Experimental investigation on the properties of poly (L-lactic acid) vascular stent after accelerated in vitro degradation

Poly (L-lactic acid) (PLLA) vascular stents are promising to be used to treat vascular stenosis. However, the degradation of these implanted stents has a great influence on the mechanical properties. In this work, we studied the factors that can influence the mechanical properties by accelerating the degradation of PLLA stents with crimping and expansion in phosphate buffer solution (PBS) at 70 degrees C. The typical influence factors such as the real-time weight-average molecular weight (M-w), crystallinity, surface morphologies, and mass loss of these samples were analyzed in detail. Results showed that radial strength of the stents increased from 877 to 1204 mmHg after accelerated degradation for 2 days and then decreased to almost 0 mmHg after 10 days. Meanwhile, radial stiffness showed an upward trend which is caused by the decrease in M-w, increase in crystallinity and local damage during the crimping and expansion process. Moreover, negligible mass loss of stents was observed in this period and the bulk degradation behavior predominated in the whole process.

Automated summary

In this study, the factors influencing the mechanical properties of poly (L-lactic acid) (PLLA) vascular stents were investigated by accelerating the degradation process. The results showed that the radial strength of the stents initially increased and then decreased, while the radial stiffness showed an upward trend. The mass loss of the stents was negligible, indicating a bulk degradation behavior.