^(125)I籽源照射对壳聚糖涂层的聚乙丙交酯载体支架体外降解性能的影响

Effect of ^(125)I seed irradiation on biodegradation properties of chitosan-coated PGLA carrier sheet in vitro

研究125I籽源持续低剂量率照射对壳聚糖涂层的聚乙丙交酯(Poly(glycolide-co-lactide),PGLA)薄层支架体外降解性能的影响。在离体条件下,模拟人体环境采用磷酸盐缓冲液(Phosphatebufferedsolution,PBS)作为降解介质,125I籽源单粒表观活度为29.6MBq,在薄层支架中5粒125I籽源按一定规律排布。采用质量损耗、弹性回复率测试和扫描电镜观察等方法来评价PGLA薄层支架的体外降解性能。照射后第2周,PGLA薄层支架的质量损耗仅减少了10%左右,弹性保持率维持在60%以上,材料纤维结构保持完好,降解行为不明显;照射第4周时,材料受照剂量最高点处的累积剂量达2.2×103Gy,PGLA薄层支架质量损耗率未超过50%,弹性保持率仍有36%,扫描电镜观察显示,部分材料纤维开始出现裂纹和缝隙,较对照组明显,表明125I籽源持续低剂量率照射4周能使PGLA薄层支架降解速率有所加快,但仍维持了约59%质量和一定的弹性,形态结构保持较好,能有效维持125I籽源的空间分布。

Biodegradation properties of chitosan-coated PGLA （poly （lactic-glycolic acid）） brachytherapy seeding carrier was investigated by continuous low-dose-rate irradiation of ^125 I seeds in vitro. PBS （phosphate-buffered solution） was used to simulate internal environment in vitro. Five ^125 I seeds with an apparent activity of 29.6MBq each were arranged in coated PGLA carrier. Weight loss, elasticity recovery rate and SEM （Scanning electron microscope） observation were used to evaluate its biodegradation properties. The coated PGLA carrier was slightly degraded by losing the weight of 10% and elasticity retention rate still kept at above 60% after two week＇s exposure. The PGLA filament structure was well maintained and only a few coating layers were detached. With a maximum dose of 2.2kGy in the coated PGLA carrier after four weeks＇ exposure to the ^125I seeds, the weight loss rate was less than 50% and elasticity retention rate was 36%. SEM observation indicated further detachment of coating layers and fissure and slit of a few filaments. The results showed that continuous low-dose-rate irradiation delivered by the ^125I seeds caused to some extent accelerated biodegradafion of chitosan-coated PGLA after four weeks＇ exposure in vitro, but majority of mass and certain elasticity were retained and the morphology structure was well maintained. The chitosan-coated PGLA carrier could maintain the space distribution of ^125 I seeds.