Degradation behaviour of self-reinforced 80L/20G PLGA devices in vitro

Abstract

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 (102.2 N) of the initial value (204.1 N) 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.