Preparation,Modification And Evaluation Of PLGA Porous Microspheres As Microcarriers

Microcarrier culture technique is a large-scale cell culture method for culturing anchorage-dependent cells.Compared with monolayer cell culture,microcarrier provides a larger culture surface area for adherent cells,which greatly increases cell yield.At present,large-scale cell culture using microcarriers is one of the development trends.Microcarrier bioreactors have been commonly used at home and abroad to produce large amount of medical biological products.In order to solve the problems of high production cost,low production value and unstable product of domestic biological products,its necessary to develope microcarrier culture technology and realize the industrialization of microcarrier application.And the design and preparation of microcarriers are the key factors to success.PLGA(poly lactic-co-glycolic acid)is a combination of polylactic acid and glycolic acid by random copolymerization.Over the past two decades,polylactic acid-glycolic acid copolymer(PLGA)has become one of the most attractive synthetic polymers for drug delivery and tissue engineering applications.PLGA is biocompatible and biodegradable,has an adjustable rate of degradation and mechanical properties,and it has been approved by the US Food and Drug Administration(FDA).As a carrier for controlled delivery of small molecule drugs,proteins and other macromolecules,PLGA has been widely used in commercial and scientific research,and it's also widely used in cell culture and tissue engineering.In this paper,PLGA microspheres(PLGA MS)with porous structure were prepared by emulsion suspension method combined with gas foaming method.The structure of PLGA microspheres was characterized by SEM and porosity test.The results showed that the size of the microspheres was 100 ?m~200?m and the distribution was uniform.The surface and interior of the microspheres showed a porous structure with a pore size of 5~20 ?m and high porosity up to 80%.The cytotoxicity analysis of PLGA microspheres by CCK-8 method showed that the microspheres had good biocompatibility.However,due to the poor hydrophilicity of PLGA materials,it is not conducive to cell adhesion.Therefore,the second part of my research works to modify the PLGA microspheres by dopamine(DPA)to prepare DPA-modified PLGA microspheres(DPA-c-PLGA MS).The DPA-c-PLGA MS was characterized by FT-IR,XPS,TGA,DSC,etc.The DPA-c-PLGA MS was characterized by FT-IR,XPS,TGA,DSC,etc.The results showed that DPA was successfully modified on the surface of PLGA microspheres.Using SEM,optical microscope,fluorescence microscope and laser confocal scanning microscopy to observe hepatocytes(L-02 cells)adhesion on the microspheres,the results showed that the ability of cell adherence of DPA-c-PLGA MS was significantly improved.In addition,type I collagen was modified on DPA-c-PLGA microspheres to simulate the three-dimensional culture environment of cells,and the effects of microcarriers on the growth of mouse fibroblasts(L929)and mesenchymal stem cells(MSC)were studied.The above results indicate that the porous PLGA microspheres prepared in this study have the potential to be used as microcarriers after modification,PLGA microspheres have important research significance and application value in three-dimensional culture of cells.