Modification Of Biologic Degradable Material Of PLA

It is a popular project to develop the application of biologic degradable medicalmaterials in the world presently. As a result of further research on biologicdegradable polymer materials used in medical field, a profound knowledge ofbiologic degradable polymer materials had been obtained. Ways used to develop thiskind of material become more and more diversiform. The variety is abundant, whichcan be gotten from nature or by chemical composition. And what is paid moreattention to is aliphatic polyester, especially PLA, raw materials of which can beeasily gained from zymolysis of starch and sweet sugar. PLA is nontoxic, degradable,and biologic consistent, and also has good mechanical property and toughness, andcan be easily molded. Through adjusting its molecular weight, and choosing acertain method of polymerizing and molding, which can adjust its mechanicalproperty and its speed of degradation, for different application in medical field. As akind of medical, biologic, and degradable material, PLA is more and more importantand meaningful to be researched and developed.As the application of PLA becomes more and more popular, pure PLA can notmeet the requirements. PLA is widely used for tissue engineered scaffolds materials.The mechanical and biologic consistent properties of PLA are important to the tissueengineering. It can not absolutely meet the requirements of tissue engineeredscaffolds materials, and need further improving. There had been a lot of research onit in and out our country. Especially the technique of chemical copolymerization isripe, such as block copolymerization and graft copolymerization, but which is morecomplex and difficult to carry out. Meanwhile the technique of chemical comixingand surface modification come into being, which are simpler comparatively. But allof these researches just respectively fasten on the modification of toughness orbiologic consistent properties of PLA. In this paper, the method of chemicalcomixing was used to modify the toughness and biologic consistent properties ofPLA synthetically. In order to improve its toughness and biologic consistentproperties, medical plasticizer PEG mixed with PLA through smelting, and furtherinterfused with low molecular weight of CHS in solvent of DMSO in this paper. Themore flexile and hydrophilic PLA-based material was obtained. The membrane wasapplied as scaffolds of cells, and the result is perfect.A series of experiments had been designed:1 PLA was respectively molded by the methods of salting out, chemicalblowing and lyophilization. Different molding method was studied toproduce porous scaffolds materials, and the method of salting out is fixed.Meanwhile, different quantity and different size of salt particles were usedto research its effect on porosity and mechanical property of themembrane;2 Medical plasticizer PEG was used to modify the mechanical property ofPLA. The mechanical effect of different content of PEG in PLA wasdiscussed through measuring the elongation at break of the membrane;and the effect on degradation was discussed through measuring the weightof the membrane and the pH of the solution.3 The hydrophilic material of CHS was used to modify the hydrophilicproperty of PLA. The effect on hydrophilic, mechanical and degradationproperty of different content of CHS in PLA were discussed, respectivelythrough measuring the contact angle, the elongation at break, and theweight of the membrane and the pH of the solution.4 The membrane was applied as scaffolds of cells, and the result was putdown.