Journal of Nano Research Vol. 31

Abstract: In a first report of its type, gainful utilization of the obnoxious weed ipomoea (Ipomoea carnea; also known as: I. fistulosa) has been achieved by developing a procedure on its basis for clean-green one pot synthesis of bimetallic Au-Ag nanoparticles. In it the leaf and the stem extracts of the weed serve as reducing as well as stabilizing agents. With the support of Scanning Electron Microscopy, Confocal Raman Spectroscopy, and X-ray based techniques, the effect of varying metal: extract stoichiometry, temperature, and stirring on controlling the shape and size of the nanoparticles has been studied. Increase in reaction temperature is seen to favour speedier formation of nanoparticles, and of smaller average size, than occurs at ambient temperatures (27±2°C). Higher extract: metal ratios also lead to nanoparticles of larger average size. When Ag (I) and Au (III) salts are used in equal molar ratios, it generates sphere-shaped nanoparticles. All-in-all, the present work offers a non-polluting, energy saving, and cost effective route for the fabrication of bimetallic Au-Ag nanoparticles. The study indirectly provides a means of controlling ipomoea, thereby offering a means to reduce the ecological degradation that is caused by the weed.

Abstract: The purpose of this study was to prepare ibuprofen loaded solid lipid nanoparticles (IBU-SLNs) that is, effective in oral drug delivery. IBU-SLNs were synthesized by co-precipitation of rapid expansion of supercritical solution (CO-RESS). The produced SLNs consisted of stearic acid as lipid matrix. The unprocessed stearic acid, ibuprofen and IBU-SLNs were characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), fourier transform infrared spectrophotometry (FTIR) and high performance liquid chromatography (HPLC). XRD patterns along with DSC showed that ibuprofen was present in both amorphous and crystalline form within lipid matrix. FTIR showed that molecular interactions that could alter the chemical structure of the IBU did not occur. The RESS process could produce ultrafine spherical particles of SLNs with high drug loading capacity. The IBU dissolution profile showed that the formulated SLNs have effectively increased the IBU solubility

Abstract: This study reports the cycle chemistries involved in depositing CdTe and PbTe nanofilms. An automated thin-layer flow cell electrodeposition system was used to deposit the films at room temperature. Cyclic voltammetry was used to study the Underpotential Deposition (UPD) of the compounds. The monolayer/cycle deposition rate was also monitored in order to insure that the film is depositing at a uniform rate. The chemical composition of the films was characterized using Energy-Dispersive X-ray Spectroscopy (EDS) on a Scanning Electron Microscope (SEM). The crystallinity of the films was studied using a glancing angle X-ray diffractometer. The bandgaps of the films were calculated using measured optical reflection data.

Abstract: In this paper a new robust and precise ordering criterion for the characterization of self-assembled hexagonal lattice like Anodic aluminum Oxide (AAO) has been proposed. In order to unveil the mechanism for the self-organization process and deposition techniques in AAO, it is necessary to be able to have a quantitative objective criterion to evaluate the amount of order through every SEM sample of a material. Most of methods in the literature are only able to characterize the extreme case of highly ordered or lowly ordered texture well. But the real challenge is in characterizing the order of medium-ordered texture which is the dual concept of near-regular texture analysis in image processing. Our method based on more advanced image processing techniques, Gabor filter-bank, are able to characterize medium-ordered AAO textures more precisely. Our idea is also able to define the domain's place of the AAO image.

Abstract: In this paper, a two-step method is developed for efficient preparation of Cu/Pt-Pd core-shell structured catalyst on Nafion-bonded carbon paper electrodes for a polymer electrolyte membrane fuel cell. Copper nanoparticles with diameter distribution of 80-160 nm are obtained by potential-modulation electrodeposition. In copper electrodeposition the charge-transfer step is fast and the rate of growth is controlled by the rate of mass transfer of copper ions to the growing centers. After the copper electrodeposition the replacement of Cu by PtPd occurs spontaneously by an irreversible redox process. The nature and composition of PtPd/Cu on pretreated carbon paper are characterized by field emission–scanning electron microscopy (FE-SEM) and energy dispersive X-ray (EDX) spectroscopy, respectively. The as prepared Cu/PtPd electrode is found in the form of core-shell structure with uniform dispersion on the surface with average nanoparticles of 41.5 nm diameter. Electrochemical activity of PtPd/Cu and conventional Pt/C on pretreated carbon paper electrodes towards oxygen reduction is studied by linear sweep voltammetry experiments. Low values of Tafel slope and free activation energy reveal that Cu/PtPd with core-shell structure shows greater electrochemical activity than conventional Pt/C catalyst. Electrochemical surface area (ECSA) results also show that Cu/PtPd with core-shell structure has greater stability than the Pt/C electrode.

Abstract: Herein, copper nanoparticles were synthesized using electrochemical method at pH 5, 6.5, 9.5 and 12.5 (coded as Cu5, Cu6.5, Cu9.5 and Cu12.5, respectively). Copper was used as electrode whereas 0.15 M oxalic acid in aqueous solution was used as an electrolyte. Effect of pH of the electrolyte solution on the morphological, structural and textural properties of prepared copper nonoparticles was studied. Prepared nanoparticles were characterized by X-ray crystallography, Field emission scanning electron microscope, transmission electron microscopy, thermogravimetric analysis, differential thermal analysis and textural analysis. The morphology and sizes of the nanoparticles prepared varied with the initial pH of the solution. Sizes of synthesized Cu particles were found to be in the range of 20 nm to 7 μm. All the particles were mesoporous in nature. Cu5 was found to contain 67% copper hydroxide and 33% copper oxalate whereas Cu6.5, Cu9.5 and Cu12.5 essentially consisted of copper hydroxide.

Abstract: NiO nanoparticles are successfully prepared by sol-gel technique. A systematic change in preparation parameters like calcination temperature, calcination time and pH value has been done in order to study the influence on crystallite size. The prepared samples are characterized by X-ray diffractometer, Transmission electron microscopy, Energy dispersive x-rays analysis and Raman spectroscopy. It is shown that crystallite size mainly depends on the calcination temperature rather than pH value or calcination time.

Abstract: Electrospinning is a simple versatile process to produce nanofibers. However, it requires careful approach to form appropriates fibers for different purposes. This report describes aspects influencing successful development of nanofiber containing BSA using electrospinning method. Optical and scanning electron microscopy, energy dispersive X-Ray and Fourier transformed infrared spectroscopy, differential scanning calorimetric, and X-Ray diffraction analysis of nanofiber were performed. Modification of PVA/BSA nanofiber with Eudragit L-100 was conducted by dip coating method. The presence of BSA increased the diameter of the fibers. Modification of PVA/BSA nanofiber with Eudragit L-100 delayed the release of BSA in acidic medium but promoting its release in intestinal mimicking medium.

Abstract: The effect of carrier gas flow rate on the morphologies of In₂O₃ nanostructures was studied in a horizontal tube furnace via chemical vapor deposition method. Under low carrier gas flow rate, there appeared randomly oriented nanorods on the substrate, while the high carrier gas flow rate resulted in the nanocubes growth. The insufficient understanding of the role of the argon carrier gas flow rate motivated us to systematically research the transportation of the grown species during the growth processes and its effect on the nanostructure growth. COMSOL simulations were applied to evaluate the distribution of the growth species in the reactor versus the carrier gas flow rate, based on the geometry of our chemical vapor deposition system and a variety of actual growth conditions. The vapor species partial along with different carrier gas rate could cause the different super saturation condition, which is mainly to be responsible for the structural transformation. A combined VLS–VS mechanism was proposed to describe the growth of the Au-catalyzed In₂O₃ nanorods, while the nanocubes were governed by catalyst free VS growth mechanism.

Abstract: The Alternating Gradient Field Magnetometer (AGFM) is an instrument whose high sensitivity (10-8 emu) allows the detection of small amounts of magnetic nanoparticles (MNPs) with high accuracy. Over the last few years, different magnetic techniques have been used for in vitro measurements of magnetic nanostructures inside biological tissues. However, in vivo studies about their distribution within the body are very scarce because their dispersion, after being delivered, reduces their magnetic signal and hinders detection. In this paper we compare the longitudinal relaxation time (T1) and magnetization measurements in mice's biological tissues for the tracking of MNPs after of an injection of iron oxide nanoparticles. Furthermore, we have correlated the AGFM data with Fast Field Cycling NMR Relaxometry (FFCNMR Relaxometry) measurements with histological analysis. The results have demonstrated that these techniques are useful for detecting minute amounts of MNPs in excised organs after in-vivo comparable to other more conventional techniques for the measurement of MNPs biodistribution and clearance. Details about the preparation of the in vivo samples, measurement protocol and statistical data processing are given.