Fabrication Of Biodegradable Nonwoven Membranes By Electrospinning And The Aplication In Drug Controlling Release

Biomedical polymer materials are very hot study at the present, and accompany with the development of human society. In recent years, people have paid more and more attention to developing biomedical polymer materials prepared by electrospinning technology because of electrospinning nanofibrous with remarkable properties, such as high length/diameter ratio, high porosity, large specific surface area, etc. Nevertheless, these materials are restricted in the biomedical fields, particularly in a drug delivery, tissue engineering and anti-adhesion membrane, owing to their poor biocompatibility and degradability. In this dissertation, two main researches have been carried out. Firstly, modification of biodegradable synthetic polyester poly(s-caprolactone)(PCL) electrospinning nanofibrous membranes by grafting natural polymer gelatin (GE) sponge and investigation of the biodegradability and biocompatibility of the modified materials; Secondly, electrospinning of biodegradable synthetic polymer poly(ethylene glycol)(PEG) and natural polymer chitosan (abbreviated as Chi) as a base material loaded with amphiphilic block copolymer of methyl ether terminated poly(ethylene glycol)-block-polylactide (MPEG-b-PLA) micelles, and study on the drug controlled release effect. The study details and results are as follows:(1) Study on modified properties and biocompatibility of the PCL nanofibrous membranesBilayer porous scaffolds were prepared by the assembling of PCL nanofibrous membranes after hydrolyzed grafting with GE sponge. Firstly, PCL nanofibrous membranes were prepared via electrospinning, and then the surface of the membranes was hydrolyzed by a dilute aqueous solution of NaOH. Secondly, the limited hydrolyzed carboxylic group was aminated by gelatin to successfully incorporate more polar functional groups. Thirdly, GE aqueous solutions were casted on the membranes. After freeze drying, crosslinking and freeze drying again, GE sponge were immobilized on PCL membrane surface. The morphologies of bilayer porous scaffolds were observed by SEM. The contact angle of the scaffolds was0°. The mechanical properties of scaffolds were measured through tensile testing, and the Young’s modules of PCL scaffolds before and after hydrolysis were66-77.3MPa and62.3-75.4MPa, respectively. Thus, the bilayer porous scaffolds showed excellent hydrophilic surface and desirable mechanical strength due to the soft hydrolysis and GE coat. The cell culture results showed that the adipose derived mesenchymal stem cells did more favor to adhere and grow on the bilayer porous scaffolds than on PCL electrospun membranes. The better cell affinity of the final bilayer porous scaffolds was not only attributed to the surface chemistry but also the introduction of bilayer porous structure. These results indicated that bilayer porous caffolds had potential application values in wound dressings and tissue engineering.(2) Synthesis of composite structural nanofibrous membrane of Chitosan/PEG for bilayer drug-loaded carrier and controlling release of drug via electrospinning.This research describes the development of a novel controlled drug release system for loading multiple drugs, which was composed of MPEG-b-PLA micelles/Chitosan/PEO composite electrospun nanofibers with core-sheath structures. Two model drugs including of hydrophobic5-FU and hydrophilic cefrapyrimidine were successfully loaded in the core and sheath region respectively, which was the bilayer drug-loaded Chitosan/PEO nanofibrous membranes. The morphology of bilayer drug-loaded nanofibrous was observed by scanning electron microscopy and transmission electron microscopy. These results indicated that MPEG-b-PLA micelles were successfully introduced into the Chitosan/PEO nanofibrous membranes. In vitro drug release assay, it was observed that the drug carrier prepared by this approach processed excellent drug release effectiveness, because of decreasing burst release rate and prolonging release time. In vitro cytotoxicity assay, it was found that bilayer drug-loaded nanofibrous could kill the HepG-2cancer cells within three days. These experimental results indicated that the bilayer drug-loaded Chitosan/PEG nanofibrous membranes had potential application values in wound dressing and drug release treatment of cancer.