Study On Electrospun Drug Loaded PLA Ultrafine Fibers And Sustained-Release

Electrospinning is one of the most important technique to produce ultrafine fibers. Because ultrafine fibers have several useful properties including small diameter,high surface area to volume ratio and high porosity, they can be used extensively, especially in biomedical fields such as tissue engineering scaffolds, drug delivery and controlled release, wound dressing and so on. However, due to the complexity of the electrospinning process and the diversity of the electrospinning parameters, one of the challenges in electrospinning is the preparation of the electrospun fibers with narrow diameter distribution. Moreover, the research of electrospun fibers in drug delivery and controlled release was developed recently and it belongs a new thesis in medicine fields.This thesis made a preliminary research on the electrospun biodegradable PLA ultrafine fibers containing three different model drugs (indomethacin (IND),aspirine (ASP) and rifampin (RFP)). The author systematically studied the influence of electrospinning parameters, the addition of three different model drugs and different amounts on fiber's morphology and structure. The influence of the addition of drugs on microstructure of electrospun PLA ultrafine fibers was also tested and analyzed by means of IR and DTA. The author used UV-spectrophotometer to characterize the release of electrospun PLA/IND,PLA/ASP,PLA/RFP and silk fibroin(SF)/RFP ultrafine fibers and studied them by means of in vitro release.The results showed that:(1) PLA could be dissolved in the mixture of chloroform and acetone(2︰1 in volume) to make even spinning solution. The fiber's diameter was reduced with the concentration of spinning solution decreasing,voltage and electrode distance increasing.(2) The addition of three different drugs could improve the electrospinning process of PLA and reduced the fiber's diameter. The fiber's diameter was also reduced by adding the amount of IND,ASP,RFP.(3) The drugs were physically mixed with PLA respectively. Most of the drugs were encapsulated within the fibers.(4)Electrospun PLA ultrafine fibers had obvious sustained release pattern: The pure drugs finished release within three hours, whereas the cumulative drug release percentage of drug loaded PLA ultrafine fibers is from 50 to 80 percent.The release rate of PLA/IND,PLA/ASP and PLA/RFP were slow with increasing PLA concentration , whereas they were more rapid when the amount of drug increased.(5)The release mechanism of three different model drugs from PLA ultrafine fibers were followed by Fick's law for diffusion. Two different biodegradable materials were used as skeletal base materials for production of RFP loaded ultrafine fibers , the hydrophobic PLA ultrafine fibers had a more sustained release pattern than hydrophilic SF during the same period.