Functionalization of carbon nanotubes with bovine serum albumin in homogeneous aqueous solution

Single-walled (SWNTs) and multiple-walled (MWNTs) carbon nanotubes were solubilized via the esterification of nanotube-bound carboxylic acids by oligomeric polyethylene glycol compounds. The water-soluble samples were used as starting materials in reactions with bovine serum albumin (BSA) protein in ambient aqueous solutions. The reaction conditions were designed for thermodynamically favorable transformation from ester to amide linkages, yielding SWNT-BSA and MWNT-BSA conjugates. The results show that the use of soluble starting nanotube materials in an indirect functionalization method represents a valuable approach to the biomodification of carbon nanotubes.     

水相合成 CdS纳米晶标记牛血清白蛋白

利用水相中直接合成的CdS纳米晶，与牛血清白蛋白(BSA)进行偶连标记。通过分子筛层析对标记后的牛血清白蛋白进行纯化，在紫外灯下即可观察到标记蛋白的荧光。对CdS纳米晶标记后的牛血清白蛋白的荧光光谱的研究表明，标记蛋白后的CdS纳米晶其荧光无明显淬灭。     

Carbon nanotubes induce malignant transformation and tumorigenesis of human lung epithelial cells

Carcinogenicity of carbon nanotubes is a major concern but has not been well addressed due to the lack of experimental models. Here, we show that chronic exposure to single-walled carbon nanotubes causes malignant transformation of human lung epithelial cells. The transformed cells induce tumorigenesis in mice and exhibit an apoptosis resistant phenotype characteristic of cancer cells. This study provides new evidence for carbon nanotube-induced carcinogenesis and indicates the potential role of p53 in the process.     

Carbon nanotubes in the liquid phase: addressing the issue of dispersion

The inherent size and hollow geometry with extraordinary electronic and optical properties make carbon nanotubes (CNTs) promising building blocks for molecular or nanoscale devices. Unfortunately, their hydrophobic nature and their existence in the form of agglomerated and parallel bundles make this interesting material inadequately soluble or dispersible in most of the common solvents, which is crucial to their processing. Therefore, various ingenious techniques have been reported to disperse the CNTs in various solvents with different experimental conditions. However, by analyzing the published scientific research articles, it is evident that there is an important issue or misunderstanding between the term "dispersion" and "solubilization". As a result many researchers use the terms interchangeably, particularly when stating the interaction of CNTs with liquids, which causes confusion among the readers, students, and researchers. In this article, this fundamental issue is addressed in order to give basic insight to the researchers who are working with CNTs, as well as to the scientists who deal with nano-related research domains.     

Carbon nanotubes and diamond-like carbon films produced by cathodic micro-arc discharge in aqueous solutions

This letter reports the synthesis of carbon nanotubes and diamond-like carbon films using cathodic micro-arc discharge in aqueous solutions. The conditions and mechanisms for the growth of these structures were briefly discussed based on the experimental observations.     

Adsorption characteristics of bovine serum albumin onto alumina with a specific crystalline structure

Bone cement containing alumina particles with a specific crystalline structure exhibits the ability to bond with bone. These particles (AL-P) are mainly composed of delta-type alumina (δ-Al₂O₃). It is likely that some of the proteins present in the body environment are adsorbed onto the cement and influence the expression of its bioactivity. However, the effect that this adsorption of proteins has on the bone-bonding mechanism of bone cement has not yet been elucidated. In this study, we investigated the characteristics of the adsorption of bovine serum albumin (BSA) onto AL-P and compared them with those of its adsorption onto hydroxyapatite (HA), which also exhibits bone-bonding ability, as well as with those of adsorption onto alpha-type alumina (α-Al₂O₃), which does not bond with bone. The adsorption characteristics of BSA onto AL-P were very different from those onto α-Al₂O₃ but quite similar to those onto HA. It is speculated that BSA is adsorbed onto AL-P and HA by interionic interactions, while it is adsorbed onto α-Al₂O₃ by electrostatic attraction. The results suggest that the specific adsorption of albumin onto implant materials might play a role in the expression of the bone-bonding abilities of the materials.     

Dimensional changes and phase transformation of TiO2 nanotubes heat-treated under oxygen-containing atmosphere

The purpose of this study was to investigate the dimensional changes and phase transition of nanotubular titanium oxide arrays after heat treatment under an oxygen-containing atmosphere. The thermodynamic background for the oxidation of titanium to titanium oxide was theoretically investigated as a function of the oxygen partial pressure. The anodized titanium nanotubes had lengths between 400 and 500 nm, thicknesses of 11 nm and an amorphous structure. The specimens heat-treated at higher oxygen partial pressures preferentially had rutile phase rather than anatase phase. The thickness of the TiO2 nanotubes was increased at a lower oxygen partial pressure.     

工业级原料制备碳纳米管的研究

为降低碳纳米管批量制备的原料成本,以焦化苯和二茂铁为主要原料(工业级),采用浮游催化热解法制备碳纳米管,用TEM、SEM、Raman、XRD等对产物的形貌和结构进行观察和表征,着重讨论了二茂铁的分解温度和苯的挥发温度对碳纳米管的制备及其形貌的影响,并对其影响机理进行了分析.研究表明:在噻吩体积分数为0.55 mL/100 mL苯、炉膛反应温度为1170℃的前提下,当二茂铁的分解温度为150℃、苯的挥发温度为50℃时,用工业级原料完全可以制备出碳纳米管,此时,碳纳米管的内径分布在0.88~1.15 nm.     

Nitrogen beam bombardment induce polarity of carbon nanotubes

The multiwalled carbon nanotubes (MWCNTs) were prepared on SiO₂ substrates using chemical vapor deposition (CVD). N ion beam bombardment to MWCNTs was performed at different beam currents of 5–15 mA in an ion-beam-assisted deposition (IBAD) system. Scanning electron microscope (SEM) and Transmission electron microscope (TEM) proved no significant crack and surface morphological change for MWCNTs after N ion beam bombardment. X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrometry (FTIR), and Raman studies indicated that higher N ion beam current (15 mA) or N atomic concentration (8.6%) induced formation of polar N-containing functional groups of N–C and N–H bonds on the surfaces of MWCNTs. The content of N–C and N–H bonds increased with N ion beam current.     

Crystal structure and formation mechanism of the secondary phase in Heusler Ni-Mn-Sn-Co materials

In the present work,crystal structure and formation mechanism of the secondary phase in Heusler NiMn-Sn-Co materials were investigated using X-ray diffraction,scanning/transmission electron microscopy and selected-area electron diffraction techniques.Experimental results showed that the secondary phase presented in both Ni_(44.1)Mn_(35.1)Sn_(10.8)Co_(10) as-cast bulk alloy and melt-spun ribbon,possessing a face-centered cubic(fcc) Ni_(17)Sn_3-type structure.The secondary phase in the as-cast bulk alloy was resulted from a eutectic reaction after the formation of a primary dendritic β phase during cooling.However in the melt-spun rapidly solidified ribbon,the secondary phase was largely suppressed as nano-precipitates distributed along the grain boundaries,which was attributed to a divorced eutectic reaction.The secondary phase exhibited partial amorphous state due to high local cooling rate.     

碳纳米管及其研究进展

综述了碳纳米管的发展背景、制备及纯化方法、性能和应用 ,并对今后碳纳米管研究存在的问题作了分析和扼要的论述     

Temperature-dependent near-infrared spectra of bovine serum albumin in aqueous solutions: spectral analysis by principal component analysis and evolving factor analysis

Fourier transform near-infrared (FT-NIR) spectra have been measured for bovine serum albumin (BSA) in an aqueous solution (pH 6.8) with a concentration of 5.0 wt% over a temperature range of 45-85 degrees C. Not only conventional spectral analysis methods, such as second-derivative spectra and difference spectra, but also chemometrics, such as principal component analysis (PCA) and evolving factor analysis (EFA), have been employed to analyze the temperature-dependent NIR spectra in the 7500-5500 and 4900-4200 cm-1 regions of the BSA aqueous solution. Intensity changes of bands in the 7200-6600 cm-1 and 4650-4500 cm-1 regions in the difference spectra indicate variations of the hydration and secondary structure of BSA in the aqueous solution, respectively. The plot of a band intensity at 7080 cm-1 in the different spectra shows a clear turning point at 63 degrees C, revealing that a significant change in the hydration occurs at about 63 degrees C. The forward and backward eigenvalues (EVs) from EFA suggest that marked changes in the hydration and secondary structure of BSA take place in the temperature ranges of 61-65 degrees C and 59-63 degrees C, respectively. In addition, the temperature of 71 degrees C marked in the EFA plots may correspond to the onset temperature of increase in the intermolecular beta-sheet structure.     

Optimization of the mechanical properties of calcium phosphate/multi-walled carbon nanotubes/bovine serum albumin composites using response surface methodology

Response surface methodology (RSM) coupled with the central composite design (CCD) was used to optimize the mechanical properties of calcium phosphate cement/multi-walled carbon nanotubes/bovine serum albumin (CPC/MWCNTs/BSA) composites. In this study, CPC composites were reinforced by multi-walled carbon nanotubes (MWCNTs) and bovine serum albumin (BSA) in order to induce high mechanical properties in the CPC/MWCNTs/BSA system. The effect of various process parameters on the compressive strength of CPC/MWCNTs/BSA composites was studied using design of experiments (DOE). The process parameters studied were: wt.% of MWCNTs (0.2–0.5 wt.%), wt.% of BSA (5–15 wt.%) and type of MWCNTs (e.g. as-pristine MWCNT (MWCNT-AP), hydroxyl group functionalized MWCNT (MWCNT-OH) and carboxyl group functionalized MWCNT (MWCNT-COOH)). Based on the CCD, a quadratic model was obtained to correlate the process parameters to the compressive strength of CPC/MWCNTs/BSA composites. From the analysis of variance (ANOVA), the most significant factor affected on the experimental design response was identified. The predicted compressive strength after process optimization was found to agree well with the experimental value. The results revealed that at 0.5 wt.% of MWCNT-OH and 15 wt.% of BSA, the highest compressive strength of 14 MPa was obtained.     

形变引发碳纳米管膜电阻变化的研究

研究了碳纳米管膜形变诱导电阻的变化.所用的碳纳米管是用热灯丝化学气相沉积法合成的.实验表明碳纳米管膜具有显著的形变诱导电阻变化的特性.室温下碳纳米管膜电阻的增减与施加形变的方向有关,其电阻相对变化量的大小与形变量之间呈近似线性关系.同多壁管膜相比,单壁管膜的电阻变化强于多壁管膜,化学处理对该效应有明显的增强作用.电阻随形变变化的原因可能是能隙变化和管之间接触电阻变化所致.     

Carbon nanotube-induced structure and phase evolution in polymer-based nanocomposites crystallized at elevated pressures

The dispersion of small weight fraction of carbon nanotube (CNT) in Nylon 6,6 introduces a significant difference in the structure and phase evolution during crystallization at ambient and elevated pressures. In the nanocomposite, the γ-phase is promoted at low crystallization pressure of ～0.1–25 MPa and is in striking contrast to pure Nylon 6,6, where γ-phase is nucleated only at crystallization pressures exceeding ～50 MPa. The differences in the behavior of Nylon 6,6 and its nanocomposites is attributed to CNT–polymer interface driven nucleation, which is also responsible for significant reduction in spherulite size and increase in crystallinity. The nanoindentation behavior of the nanocomposite is assessed via nanoscale deformation experiments, which indicated that a significantly higher indentation-force is required for the Nylon 6,6–CNT nanocomposite as compared to Nylon 6,6 to produce a constant displacement. The observed significantly higher modulus and hardness is primarily CNT-induced effect. This observation is of particular relevance to functional devices because they are most likely to experience force in the nanonewton range, which can induce deformation at the micro- and/or nanometer scale.