Preparation And Drug Release Property Of Graphene Oxide/Polymer Nanofiber Membranes

Electrospinning is considered to be an ideal technology for preparing nanofibers because of its simple process,low price and wide range of raw materials.The nanofibers have a wide use value and application prospect,especially in tissue engineering scaffold materials and drug controlled release carriers.Generally,polymer materials used for electrospinning are classified into natural polymers and synthetic polymers.In natural polymer,chitosan(CS)is the only macromolecular basic aminopolysaccharide in natural polysaccharides,which has excellent biocompatibility,biodegradability,wound healing ability and antibacterial properties,but its mechanical strength is not strong enough.In synthetic polymer,due to the large amount of ester bonds,the polylactic acid(PLA)has a poor hydrophilicity,which reduces its biocompatibility with other substances,and the strength often fails to meet the requirements.Graphene oxide(GO)has excellent physical and chemical properties,which can be used as a reinforcing material to improve the mechanical properties of the matrix.Meanwhile,its abundant oxygen-containing functional groups make it hydrophilic.The purpose of this thesis is to study the preparation of composite nanofibers by combining GO with natural polymer CS and synthetic polymer PLA respectively.On the one hand,it ensures good physical and chemical properties and biological properties of CS and PLA;On the other hand,it can effectively improve the mechanical properties of CS and PLA and the hydrophilic properties of PLA.Sequentially,it provides a basis for further exploration of its application in biomedical applications.Firstly,CS was used as the raw material of natural polymer materials,and the electrospinning process parameters of pure CS and CS/GO nanofibers were established and optimized.It was found that the effect of cosolvent volume ratio on the electrospinning of pure chitosan was mainly related to the relationship between solvent volatility and humidity.Both strong volatile solvent and too low ambient humidity always caused needle blockage.With the cosolvent volume ratio of 8:2,it was found that the optimal spinning concentration of chitosan was 4 wt%.It was verified that GO and CS had good compatibility by SEM,FT-IR,Raman,mechanical properties tests.The addition of GO maked CS/GO composite nanofibers smaller in diameter and more uniform in size.Meanwhile,the mechanical properties of the materials was improved effectively.The tensile strength and Young's modulus were increased by 101.04% and 199.29% respectively,when the content of GO was 0.8%.Secondly,PLA was used as as the raw material of synthetic polymer materials,the electrospinning process parameters of PLA/GO nanofibers were established and optimized.The composite nanofiber membrane was successfully prepared by electrostatic blending and coaxial co-spinning process.It was found that the addition of GO also improved the hydrophilicity and mechanical properties of the material.In the coaxial co-spinning process,polyethylene glycol(PEG)with excellent hydrophilicity was added to the sheath layer,and a controllable pro-hydrophobic composite nanofiber membrane was obtained by different content ratio of PLA/PEG.Finally,after the doxorubicin hydrochloride(DOX)and paclitaxel(PTX)loaded,the composite nanofibers of PLA and GO were studied on the drug release property and their anti-tumor properties were studied in vitro.It was proved by FT-IR,XRD and SEM that DOX and PTX were successfully loaded,and the surface of the nanofibers was smooth without obvious drug particles.The content of doxorubicin and paclitaxel were detected by high performance liquid chromatography and ultraviolet spectrophotometer.And the standard curve,drug loading rate and encapsulation efficiency were also obtained.It was found that the addition of GO could increase the drug loading rate.In the coaxial sheath,the adsorption of PEG could increase the encapsulation efficiency of DOX.According to the in vitro drug release curve,when the release medium was pH=7.4 PBS buffer,the maximum release amount of DOX was 45.09%,and the maximum release amount of PTX was 35.87%.Cell experiments proved that the unloaded nanofibers have no obvious cytotoxicity,while the composite nanofibers loaded with DOX and PTX could effectively inhibit the proliferation of human breast cancer cell MCF-7.