Study On Degradation Of Electrospun PLA,PLGA And Silk Fiber Membranes

The electrospinning technique is one of the most important methods of producing continuous nanofibers with diameter range from several micrometers to tens of nanometers. With small diameter, high surface area to volume ratio and high porosity, nanofiber can be used in tissue engineering and biomedical engineering.In this paper, three degradable materials, PLA,PLGA and SF(silk fibroin) were elected to electrospin and studied on the degradation of them detailedly. Through the membranes of the weight loss, molecular weight, breaking intensity and SEM observation of the changes in morphology, meanwhile through X-ray diffraction and DTA testing in the process of degradation of crystal changes, the degradation of three types of fiber membranes performance were characterized. Our group has studied the conditions of electrospun PLA, PLA membranes were obtained on this basis,and then immersed in PBS solution to degradate. The molecular weight of the first two weeks declined significantly and faster than the rate of weight loss and breaking intensity. The fibers were uneven and broken in the degradation of 16 weeks. During the degradation process, crystal of samples decreased gradually.Before studying the degradation of PLGA membrane, firstly, the effect of concentration,voltage and distance on the morphology and structure of the PLGA fibers were studied. The optimum conditions were as follows: the concentration of 7%, voltage 20kV, distance 13cm. PLGA membranes were immersed in PBS solution to degradate.Degradation of PLGA membranes was faster than PLA membranes. There is a rapid increase in weight loss and the molecular weight reduction in two weeks, but the weight loss rate is still lagging behind the decline in the molecular weight reduction. At the same time, the fibers have been some fracture, breaking intensity decreased rapidly. The fibers disappeared in the10 weeks; the sample had become hard, brittle and small pieces. X-ray diffraction and DTA tests found that PLGA fiber membranes were amorphous polymer before and after degradation. In vitro degradation process of electrospun SF membranes in PBS solution, the weight loss was very small and the breaking intensity declined slowly.SEM observed that a large number of fibers broke in 10 weeks. IR test found that electrospun SF membranes after ethanol post-treatment were mainlyβ-sheet structure, random coil emergenced and increased gradually with the degradation time.