研究人员发现石墨烯对人体活性细胞有毒性

根据美国布朗大学(Brown University)研究人员的研究发现，石墨烯 (grapheme)──这种被誉为半来半导体材料的新宠── 可能会破坏活细胞功能。如果布朗大学的毒性研究结果进一步经过多方研究证实的话，石墨烯最终可能会像碳纳米管一样被归类在有害物质范围。 “石墨烯比碳纳米管更容易产生，而且在许多应用中都能取代碳纳米管，”布朗大学病理学和实验室医学系教授Agnes Kane表示。 石墨烯具有许多独特的功能，但最重要的是它经常是由天然矿物──石墨制造而来，其方式是经由化学或机械剥离方式分离碳薄层，形成可能产生吸入暴露的干燥粉末。病理学家已经针对碳纳米管和其他有关的碳材料展开研究了，但是这是第一次针对2D纳米材料进行毒性测试。 Agnes Kane所主导的布朗大学研究团队在展开石墨烯的毒性研究后发现，就像碳奈米管一样，石墨烯的确会破坏活性细胞功能。为了找出其中的原因，Kane还邀请工程系教授高华健(Huajian Gao)加入这一研究团队，以期为石墨烯材料与活性细胞的互动关系建立详细的电脑模拟图。 该研究团队是在偶然间发现这样的结果，因为他们一开始模拟石墨烯与活细胞间互动关系所显示的结果是良性的。然而，Kane的生物小组经由过去的毒性实验结果已经知道石墨碎片事实上会干扰到活细胞的正常功能。后来才发现，原来第一代模拟过于简单，将石墨烯碎片建模为正方形，而现实世界中的石墨碎片边缘锋利边角尖锐，可穿透细胞壁并吸附其余的碎片。经过高华健教授修改模拟后成功为Kane的毒性实验重新进行建模。

石墨烯(G)碎片边缘尖锐，易穿透细胞薄膜
Source：Kane Lab / Brown UniversitygTMesmc

经过修正模拟后发现了石墨烯将干扰细胞正常功能的机制，布朗大学病理学和实验室医学教授Annette von dem Bussche就能透过显示细胞受干扰的详细影像，重覆进行毒性实验。后续的研究将针对人类的肺、皮肤与免疫细胞在培养皿中进行实验，以确定石墨烯薄层是否会穿透活性细胞并且被吞噬。 所有令人感兴趣的纳米材料都具有独特的性能，因此，尽管宣称具有危险性但也不致于影响其材料应用，而且也有许多有毒的材料仍成功地用于半导体制造中，例如铅、汞与镉等。事实上，布朗大学的研究人员们还针对多种纳米材料进行毒性研究，以期作为开发更安全制造与处理方法的先决条件，以便在整个生命周期都能善加利用。 “纳米材料最佳之处在于你可为其进行建构，使其具有所需的特定性能。”Kanes说，“因此，我们可以透过计算建模的方式，为这些材料进行修改，使其毒性降低。” 石墨烯一直被视为一种具有发展前景的新式材料，可望取代硅晶用于未来的半导体中。 本文授权编译自EE Times，版权所有，谢绝转载 编译：Susan Hong 参考英文原文：Graphene Said to Pose Health Hazard，by R. Colin Johnson

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{pagination} Graphene Said to Pose Health Hazard R. Colin Johnson PORTLAND, Ore. — A team of researchers at Brown University has concluded that graphene -- the darling material of semiconductor futurists -- disrupts functions of living cells. If the results of the Brown toxicity study are confirmed by others, graphene could end up in the same hazardous-material category as its cylindrical relatives, carbon nanotubes. "Graphene is easier to produce than carbon nanotubes and can replace them in many applications," Agnes Kane, a professor at Brown, told me: Graphene has many unique features, but most important is that it is often manufactured from graphite -- a naturally occurring mineral -- by chemical or mechanical exfoliation, which separates the carbon layers, resulting in dry powders with the potential for inhalation exposure. As a pathologist, we have studied nanotubes and other related carbon materials, but this is the first two-dimensional nanomaterial we've tested for toxicity. The Brown research team led by Kane, chair of the school's Department of Pathology and Laboratory Medicine, began with toxicity studies of graphene, which showed that indeed it did disrupt cell functions as nanotubes do. To discover why, Kane recruited a colleague in engineering for her team, professor Huajian Gao, who created atomically detailed computer simulations of the graphene material interacting with a living cell. The mechanism discovered by the team was unexpected, since initial simulations of graphene interacting with living cells indicated it was benign. However, Kane's biology group knew from toxicity experiments that graphene fragments did, in fact, interfere with normal functions in living cells. It turned out that first-generation simulations were too simple, modeling graphene fragments as squares, whereas real-world graphene fragments have sharp, pointy edges that can penetrate cell walls drawing the rest of the fragment inside after it. Gao's revised simulations successfully modeled Kane's toxicity experiments. The sharp bottom corner of a piece of graphene (G) penetrating a cell membrane due to its nanoscale rough edges and sharp corners (scale bar is two microns). (Source: Kane Lab / Brown University) After the simulations revealed the mechanism by which graphene was interfering with normal cell function, Annette von dem Bussche, a professor of pathology and laboratory medicine, was able to repeat the toxicity experiments with detailed images that showed how the cells were being disrupted (see photo). The follow-up studies were performed on human lung, skin, and immune cells in Petri dishes, and confirmed that graphene sheets as large as 10 microns can pierce and be swallowed up by living cells. All interesting nanomaterials have peculiar properties, and being declared hazardous does not doom a material, since many hazardous materials are already successfully used in semiconductor manufacturing, including lead, mercury, and cadmium. In fact, the Brown researchers are investigating a variety of nanomaterials for toxicity, as a prelude to developing safer methods of manufacturing, handling, and utilizing them throughout their lifecycles. "The great thing about nanomaterials is that you can engineer them to have specific desirable properties," said Kane. "Using computational modeling, we hope to modify these materials to make them less toxic." Graphene is considered a promising candidate to replace silicon in future semiconductors. Funding for the Brown research was provided by the National Science Foundation and the National Institute of Environmental Health Sciences. Robert Hurt, a professor of engineering, and doctoral candidates Yinfeng Li (now a professor at Shanghai Jiao Tong University), Hongyan Yuan, and Megan Creighton also contributed to the work.