Journal of Nano Research Vol. 58

Abstract: Wnt-β Catenin pathway has an important role in many cancers. Wnt-1 protein from the Wnt protein family, which regulates this pathway, has a special effect on the development of breast cancer. Monoclonal antibodies attaching to metal nanoparticles have an important role in the diagnosis and treatment of cancers.In this study, the anti-Wnt-1monoclonal antibody was conjugated to the gold nanoparticles synthesized by theTurkevichmethod. Conjugation was achieved using the EDC-NHS method. The density of the monoclonal antibodies bonded to gold nanoparticles was measured by Roche Cobas Integra 400 Plus device. MCF-7 and MDA-MB-231 breast cancer cell lines were treated with conjugated nanoparticles for 48 h, followed by performing a double-staining method to detect apoptosis cells.The results showed that inhibition of Wnt-1 protein in extracellular matrix causes apoptosis and gold nanoparticles to have a positive effect on Anti-Wnt-1monoclonal antibodies, leading to an increase in the number of conjugating nanoparticles.

Abstract: In nanotechnology, fungal mediated green synthesis of silver nanoparticles (AgNPs) has tremendous application in the development of antimicrobial systems but the mechanism behind the synthesis is yet to be understood. This study aims to synthesize the silver nanoparticles via a green chemistry route using mycellial aqueous extract of agriculturally beneficial fungi Trichoderma harzianum. Two different concentrations (1 mM and 2.5 Mm) of aqueous silver salt (AgNO₃) were used and mixed as 1:1 ratio with aqueous extract of T. harzianum at room temperature and the pH of the reaction mixture was monitored until it stabilized. Formation of AgNPs was confirmed by using UV-Vis spectroscopic analysis. For further insight, AgNPs were characterized by using HR-TEM and XRD, which clearly showed appearance of crystalline, monodispersed round-shaped particles of 3-20 nm in size. The synthesised NPs were subjected to antimicrobial assay against gram +ve and gram –ve bacteria using the disk diffusion method. The focused species was Clavibacter michiganensis subsp michiganensis, which is the causitive pathogen of Tomato canker disease and we hypothesised that the synthesised AgNPs might be useful to control this pathogen. Appreciable antibiotic activity was monitored even at a low concentration of 1mM level, while the zone of inhibition was positively increased at 2.5 mM. Our results clearly indicate that the present process is an excellent candidate for industrial scale production of AgNPs, and has the potential to control the bacterial pathogen cmm.

Abstract: Magnetotactic bacteria integrated magnetosomes, which are unique organelles that contain nanosized crystals of biogenic magnetic iron minerals with the ability to respond to the external magnetic fields. The biogenic magnetic nanoparticles (magnetosomes) show high biocompatibility in medical applications especially as scavengers to eliminate intracellular reactive oxygen species. The aim of this study was to highlight the impact of magnetosome formation and antioxidant systems in the suppression of oxidative stress on the magnetotactic bacteria cells. To assess the changes in ROS levels under different magnetic field intensity conditions, cells were cultured under the microaerobic condition in medium containing the high and low intensity of magnetic field. Treatment of magnetic field with an intensity of 500 mT during 50 hours bionormalization process of magnetotactic bacteria increased the antioxidant enzyme activity for eliminating of free radicals by 64%. We concluded that magnetosomes production plays an important role in decreasing or eliminating ROS. This is the first study to demonstrate that the magnetic field assisted magnetosome formation and antioxidants defense systems in Magnetospirillum gryphiswaldense MSR-1.

Abstract: In this article we have developed an analytical model for Tri-gate Metal Oxide Semiconductor Field Effect Transistor (TG MOSFET) including Quantum effects for High-k/Ge material. The Schrodinger–Poisson’s equation is used to develop the analytical Quantum model using Variational method. A mathematical expression for charge centroid is obtained and then an inversion charge model was developed with quantum effects by means of oxide capacitance for different channel thickness and gate oxide thickness. The compact model is shown to reproduce transfer characteristics, transconductance and C-V curves of Tri-gate MOSFETs using the model and is compared with the device for Si/SiO₂ material. The results of both the model are compared to the simulated results. The comparison shows the accuracy of the proposed model for the high-k and Ge material.

Abstract: 3D Simulation was carried out and compared with fabricated ZnO NWFET. The device had the following electrical output characteristics: mobility value of 10.0 cm²/Vs at a drain voltage of 1.0 V, threshold voltage of 24 V, and subthreshold slope (SS) of 1500 mV/decade. The simulation showed that the device output results are influenced by two main issues: (i) contact resistance (R_con ≈ 11.3 MΩ) and (ii) interface state trapped charge number density (Q_IT = 3.79 x 10¹⁵ cm^-2). The Q_IT was derived from the Gaussian distribution that depends on two parameters added together. These parameters are: an acceptor-like exponential band tail function g_GA(E) and an acceptor-like Gaussian deep state function g_TA(E). By de-embedding the contact resistance, the simulation is able to improve the device by producing excellent field effect mobility of 126.9 cm²/Vs.

Abstract: The changes in structural and optical properties of the Cu₂O films obtained on the glass with different concentrations of Au by the chemical bath method were studied in this work. Lattice parameter, crystal size, preferential orientation and surface tension of the films were calculated using X-ray diffraction data which showed that all of the films were in polycrystalline form. It was determined that the structural parameters of all films were changed with the doping ratio. The surface morphology of the films was imaged using a field emission scanning electron microscope. The optical properties of the films were discovered using the optic spectrometer. Changes in the optical properties were discovered as a function of Au ratio. It was determined that the energy band gap value (2.12 eV-2.02 eV), the refractive index, the extinction coefficient, the real and dielectric coefficients, the optical conductivity, and the skin depth of films varied with Au doping ratio.

Abstract: An organic nanocomposites, based on a conjugated polymer (MEH-PPV) as electron donor material and carbon nanopearls (CNPs) as electron acceptor material, have been elaborated and optoelectronically studied. The effect of CNPs concentration on the electric and photoelectric properties in these blends has been investigated. Dielectric measurements demonstrate that the blend conductivity displays a dramatic increase, reaching 0.6 S/m for a CNPs concentration about 1 wt.%. The elaborated organic nanocomposites were used as photoactive materials in organic solar cells.

Abstract: A promising two-dimensional material for applications in optoelectronic and photonics, MoS₂ is in focus since last decade. Its optical, structural and electronic properties are of practical importance along with its exciton dynamics. MoS₂ thin films were synthesized with Chemical Vapour Deposition (CVD) technique on Si/SiO₂ substrates. The thickness dependent regularities were controlled and examined to quantitatively control the film quality with thickness variation. Various characterization techniques were employed to investigate structural and morphological changes induced systematically to reveal the van der waal stacked layers of MoS₂ material. The In-plane characteristic mode E¹_2g and out of plane A_1g vibrational modes were detected in different configurations of film’s structure. Optical absorption spectra gave us information on photon energy with the absorbance; extrapolation of this curve gave optical bandgap (E_g) in the form of Tauc plot. These energies can be associated to interband electronic transitions in the Brillouin zone. The intrinsic excitonic response as a consequence of layer stacking and velly indexing can be attributed to this change in bandgap from 1.68 to 1.91 eV. Surface morphology of the as-grown films also provides better understanding of MoS₂ material with root mean square (RMS) roughness in the range of 1.32 to 3.85 nm.

Abstract: One-dimensional nanostructures have been the focus of recent research interests because they possess high aspect ratio. In this study, bismuth sulphide nanorods have been synthesized via a simple microwave irradiation of bismuth dithiocarbamate complex in ethylene glycol (EG) and N,N-dimethyl formamide (DMF) solvents. The optical properties of the nanorods was studied by UV-vis spectroscopy, and the structural characterization was carried out using powder X-ray diffraction (p-XRD) analysis, transmission electron microscopy (TEM, HRTEM), scanning electron microscopy (SEM), and selected area electron diffraction (SAED). The XRD patterns indicated cubic phase, and the TEM analysis confirmed rod-like morphology with mean diameter of about 60 nm and irregular lengths. The role of the solvents on the nanostructures was discussed, and the band gap energies were estimated from Tauc plot. The synthesized bismuth sulphide nanorods exhibited quantum confinement effect. The synthesis approach via microwave irradiation of single source precursor is facile and efficient, thus promotes the production of large scale Bi₂S₃ nanorods by an environmentally friendly approach.

Abstract: In the present work we studied the effect of temperature and molarity on microstructural and optical properties of Ag₃O₄ thin films deposited by spray pyrolysis. Transparent conductive thin films of silver oxide (Ag₃O₄) were prepared by using an aqueous solution of silver nitrate (AgNO₃) and sprayed onto heated soda glass substrate at 350 °C and annealed at 550°C. X-ray diffraction showed that the films have a monoclinic structure with a preferential orientation along the (031) direction. A visible shift of the main peak as a function of temperature and solution molarity is observed. The lattice parameters a, b and c are estimated to be 3.68, 9.30 and 5.20Ǻ respectively. Scanning Electron Microscopy (SEM) analysis shows that all films are nanostructured and homogeneous with dense surfaces. Transmittance and reflectance measurements are performed in the spectral range 200-1600 nm and yielded a band gap energy (E_g) varying in the range 3.07-3.25 eV. Refractive index was studied in terms of Moss, Ravindra and Herve–Vandamme models. The optical constants such as the oscillator energy (E₀), static refractive index (n₀), dispersion energy (E_d) and dielectric parameters (ε_r ) of the films were derived from the analysis and discussed.