Preparation And Property Of The Degradable Biomedical Membrane

Adhesion is one of the unresolved problems in surgical, and it directly affects the result of the operation. Degradable biomedical membrane is a biological barrier membrane, whose mechanism is to segregate the inflamed or trauma from the tissue and prevent the fibroblast inrushing the traumatic surface. And the controllable degradation time can assure the trauma of insulating until metaplasia. The membrane can effectively avoid the adhesion.This paper worked out a new kind of membrane for prevention of adhesion by studying the preparation, degradation and drug release of the PDLLA membrane and chitosan membrane.This experiment prepared membranes by solvent evaporation method, studied the preparative process of the membrane and the main factors of effecting its capability , including the molecular weight, the kinds of the solvent, temperature , humidity and the character of the mould etc. The article studied the degradation performance of the PDLLA membrane and the chitosan membrane in vivo and in vitro. It also studied the drug release of the PDLLA membrane and the PDLLA/chitosan composite membrane, and discussed the mechanism of the two materials as well.It can produce the better character membrane by using the PDLLA as matrix whose molecular weight is 20000, the ethyl acetate as solvent, when the temperature is about 20℃,the relative humidity is about 40%.The conclusion of the degradation shows that the weigh-loss of the chitosan membrane and the pH of the soak have little changes, it proves chitosan is not hydrolyze. Compare with the PDLLA membrane, the weigh-loss and the pH of the composite membrane changes a lot. It proved that the composite membrane's degradation speed was faster than the PDLLA membrane's. The bigger the molecular weight is, the less the weight losses, so as the slower the degradation speed is. With the comparison of the SEM, the experiment shows that the composite membranedegradation speed obviously faster than the PDLLA membrane, which lead to the conclusion that the degradation time of the PDLLA membrane and the PDLLA/chitosan composite membrane whose molecular weight is about 20000 fit the clinical demand.The conclusion of the drug release in vivo shows that the rate of release is in inverse proportion with the molecular weight of the matrix , and it increases when the quantity of the drug increase. When the proportion of the matrix and drug is 1:1, the matrix's molecular weight is about 20000, the PDLLA membrane and the PDLLA/chitosan composite membrane have better capability. After three weeks, the accumulative release will reach 50%. The drug is able to function better in the early treat.The discussion of the degradation mechanism: Chitosan is not hydrolyze in neutral soak in vitro. The mechanism of degradation of the PDLLA membrane in vivo and in vitro is similar, both represent the simple hydrolyze. The degradation of he composite membrane mainly represent the PDLLA hydrolyze of, chitosan can hydrolyze when there are acid product which is PDLLA's catabolite in vitro. In vivo, PDLLA hydrolyze and chitosan zymohydrolysis are all exist.