Supercritical Carbon Dioxide Treatment of Porous Silicon Increases Biocompatibility with Cardiomyocytes

Porous silicon is of current interest for cardiac tissue engineering applications. While porous silicon is considered to be a biocompatible material, it is important to assess whether post-etching surface treatments can further improve biocompatibility and perhaps modify cellular behavior in desirable ways. In this work, porous silicon was formed by electrochemically etching with hydrofluoric acid, and was then treated with oxygen plasma or supercritical carbon dioxide (scCO₂). These processes yielded porous silicon with a thickness of around 4 μm. The different post-etch treatments gave surfaces that differed greatly in hydrophilicity: oxygen plasma-treated porous silicon had a highly hydrophilic surface, while scCO₂ gave a more hydrophobic surface. The viabilities of H9c2 cardiomyocytes grown on etched surfaces with and without these two post-etch treatments was examined; viability was found to be highest on porous silicon treated with scCO₂. Most significantly, the expression of some key genes in the angiogenesis pathway was strongly elevated in cells grown on the scCO₂-treated porous silicon, compared to cells grown on the untreated or plasma-treated porous silicon. In addition, the expression of several apoptosis genes were suppressed, relative to the untreated or plasma-treated surfaces.     

Gellan-Xanthan Hydrogel Conduits with Intraluminal Electrospun Nanofibers as Physical,Chemical and Therapeutic Cues for Peripheral Nerve Repair

Optimal levels of functional recovery in peripheral nerve injuries remain elusive due to the architectural complexity of the neuronal environment. Commercial nerve repair conduits lack essential guidance cues for the regenerating axons. In this study, the regenerative potential of a biosimulated nerve repair system providing three types of regenerative cues was evaluated in a 10 mm sciatic nerve-gap model over 4 weeks. A thermo-ionically crosslinked gellan-xanthan hydrogel conduit loaded with electrospun PHBV-magnesium oleate-N-acetyl-cysteine (PHBV-MgOl-NAC) nanofibers was assessed for mechanical properties, nerve growth factor (NGF) release kinetics and PC12 viability. In vivo functional recovery was based on walking track analysis, gastrocnemius muscle mass and histological analysis. As an intraluminal filler, PHBV-MgOl-NAC nanofibers improved matrix resilience, deformation and fracture of the hydrogel conduit. NGF release was sustained over 4 weeks, governed by Fickian diffusion and Case-II relaxational release for the hollow conduit and the nanofiber-loaded conduit, respectively. The intraluminal fibers supported PC12 proliferation by 49% compared to the control, preserved up to 43% muscle mass and gradually improved functional recovery. The combined elements of physical guidance (nanofibrous scaffolding), chemical cues (N-acetyl-cysteine and magnesium oleate) and therapeutic cues (NGF and diclofenac sodium) offers a promising strategy for the regeneration of severed peripheral nerves.     

Effect of crosslinking method on collagen fiber-fibroblast interactions

Collagen, the major structural protein of the extracellular matrix in animals, is a versatile biomaterial used in various tissue engineering applications. Cross-linking influences the mechanical properties, resorption kinetics, and biocompatibility of collagen-based biomaterials. In this study, we evaluated the effects of crosslinking on collagen fiber-fibroblast interactions in vitro. Collagen fibers were left untreated or crosslinked by ultraviolet (UV) irradiation, dehydrothermal (DHT) treatment (3 or 5 days), or hexamethylenediisocyanate (HMDIC) exposure. The initial attachment, proliferation (through 8 days), and morphology of human dermal fibroblasts were evaluated on control and crosslinked bundles of 200 collagen fibers in vitro. Initial attachment (number of fibroblasts at day 0) was increased on UV and DHT5-treated collagen fiber bundles. Fibroblast proliferation was similar for control, UV crosslinked, and DHT crosslinked fibers. In contrast, fibroblast attachment was significantly decreased and proliferation was delayed on HMDIC crosslinked fibers. These results, coupled with our previous studies, suggest that UV crosslinking of collagen fibers provides a combination of biocompatibility, mechanical properties, and strength retention suitable for various tissue engineering applications. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1493–1498, 1997     

A Complex Evaluation of the In-Vivo Biocompatibility and Degradation of an Extruded ZnMgSr Absorbable Alloy Implanted into Rabbit Bones for 360 Days

The increasing incidence of trauma in medicine brings with it new demands on the materials used for the surgical treatment of bone fractures. Titanium, its alloys, and steel are used worldwide in the treatment of skeletal injuries. These metallic materials, although inert, are often removed after the injured bone has healed. The second-stage procedure—the removal of the plates and screws—can overwhelm patients and overload healthcare systems. The development of suitable absorbable metallic materials would help us to overcome these issues. In this experimental study, we analyzed an extruded Zn-0.8Mg-0.2Sr (wt.%) alloy on a rabbit model. From this alloy we developed screws which were implanted into the rabbit tibia. After 120, 240, and 360 days, we tested the toxicity at the site of implantation and also within the vital organs: the liver, kidneys, and brain. The results were compared with a control group, implanted with a Ti-based screw and sacrificed after 360 days. The samples were analyzed using X-ray, micro-CT, and a scanning electron microscope. Chemical analysis revealed only small concentrations of zinc, strontium, and magnesium in the liver, kidneys, and brain. Histologically, the alloy was verified to possess very good biocompatibility after 360 days, without any signs of toxicity at the site of implantation. We did not observe raised levels of Sr, Zn, or Mg in any of the vital organs when compared with the Ti group at 360 days. The material was found to slowly degrade in vivo, forming solid corrosion products on its surface.     

激光熔覆生物陶瓷涂层生物相容性体内研究

将激光熔覆原位合成的钙磷涂层及TC4分别植入健康的Mongrel成年狗,术后15天、60天和180天观察涂层与基材、涂层与机体组织的结合形态及植入后对动物的组织影响.此外,用涂层材料进行肌肉植入实验,分别在15天、37天、60天和180天观察其组织生长形态.结果表明:激光熔覆原位合成的钙磷涂层在动物体内其表面有新骨产生,说明了涂层材料在机体内具有诱导骨生成的生物活性;观察动物的植入部位无感染,无组织吸收或增生等不良反应,材料与肌肉间未发现有不良反应,材料与肌肉界面覆盖的结缔组织层随种植时间延长而增厚.激光熔覆原位合成的钙磷涂层具有良好的体内生物相容性和活性,是一种体内生物陶瓷涂层材料.     

原位自生C/C复合材料SiC涂层的物相组成与形成机理

利用X射线衍射仪(XRD)和扫描电子显微镜(SEM)等检测手段,观察并研究了原位自生C/C复合材料SiC涂层的物相组成和显微结构特点,并根据SiC固态相变规律和元素互扩散原理,探讨了低压Ar气氛反应烧结制备SiC涂层的形成机理。结果表明,低压保护气氛的引入显著提高了反应烧结过程中液态Si在C/C复合材料表面的润湿性,促进C、Si原子互扩散。在此条件下,多晶Si粉与石墨碳反应形成β-SiC稳定相,且该涂层内部衬度均匀,具有鳞片状和细针状纳米晶须结构,从而改善了C/C复合材料的生物相容性。     

Medical application of carbon-nanotube-filled nanocomposites: the microcatheter

Carbon nanotubes hold great promise for use in biomedical fields. Among numerous potential applications, including DNA and protein sensors, bioseparators, biocatalysts, and tissue scaffolds, this article emphasizes the use of carbon-nanotube-filled polymer composites as medical devices, namely, microcatheters. The currently hot topic of the biocompatibility (e.g., toxic properties) of carbon nanotubes is discussed. In addition, critical issues that must be clarified for the full utilization of current carbon-nanotube science and technology in biomedical fields are discussed.     

几种齿科合金生物相容性的比较

用银钯合金、镍铬合金、钴铬合金、2号合金的浸提液体外培养小鼠成纤维细胞(L929),以含10%胎牛血清的RPMI1640培养基作为阴性对照组。用5种浸提液分别培养L929细胞4 h、7 h、24 h、48 h后,用MTT法检测细胞增值率并计算caspase-3活化度。在荧光显微镜下观察48 h后各组细胞的状态。使用凋亡相关因子caspase-3的表达强度辅以时间梯度分析其与齿科合金生物相容性的相关性。结果表明:加样培养48 h后各实验组均有大量凋亡细胞,但是有明显的不同,在镍铬合金组内可见橙色坏死细胞;各组细胞的毒性为0级,其细胞增值率的排序为:钴铬合金组>2号合金组>银钯合金组>镍铬合金组;各实验组的Caspase-3活性有显著的差异(P<0.01),Caspase-3活化度由高到低的排序为:钴铬合金组>2号合金组银钯合金组>镍铬合金组。各时间点Caspase-3活化度也有显著的差异(P<0.01),其由大到小的排序为:4 h、48 h、7 h、24 h;这几种齿科合金生物相容性由高至低的排序为:钴铬合金>2号合金>银钯合金>镍铬合金。镍离子、银离子是影响其生物相容性的主要因素。在时间梯度的辅助下评价4种齿科合金生物相容性,Caspase-3与MTT的结果一致.     

磷酰胆碱共聚物(MPC-co-EHMA)的合成及对聚氨酯膜的生物相容性影响

2-甲基丙烯酰氧乙基磷酰胆碱(MPC)与甲基丙烯酸异辛酯(EHMA)通过自由基聚合制备共聚物PMEH20,并将PMEH20添加到基材聚氨酯中制备了共混膜。牛血清蛋白(BSA)吸附性测试显示当PMEH20质量分数为15%时,BSA吸附量比空白聚氨酯下降了81.7%;血小板粘附性能测试显示,含有PMEH20的聚氨酯共混膜粘附了更少的血小板;动态水接触角测试发现共混膜中磷酰胆碱基团可以通过翻转重排于薄膜表面;薄膜力学性能测试显示,在PMEH20质量分数达到10%时,膜材料的综合力学性能最好。     

基因/蛋白质组学技术在生物材料生物相容性研究中的应用

生物材料的生物相容性是生物材料研究领域的关键科学问题。分子生物学技术的发展使生物材料的生物相容性评价从动物水平和细胞水平深入到分子水平。生物组学技术的发展为高通量进行生物材料分子生物相容性评价、阐明生物材料与生物体的相互作用机理提供了有效的手段。本文综述了生物材料生物相容性研究现状及基因组学、蛋白质组学技术在生物材料生物相容性研究中的应用。