Surface-enhanced Raman scattering from the individual metallic single-walled carbon nanotubes

A new experimental technique has been presented to investigate the surface-enhanced Raman scattering (SERS) on “individual and untouched” single-walled carbon nanotubes (SWNTs) deposited onto gold or silver film-covered substrate through a direct CVD method. It was found that the radial breathing mode for SERS shows a narrower linewidth than the normal Raman spectroscopy (NRS). Relative to NRS, the SERS spectra also revealed a preferable contribution to some metallic component of the G line. However no obvious difference for D and G′ between SERS and NRS has been revealed, which is different from the previous results on bulk SWNT samples.     

Folate‐Conjugated PEG on Single Walled Carbon Nanotubes for Targeting Delivery of Doxorubicin to Cancer Cells

A highly effective drug carrier is constructed by coating folic acid‐terminated poly(ethylene glycol) (PEG‐FA) on single walled carbon nanotubes (SWNTs) in a facile non‐covalent method. The anti‐cancer drug, doxorubicin (DOX), is further loaded on the surface of SWNTs at a very high loading efficiency, 149.3 ± 4.1%. The drug system (DOX/PEG‐FA/SWNTs) exhibits excellent stability under neutral pH conditions such as serum, but dramatically releases DOX at reduced pH typical of the tumour environment and intracellular lysosomes and endosomes. With the help of FA, DOX/PEG‐FA/SWNTs tend to selectively attach onto cancer cells and enter the lysosomes or endosomes by clathrin‐mediated endocytosis. This can greatly improve the pharmaceutical efficiency and reduce potential side effects.

     

Breakthrough in carbon nanotube growth: unique alloy nanocatalysts lead to the chirality specified tubes

<正>Since Dr.Iijima reported his observation of tubular carbon under transmission electron microscopy(TEM)in 1991,carbon nanotubes(CNTs)have attracted intensive attention.A single-walled CNT(SWNT)is a seamless cylinder formed by rolling a piece of graphene,the honeycombstructured sp2 carbon.This unique structure endows SWNTs     

聚(2-甲氧基-5-辛氧基)对苯乙炔/单壁碳纳米管复合材料的光物理性能研究

采用原位脱氯化氢缩合聚合法制备了聚(2-甲氧基-5-辛氧基)对苯乙炔/单壁碳纳米管(PMOCOPV/SWNTs)复合材料. 红外光谱和拉曼光谱证实了在SWNTs表面的包覆层为PMOCOPV. 高分辨透射电子显微镜观察发现, PMOCOPV/SWNTs复合材料直径为4~7 nm, 其中PMOCOPV包覆层厚度约为2~5 nm. 紫外-可见吸收光谱表明, 随着SWNTs含量的增加, PMOCOPV/SWNTs的吸收发生蓝移且强度提高. 荧光光谱研究表明, 随着SWNTs含量的增加, PMOCOPV/SWNTs的最大发射波长发生蓝移且强度减小, SWNTs与PMOCOPV之间形成了光致电子转移体系, 使π电子离域程度增加, 导致荧光量子效率降低. 根据E_g与入射光子能量hν的关系, 拟合了PMOCOPV/SWNTs薄膜的光学禁带宽度, 发现随着SWNTs含量的增加, E_g逐渐减小. 采用简并四波混频方法测试其三阶非线性极化率χ⁽³⁾, 结果表明, 随着SWNTs含量的增加, PMOCOPV/SWNTs复合体的非线性光学响应逐渐增强, 说明PMOCOPV与SWNTs之间形成了分子间光致电子转移体系, 产生了复杂的分子间π-π电子非线性运动.     

毛细管电泳电化学法检测过氧化氢

以金微盘电极和离子液体修饰单壁碳纳米管糊微盘电极分别作为毛细管电泳电化学检测器,试验了两种电极对过氧化氢的响应情况,将金微盘电极与毛细管电泳联用,对过氧化氢进行了定性和定量检测.探讨了分离电压、缓冲溶液pH值和工作电位等条件对H2O2检测的影响.实验结果表明,峰电流与H2O2浓度在1.0×10-6～1.0×10-5mo...     

Bare gold nanoparticles mediated surface-enhanced Raman spectroscopic determination and quantification of carboxylated single-walled carbon nanotubes

The paper proposes a simple and portable approach for the surface enhanced Raman scattering (SERS) spectroscopy in situ determination of carboxylated single walled carbon nanotubes (SWNTs) in river water samples. The method is based on the subsequent microfiltration of a bare gold nanoparticles solution and the water sample containing soluble carbon nanotubes by using a home-made filtration device with a small filtration diameter. An acetate cellulose membrane with a pore size of 0.2 μm first traps gold nanoparticles to form the SERS-active substrate and then concentrates the carbon nanotubes. The measured SERS intensity data were closely fit with a Langmuir isotherm. A portable Raman spectrometer was employed to measure SERS spectra, which enables in situ determination of SWNTs in river waters. The limit of detection was 10 μg L⁻¹. The precision, for a 10 mg L⁻¹ concentration of carbon nanotubes, is 1.19% intra-membrane and 10.5% inter-membrane.     

Ring formation mechanism of single-walled carbon nanotubes: Energy conservation between curvature elasticity and inter-tube adhesion

Rings of single-walled carbon nanotubes (SWNTs) exist widely during water evaporation from their dispersions at low concentration on such substrates as silica wafer. We examine the phenomenon in terms of energy conservation between the increased significant curvature energy and the inherent inter-tube van der Waals (vdW) attraction potentials. And thereby, the observed multi ring structures for coarse and long SWNT bundles have also gained detailed interpretation. We conclude that carbon nanotubes (CNTs) coil into rings by their own elastic mechanism. The formed rings with different width and diameters originate from appropriate sizes of SWNTs or the bundles. Specially, the associated elasticity may have prospective potentials to reveal other fascinating self-assembling phenomenon on CNTs, for instance, the known liquid crystallinity of them. Besides, we have also analyzed the external factors to the ring formation, both statistically and dynamically.     

锯齿型单壁碳纳米管能隙的第一性原理研究

本文采用基于广义梯度近似(GGA)的第一性原理方法,对锯齿型单壁碳纳米管(7,0)、(8,0)、(9,0)、(12,0)的能带结构和能隙进行理论计算.结果表明,各孤立管能隙值跟紧束缚(TB)近似所推出的结论有很大的出入,但跟实验观测结果比较接近.本文对引起这一差异的原因做了初步探讨.     

Speciation and detection of arsenic in aqueous samples: A review of recent progress in non-atomic spectrometric methods

Inorganic arsenic (As) displays extreme toxicity and is a class A human carcinogen. It is of interest to both analytical chemists and environmental scientists. Facile and sensitive determination of As and knowledge of the speciation of forms of As in aqueous samples are vitally important. Nearly every nation has relevant official regulations on permissible limits of drinking water As content. The size of the literature on As is therefore formidable. The heart of this review consists of two tables: one is a compilation of principal official documents and major review articles, including the toxicology and chemistry of As. This includes comprehensive official compendia on As speciation, sample treatment, recommended procedures for the determination of As in specific sample matrices with specific analytical instrument(s), procedures for multi-element (including As) speciation and analysis, and prior comprehensive reviews on arsenic analysis. The second table focuses on the recent literature (2005–2013, the coverage for 2013 is incomplete) on As measurement in aqueous matrices. Recent As speciation and analysis methods based on spectrometric and electrochemical methods, inductively coupled plasma-mass spectrometry, neutron activation analysis and biosensors are summarized. We have deliberately excluded atomic optical spectrometric techniques (atomic absorption, atomic fluorescence, inductively coupled plasma-optical emission spectrometry) not because they are not important (in fact the majority of arsenic determinations are possibly carried out by one of these techniques) but because these methods are sufficiently mature and little meaningful innovation has been made beyond what is in the officially prescribed compendia (which are included) and recent reviews are available.     

CVD法制备单壁碳纳米管的纯化与表征

针对CVD法合成的单壁碳纳米管的特点提出了较为有效的纯化方法，并对纯化后碳管的存在形式进行了表征.结果表明,CVD法制备的单壁碳纳米管中所含的载体和催化剂绝大部分可以通过盐酸除去.在表面活性剂溶液中超声分散碳纳米管,可以使管与无定形碳及石墨状碎片进行有效的剥离.空气加热氧化法和稀硝酸回流法可有效地去除碳杂质,稀硝酸回流可以在纯化的同时对管的末端及侧壁进行功能化.