the increase of the proportion of gelatin in the shell, the fiber diameter and the diameter distribution increased. However, the fiber diameter showed a trend of decrease at first and then increase, the diameter distribution became narrowed firstly and then broaded with the increasing of voltage. When the receiving distance increased, the fiber diameter increased firstly and then decreased, but the diameter distribution basically remained unchanged. And the fiber diameter and diameter distribution increased with the increasing of shell velocity. If the voltage, receiving distance and the composition ratio of PLGA/gelatin in shell were different, the water absorption of fibers were decreased at first and then increased with the increase of flow rate. The water uptake reached the minimum value in the flow rate of 0.5mL/h.Secondly, the degradation behavior of PLGA/gelatin electrospun nanofibers in vitro was studied. The surface morphology of fibers was characterized through scanning electron microscope (SEM). And the influences of voltage, receiving distance and shell velocity on the weight loss of fibers were studied. The results showed that under different voltages, the overall degradation rate of fibers was in the range of 5%-28%, and the weight loss of fibers increased gradually with the increasing of degradation time, but after 18d, the degradation rate of fiber changed slowly. If the parameter was changed into different distances, the overall degradation rate of fibers was between 12% and 48%, and in the early stage of degradation, the weight loss of fibers increased gradually with the increasing of distance, yet the weight loss rate basically unchanged after degradation of 24d. When the shell velocity was different, the overall degradation was between 10% and 34%. Furthermore, the degradation rate of fibers increased with the increase of flow rate in the initial stage, and also after degradation of 24 d, the weight loss rate was slowing down obviously.Finally, PLGA/gelatin drug-loaded electrospun fibers were prepared. The internal structure and chemical composition of fibers were investigate by transmission electron microscopy (TEM) and infrared spectroscopy (FTIR). And then the effects of different drug concentration, PLGA/gelatin composition, shell velocity, cross-linking time and pH on drug release were studied. It was found that the smaller drug content, the larger proportion of gelatin in shell and pH were more benefit to the release of drug, however, the rate of drug release decreased with the increasing of shell velocity and cross-linking time.