Journal of Nano Research Vol. 67

Abstract: Barium hexaferrite (BaFe₁₂O₁₉) nano- pigment is a pigment with high near infrared reflection in the wavelength range of 1400-2500 nm. The BaFe₁₂O₁₉ nano- pigments were synthesized by the traditional and modified polyacrylamide gel method and characterized by thermogravimetric and differential scanning calorimetry (TG-DSC) analyses, X-ray powder diffraction (XRD), fourier transform infrared (FTIR), transmission electron microscopy (TEM), and UV-Visible spectrophotometer. The physicochemical properties of BaFe₁₂O₁₉ nanopigments are strongly dependent on the synthesis route. The introduction of carbon particles into the BaFe₁₂O₁₉ precursor accelerates the formation of BaFe₁₂O₁₉ phase, reduces its particle diameter and changes its color properties. The modified polyacrylamide gel method makes it possible to obtain a high efficient near infrared reflection BaFe₁₂O₁₉ nano- pigments with a solar reflectance SR>90%. The high near infrared reflection makes BaFe₁₂O₁₉ nano- pigments have potential applications in the field of heat shielding.

Abstract: In this study, dense zinc oxide nanowires were electrochemically synthesized on sputtered zinc oxide buffer layers substrates using a solution of zinc chloride as a precursor. The control of nanowires density was studied. X-Ray Diffraction patterns revealed the formation of pure wurtzite zinc oxide structure. The mechanism of the formation of zinc oxide nanorods from the nucleation to the growth stage is proposed based on the study of the deposition parameters. Optical analysis reveals that these films can be involved in solar cells as window layers. Moreover, controlling structural properties of the buffer is an excellent way to control the formation of nanorods during the nucleation step. In fact, Scanning Electronic Microscopy images and reflectometry analysis showed that the buffer layer consists of dense nanoparticles, with a density that increases by increasing the radiofrequency frequency power, This can be explained by the densification of the nanorods deposited thereon.

Abstract: Graphene oxide/sulphur compound was synthesized by Hammers method. The chemical composition, presence/quantity of functional groups, exfoliation level, number of layers, crystallite size of graphene oxide/sulphur were characterized by X-ray diffraction, Raman spectroscopy, and scanning electron microscopy images. The current-voltage characteristics of the samples were measured in air at room temperature. In the I - V characteristic curve of graphene oxide/sulphur compound with the ratio of oxygen to carbon of 3.54 and that to sulphur of 42.54, negative differential resistance was observed. The negative differential resistance is attributed to current carrier transitions between the localized states formed by functional groups.

Abstract: Present work illustrates synthesis of Cr doped WO₃ nanostructures (NS) (2 wt. %, 4 wt. % and 6 wt. %) by co precipitation method using surfactants and reported enhanced impedance, capacitance-voltage and current-voltage (I-V) characteristics. NS were characterized by cyclic voltammetry (CV), scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-Visible (UV-Vis) spectroscopy, pelletized samples performed I-V, C-V and impedance measurements. Impedance results reveal that the pelletized samples of highest doped Cr showed remarkable increase in admittance with respect to the biased voltage. I-V characteristics of highest doped Cr exhibited enhanced surface conductivity as compared with applied current. The output power considerably increases for the 6 wt. % of Cr doped WO₃ and doping percentage of Cr increases surface conductivity, power output, admittance considerably enhances in the material matrix. This work demonstrated that Cr doped WO₃ has more sensitivity towards I-V, C-V and impedance value considerably varies with the applied bias voltage. The limitation is not certain in case of doped nanomaterials of Cr-WO₃, since these materials possesses nonlinear properties and can find applications in the diversified filed of nano electronics. The authors reported work can be a key guide for the upcoming researchers in the area of biomedical devices, nanoelectronics, sensors, wherein Cr-WO₃ NS finds applications because of its enhanced I-V, C-V, Impedance characteristics. The work has been carried out to understand the electrical and electronic properties of doped nanomaterials in the original work place and analysis has been carried out at various institutions where the provisions for the experimentation is being made.

Abstract: The rapid glucose detection is great significance in the food, biological and medical fields. In this paper, we show an unusual strategy for the synthesis of α-Fe₂O₃/g-C₃N₄ composite material with C-O-Fe bonds for applications in glucose detection. The structural composition and the existence of C-O-Fe bonds of α-Fe₂O₃/g-C₃N₄ were evaluated by XRD, FTIR, SEM, TEM and XPS. Due to the formation of C-O-Fe bonds, the BET surface area and electron transport ability of α-Fe₂O₃/g-C₃N₄ are improved. The electrochemical experiments revealed that the α-Fe₂O₃/g-C₃N₄ sensor exhibited a fast response time (< 5 s), a low detection limit (2.3 μM) and a wide linear range (0.1 mM - 5 mM). Furthermore, the powerful C-O-Fe binding energy provides a guarantee for the reasonable stability of the α-Fe₂O₃/g-C₃N₄ sensor. The presence of high concentrations of KCl, citric acid, ascorbic acid, dopamine and sucrose appeared to have no effects on the detection of glucose, indicating a high selectivity of this sensor.

Abstract: Biosynthesis of novel metal nanoparticles (especially silver) using plant derivatives has received increasing attention due to their eco-friendly and potential applications in pharmaceutical and medical fields. In this study, silver nanoparticles were synthesized by using aqueous extract of Lamium album as a biocompatible and green method. The synthesized silver nanoparticles were characterized by Ultraviolet-visible (UV–vis) Spectroscopy, Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), and Dynamic Light Scattering (DLS) Analysis. Inhibitory activity of silver nanoparticles on fungal growth was evaluated and inhibition of Candida albicans biofilms formation was measured using XTT assay. Their antioxidant and cytotoxic properties have also been evaluated.The synthesized AgNPs were mostly spherical in shape with an average size of nearly 25.2 nm. The AgNPs were crystalline in nature and have a face-centered cubic structure. The results of zeta potential value for AgNPs were −30 mV indicating the normal stability of the synthesized nanoparticles in colloidal systems. The result of antifungal activities showed that the biosynthesized silver nanoparticles had inhibitory activity against Candida albicans, C. tropicalis, C. krusei, C. glabrata, C. dubliniensis, C. parapsilosis, Cryptococcus neoformance, Aspergillus flavus, A. clavatus, Aspergillus fumigatus, Pseudallescheria boydii and Exophiala dermatitidis. The nanoparticles inhibited the Candida albicans biofilm formation in a dose-dependent manner. The cytotoxicity study of silver nanoparticles was revealed IC50 of 110.75 μg/mL against liver cell lines. The recognized bioactivity confirmed by the synthesized silver nanoparticles directs towards the potential for using as an antioxidant, antifungal, and cytotoxic agent.Keywords: Green synthesis, Antifungal activities, Silver nanoparticles, Lamium album, Biofilm formation.

Abstract: Magnetic nanoparticles (MNPs) have many uses for biomedical applications including drug delivery, magnetic resonance imaging (MRI) contrast agents, theranostics and hyperthermia. MNPs photo-thermally heated by laser light could be used to treat the typically difficult to access tumors such as glioblastomas. Due to their high magnetic saturation, monometallic iron nanoparticles would have an edge over iron oxide nanoparticles currently being investigated for hyperthermia. The goal of this study was to synthesize spherical iron nanoparticles less than 10 nm in diameter by thermal decomposition. The ability of various biocompatible coatings to protect the metallic iron nanoparticles from oxidation was investigated. Coatings studied included Brij, polyethylene glycol and iron oxide. Transmission electron microscopy and Mössbauer spectroscopy were utilized to characterize the coated and uncoated iron nanoparticles’ size and oxidation state to evaluate the effectiveness of the coatings and the procedures in which the coatings were applied. A ferrite shell was found to provide the best stabilization; however, its longer synthesis time increased particle size distribution. Polymer coatings provided biocompatibility but did not prevent oxidation.

Abstract: The W18O49 nanoparticles were synthesized by solvothermal method with tungsten chloride as raw material and n-propanol as solvent. Polyethylene glycol 400 (PEG-400) was modified for W18O49 nanoparticles (W18O49@PEG). The structure and morphology of W18O49 and W18O49@PEG were characterized by XRD and SEM. Methylene blue aqueous solution was used as wastewater adsorption model. And the comparative experiments with other absorbent materials, such as artificial zeolite and activated carbon were also conducted. The results revealed that after modifying by PEG-400, W18O49 has a better adsorption performance than other materials due to its large specific surface area and high surface energy. Finally adsorption circulation experiment was performed，the results indicate that the W18O49@PEG nanoparticles show great potential in the treatment of colored wastewater.

Abstract: The effects of the application of constant electric fields on the dynamics of a confined water droplet between two different surfaces are investigated, by using a molecular dynamics method. It is found that the water molecules responded to the electric field, which partially depends on the wettability of the different surfaces. The results reveal that the application of external electric fields causes to create extra pressure on the surfaces, which are theoretically justified. The induced pressure could be experienced by multilayer nano-filters, which are used in desalination processes, with the aid of an external electric field, and may reduce the water filters shelf life.

Abstract: Reasoning of particular mechanism of anomalous thermal transport behaviours are not identified yet for the nanofluids. In this study, iron oxide (Maghemite: MH) and graphene (Gr) flake dispersed deionized water (DW) hybrid nanofluid system were developed for the first time to evaluate the thermal conductivity (TC) enhancements along with the analysis of anomalous TC behavior implementing modified effective medium theories (EMTs). A solvo-thermal two-step method was used to develop the MH nanoparticle and exfoliated Gr flake dispersed hybrid nanofluids with different compositions. Stability of as-prepared hybrid nanofluids were monitored using Ultraviolet-Visible (UV-Vis) spectroscopy. The maximum sedimentation rate was observed ~ 8.4 % after 600 hours. The results showed an overall maximum TC enhancement of ~ 43 % at 25 °C. EMTs were modified with the consideration of flat geometry of Gr flake. It is found that, modified EMTs with the crumpled factor (due to the non-flatness or crumple of Gr flake) of ~ 0.205 the predicted effective TC enhancements are agreed with the experimental TC’s of Gr-NMP/MH-DW hybrid nanofluids samples. The estimated crumple factor value of exfoliated Gr flakes using images analysis was also found nearly similar (~ 0.232). This agreement exposed that, Gr flake’s with negligible thickness compared to its extremely wide basal plane dimensions and its non-flatness or crumpled geometry in the nanofluids have the leading impacts on the effective TC properties of the Gr flake dispersed nanofluids. This modified model opens the new doors to analyse the insight of the thermophysical properties of various types of nanofluids by introducing potential other parameters.