moving to a Graphene world（石墨烯专题）

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      法国皇帝拿破仑曾经说过：“笔比剑更有威力”，然而他在200年前说这话的时候绝对不会想到，人类使用的普通铅笔中竟然包含着地球上强度最高的物质！石墨烯被为“完美原子晶体”，作为二维结构单层碳原子材料，强度相当于钢的100倍，导电性能好、导热性能强，这是目前世界上最薄的材料，仅有一个原子厚。
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' x) P8 @) b0 d, ^/ r瑞典皇家科学院 2010年10月5日宣布，将诺贝尔物理学奖授予英国曼彻斯特大学科学家安德烈海姆和康斯坦丁诺沃肖洛夫，以表彰他们在石墨烯材料方面的卓越研究。

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扫描隧道显微镜显示一个接近完单层美石墨烯的8nm波浪
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石墨层叠的六角模型: v3 _" J0 {+ \' u" U$ f/ N3 T8 r
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平凡的铅笔蕴涵伟大的科学发现1 p* k3 H, v; F5 Y# W# c
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/ l" Y' ~" e; ]两根头发与2百万个碳纳米管
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9 F! N& V0 q9 }8 }: ~4 Y石墨烯中的单个碳原子
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无定形碳
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中子活化石墨放射自显影术:9毫米热(红色)显示较高的活性
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“太空电梯”缆线) O+ p6 ^2 [: o9 s* ?

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$ f/ A: ~0 P9 x: M; y$ g; t3 U% T富勒烯与螺旋状星云

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石墨烯与干细胞
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Graphene for Controlled and Accelerated Osteogenic Differentiation of Human Mesenchymal Stem Cells.（石墨烯控制和加速间充质干细胞成骨分化）( I+ y2 {. L& \( K! j, B; ^
Nayak TR, Andersen H, Makam VS, Khaw C, Bae S, Xu X, Ee PL, Ahn JH, Hong BH, Pastorin G, Ozyilmaz B
( V/ @; ^- ]% [# TModern tissue engineering strategies combine living cells and scaffold materials to develop biological substitutes that can restore tissue functions. Both natural and synthetic materials have been fabricated for transplantation of stem cells and their specific differentiation into muscles, bones and cartilages. One of the key objectives for bone regeneration therapy to be successful is to direct stem cells' proliferation and to accelerate their differentiation in a controlled manner through the use of growth factors and osteogenic inducers. Here we show that graphene provides a promising biocompatible scaffold that does not hamper the proliferation of human mesenchymal stem cells (hMSCs) and accelerates their specific differentiation into bone cells. The differentiation rate is comparable to the one achieved with common growth factors, demonstrating graphene's great potential for stem cell research.
$ a+ }! m! d' c% \) O5 n: N5 \9 D, APublished 2 May 2011 in ACS Nano.  
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石墨烯减缓细胞毒
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Protein Corona-Mediated Mitigation of Cytotoxicity of Graphene Oxide（石墨烯氧化物对蛋白晕状调节细胞毒的减缓）$ c! c2 B% C) J1 F1 D& d
Wenbing Hu, Cheng Peng, Min Lv, Xiaoming Li, Yujie Zhang, Nan Chen, Chunhai Fan,* and Qing Huan3 H% X- o9 B4 G1 g2 h& i! X- o6 k
Laboratory of Physical Biology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, People's Republic of China+ g+ |  [+ d2 J: i9 d& j- W

* e" t. B/ f, X- RABSTRACT Graphene is a single layer of sp2-bonded carbons that has unique and highly attractive electronic, mechanical, and thermal properties. Consequently, the potential impact of graphene and its derivatives (e.g., graphene oxide, GO) on human and environmental health has raised considerable concerns. In this study, we have carried out a systematic investigation on cellular effects of GO anosheets and identified the effect of fetal bovine serum (FBS), an often-employed component in cell culture medium, on the cytotoxicity of GO. At low concentrations of FBS (1%), human cells were sensitive to the presence of GO and showed concentration-dependent cytotoxicity. Interestingly, the cytotoxicity of GO was greatly mitigated at 10% FBS, the concentration usually employed in cell medium. Our studies have demonstrated that the cytotoxicity of GO nanosheets arises from direct interactions between the cell membrane and GO nanosheets that result in physical damage to the cell membrane. This effect is largely attenuated when GO is incubated with FBS due to the extremely high protein adsorption ability of GO. The observation of this FBS-mitigated GO cytotoxicity effect may provide an alternative and convenient route to engineer nanomaterials for safe biomedical and environmental applications.

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# n+ X  K! p- b  ]2 A' v% R* F石墨烯带来单个DNA分子测序革命) p5 x- A  e4 z+ F: S

, O' g' t& Y5 b( @0 oGraphene could revolutionize DNA sequencing6 m! M: @( q0 @* S
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DNA单链穿越石墨烯小孔
" V( m8 I, o6 IPassing through a gap in the wonder material0 O2 p5 L: _( \+ P
By feeding individual strands of DNA through nanometre-sized holes, researchers in the Netherlands say they have proved the principle of a revolutionary new DNA sequencing technique. The breakthrough is part of a worldwide race to develop fast and low-cost strategies to analyse these codes that underpin the chemistry of life.
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The genetic profile – or "genome" – of an organism is determined by recording the full sequence of acid base pairs that make up its DNA. In 2003, the Human Genome Project made history by determining the entire human genetic code – 3 billion DNA base pairs that took 13 years to analyse using a technique that has changed very little since the late 1970s. 0 j8 }, s  c) H+ O$ V; D
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This pioneering project used a "shotgun" approach, which first isolates a DNA strand and forces it to copy itself millions of times over in a chemical reaction. These strands are then "blasted" into tiny fragments because current techniques can only analyse very short sections of DNA. Finally, a supercomputer matches up overlapping base patterns to piece together the full genome.
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8 ~: T/ D: R+ _* P7 m; Y' _  yHowever, with the promise of personalized medicine, scientists are working to develop new technologies that could rapidly sequence an individual's genetic make-up. In addition to the human genome there are also slight variations in DNA sequences and processes that give people their phenotypes such as "blue eyes" or "blond hair". $ L& C6 }1 j& x. g( y  n% X
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In 2008, physicsworld.com reported one promising idea that involves passing DNA through tiny punctures in a sheet of graphene – an extremely strong sheet of carbon just one atom thick. A voltage is applied along the graphene surface as DNA strands are passed slowly through the slit one base at a time. The idea is that each of the four bases – A, C, G and T – will have a unique effect on the conductance of graphene across the gap.
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Now, Cees Dekker and his colleagues at the Kavli Institute of Nanoscience are the first team to demonstrate DNA motion through graphene, although their technique cannot yet read the genetic code.
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" q( Q( A3 N. D2 fThey create a series of pores ranging from 5 to 25 nm in diameter by placing flakes of graphene over a silicon nitride membrane and drilling nanosized holes in the graphene using an electron beam. By applying a voltage of 200 mV across the graphene membrane, a series of spikes are observed in an electric current that scales the gap. These, say the researchers, correspond to drops in conductance when DNA strands slide across the gap via a biochemical process known as translocation.
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& `/ R! \1 U6 @! W9 a' h0 p6 X6 \- p" sThe researchers intend to develop their research by identifying which spikes correspond to particular bases. Dekker told physicsworld.com that one area of science that could benefit in particular from ultrafast sequencing is epigenetics – that is, the study of changes in phenotypes that are not related to changes in underlying DNA sequences. " h. d+ s: x' H/ I" j: D

7 e' _- K) U6 F# V8 [: LHenk Postma, a researcher at California State University, Northridge, who is also developing nanopore sequencing, is excited by the result. "They have demonstrated that DNA does indeed go through little holes in graphene, and that it does so with great speed. Both of these are important advancements towards using graphene for DNA sequencing," he says.
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This research is published in Nano Letters.# G9 X. [0 W8 V3 I/ h6 s8 Z
About the author：James Dacey is a reporter for physicsworld.com
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石墨烯纸张可在常温直接杀菌7 h8 R6 b7 }5 Y1 j0 d/ U9 L

! O4 _  Q$ B6 J7 kGraphene Kills Bacteria
2 V0 [! h' {( `5 K7 L6 WGraphene could be used to make antibacterial paper, according to new work by researchers at the Chinese Academy of Sciences in Shanghai. The researchers have found that graphene derivatives, like graphene oxide and reduced graphene oxide, inhibit the growth of E. Coli bacteria. This is an important finding, because previous studies showed that graphene, and particularly graphene oxide, is biocompatible and that biological cells can grow well on graphene substrates. While other nanoparticles, like silver, are well known antibacterial materials, they are often cytotoxic.% ?2 b1 U* p* E, K3 \2 H
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Transmission electron microscopy showed that the cell membranes of E. Coli bacteria placed on the graphene sheets were severely destroyed. According to the researchers, this occurs because graphene enters the endosome of the cell’s cytoplasm, pushing it out of the cell. Almost 99% of the cells were destroyed after just two hours in contact with a 85 g/mL solution of graphene oxide at 37 °C. In contrast, the nanosheets were not toxic to mammalian cells under the same conditions.
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) z& g% K' e/ Q! {! qThe team is now further studying why and how graphene oxide is antibacterial. “Ultimately we wish to develop new antibacterial materials from graphene that could be directly applied onto skin to aid in wound healing,” says Chunhai Fan. “However, we are aware that it is still a challenge to mass produce graphene nanomaterials, and particularly to fabricate large-scale graphene paper.” $ [5 \' r6 r7 E( E
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5 R( j, C' @* z4 c石墨烯包裹帮助电子显微镜进行细菌真实大小成像
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* Z, s6 c3 r* x! U  SGraphene Cloak Protects Bacteria, Leading to Better Images* d- ^! \6 D) q+ u; c& N: W/ t
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ScienceDaily (Mar. 18, 2011) — It's a cloak that surpasses all others: a microscopic carbon cloak made of graphene that could change the way bacteria and other cells are imaged.
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Vikas Berry, assistant professor of chemical engineering at Kansas State University, and his research team are wrapping bacteria with graphene to address current challenges with imaging bacteria under electron microscopes. Berry's method creates a carbon cloak that protects the bacteria, allowing them to be imaged at their natural size and increasing the image's resolution.
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: _* Y% D$ G1 t0 `4 _! i/ bGraphene is a form of carbon that is only one atom thick, giving it several important properties: it's impermeable, it's the strongest nanomaterial, it's optically transparent and it has high thermal conductance.% t9 B9 M% m+ B
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"Graphene is the next-generation material," Berry said. "Although only an atom thick, graphene does not allow even the smallest of molecules to pass through. Furthermore, it's strong and highly flexible so it can conform to any shape.". V0 V: r( u: ?0 _7 A0 I

1 n+ B5 ~9 n9 ?% ?Berry's team has been researching graphene for three years, and Berry recently saw a connection between graphene and cell imaging research. Because graphene is impermeable, he decided to use the material to preserve the size of bacterial cells imaged under high-vacuum electron microscopes.
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: E1 i, B& w  x& J# ]The research results appear in the paper "Impermeable Graphenic Encasement of Bacteria," which was published in a recent issue of Nano Letters, a monthly scientific journal published by the American Chemical Society. The team's preliminary research appeared in Nature News in 2010./ E" M) g3 l; F( e. Y4 V

9 ^( L( O6 c' o0 g. OThe current challenge with cell imaging occurs when scientists use electron microscopes to image bacterial cells. Because these microscopes require a high vacuum, they remove water from the cells. Biological cells contain 70 to 80 percent water, and the result is a severely shrunk cell. As a result, it is challenging to obtain an accurate image of the cells and their components in their natural state.
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) J8 }6 P9 K. l$ L  v) k5 uBut Berry and his team created a solution to the imaging challenge by applying graphene. The graphene acts as an impermeable cloak around the bacteria so that the cells retain water and don't shrink under the high vacuum of electron microscopes. This provides a microscopic image of the cell at its natural size.2 _% H; {: j# [( D
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The carbon cloaks can be wrapped around the bacteria using two methods. The first method involves putting a sheet of graphene on top of the bacteria, much like covering up with a bed sheet. The other method involves wrapping the bacteria with a graphene solution, where the graphene sheets swaddle the bacteria. In both cases the graphene sheets were functionalized with a protein to enhance binding with the bacterial cell wall.6 A5 s! T& a! }0 s& x% J, ~$ Z

; i8 H$ Y* ]$ C/ u7 L& HUnder the high vacuum of an electron microscope, the wrapped bacteria did not change in size for 30 minutes, giving scientists enough time to observe them. This is a direct result of the high strength and impermeability of the graphene cloak, Berry said.
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2 E- I! e& l9 s4 D2 j$ o: WGraphene's other extraordinary properties enhance the imaging resolution in microscopy. Its electron-transparency enables a clean imaging of the cells. Since graphene is a good conductor of heat and electricity, the local electronic-charging and heating is conducted off the graphene cloak, giving a clear view of the bacterial cell well. Unwrapped bacterial cells appear dark with an indistinguishable cell wall.
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"Uniquely, graphene has all the properties needed to image bacteria at high resolutions," Berry said. "The project provides a very simple route to image samples in their native wet state."" I5 w7 R2 }) d8 e4 c3 |- i

, m  z0 @9 i$ a( e+ SThe process has potential to influence future research. Scientists have always had trouble observing liquid samples under electron microscopes, but using carbon cloaks could allow them to image wet samples in a vacuum. Graphene's strong and impermeable characteristics ensure that wrapped cells can be easily imaged without degrading them. Berry said it might be possible in the future to use graphene to keep bacterium alive in a vacuum while observing its biochemistry under a microscope." J6 o& F6 f5 v7 {1 p/ M$ l
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The research also paves the way for enhanced protein microscopy. Proteins act differently when they are dry and when they are in an aqueous solution. So far most protein studies have been conducted in dry phases, but Berry's research may allow proteins to be observed more in aqueous environments.( y5 `4 N2 b7 ^, @

" S. s' W4 u+ N: ~' q/ `"This research could be the point of evolution for processing of sensitive samples with graphene to achieve enhanced imaging," Berry said.
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Other researchers involved in the project include Daniel Boyle, research assistant professor in biology; Nihar Mohanty, doctoral student in chemical engineering, India; Ashvin Nagaraja, former master's student in electrical engineering; and Monica Fahrenholtz, a May 2010 chemical engineering graduate from Clearwater.* K( o0 C9 }$ l3 Y5 G
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细菌呼吸作用将石墨烯氧化物还原
( E* x5 z9 u8 K4 aReduction of Graphene Oxide via Bacterial Respiration
) O" h: u& A8 t4 B+ ]: F. CEverett C. Salas†, Zhengzong Sun‡, Andreas L
! R! X% e) \; d0 jACS Nano, 2010, 4 (8), pp 4852–4856  DOI: 10.1021/nn101081t    Publication Date (Web): July 21, 20100 Q; ]& }3 F( _9 Y  o
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Here we present that graphene oxide (GO) can act as a terminal electron acceptor for heterotrophic, metal-reducing, and environmental bacteria. The conductance and physical characteristics of bacterially converted graphene (BCG) are comparable to other forms of chemically converted graphene (CCG). Electron transfer to GO is mediated by cytochromes MtrA, MtrB, and MtrC/OmcA, while mutants lacking CymA, another cytochrome associated with extracellular electron transfer, retain the ability to reduce GO. Our results demonstrate that biodegradation of GO can occur under ambient conditions and at rapid time scales. The capacity of microbes to degrade GO, restoring it to the naturally occurring ubiquitous graphite mineral form, presents a positive prospect for its bioremediation. This capability also provides an opportunity for further investigation into the application of environmental bacteria in the area of green nanochemistries.
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石墨烯生物传感器用于疾病诊断1 g% l7 S+ c/ c# \
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A flash of light turns graphene into a biosensor5 W! D# v9 N) ]6 s
Disease diagnosis, toxin detection and more are possible with DNA-graphene nanostructure# |' a5 U: V; v
Biomedical researchers suspect graphene, a novel nanomaterial made of sheets of single carbon atoms, would be useful in a variety of applications. But no one had studied the interaction between graphene and DNA, the building block of all living things. To learn more, PNNL's Zhiwen Tang, Yuehe Lin and colleagues from both PNNL and Princeton University built nanostructures of graphene and DNA. They attached a fluorescent molecule to the DNA to track the interaction. Tests showed that the fluorescence dimmed significantly when single-stranded DNA rested on graphene, but that double-stranded DNA only darkened slightly – an indication that single-stranded DNA had a stronger interaction with graphene than its double-stranded cousin. The researchers then examined whether they could take advantage of the difference in fluorescence and binding. When they added complementary DNA to single-stranded DNA-graphene structures, they found the fluorescence glowed anew. This suggested the two DNAs intertwined and left the graphene surface as a new molecule.
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DNA's ability to turns its fluorescent light switch on and off when near graphene could be used to create a biosensor, the researchers propose. Possible applications for a DNA-graphene biosensor include diagnosing diseases like cancer, detecting toxins in tainted food and detecting pathogens from biological weapons. Other tests also revealed that single-stranded DNA attached to graphene was less prone to being broken down by enzymes, which makes graphene-DNA structures especially stable. This could lead to drug delivery for gene therapy. Tang will discuss this research and some of its possible applications in medicine, food safety and biodefense.
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' ?" m' |6 g9 ~8 K& s" j. ZReference: Zhiwen Tang, Biofunctionalization of Graphene for Biosensing and Imaging, Tuesday, September 22, 3:30 – 5:30 p.m. in Ross Island/Morrison at the Doubletree Lloyd Center, Portland, Ore.
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石墨烯形成心肌轴突用于细胞电生理信号的高灵敏度、非侵入式检测* b- G$ U8 Z) m1 ^  g/ l. u

$ \1 x' w; n$ g- z% R$ O/ BGraphene and Nanowire Transistors for Cellular Interfaces and Electrical Recording7 |6 X+ I1 x8 Q6 g7 k( S
AbstractFull Text HTMLHi-Res PDF[2442 KB]PDF w/ Links[315 KB]Supporting InfoFiguresCiting ArticlesTzahi Cohen-Karni†, Quan Qing‡, Qiang Li§, Ying Fang*§ and Charles M. Lieber*†‡ ! m, K  q. y$ j* y! V3 I
Nano Lett., 2010, 10 (3), pp 1098–1102
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9 ^- v4 j$ J- ENanowire field-effect transistors (NW-FETs) have been shown to be powerful building blocks for nanoscale bioelectronic interfaces with cells and tissue due to their excellent sensitivity and their capability to form strongly coupled interfaces with cell membranes. Graphene has also been shown to be an attractive building block for nanoscale electronic devices, although little is known about its interfaces with cells and tissue. Here we report the first studies of graphene field effect transistors (Gra-FETs) as well as combined Gra- and NW-FETs interfaced to electrogenic cells. Gra-FET conductance signals recorded from spontaneously beating embryonic chicken cardiomyocytes yield well-defined extracellular signals with signal-to-noise ratio routinely >4. The conductance signal amplitude was tuned by varying the Gra-FET working region through changes in water gate potential, Vwg. Signals recorded from cardiomyocytes for different Vwg result in constant calibrated extracellular voltage, indicating a robust graphene/cell interface. Significantly, variations in Vwg across the Dirac point demonstrate the expected signal polarity flip, thus allowing, for the first time, both n- and p-type recording to be achieved from the same Gra-FET simply by offsetting Vwg. In addition, comparisons of peak-to-peak recorded signal widths made as a function of Gra-FET device sizes and versus NW-FETs allowed an assessment of relative resolution in extracellular recording. Specifically, peak-to-peak widths increased with the area of Gra-FET devices, indicating an averaged signal from different points across the outer membrane of the beating cells. One-dimensional silicon NW- FETs incorporated side by side with the two-dimensional Gra-FET devices further highlighted limits in both temporal resolution and multiplexed measurements from the same cell for the different types of devices. The distinct and complementary capabilities of Gra- and NW-FETs could open up unique opportunities in the field of bioelectronics in the future.
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