Preparation And Properties Of PLLGC/BMPLGA Microcarriers

Bone tissue defects caused by congenital diseases,trauma and osteitis are a major problem in clinical medicine.Compared with traditional medical methods,tissue engineering provides a new way of thinking and treatment for the treatment of such diseases,and has broad prospects for development.The microcarrier can provide a sufficient number of cells for the lesion,and can be injected into the body to repair the defect of the bone tissue.It is a special type of tissue engineering scaffold,and the method is simple and effective.Polyglycolide(PLGA)is a widely used tissue engineering material with good biocompatibility and degradability,but it also has the disadvantages of poor toughness and degradation to produce acidic substances.PLLGC is a terpolymer synthesized by copolymerization of lactide,glycolide and caprolactone,and the introduction of caprolactone enables the polymer to have good toughness and processability.In this paper,maleic anhydride was introduced on the basis of PLGA,and further graft modification with1,4-butanediamine was carried out.The introduction of 1,4-butanediamine can reduce the acidity produced by degradation and regulate the degradation rate.Three microcarriers with good performance of PLLGC,BMPLGA and PLLGC/BMPLGA were prepared by emulsion method,which is expected to be used in tissue engineering.High purity L-lactide and glycolide were prepared from L-lactic acid and glycolic acid.The ternary copolymer PLLGC was synthesized by ring-opening polymerization by mixing the two with ?-caprolactone and stannous octoate as a catalyst.The PLLGC porous microcarriers were prepared by emulsion method using gelatin as pore-forming agent.The effects of stirring temperature,stirring speed,polymer PLLGC concentration and gelatin dosage on the particle size,morphology and surface structure of porous microcarriers were investigated.The results showed that the preferred conditions for preparing PLLGC microcarriers were water bath temperature 0°C,stirring speed 300 rpm,PLLGC concentration1wt%,gelatin dosage 2.5 ml,concentration 7.5 wt%;PLLGC microcarriers prepared under these conditions had a particle size of about 200 ?m.There is a uniform pore structure,and the surface diameter of the microcarrier is 8.1±2 ?m.High purity D,L-lactide was prepared from D,L-lactic acid.Using BPO as an initiator and stannous octoate as a catalyst,D,L-lactide,glycolide and maleic anhydride were prepared into a polymer MPLGA by melt copolymerization.The MPLGA was further modified with1,4-butanediamine to prepare a polymer BMPLGA.The BMPLGA porous microcarriers wereprepared by emulsion method using gelatin as pore-forming agent.The effects of stirring speed,stirring temperature,BMPLGA concentration and gelatin dosage on the particle size,morphology and surface structure of the microcarriers were investigated.The results showed that the preferred conditions for preparing microcarriers were water bath temperature 0?,stirring speed 300 rpm,BMPLGA concentration 1wt%,gelatin dosage 1 ml,concentration 7.5wt%;Microcarriers prepared under these conditions had a particle size of 200-250 ?m.There is a uniform pore structure,and the diameter of the microcarrier is 21.7±10 ?m.The PLLGC/BMPLGA composite porous microcarriers were prepared by emulsion method using gelatin as pore-forming agent.The effects of stirring speed,stirring temperature,polymer dosage and gelatin dosage on the particle size,morphology and surface structure of the composite microcarriers were investigated.The results showed that the optimum conditions for preparing PLLGC/BMPLGA composite porous microcarriers were water bath temperature 0?,stirring speed 300 rpm,mass ratio of PLLGC to BMPLGA 1:3,gelatin dosage 2.5 ml,5.0 wt%;The PLLGC/BMPLGA composite porous microcarrier prepared under these conditions has a particle size of 200-300 ?m and a uniform pore structure.The surface pore diameter of the microcarrier is 23.4±5 ?m.In vitro degradation experiments of PLLGC,BMPLGA and PLLGC/BMPLGA microcarriers were carried out in PBS buffer solution.The experimental results show that after the degradation of the microcarriers,the PLLGC microcarriers make the p H of the solution the lowest,and the BMPLGA microcarriers make the p H of the solution the highest.This demonstrates that the mixing of PLLGC and BMPLGA reduces the acidity produced by microcarrier degradation relative to a single PLLGC microcarrier.After the same time of degradation,the mass loss of BMPLGA microcarriers was the most,and the mass loss of PLLGC microcarriers was the least,indicating that the degradation rate of PLLGC/BMPLGA microcarriers can be controlled by controlling the amount of two polymers.Corneal epithelial cells were cultured on three microcarriers,PLLGC,BMPLGA,and PLLGC/BMPLGA.The growth and proliferation of cells on the microcarriers were studied by observing the cell morphology and CCK-8 method.The results showed that corneal epithelial cells can grow and proliferate normally on PLLGC,BMPLGA and PLLGC/BMPLGA microcarriers,and the growth of cells on the three microcarriers is basically the same.This indicates that all three microcarriers are non-cytotoxic and have good biocompatibility.