Välimaa T, Laaksovirta S
Institute of Biomaterials, Tampere University of Technology, PO Box 589, FIN-33101 Tampere, Finland.
Biomaterials. 2004 Mar-Apr;25(7-8):1225-32. doi: 10.1016/j.biomaterials.2003.08.072.
In vitro degradation of self-reinforced PLGA 80L/20G material and bioabsorbable stents was studied in artificial urine and phosphate buffer solution (PBS) to define if the media have an effect on the degradation rate in urological applications. After six weeks, the Mv of the samples immersed in PBS was 40% (16.7 kDa) from the initial value and 57% (24.0 kDa) for the samples immersed in artificial urine. The strength loss of samples that were immersed in PBS was slower when compared with samples in artificial urine. The bending strength of samples immersed 15 weeks in artificial urine was 43% (21.7 MPa) of the bending strength of samples immersed in PBS (50.9 MPa), and the shear strength was 13% (artificial urine 3.7 MPa, PBS 28.8 MPa), respectively. The maximum compression force in PBS was slightly over at the initial level after 2 weeks of immersion. It decreased to half (102.2N) of the initial value (204.1N) in 8 weeks, and after 12 weeks it was 25% (50.8 N) of the initial value. The compression force in artificial urine was 35% (66.8 N) of the initial value (193.9 N) after 8 weeks. In 12 weeks it had lowered to 26 N in artificial urine, which was 14% of the initial value. The degradation rate of self-reinforced L-lactic and glycolic acid stents in vitro tests in artificial urine was coinciding with our clinical test. Based on these results, it is possible to make a sufficiently accurate in vitro model for the degradation rate of bioabsorbable polymers for urological applications.
在人工尿液和磷酸盐缓冲溶液（PBS）中研究了自增强聚乳酸-乙醇酸共聚物80L/20G材料及生物可吸收支架的体外降解情况，以确定这些介质在泌尿外科应用中是否会对降解速率产生影响。六周后，浸泡在PBS中的样品的重均分子量（Mw）相对于初始值下降了40%（降至16.7 kDa），而浸泡在人工尿液中的样品下降了57%（降至24.0 kDa）。与浸泡在人工尿液中的样品相比，浸泡在PBS中的样品强度损失较慢。在人工尿液中浸泡15周的样品的弯曲强度为浸泡在PBS中的样品（50.9 MPa）弯曲强度的43%（21.7 MPa），剪切强度分别为13%（人工尿液中3.7 MPa，PBS中28.8 MPa）。浸泡在PBS中的样品在浸泡2周后最大压缩力略高于初始水平。在8周时降至初始值（204.1 N）的一半（102.2 N），12周后为初始值的25%（50.8 N）。在人工尿液中浸泡8周后，压缩力为初始值（193.9 N）的35%（66.8 N）。12周后在人工尿液中降至26 N，为初始值的14%。自增强左旋乳酸和乙醇酸支架在人工尿液中的体外降解速率测试结果与我们的临床试验结果一致。基于这些结果，有可能为泌尿外科应用的生物可吸收聚合物降解速率建立一个足够准确的体外模型。
