外科吻合用生物可降解纳米钕铁硼磁性复合材料的研制

摘要

背景:普通外科手术中,磁吻合技术以操作简便、吻合迅速、对位准确、吻合质量确定、应用范围广泛等优点备受关注,但磁材料留置体内可能会对机体产生一些不良的影响,生物可降解纳米磁性复合材料有望解决此问题.目的:研制适用于外科吻合用的生物可降解纳米钕铁硼磁性复合材料,并评价其主要磁性能、体外降解性能.方法:采用高能球磨法制备纳米钕铁硼微粒,以溶剂挥发法将纳米钕铁硼微粒与生物可降解材料聚乳酸/羟基乙酸共聚物复合(聚乳酸/羟基乙酸共聚物含量分别为2.5%、5%、7.5%、10%、20%、30%、40%、50%),在特定温度(60,80,100,120,140℃)、压力(6,8,10,12,14 MPa)条件下,以温压成型工艺压制生物可降解聚乳酸/羟基乙酸共聚物-纳米钕铁硼磁性复合材料,检测其最大磁能积.采用磷酸盐缓冲液恒温振荡浸泡法进行生物可降解聚乳酸/羟基乙酸共聚物-纳米钕铁硼磁性复合材料(聚乳酸与羟基乙酸摩尔比分别为90/10、70/20、50/50)体外降解实验,扫描电镜观察磁体降解前后显微形态结构变化及降解时间与聚乳酸/羟基乙酸共聚物摩尔比的关系.结果与结论:生物可降解纳米钕铁硼磁性复合材料的磁性能在一定范围内与纳米钕铁硼微粒含量、成型温度及成型压力呈正比,与聚乳酸/羟基乙酸共聚物含量呈反比.在工艺参数为温度120℃、压力12 MPa、聚乳酸/羟基乙酸共聚物含量为5%时其磁性能最佳,最大磁能积为45 kJ/m3.生物可降解纳米钕铁硼磁性复合材料在体外的降解过程与聚乳酸/羟基乙酸共聚物内部组分的摩尔比密切相关,降解时间与聚乳酸含量呈正比,与羟基乙酸含量呈反比,聚乳酸与羟基乙酸摩尔比90/10、70/20、50/50组的降解高峰期分别为8,6,4周.%BACKGROUND:Magnamosis is regarded as a fast, convenient, and safe approach of surgical anastomosis in general surgery. Biodegradable Nano-magnetic composite materials with good biocompatibility and degradation of adjustability wil solve the potential problems of magnets left in the body.OBJECTIVE:To develop biodegradable Nano-NdFeB composite materials and to evaluate the magnetic energy product and degradation performancein vitro. METHODS: NdFeB nanoparticles were prepared with high-energy bal miling and Nano-NdFeB magnetic particles bonded biodegradable polymer material poly-L-lactide-co-glycolide (PLGA content 2.5%, 5%, 7.5%, 10%, 20%, 30%, 40%, 50%) by the means of solvent evaporation method. The fabrication procedures of biodegradable PLGA-Nano-NdFeB composite materials by warm compaction process under certain pressure (6, 8, 10, 12, 14 MPa) and temperature (60, 80, 100, 120, 140℃) were investigated to reveal their effects on the maximum magnetic energy product. The vitro degradation experiment of PLGA-Nano-NdFeB composite materials (PLGA molar ratio 90/10, 70/20, 50/50) was done with the magnets soaked in 10% PBS at 37℃constant temperature folowed by phugoid oscilation. Microstructure changes were observed by scanning electron microscopy before and after degradation. The relationship between PLGA molar ratio and degradation time was also investigated. RESULTS AND CONCLUSION: The magnetic energy product of biodegradable PLGA-Nano-NdFeB composite materials was in direct proportion with the content of PLGA-Nano-NdFeB magnetic particles, temperature and pressure during warm compaction process, but in inverse proportion with PLGA content within a certain range. The best energy product of biodegradable PLGA-Nano-NdFeB composite materials was 45 kJ/m3 at 120℃, 12 MPa and PLGA content 5%. The degradation time of biodegradable PLGA-Nano-NdFeB composite materials was closely related to molar ratios of PLGA, directly proportional to PLA content and inversely proportional to PGA content. The degradation peak of molar ratios of PLGA (90/10), (70/20), (50/50) occurred at weeks 8, 6, 4, respectively.