International Journal of Nano Dimension
Year:2018 | Volume:9 | Issue:2|Papers Count:10

The present study evaluates the biosynthesis of silver nanoparticles (SNPs) mediated by xerophytic plants, Cynanchum viminale and Cynanchum sarcomedium. The reaction between plant extracts and silver nitrate solution resulted in a yellowish brown/dark brown colored solution which suggests the formation of SNPs. Physical characteristics of synthesized SNPs were determined using UV-Vis spectral, Scanning electron microscopy (SEM) and Energy dispersion X-ray spectroscopy (EDAX) analyses. The UV-Vis spectrum showed a maximum absorbance of SNPs at 500 nm for SNPs synthesized by C. viminale whereas maximum absorbance of 1.87 was observed at 400 nm for C. sarcomedium. Agglomerated nanoparticles were synthesized by C. viminale with an average diameter of ~ 60-68 nm as depicted by SEM. Nearly spherical nanoparticles of average size of ~ 60-85 nm were obtained by C. sarcomedium extract. A strong signal of silver at 3 KeV was confirmed by EDAX analysis for SNPs produced by both plants. Thus, the present green synthesis offers a viable and an ecofriendly way of fabrication of benign SNPs without any huge inputs in terms of energy and waste.

A three-dimensional micromechanical finite element model is developed to study the viscoelastic behavior of the silica nanoparticle/polyimide nanocomposites. The representative volume element (RVE) of the model consists of three phases including silica nanoparticle, polyimide matrix and interphase which surrounds the nanoparticle. The interphase region is created due to the interaction between the silica nanoparticle and the polymer matrix. The effects of different important parameters such as interphase material properties and thickness, silica nanoparticle volume fraction and geometry as well as type of nanoparticles distribution are investigated. It is found that the interphase significantly affects the viscoelastic behavior of the nanocomposites. Also, the results reveal that with decreasing the nanoparticle diameter or increasing volume fraction, the creep strain of the nanocomposite reduces. Moreover, the creep strain of the nanocomposites decreases with the uniform distribution of the nanoparticles inside the polymer matrix. It is shown that for the elastic properties of the nanocomposites, while the predictions without interphase are far from the reality, the predicted mechanical properties with interphase demonstrate very good agreement with experimental data.

Treatment methods for breast cancer are not specific and each one has its own drawbacks. For this reason, scientists are seeking ways in which specifically affect cancer cells. Photothermal therapy is a method that uses near-infrared (NIR) laser energy to create sufficient heat to destroy cancer cells. In this study, the photothermal effect of gold nanorods (GNRs) was investigated for breast cancer treatment in vitro and in vivo. GNRs with the peak absorption of 808 nm were synthesized and conjugated with Herceptin (anti- HER2). After confirming the characteristics of the prepared conjugate, the therapeutic effect of the new agent was studied on SK-BR-3 cell line and BALB/c mouse model bearing breast tumor using the NIR laser. The cytotoxicity assay showed the biocompatibility of PEGylated GNRs-HER conjugate. Through the in vitro photothermal study, significant cell death was observed in breast cancer cells incubated with the conjugate along with the laser irradiation. Afterward, the biodistribution of the conjugate in the mouse model with breast tumor showed the considerable localization of new agent in breast tumor in comparison with other organs 24 h postinjection. The animal study showed a significant decrease in tumor growth rate as well as the increased lifespan of treated mice with breast tumor in comparison with the control groups.

Emerging trend in semiconductor nanotechnology motivates to design various crystalline nanotubes. The structural and electronic transport properties of single walled zigzag Gallium Arsenide nanotubes have been investigated using Density Functional Theory (DFT) and Non-Equilibrium Green’s Function (NEGF) based First Principle formalisms. Structural stability and enhanced electronic transmission property of Gallium Arsenide nanotubes (NT’s) have been analyzed for the chiral vector 3 ≤ n ≤ 7. This analysis based on the Perdew Burke Ernzerhoff type of parameterization along with Generalized Gradient Approximation (GGA) procedure. Several structural properties like dependency of diameter along with bond length, buckling and band gap have been analyzed. The investigation confirms that buckling property and bond length of these nanotubes decreases as the diameter of the tubes are increasing. It has been observed that (7, 0) nanotube is being considered as most stable nanotube among all. Binding energy also increases with the increasing diameter of the tubes. This two probe experiment is being carried out at room temperature when two opposite bias voltages have given at the end of these nanotubes using electrical doping procedure. Introducing this procedure a potential drop has been created between the two electrodes’ chemical potential level. Due to this potential drop, the device performance has been enhanced and results in the flow of high conducting current through the central part of the NTs’.

Present work focuses on the synthesis strategies for different CuO nanostructures along with associated formation mechanisms and their interesting fundamental properties, and promising applications in biological and environmental remediation. We present a variety of synthesis techniques for producing diverse types of CuO nanostructures with various morphologies such as nanoparticles, nanoleaves, nanotubes, and nanoflowers. The effect of synthesis parameters on manipulating the nanoscale features along with the associated growth mechanisms for these unique morphologies is also discussed. The surface, electronic and optical properties of these nanostructures is also detailed. The photocatalytic and antimicrobial applications of these nanostructures are systematically introduced and summarized. Congo red and Malachite green organic dyes were degraded by these CuO nanostructures and it was found that CuO nanoflowers are more favorable for the degradation of Congo red and Malachite Green due to their higher surface sites and surface defects. Overall, in addition to size, morphology has a significant effect on the properties and applications of nanomaterials. The synthesized novel hierarchical CuO nanostructures with large surface areas and carefully defined surfaces are best suited for treating industrial effluents.

Zinc oxide (ZnO) nanoparticles have received growing attention for several biomedical applications. Nanoparticles proposed for these applications possess the potential to interact with biological components such as the blood, cells/ tissues following their administration into the body. Hence we carried out in vivo investigations in Swiss Albino Mice to understand the interaction of ZnO nanorods with the biological components following intravenous and oral routes of administration to assess nanoparticles safety. Intravenously injected ZnO nanorods were found to induce the significant reduction in the red blood cells and platelet counts. Elevated levels of serum enzymes such as serum glutamate oxaloacetate transaminase, serum glutamate pyruvate transaminase were observed following intravenous and oral administration. Also, increased levels (p<0.05) of oxidative stress markers such as glutathione in the liver of intravenous treated mice and liver, spleen of oral treated mice; and lipid peroxidation in the spleen of intravenous treated mice compared to untreated mice. Significant DNA damage was observed in liver, spleen, and kidney of mice treated intravenously; liver and kidney of mice treated orally compared to untreated mice. Histology revealed focal venous congestion in the liver of intravenous and oral treated mice; more red pulp congestion in the spleen of oral treated mice compared to the intravenous treated group; pulmonary vascular congestion in intravenous (mild) and oral treated mice (moderate). In conclusion differences in the histology of the organs tested could be due to the differences in the distributed concentrations of nanoparticles. These findings can be considered helpful for the development of biocompatible nanoparticles for biomedical applications.

Nanostructured Ni2As2O7 semiconductor samples were synthesized by a solid state method among As2O3 and Ni(NO3)2.6H2O raw materials at 650oC (S1) and 750oC (S2) as reaction temperatures. The synthesized nanomaterials were characterized by powder X-ray Diffraction (PXRD) technique and Fourier-Transform Infrared (FTIR) spectroscopy. The Rietveld analysis showed that the obtained materials were crystallized well in the triclinic crystal structure with the space group P1. The data of Rietveld analysis showed that the purity of the synthesized nanomaterials was increased by increasing the reaction temperature. The morphologies of the synthesized materials were studied by field emission scanning electron microscope (FESEM). It was found that the morphology of the obtained materials was changed from homogeneous sponge to particles and somewhat porous structure, by increasing the reaction temperature. Besides, the average particle sizes were increased considerably by increasing the reaction temperature. Ultraviolet-visible spectra analysis showed that the synthesized Ni2As2O7 nanomaterials had strong light absorption in the ultraviolet light region. The direct optical band gap energies were 3.20, 3.90, 4.80 eV and 2.9, 3.40, 4.70 eV for S1 and S2, respectively. The data showed that the band gaps were decreased by increasing the reaction temperature that can be due to the increasing the crystallite sizes of the targets.

Pure (S1) and Dy3+-doped α-Fe2O3 (S2 and S3) nanoparticles were prepared by a combustion synthesis method at 700oC for 8 h using Fe(acac)3 (Tris(acetylacetonato)Iron(III)) as raw material. Characterizations of the prepared powders were carried out by powder X-ray diffraction (PXRD). Structural analysis was performed by the FullProf program employing profile matching with constant scale factors. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), electrochemical impedance spectroscopy (EIS), elemental maps analysis and energy-dispersive X-ray spectroscopy (EDS) were also performed to determine the dopant amount in the a-Fe2O3 crystal structure (S3). The results showed that the patterns had a main hexagonal structure with space group R. The cell parameters data, calculated by rietveld analysis, showed that the cell parameters were decreased with increasing the dopant (Dy3+) amount in the a-Fe2O3 crystal structure. The average particles sizes estimated from TEM images for S3 were about 60 nm. Besides, the magnetic properties of S1 and S3 were measured by vibrating sample magnetometer (VSM). It was found that with the addition of Dy3+ ions into the Fe2O3 system, the coercivity was decreased and the remanent magnetization was abruptly increased. The influence of dysprosium addition was also studied using electrochemical impedance spectroscopy. This study showed that in the presence of dysprosium ion, the charge transfer resistant increased in the electrochemical process.

The acid oxidation of carbon nanotube generally results in opening the close ends of the nanotube and to make surface modifications. Herewith, Multiwall carbon nanotubes (MWCNTs) were oxidized in acids at high temperature experimental conditions which led to the formation of graphene quantum dots (GQDs). High resolution transmission electron microscope (HRTEM), energy dispersive X-ray spectroscopy (EDS), IR Infrared study showed the formation of 5-10 nm diameter GQDs and their crystalline structure having the inter-planner distance of 2.40 Å and 2.14 Å were confirmed by the electron diffraction. The UV visible spectroscopy showed the lowest exciton peak at 4eV. Photoluminescence (PL) studies showed the Photoluminescence peak in visible range which is independent of excitation wavelengths. A mechanism for the formation of highly crystalline graphene quantum dots during the high temperature acid oxidation of MWCNTs is proposed in the paper.

The present study aims at study on combined effect of zinc oxide nanoparticles (ZnO) with common agricultural fungicides. Nanoparticles were synthesized using chemical reduction process and characterized through UV-Visible spectroscopy, X-ray diffraction (XRD), Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM). Synthesized nanoparticles were observed to be in size range of 12-63 nm as confirmed by TEM micrograph. DLS established polydisperse nature of nanoparticles and provided effective hydrodynamic diameter of 76.15 nm, confirming the hypothesis of particles being in nano range. Nanoparticles were tested against fungal phytopathogens, namely A. alternata, A. niger, B. cinerea, F. oxysporum and P. expansum. Nanoparticles used in the study exhibited good antifungal activity. Both classes of nanoparticles (green and chemically synthesized) were individually tested against fungal phytopathogens and in combination with fungicides. Nanoparticles positively influenced the inhibitory effects of fungicides. P. expansum was observed to be the most sensitive fungus. It exhibited sharp decrease in MIC values from 2 mg/mL for carbendazim and 4 mg/mL for thiram to 0.25 mg/mL when carbendazim and thiram were used in combination with green ZnO NPs. Mean MIC value (mean ± sd) for combination of all three fungicides with green ZnO NPs was 0.83±0.4 mg/mL and for chemical ZnO NPs was 1.17±0.7 mg/mL. Hence, green ZnO NPs showed better inhibition of test fungi when compared to chemically synthesized ZnO NPs. In summary, the study reports synthesis of ZnO nanoparticles with good antimicrobial potential and amelioration of activity of fungicides was observed when used in combination with nanoparticles.