Biogenic synthesis of biopolymer‐based Ag–Au bimetallic nanoparticle constructs and their anti‐proliferative assessment

This study reports an eco‐friendly‐based method for the preparation of biopolymer Ag–Au nanoparticles (NPs) by using gum kondagogu (GK; Cochlospermum gossypium), as both reducing and protecting agent. The formation of GK‐(Ag–Au) NPs was confirmed by UV‐absorption, fourier transformed infrared (FTIR), atomic force microscopy (AFM), scanning electron microscope (SEM) and transmission electron microscope (TEM). The GK‐(Ag–Au) NPs were of 1–12 nm in size. The anti‐proliferative activity of nanoparticle constructs was assessed by MTT assay, confocal microscopy, flow cytometry and quantitative real‐time polymerase chain reaction (PCR) techniques. Expression studies revealed up‐regulation of p53, caspase‐3, caspase‐9, peroxisome proliferator‐activated receptors (PPAR) PPARa and PPARb, genes and down‐regulation of Bcl‐2 and Bcl‐x(K) genes, in B16F10 cells treated with GK‐(Ag–Au) NPs confirming the anti‐proliferative properties of the nanoparticles.Inspec keywords: nanomedicine, transmission electron microscopy, genetics, cellular biophysics, molecular biophysics, enzymes, nanofabrication, gold, silver, scanning electron microscopy, nanoparticles, Fourier transform infrared spectra, atomic force microscopy, biomedical materialsOther keywords: size 1.0 nm to 12.0 nm, Ag‐Au, anti‐proliferative assessment, eco‐friendly‐based method, anti‐proliferative activity, anti‐proliferative properties, biopolymer‐based Ag–Au bimetallic nanoparticle, Cochlospermum gossypium, gum kondagogu, biopolymer preparation, biogenic synthesis, UV‐absorption, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, MTT assay, confocal microscopy, flow cytometry, caspase‐3, caspase‐9, peroxisome proliferator‐activated receptors, Bcl‐2 gene, Bcl‐x(K) gene, B16F10 cells     

Functionalization of carbon nanotubes with magnetic nanoparticles: general nonaqueous synthesis and magnetic properties

A novel approach has been developed to synthesize magnetic nanoparticle and carbon nanotube (CNT) core-shell nanostructures, such as CoO/CNTs and Mn(3)O(4)/CNTs, by the nonaqueous solvothermal treatment of metal carbonyl on CNT templates using hexane as the solvent. The morphological and structural characterizations indicate that numerous cubic CoO or tetragonal Mn(3)O(4) nanoparticles are deposited on the surfaces of the CNTs to form CNT-based core-shell nanostructures. It is revealed that the hydrophobic interaction between nanoparticles and CNTs in hexane plays the critical role for the formation of CNT-based core-shell nanostructures. A physical property measurement system (PPMS-9, Quantum Design) analysis indicates that the CoO/CNT core-shell nanostructures show weak ferromagnetic performance at 300?K due to the ferromagnetic Co clusters and the uncompensated surface spin states, while the Mn(3)O(4)/CNT core-shell nanostructures display ferromagnetic behavior at low temperature (34.5?K), which transforms into paramagnetic behavior with increasing temperature.     

Facile synthesis of porous hollow iron oxide nanoparticles supported on carbon nanotubes

Porous hollow iron oxide nanoparticles (PHNPs) supported on carbon nanotubes (CNTs) were facilely synthesized by etching Fe@Fe_xO_y/CNT with dilute nitric acid aqueous solution at ambient temperature without the assistance of any surfactants and ligands. The mean diameter of hollow iron oxide nanoparticles was about 17 nm, with a wall thickness of about 4 nm. The formation mechanism of PHNPs is discussed based on the characterization results from TEM, XRD and H₂-TPR. The combination of nanoscale Kirkendall effect and selective acid etching is proposed to be responsible for the formation of CNT supported PHNPs, through a transformation from core/void/shell structures to hollow nanoparticles.     

CVD synthesis of carbon nanotubes

Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.     

Preparation of highly oxidized nitrogen-doped carbon nanotubes

A method for the preparation of highly oxidized nitrogen-doped carbon nanotubes (N-CNTs) from KMnO(4) + H(2)SO(4) solution is described. The atomic ratio of C/O in oxidized N-CNTs is as low as 1.2. The x-ray photoelectron spectroscopy results show that about 75% of the carbon atoms are oxidized and bound to oxygen-containing functional groups. The oxidation reaction mainly occurs at the outer sidewalls, which destroys the graphene stack to an sp(3)-rich structure and helps to preserve the tubular structure of the inner N-CNTs. The oxidized N-CNTs show an energy gap of ~2.1 eV.     

Controllable synthesis and magnetic properties of Fe–Co alloy nanoparticles attached on carbon nanotubes

Fe–Co alloy nanoparticles with different size were attached on the carbon nanotubes through adjusting the ratio of the metal to carbon in the mixed solution of nitrate with Fe:Co = 1:1 (molar ratio) via wet chemistry. X-ray powder diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and energy-dispersive X-ray spectrometry (EDX) indicated that the Fe–Co alloy nanoparticles attached on the surface of carbon nanotubes has body-centered cubic (bcc) structure, with sizes in the range of 13–25 nm and in the shape of spheroids. Magnetization measurements indicated that both the coercivities and the saturation magnetizations altered with size changes of the Fe–Co alloy nanoparticles. The saturation magnetization decreases with decreasing the Fe–Co alloy nanoparticles’ sizes. A decrease in coercivity with increasing Fe–Co size together with a local maximum coercivity at size of ca. 15 nm is visible. A linear relationship between the inverse particle diameter and the coercivity was found for larger particles. These demonstrated that the chemical method here is promising for fabricating Fe–Co alloy nanoparticles coated on carbon nanotubes for magnetic storage applications.     

Large-scale synthesis of BN nanotubes using carbon nanotubes as template

Boron nitride nanotubes (BN-NTs) were synthesized in large scale by the reaction of NaBH₄ and NH₄Cl in the temperature range of 500-600 °C for 10-18 h, where carbon nanotubes (CNTs) were mixed together with the reactants to serve as template. Pure BN-NTs were obtained by oxidizing the product at about 800 °C in air atmosphere. The structure and morphology of the product with a surface area of 106.635 m²/g were characterized by X-ray diffraction, transmission electron microscopy, Fourier transformation infrared spectroscopy, and thermogravimetric analysis. Large scale preparation of BN-NTs could be realized by this simple and effective route.     

Iron oxide/gold nanoparticles‐decorated reduced graphene oxide nanohybrid as the thermo‐radiotherapy agent

The main focus of the current study is the fabrication of a multifunctional nanohybrid based on graphene oxide (GO)/iron oxide/gold nanoparticles (NPs) as the combinatorial cancer treatment agent. Gold and iron oxide NPs formed on the GONPs via the in situ synthesis approach. The characterisations showed that gold and iron oxide NPs formed onto the GO. Cell toxicity assessment revealed that the fabricated nanohybrid exhibited negligible toxicity against MCF‐7 cells in low doses (<50 ppm). Temperature measurement showed a time and dose‐dependent heat elevation under the interaction of the nanohybrid with the radio frequency (RF) wave. The highest temperature was recorded using 200 ppm concentration nanohybrid during 40 min exposure. The combinatorial treatments demonstrated that the maximum cell death (average of 53%) was induced with the combination of the nanohybrid with RF waves and radiotherapy (RT). The mechanistic study using the flow cytometry technique illustrated that early apoptosis was the main underlying cell death. Moreover, the dose enhancement factor of 1.63 and 2.63 were obtained from RT and RF, respectively. To sum up, the authors’ findings indicated that the prepared nanohybrid could be considered as multifunctional and combinatorial cancer therapy agents.Inspec keywords: radiation therapy, toxicology, gold, biomedical materials, nanofabrication, nanoparticles, iron compounds, cancer, nanomedicine, cellular biophysics, tumours, graphene compounds, biothermicsOther keywords: graphene oxide nanohybrid, combinatorial cancer treatment agent, cell toxicity assessment, MCF‐7 cells, dose‐dependent heat elevation, multifunctional cancer therapy agents, thermoradiotherapy agent, graphene oxide‐iron oxide‐gold nanoparticles, temperature measurement, radiofrequency wave, flow cytometry, time 40.0 min, CO‐FeO‐Au     

One-step synthesis of N,P co-doped porous carbon electrocatalyst for highly efficient nitrogen fixation

Heteroatom-doped porous carbon has attracted many researchers'interests owing to their hierarchical porous and more active sites for nitrogen reduction reaction...     

Single‐wall and multi‐wall carbon nanotubes promote rice root growth by eliciting the similar molecular pathways and epigenetic regulation

Organisms are constantly exposed to environmental stimuli and have evolved mechanisms of protection and adaptation. Various effects of nanoparticles (NPs) on crops have been described and some results confirm that NPs could enhance plant growth at the physiological and genetic levels. This study comparatively analysed the effect of carbon nanotubes (CNTs) on rice growth. The results showed that single‐wall CNTs were located in the intercellular space while multi‐wall CNTs penetrated cell walls in roots. CNTs could promote rice root growth through the regulation of expression of the root growth related genes and elevated global histone acetylation in rice root meristem zones. These responses were returned to normal levels after CNTs were removed from medium. CNTs caused the similar histone acetylation and methylation statuses across the local promoter region of the Cullin‐RING ligases 1 (CRL1) gene and increased micrococcal nuclease accessibility of this region, which enhanced this gene expression. The authors results suggested that CNTs could cause plant responses at the cellular, genetic, and epigenetic levels and these responses were independent on interaction modes between root cells and CNTs.Inspec keywords: crops, multi‐wall carbon nanotubes, single‐wall carbon nanotubes, nanobiotechnology, cellular biophysics, genetics, enzymes, biochemistry, molecular biophysicsOther keywords: single‐wall carbon nanotubes, multiwall carbon nanotubes, rice root growth, molecular pathways, epigenetic regulation, environmental stimuli, crops, intercellular space, cell walls, global histone acetylation, rice root meristem zones, histone acetylation, methylation statuses, local promoter region, CRL1 gene, micrococcal nuclease accessibility, root growth related gene expression, plant responses, cellular levels, epigenetic levels, genetic levels, interaction modes, C     

Systematic study on synthesis and purification of double-walled carbon nanotubes synthesized via CVD

Carbon nanotubes have unique properties, such as thermal and electrical conductance, which could be useful in the fields of aerospace, microelectronics and biotechnology. However, these properties may vary widely depending on the dimensions, uniformity and purity of the nanotube. Nanotube samples typically contain a significant percentage of more allotropes forms of carbon as well as metal particles left over from catalysts used in manufacturing. Purity characterization of double-walled carbon nanotubes (DWCNTs) is an increasingly popular topic in the field of carbon nanotechnology. In this study, DWCNTs were synthesized in a catalytic reaction, using Fe:MgO as catalyst and methane or methane/ethanol as carbon feedstock for chemical vapor deposition (CVD). The addition of ethanol as carbon feedstock allowed to investigate the influence of oxygen on the sample quality. The purification of the as-produced material from the metallic particles and the catalyst support was performed by sonication in an acid solution. The influence of the duration of the acid treatment using ultrasound on the sample purity was investigated, and the optimal value of this parameter was found. Transmission electron microscopy (TEM) images confirmed the removal of impurities and served to elucidate the morphology of the samples. The purity of carbon nanotubes was analyzed using thermal gravimetric analysis (TGA). The Raman spectra of the samples, as a measure of the concentration of defects, were also reported.     

以NiZnAl催化剂制备碳纳米管及其反应活性的研究

采用FC化合物作为一种新型催化剂--NiZnAl催化剂的前驱物,以催化热解法合成出了碳纳米管.管状、竹节状、鱼骨状和分叉状等多种形态的碳纳米管均被观测到.在碳纳米管生长过程中位于其顶端的准液态金属颗粒是其形成多种形态碳纳米管的关键.Zn的添加可能使得经煅烧和还原后的Ni催化剂的活性产生了微妙的变化.     

Neuroblastoma cells displacement by magnetic carbon nanotubes

In this paper, as-produced multiwall carbon nanotubes (MWNTs) have been analyzed by scanning electron microscopy and energy dispersive X-ray spectrometry, revealing the presence of Fe, Al, and Zn residuals and impurities. MWNTs have then been dispersed in Pluronic F127 aqueous solution and used to seed neuroblastoma cell lines (HN9.10e and SH-SY5Y) for three days. We found that MWNTs interact with cells and induce, under a permanent constant magnetic field, the cell displacement toward the magnetic source.     

磁性多孔碳材料的研究进展

磁性多孔碳材料同时具有磁性和多孔性质,其拥有丰富的孔道结构、高的比表面积、高孔容、良好的活性位点和磁性可分离等优异的性能,可以很好的解决多孔碳材料在应用过程中难分离回收等问题,因此,磁性多孔碳材料已经在吸附领域得到广泛的应用.按照孔径大小、磁性强弱以及组合方式的不同将磁性多孔碳材料进行了分类,并综述了近年来磁性多孔碳材...     

卵磷脂改性磁性碳纳米管的制备及生物相容性

采用生物活性两亲性分子卵磷脂(PC), 对制备的磁性碳纳米管(Fe₃O₄/CNTs)进行非共价修饰, 得到了内部为疏水端、外部为带电亲水基团的类膜结构包覆的改性复合材料Fe₃O₄/CNTs-PC。在溶液中带电基团通过溶剂化作用及亲水作用, 在复合材料表面形成水化层, 提高复合材料的自由水含量。在蛋白质吸附实验与复钙化凝血时间评价中, Fe₃O₄/CNTs-PC对蛋白质吸附量仅为0.1368 mg/mg, 复钙化凝血时间延长至324 s, 具有很好的生物相容性。     

Highly ordered carbon nanotubes based on porous aluminum oxide

Highly ordered carbon nanotubes (CNTs) are widely pursued due to their unique properties. Anodic aluminum oxide (AAO) exhibits great possibility for this purpose. Here, CNTs based on AAO templates were produced using acetylene or ethylene as the hydrocarbon sources with or without the presence of Co catalysts. CNTs grown on the Co-embedded AAO samples were normally confined within the nanopores of the AAO template. It was found that C2H4 normally requires 100 degrees C higher pyrolysis temperature than C2H2 under otherwise identical conditions. The pyrolysis temperature is greatly reduced with the presence of Co catalysts. CNTs can grow out of the nanopores if Co particles are present at the bottom of the nanopores, and if the nanopores are short in length or large in diameter. The graphitization of AAO-template grown CNTs was studied by Raman spectroscopy. CNTs produced from ethylene are generally better in graphitization than those from acetylene, and CNTs grown with the presence of Co catalysts deposited at the bottom of nanopores are better than those without Co catalysts or with Co catalysts coated on the entire inner wall of nanopores. The growth temperature is found not to play a critical role in graphitization.     

Biogenic gold nanoparticles for reduction of 4‐nitrophenol to 4‐aminophenol: an eco‐friendly bioremediation

The present study investigated the synthesis of gold nanoparticles (AuNPs) using mangrove plant extract from Avicennia marina as bioreductant for eco‐friendly bioremediation of 4‐nitrophenol (4‐NP). The AuNPs synthesised were confirmed by UV spectrum, transmission electron microscopy (TEM), X‐ray diffraction, Fourier transmission infrared spectroscopy (FTIR), dynamic light scattering (DLS), and zeta potential. The AuNPs were found to be spherical in shape with size ranging from 4 to 13 nm, as evident by TEM and DLS. Further, the AuNPs were encapsulated with sodium alginate in the form of gold nano beads and used as heterogeneous catalyst and degrading agent to reduce 4‐NP. This reduction in 4‐NP into 4‐aminophenol was confirmed by UV and FTIR. The aqueous solution of 4‐NP peaked its absorbance at 320 nm, and shifted to 400 nm, with an intense yellow colour, appeared due to formation of 4‐nitrophenolate ion. After the addition of AuNps, the 4‐NP solution became colourless and peaked at 400 nm and reduced to 290 nm corresponding to the formation of 4‐aminophenol. Hence, the present work suggested the AuNPs as the potent, eco‐friendly bionanocomposite catalyst for bioremediation of 4‐NP.Inspec keywords: gold, nanoparticles, nanobiotechnology, nanofabrication, ultraviolet spectra, transmission electron microscopy, X‐ray diffraction, Fourier transform spectra, infrared spectra, electrokinetic effects, catalysts, nanocomposites, biochemistryOther keywords: biogenic gold nanoparticles, 4‐nitrophenol, 4‐aminophenol, eco‐friendly bioremediation, mangrove plant extract, Avicennia marina, bioreductant, UV spectrum, transmission electron microscopy, TEM, X‐ray diffraction, Fourier transmission infrared spectroscopy, FTIR, dynamic light scattering, DLS, zeta potential, degrading agent, 4‐nitrophenolate, bionanocomposite catalyst, size 4 nm to 13 nm, wavelength 400 nm, wavelength 290 nm, Au