title: The Use of Graphene and Its Derivatives for Liquid-Phase Transmission Electron Microscopy of Radiation-Sensitive Specimens.
abstract: 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.
authors.affiliation: Department of Chemistry, University of California , Berkeley, California 94720, United States.|Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: Hoduk
authors.identifier: 0000-0002-0082-0637
authors.initials: H
authors.lastname: Cho
authors.affiliation: Department of Chemistry, University of California , Berkeley, California 94720, United States.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Jones
authors.affiliation: Department of Chemistry, University of California , Berkeley, California 94720, United States.|The Hamburg Centre for Ultrafast Imaging, University of Hamburg , Luruper Chaussee 149, 22761 Hamburg, Germany.
authors.forename: Son C
authors.initials: SC
authors.lastname: Nguyen
authors.affiliation: Department of Chemistry, University of California , Berkeley, California 94720, United States.|Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Hauwiller
authors.affiliation: Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.|Department of Physics, University of California , Berkeley, California 94720, United States.|Kavli Energy NanoScience Institute , Berkeley, California 94720, United States.
authors.forename: Alex
authors.initials: A
authors.lastname: Zettl
authors.affiliation: Department of Chemistry, University of California , Berkeley, California 94720, United States.|Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.|Kavli Energy NanoScience Institute , Berkeley, California 94720, United States.|Department of Materials Science and Engineering, University of California , Berkeley, California 94720, United States.
authors.forename: A Paul
authors.identifier: 0000-0001-6895-9048
authors.initials: AP
authors.lastname: Alivisatos
mesh_terms: D004247:DNA / Q000737:chemistry; D004583:Electrons; D006046:Gold / Q000737:chemistry*; D006108:Graphite / Q000737:chemistry* / Q000528:radiation effects; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D053768:Metal Nanoparticles / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D010087:Oxides / Q000737:chemistry; D010316:Particle Size; D017655:Silicon Compounds / Q000737:chemistry; D013048:Specimen Handling; D013059:Spectrum Analysis, Raman; D013499:Surface Properties; D014867:Water
chemical_list: D010087:Oxides; D017655:Silicon Compounds; D014867:Water; D006046:Gold; D006108:Graphite; D004247:DNA; C032734:silicon nitride
keywords: DNA nanotechnology; Liquid-phase TEM; bioimaging; graphene liquid cell; radiation damage; radical scavenger