纳米铁显影增强硅橡胶的制备及影像可视性评价

Objective To explore the feasibility of iron nanoparticles as radiopaque agents for modifying medical silicone rubber and to evaluate image visibility of modified materials.Methods Methyl vinyl silicone elastomer was mixed with iron nanoparticles,carbon-coated ferric nanoparticles,respectively,in accordance with the designed formula ratios.The composites were blended,mixed,molded and vulcanized with.Two groups of new materials,iron nanoparticle enhanced silicone rubber (INESR,Group1) and carbon-coated ferric nanoparticle enhanced silicone rubber(Fe/CESR,Group2),were harvested.Medical silicone rubber was as a negative control group.CT scanning of each group of material samples in vitro was performed,and both CT images and measured CT values were collected.Differences in CT mean values between the groups were compared.Samples of new material groups were implanted subcutaneously in a dog and standardized radiographic images were obtained.X-Ray Diffraction was used to analyze the component stability of iron nanoparticles dispersing in the silicone rubber.Results Two groups of radiographic image enhanced silicone rubber were prepared.The X-ray images of new composites were clearly visible both in vitro and in vivo.CT values were increased with the increase of added metal nanoparticles and metal atomic weight.CT mean values of each group and the materials in Group 1 and Group2 with the same material formulation were significantly different (P＜0.001).After placed for 180 days,the diffraction peak positions of elemental iron in both groups of materials remained essentially unchanged,and it showed that dispersed iron nanoparticles and carbon-coated iron nanopaarticles in silicone rubber were stable.Conclusion The metal nanoparticles of iron and carbon-coated ferrum can be used as radiographic markers for improving quality of X-Ray image of the medical silicone rubber.     

无机纳米填料对植入硅橡胶生物相容性的影响北大核心

背景:硅橡胶是人体组织、器官外科修复重建的常用生物材料,但其自身存在生物相容性缺陷,无机纳米填料为植入硅橡胶的生物相容性改良和构建具有特定功能的复合材料提供了新契机。目的:综述植入硅橡胶添加无机纳米填料改性在生物相容改良研究方面已取得的成果及不足。方法:在PubMed、Web of Science和Medline等英文生物医学数据库,输入“siloxane,silicone rubber,inorganic nano-filler,metal nano-filler,metal oxide nano-filler,carbon nanoparticles”关键词,在万方、CNKI和维普等中文数据库输入“硅橡胶、无机纳米填料、纳米金属、纳米金属氧化物、纳米碳”关键词,分别检索出与无机纳米填料改性硅橡胶的相关文献,时间跨度从2014年1月至2020年10月。结果与结论:利用纳米金属及其氧化物和纳米新碳填料对植入硅橡胶本体或表面进行改性,增进了硅橡胶的生物相容性,可在细胞生长、抗凝血、表面特性、力学性能、耐久性、抗感染功能化等方面产生积极影响。未来需研究不同纳米填料对硅橡胶表面性质(如拓扑结构、电荷、湿润性)造成的细胞增殖移行机制、纳米金属杀菌剂在硅橡胶表面控释阳离子的细菌-纳米粒子相互作用调节策略,以及植入后潜在的纳米毒性。     

铁质纳米粉体对甲基乙烯基硅橡胶力学性能的影响

目的探讨铁质纳米粉体改性甲基乙烯基硅橡胶的力学性能变化及其在基胶中的分散状态。方法根据国家标准对前期制备出的纳米铁粉增强硅橡胶和碳包铁粉增强硅橡胶复合材料进行邵氏A硬度、拉伸强度、扯断伸长率、扯断永久变形率、撕裂强度等力学性能指标测试,使用热场发射扫描电镜（TFE．SEM）观察复合材料的表面形貌和断口形貌,了解纳米铁在硅橡胶基体的分散状态。结果复合材料试件的邵氏A硬度、拉伸强度、扯断伸长率、扯断永久变形率、撕裂强度的均值随着铁质纳米粉体添加量的增加而增加。当纳米铁在配方中的份数大于17份、碳包铁的份数大于19份时,复合材料的拉伸强度均值不再增加反而呈下降趋势;当铁质纳米粉体的在配方中超过15份时,扯断伸长率、撕裂强度的均值开始下降。铁质纳米微粒在硅橡胶的表面分散均匀,在配方比为85：15的硅橡胶,纳米铁试样的断面及配方比87：13的硅橡胶／碳包铁试件的断面,可观察到粉体的团聚体。结论纳米铁粉体和碳包铁粉体对甲基乙烯基硅橡胶力学性能的补强作用主要取决于纳米粉体的粒径、添加量以及在基胶中的团聚程度。     

医用硅橡胶的生物相容性缺点及现代改良

硅橡胶具有性能稳定、易于塑形、产品效益可观的优点,已广泛应用于生物医学工程领域和医疗卫生行业.尽管如此,硅橡胶在生物医学领域中的应用仍然受到其自身缺陷的挑战.表面疏水性、自身影像相容性欠佳、长期植入体内后发生钙化乃是医用硅橡胶制品在生物相容性方面亟待克服的缺点.近几年来国内外专家针对以上缺点进行了诸多改良研究,热点主要集中于硅橡胶的表面湿润性增加、X-线阻射功能增强、防钙化预处理等方面.取得了阶段性成果,但尚未使医用硅橡胶的生物相容性达到理想的境界.     

评价纳米生物材料安全性的研究进展

由于纳米生物材料独特的物理化学性质，将被人们广泛应用于材料、化妆品、医药等众多领域。使研究者、生产者和消费者今后将有许多机会接触纳米生物材料。特别是在医药卫生领域应用时与人体密切相关，纳米生物材料的安全性格外引起了各方面的关注和争论。文中综述了国内外对纳米生物材料安全性评价的研究进展，并综述了纳米生物材料在体内转移的途径，最后提出在纳米技术形成产业之前，人类应有机会了解其对环境和人类健康的影响，因此对纳米生物材料的安全性评价进行深入研究已经成为当务之急。     

Fe3O4磁性微粒的制备及表征

背景：磁性微粒作为一种磁性载体在固定化酶、免疫检测、靶向载药治疗及细胞分离等生物医学领域得到了广泛的应用。 目的：制备分散稳定性好,相对磁性强的纳米级Fe₃O₄微粒。 方法：以氯化亚铁、氯化铁、氢氧化钠为主要原料,采用化学共沉淀法合成Fe₃O₄磁性粒子。 结果与结论：用正交设计法优化了Fe₃O₄微粒的合成工艺条件,得到制备Fe₃O₄粒子的最佳实验条件为Fe²⁺/Fe³⁺的物质的量之比为2∶1、共沉淀时的pH值为11、熟化温度为90 ℃、表面活性剂聚乙二醇的用量为40 mL,此时制得的Fe₃O₄粒子粒径最小,为78 nm,Fe₃O₄溶液的分散稳定性最好,相对磁性最强。从Fe₃O₄的扫描电镜图可以看出,Fe₃O₄微粒晶体颗粒为纳米级。     

空气介质阻挡辉光放电增强硅橡胶/铁质纳米复合材料的表面亲水性

背景：医用硅橡胶的固有缺点是X射线显影性能欠佳和表面疏水性。添加显影标记物铁质纳米微粒可赋予硅橡胶X射线影像可视性的功能,铁质纳米微粒本体改性硅橡胶表面湿润性的变化尚不清楚,设想表面处理以提高硅橡胶/铁质纳米微粒复合材料的亲水性。 目的：观察硅橡胶/铁质纳米微粒复合材料表面湿润性、亲水改性及表征。 方法：使用空气介质阻挡辉光放电分别对前期制备出的配方比为95∶5,90∶10,85∶15的硅橡胶/纳米铁(INESR)和硅橡胶/碳包铁(Fe/CESR)复合材料表面进行改性,对照组为甲基乙烯基硅橡胶(MVSR)。 结果与结论：INESR和Fe/CESR与MVSR相比,表面水接触角减小幅度不大,疏水性未获得明显改善。经空气介质阻挡辉光放电对硅橡胶/铁质纳米微粒复合材料处理后,表面的亲水性得到较大提高,不同配方比INESR和Fe/CESR的水接触角均降低(P < 0.05);扫描电镜显示改性使试件表面受到刻蚀,粗糙度增加,但无空洞或裂隙;X射线光电子能谱分析表明材料表面的化学成分均发生变化,含氧基团大幅增加,含碳基团则明显减少,含硅基团小幅增加,出现含氮基团,说明改性使氮元素被结合到试件的表面,空气介质阻挡辉光放电处理硅橡胶/铁质纳米微粒复合材料的表面可实现亲水改性。     

无机纳米粒子掺杂生物活性碳纳米纤维的制备及性能评价

背景：已有研究表明向生物惰性碳纳米纤维中引入具有成骨活性的β-磷酸三钙纳米粒子,可显著提高碳纳米纤维的生物活性,而某些二价离子掺杂的β-磷酸三钙也被报道能够促进新骨的生成。 目的：考察适量锌离子、镁离子的引入对β-磷酸三钙@碳纳米纤维材料形貌及成骨活性的影响。 方法：以聚丙烯腈、磷酸三乙酯、硝酸钙、硝酸锌、硝酸镁等为原料,采用溶胶-凝胶、静电纺丝与原位烧结碳化相结合的方法制备锌或镁离子掺杂的β-磷酸三钙@碳纳米纤维材料。将所得复合纳米纤维材料及未掺杂锌或镁离子掺杂的β-磷酸三钙@碳纳米纤维与成骨细胞MC3T3-E1体外共培养,观察细胞的黏附、增殖和形态变化。 结果与结论：β-磷酸三钙@碳纳米纤维形貌均匀,表面可见直径为数十纳米的无机粒子均匀分布,锌或镁离子的引入对纤维形貌无明显影响;复合纤维主要由碳元素组成,钙、锌、镁元素等均匀分布于纤维中,且各元素相对含量与投料比相符。与未掺杂锌或镁离子的β-磷酸三钙@碳纳米纤维相比,MC3T3-E1成骨细胞更易在锌或镁离子掺杂的β-磷酸三钙@碳纳米纤维材料表面黏附,细胞增殖和铺展状态也更好。表明在β-磷酸三钙@碳纳米纤维的基础上,引入锌或镁离子掺杂,能进一步提高材料的细胞相容性及生物活性。     

外科植入硅橡胶材料钙化及抗钙化研究进展

硅橡胶钙化是材料植入体内后其表面或基质内出现病理性矿化的现象,尚无有效防治方法.钙化的重要过程是材料表面的磷酸根离子与钙离子结合启动成核聚集,缓慢增大、融合,逐渐形成较大的羟基磷灰石钙盐堆积.其研究已发展到细胞和基因水平,如基质Gla蛋白质簇是一种硅橡胶假体周围组织钙化的抑制因子.钙化过程中有机模板对无机晶体的调制作用需理论上的突破.硅橡胶自身局部抗钙化性能受到重视.揭示硅橡胶钙化和钙化抑制的机理,可为构建新型抗钙化功能材料提供依据.     

Aspects of silicone rubber as an encapsulant for neurological prostheses

Silicone rubber is not, at first sight, a promising material with which to encapsulate a piece of implantable microelectronics expected to last ten or twenty years. It is well known to be very permeable to water. In fact, if correctly applied, it performs very well for ten years, possibly longer. The paper considers the part player by osmosis in achieving satisfactory performance combined with simple technology.     

Aspects of silicone rubber as encapsulant for neurological prostheses

The paper presents some measurements of the hydrothermal stability of experimental adhesive joints in water at 100°C. The joints are between one adhesive silicone rubber and ten metal or metal-oxide adherends, all combinations of interest to the neurological prosthesis maker. The probable adhesion mechanism is then considered, in the search for some parameter by which the experimental results could have been predicted. Evidence is produced that physical adsorption plays little or no part in the adhesion, but that hydrothermal stability seems to be a function of the adherend ionic charge. In pursuit of this idea, the valency, the Slater potential and the iso-electric point for the surface (IEPS) of the adherend are examined as possible prediction parameters. It is concluded that, at least in neutral and acidified water, the IEPS is a promising predictor, with the benefit that it is experimentally determinable for adherends of unknown composition. The most stable joints seem to occur when the charge density on the adherend has an optimum negative value.     

Aspects of silicone rubber as encapsulant for neurological prostheses Part 4: Two-part rubbers

The durability of the adhesion, in the presence of water, of three two-part silicone rubbers to five adherends of practical interest is examined. The results are contrasted with those obtained, in previous work, from single-part material. It is concluded that two-part rubbers promise outstanding performance in particular circumstances.     

Superior in vitro biological response and mechanical properties of an implantable nanostructured biomaterial: Nanohydroxyapatite–silicone rubber composite

A potential approach to achieving the objective of favorably modulating the biological response of implantable biopolymers combined with good mechanical properties is to consider compounding the biopolymer with a bioactive nanocrystalline ceramic biomimetic material with high surface area. The processing of silicone rubber (SR)–nanohydroxyapatite (nHA) composite involved uniform dispersion of nHA via shear mixing and ultrasonication, followed by compounding at sub-ambient temperature, and high-pressure solidification when the final curing reaction occurs. The high-pressure solidification approach enabled the elastomer to retain the high elongation of SR even in the presence of the reinforcement material, nHA. The biological response of the nanostructured composite in terms of initial cell attachment, cell viability and proliferation was consistently greater on SR–5 wt.% nHA composite surface compared to pure SR. Furthermore, in the nanocomposite, cell spreading, morphology and density were distinctly different from that of pure SR. Pre-osteoblasts grown on SR–nHA were well spread, flat, large in size with a rough cell surface, and appeared as a group. In contrast, these features were less pronounced in SR (e.g. smooth cell surface, not well spread). Interestingly, an immunofluorescence study illustrated distinct fibronectin expression level, and stronger vinculin focal adhesion contacts associated with abundant actin stress fibers in pre-osteoblasts grown on the nanocomposite compared to SR, implying enhanced cell–substrate interaction. This finding was consistent with the total protein content and SDS–PAGE analysis. The study leads us to believe that further increase in nHA content in the SR matrix beyond 5 wt.% will encourage even greater cellular response. The integration of cellular and molecular biology with materials science and engineering described herein provides a direction for the development of a new generation of nanostructured materials.