ANALYSIS OF MATERIAL MECHANICAL PROPERTIES FOR SINGLE-WALLED CARBON NANOTUBES

Abstract The carbon-carbon bond between two nearest-neighboring atoms is mod- eled as a beam and the single-walled carbon nanotubes are treated as the space frame structures in order to analyze the mechanical properties of carbon nanotubes. Based on the theory of Tersof- Brenner force feld, the energy relationships between the carbon-carbon bond and the beam model are obtained, and the stifness parameters of the beam are determined. By applying the present model, the Young’s moduli of the single-walled carbon nanotubes with diferent tube diameters are determined. And the present results are compared with available data.

Effect of Single-walled Carbon Nanotubes on Cellulose Phenylcarbamate Chiral Stationary Phases

Single-walled carbon nanotubes（SWNTs） have a high adsorption ability and nanoscale interactions. Cellulose trisphenylcarbamates possess high enantioseparation ability in high-performance liquid chromatography（HPLC）. Single-walled carbon nanotubes mixed with cellulose trisphenylcarbamate are coated on the silica gel as chiral stationary phases and higher enantioseparation factors are obtained. After a single-walled carbon nanotube is linked to the 6-pesition of cellulose 2,3-bisphenylcarbamate, its enantioseparation resolution increases compared to that of the cellulose trisphenylcarbamate. It is the first time that SWNTs have been applied to enantioseparation. The results indicate that the single-walled carbon nanotubes are good promoters of chiral recognition. This method can be used to improve the enantioseparation efficiency of the polysaccharide chiral stationary phases.

Purification of Single-walled Carbon Nanotubes Grown by a Chemical Vapour Deposition(CVD) Method

A procedure for purification of single walled carbon nanotubes(SWNTs) grown by the chemical vapour deposition(CVD) of carbon monooxide has been developed. Based on the result from TGA/DTA of as prepared sample, the oxidation temperature was determined. The process included sonication, oxidation and acid washing steps. The purity and yield after purification were determined and estimated by TEM. Moreover, for the first time, a loop structure for CVD SWNTs has been observed.

Effect of a Nerve Graft Substitute Single-walled Carbon Nanotubes on Rat Pheochromocytoma Cells

Carbon nanotubes （CNTs） were extensively explored for their beneficial use in nervous system tissue engineering. However, an important concern regarding the use of CNTs is their toxicity during the interaction between cells and the nano particles. The rat pheochromocytoma cell line （PC12） was co-cultured with three types of single-walled carbon nanotubes （SWNTs）, purified raw SWNTs （C）, hydroxyl purified SWNTs （C-OH） and carboxyl purified SWNTs （C-COOH） at 25 μg/mL and 100 μg/ml. The experimental results revealed that SWNTs at the concentration below 100 μg/mL did not affect the cell viability. Notably, powerful antioxidant system in nerous system tissue is able to counteract with the toxicity of CNTs, which is characterized by the prominently enhanced expression of main antioxidant enzymes （catalase （CAT）, superoxide dismutase （SOD）, glutathione peroxidase （GPx） and glutathione-S-transferase （GST））. Therefore, we believe that CNTs can be good candidates for the fabrication of biomedical scaffolds for the nerve tissue repair.

Splitting Phenomenon Induced by Magnetic Field in Metallic Carbon Nanotubes

In the framework of the tight-binding model, the excitons states and linear absorption spectra are calculated in the metallic single-walled carbon nanotubes, with the axial magnetic field applied. From our calculations, it is found that for the Mll and M22 transitions, the exeiton states are split into four separate column states by the applied magnetic field due to the symmetry breaking. More interesting is that the splitting can be directly reflected from the linear absorption spectra~ which are dominated by four main absorption peaks. In addition, the splitting with increasing the axial magnetic field is also calculated, which increases linearly with the applied magnetic field. The obtained results are expected to be detected by the future experiments.

Electronic Detection of Escherichia coli O157︰H7 Using Single-Walled Carbon Nanotubes Field-Effect Transistor Biosensor

Field effect transistors (FET) based on Single-Walled Carbon Nanotubes (SWNTs) become the hot topic in fields of nano-electronic, clinical diagnostics, environmental testing etc. in recent years. In this paper, we reported a simple, scalable way to enrich semiconducting SWNTs by using HNO3/H2SO4. Then carbon nanotube field-effect transistors (CNTFET) biosensor was fabricated with the enrichment SWNTs for Escherichia coli O157︰H7 detection. The response of each CNTFET was monitored in real time before and after introduction of the Escherichia coli O157︰H7 at various concentrations. The results show that CNT-FET biosensors we fabricated are sensitive to change of concentration of solution and response time is really short.

一种基于SWNTs/Nafion/CuNPs纳米复合材料的经济易制备型非酶尿酸传感器

通过电沉积金属铜于SWNTs/Nafion修饰的玻碳电极表面构建了一种经济且简单易制备的非酶尿酸传感器。采用扫描电镜和能谱仪表征了纳米材料的形貌和成分,并考察了不同扫速和p H值对修饰电极的影响。在优化条件下,尿酸的线性范围为0.1～1 000μmol·L-1,检出限（S/N=3）为0.058 5μmol·L-1。采用标准加入法检测人体血清中尿酸的回收率为97.2%～103.9%,相对标准偏差（RSD）为0.04%～0.11%。该非酶法与GOD-POD酶法的结果高度一致,且传感器经济易制备、灵敏性高、稳定性好、重现性高。

豆荚型纳米材料C_(60)@SWNTs的制备和表征

通过气相扩散的方法将C60填入单壁碳纳米管(SWNTs),制备了豆荚型纳米材料C60@SWNTs,并利用高分辨电子显微镜(HPREM)和拉曼光谱(Raman spectra)对其进行了表征.结果均证明C60以较高的比例填充入单壁碳纳米管中.HRTEM结果表明,填入单壁碳纳米管的C60之间的距离与面心立方C60晶体中C60之间的距离有细微的差别,说明C60分子与SWNTs间存在弱的范德华相互作用.此外,还观察到在电子束的照射下,C60在SWNT中两两聚合的现象.

Dielectrophoretic assembly of semiconducting single-walled carbon nanotube transistor

A novel burning technique for making a semiconducting single-walled carbon nanotubes （SWNTs） transistor assembled by the dielectrophoretic force was suggested. The fabrication process consisted of two steps. First, to align and attach a bundle of SWNTs between the source and drain, the alternating （AC） voltage was applied to the electrodes. When a bundle of SWNTs was connected between two electrodes, some of metallic nanotubes and semi-conducing nanotubes existed together. The second step is to burn the metallic SWNTS by applying the voltage between two electrodes. With increasing the voltage, more current flowed through the metallic SWNTs, thus, the metallic SWNTs burnt earlier than the semiconducting one. This technique enables to obtain only semi-conducting SWNTs connection in the transistor. Through the 1--V characteristic graph, the moment of metallic SWNTs burning and the characteristic of semi-conducing nanotubes were verified.

Carbon Nanotube Based Chemical Sensors

Carbon nanotubes CNTs)have been receiving enormous attention in the last decade due to their extraordinary mechanical properties and unique elec- tronic properties.This combination has produced an unprecedented range of applications for CNTs:elec- tronic,logic and memory chips,chemical and biosen- sots,composites,lithium batteries,gas storage,filters and membranes,etc.This presentation will focus on carbon nanotube based sensors and discuss fabrication, testing and performance.

PBO/SWNT复合纤维的合成与性能

利用原位聚合法成功制备了聚对苯撑苯并双噁唑(PBO)/单壁碳纳米管(SWNT)复合物,并用干喷湿纺法对聚合物进行了纺制。SWNT采用强氧化性酸处理,形成羧基化的单壁碳纳米管(SWNT-COOH)。用拉曼光谱(Ram an)、X射线光电子能谱(XPS)、强度测定、热重分析等分别对SWNT、PBO/SWNT复合纤维进行了表征。研究表明,碳纳米管经过酸处理后,表面含有较多的羟基和羧基官能团。PBO/SWNT复合纤维保持了PBO纤维的优异耐高温性能,纤维拉伸强度与同条件下PBO纤维相比提高了50%。

SWNT随机网络TFT输出特性的仿真及实验验证

为了准确表征单壁碳纳米管(SWNT)随机网络薄膜晶体管(TFT)的输出特性,采用蒙特卡罗方法实现对沟道区域SWNT随机分布情况的仿真,并且通过在弹道输运模型中引入与栅压相关的拟合参数α(Vg)拟合碳管间、碳管与金属电极间接触的影响,最终获得SWNT随机网络TFT输出特性的仿真结果。实验中,以溶液浸泡法制备SWNT薄膜作为TFT沟道材料,以与传统工艺兼容的淀积、刻蚀等步骤制备了TFT,并进行了器件输出特性的测试。实验验证表明,沟道宽度为50μm、长度为10μm TFT的输出特性测试数据与仿真拟合的误差仅为5.6%。此仿真方法能较准确地描写SWNT随机网络TFT的输出特性,通过对蒙特卡罗仿真参数的调整,能预测薄膜晶体管跨导随几何尺寸的变化。

利用单壁碳纳米管介导植物瞬时遗传转化的研究

为验证单壁碳纳米管(SWNT)介导的新型的植物遗传转化方法的有效性,利用羧基化的单壁碳纳米管(COOH-SWNT)为原材料,构建了聚乙烯亚胺(PEI)修饰的羧基化单壁碳纳米管复合物(PEI-SWNT),探索验证PEI-SWNT复合物对外源基因的结合比例以及保护作用,使用PEI-SWNT复合物将RED以及UBQ10-EGFP等荧光质粒转化到油菜的原生质体和烟草叶片中。结果表明,PEI-SWNT纳米材料成功与外源目的基因结合,并对外源目的基因进行保护,使其免于核酸酶的降解,PEI-SWNT携带目的基因进入受体细胞后,可以成功地在受体细胞内进行基因表达。

Wafer Scale Synthesis of Dense Aligned Arrays of Single-Walled Carbon Nanotubes

Here we present an easy one-step approach to pattern uniform catalyst lines for the growth of dense,aligned parallel arrays of single-walled carbon nanotubes(SWNTs)on quartz wafers by using photolithography or polydimethylsiloxane(PDMS)stamp microcontact printing(μCP).By directly doping an FeCl3/methanol solution into Shipley 1827 photoresist or polyvinylpyrrolidone(PVP),various catalyst lines can be well-patterned on a wafer scale.In addition,during the chemical vapor deposition(CVD)growth of SWNTs the polymer layers play a very important role in the formation of mono-dispersed nanoparticles.This universal and effi cient method for the patterning growth of SWNTs arrays on a surface is compatible with the micro-electronics industry,thus enabling of the fabrication highly integrated circuits of SWNTs.

Synthesis of single-walled carbon nanotubes by the vertical floating catalyst method

The vertical floating catalyst method is first used to produce single-walled carbon nanotubes (SWNTs) continuously on a large scale by a newly developed technique and pyrolysis of n-hexane. Diameter distributions, micro-structure and purity of the SWNTs film, rope and web are measured by Raman spectroscopy and electron microscope. The results show that SWNTs product has a high degree of orientation, a wide distribution of diameters (0.7-2.0 nm) and high purity of 】 80 %.

Recent progresses on the new condensed forms of single-walled carbon nanotubes and energy-harvesting devices

We demonstrate an effective method to prepare a new condensed form of single-walled carbon nanotubes(crystal of SWNTs) using a series of diamond wire drawing dies.X-ray diffraction indicates that the SWNTs form a two-dimensional triangular lattice with a lattice constant of 19.62 ?.An intertube spacing of 3.39 ? of between adjacent SWNTs results in a sharp(002) reflection in the X-ray diffraction pattern.Meanwhile,we developed an approach based on the Coulomb explosion to separate SWNTs from their bundle.The separated SWNTs have a typical length of several microns and form a nanotree at one end of the original bundle.The separation is convenient and involves no surfactant.In studying devices comprising SWNTs,we find that a four-probe technique can be employed to study the filling of and flow within the inner channel of an individual SWNT.Current/voltage can drive water molecules to have directional flow along an SWNT,and the flowing of water inside an SWNT can induce a voltage gradient force(an induced electromotive force) along the SWNT.This energy conversion is realized by the mutual coupling of water dipoles and charge carriers present in SWNTs.The results suggest that SWNTs can be exploited as molecular channels for water and may find potential application in nanoscale energy conversion.Moreover,a surface-energy generator comprising SWNTs was demonstrated to harvest the surface energy of ethanol.The performance(the induction rate for Voc,the value of Voc and the output power) can be significantly enhanced by the Marangoni effect.

Demonstration of Covalent Sidewall Functionalization of Single Wall Carbon Nanotubes by NMR Spectroscopy:Side Chain Length Dependence on the Observation of the Sidewall sp^(3)Carbons

Carboxylic acid-functionalized single walled carbon nanotubes(SWNTs)prepared via the reaction of an amino acid,NH2(CH2)nCO2H where n=1(glycine,GLY),5(6-aminohexanoic acid,AHA),10(11-aminoundecanoic acid,AUDA),with fl uorinated single walled carbon nanotubes(F-SWNTs)have been characterized by MAS 13C NMR spectroscopy.The ease of observing the aliphatic CH2 groups and the resolution of the signal are dependent on the length of the amino acid’s aliphatic chain.We have proposed that where substituent chains are short(making NMR data collection difficult)chemical modification to extend the chain length should alleviate analysis problems.In this regard,we have investigated the esterifi cation of the carboxylic acid termini.The amino acid-functionalized SWNTs were esterified with an appropriate alcohol to ensure parity of the overall substituent length,i.e.,GLY-SWNT(C1)+1-dodecanol(C_(12))=DOD-GLY-SWNT(1),AHA-SWNT(C_(5))+1-octanol(C_(8))=OCT-AHA-SWNT(2),and AUDA-SWNT(C_(10))+1-propanol(C_(3))=PRO-AUDA-SWNT(3).The 13C NMR shift for the sp3 nitrogen-substituted carbon atoms of the SWNT sidewall is observed atδ≈75 ppm.Increasing the length of SWNT sidewall functional groups enhances the ability to observe the sidewall sp^(3)carbon.The methylene carbon signal intensity is less attenuated in the dipolar dephasing spectrum of the ester-functionalized SWNTs than their associated amino acid derivatives,suggesting more motional freedom of the side chain in the solid state.The confi rmation of the dipolar dephasing spectral effects was assisted by the characterization of the ester of AUDA-SWNT with 1,3-propanediol:PPD-AUDA-SWNT(4).

Effects of Gamma Irradiation for Sterilization on Aqueous Dispersions of Length Sorted Carbon Nanotubes

There is currently great interest in the potential use of carbon nanotubes as delivery vessels for nanotherapeutics and other medical applications. However, no data are available on the effects of sterilization methods on the properties of nanotube dispersions, the form in which most medical applications will be processed. Here we show the effects of gamma irradiation from a 60Co source on the dispersion and optical properties of single-wall carbon nanotubes in aqueous dispersion. Samples of different length-refined populations were sealed in ampoules and exposed to a dose of approximately 28 kGy, a level sufficient to ensure sterility of the dispersions. In contrast to literature results for solid-phase nanotube samples, the effects of gamma irradiation on the dispersion and optical properties of the nanotube samples were found to be minimal. Based on these results, gamma irradiation appears sufficiently non-destructive to be industrially useful for the sterilization of nanotube dispersions.

Carbon Nanotubes Inhibit the Hemolytic Activity of the Pore-Forming Toxin Pyolysin

Functionalized carbon nanotubes have already demonstrated great biocompatibility and potential for drug delivery.We have synthesized acid oxidized and non-covalently PEGlyated single-walled carbon nanotubes(SWNTs),which were previously prepared for drug delivery purposes,and explored their potential for detoxification in the bloodstream.Our investigations of the binding of SWNTs to a pore-forming toxin pyolysin show that SWNTs prevented toxin-induced pore formation in the cell membrane of human red blood cells.Quantitative hemolysis assay and scanning electron microscopy were used to evaluate the inhibition of hemolytic activity of pyolysin.According to Raman spectroscopy data,human red blood cells,unlike HeLa cells,did not internalize oxidized SWNTs.Molecular modeling and circular dichroism measurements were used to predict the 3-D structure of pyolysin(domain 4)and its interaction with SWNTs.The tryptophan-rich hydrophobic motif in the membrane-binding domain of pyolysin,a common construct in a large family of cholesterol-dependent cytolysins,shows high affinity for SWNTs.

Local modulation of exc辻ons and trions in monolayer WS2 by carbon nanotubes

Mixed dimensional van der Waals(VdW)heterostructures constructed by one-dimensional(1D)and two-dimensional(2D)materials exhibit extra degree of freedom to modulate the electronic and optical properties due to the combination of difterent dimensionalities.The charge transfer at the intertace between 1D and 2D materials plays a crucial role in the optoelectronic properties and performance of the heterostructure-based devices.Here,we stacked single-walled carbon nanotubes(SWNTs)on monolayer WS2 for a mixed dimensional vdW heterostructure,and investigated the local modulation of excitions and trions in WS2 by SWNTs.Different directions of charge transfer between SWNTs and WSz are evidenced by the photoluminescence(PL)spectra of WS2.The PL intensity can be either enhanced or weakened by individual SWNTs.In our work,the PL intensity of WS2 is enhanced and the exciton peak position heterostructure is red-shifted about 3 meV due to the charge transfer from WS2 to an individual SWNT(SWNT#1).The change of PL by another SWNT(SWNT#2)can not be well-resolved in far fild,but scanning near field optical microscope(SNOM)measurements show that the PL intensity of WS2 is weakened by the SWNT.The peak position of exciton is blue-shifted by^1 meV while that of trion is redshifted by^1 meV due to the charge transfer from the SWNT to WS2,These results give insight into the charge transfer at the interface of SWNTWS2 heterostructure,and can be useful for design of optoelectronic devices based on mixed dimensional vdW heterostructures.