The Use of Graphene and Its Derivatives for Liquid-Phase Transmission Electron Microscopy of Radiation-Sensitive Specimens
The Use of Graphene and Its Derivatives for Liquid-Phase Transmission Electron Microscopy of Radiation-Sensitive Specimens
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DOI：
10.1021/acs.nanolett.6b04383
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发表时间：
2017-01-01
期刊：
影响因子：
10.8
通讯作者：
Alivisatos, A. Paul
中科院分区：
文献类型：
--
作者：
Cho, Hoduk;Jones, Matthew R.;Alivisatos, A. Paul
生物样品的液相电子显微镜面临的主要挑战之一是电子束辐照的破坏效应。众所周知，强电离电子束会导致周围水分子的辐射分解，导致活性自由基物种的形成。在这项研究中，我们使用DNA组装的Au纳米粒子超晶格(DNA-AuNP超晶格)作为模型系统来证明石墨烯及其衍生物可以用于缓解电子束诱导的损伤。当液体电池窗口材料是石墨烯时，我们可以想象DNA-AuNP超晶格在它们自然的盐水环境中，但当它是氮化硅时，我们就不能想象了。在后一种情况下，组装的AuNPs的初始解离之后是它们的随机聚集和刻蚀。使用石墨烯包裹的氮化硅窗口，我们能够复制用石墨烯液体电池获得的稳定的DNA-AuNP超晶格的观察。然后，我们进行了相关的拉曼光谱和透射电子显微镜研究，比较了电子束辐照石墨烯在有水存在和没有水存在的情况下的影响，发现石墨烯与水辐解的产物发生了反应。我们将石墨烯的保护作用归因于它能够有效地清除活性自由基物种，特别是已知会导致DNA链断裂的羟基自由基。我们证实了这一点，证明了当氧化石墨烯和石墨烯量子点直接添加到溶液中时，稳定的DNA-AuNP组装可以在氮化硅液体细胞中成像，这两种量子点最近也被报道为有效的自由基清除剂。我们预计，我们的研究将为利用石墨烯及其衍生物作为生物相容的自由基清除剂以减轻辐射损伤的影响，利用液态电子显微镜研究生物标本开辟更多的机会。
One of the key challenges facing liquid-phase transmission electron microscopy (TEM) of biological specimens has been the damaging effects of electron beam irradiation. The strongly ionizing electron beam is known to induce radiolysis of surrounding water molecules, leading to the formation of reactive radical species. In this study, we employ DNA-assembled Au nanoparticle superlattices (DNA-AuNP superlattices) as a model system to demonstrate that graphene and its derivatives can be used to mitigate electron beam-induced damage. We can image DNA-AuNP superlattices in their native saline environment when the liquid cell window material is graphene, but not when it is silicon nitride. In the latter case, initial dissociation of assembled AuNPs was followed by their random aggregation and etching. Using graphene-coated silicon nitride windows, we were able to replicate the observation of stable DNA-AuNP superlattices achieved with graphene liquid cells. We then carried out a correlative Raman spectroscopy and TEM study to compare the effect of electron beam irradiation on graphene with and without the presence of water and found that graphene reacts with the products of water radiolysis. We attribute the protective effect of graphene to its ability to efficiently scavenge reactive radical species, especially the hydroxyl radicals which are known to cause DNA strand breaks. We confirmed this by showing that stable DNA-AuNP assemblies can be imaged in silicon nitride liquid cells when graphene oxide and graphene quantum dots, which have also recently been reported as efficient radical scavengers, are added directly to the solution. We anticipate that our study will open up more opportunities for studying biological specimens using liquid-phase TEM with the use of graphene and its derivatives as biocompatible radical scavengers to alleviate the effects of radiation damage.