Current Nanomaterials - Volume 2, Issue 1, 2017

Background: Gold nanoparticles (GNPs) are of tremendous interest due to their wide application range in the field of therapeutics and diagnostics. However, its potential is limited by its mode of synthesis utilizing different chemicals which are costly, hazardous and often labor-intensive. Nevertheless, the GNPs synthesized through green methods by using plant extracts can overcome these limitations and have wider acceptance. Objective: The present study intends to synthesize and characterize the GNPs by exploiting the bioreducing properties of Heartleaf moonseed leaf extract (HMLE), a well-known medicinal plant. Method: Different volume fractions (1-6%) of aqueous- ethanoic extract of Heartleaf moon seed were used for GNPs synthesis via microwave heating for a minute. The synthesis of GNPs was confirmed by UV-visible spectroscopy and characterized by Zeta potential measurement, Fourier Transform Infra- red Spectroscopy (FTIR), X- ray Diffraction studies (XRD) and Transmission Electron Microscopy (TEM). Results: UV-visible spectroscopy confirmed GNP formation giving a characteristic peak at 560 nm. Zeta potentiometer showed the charge of GNPs as -30.3mV. XRD pattern of gold that is (111), (200), (220) and (311) was obtained due to Bragg reflections corresponding to different lattice planes of GNPs. FTIR analysis indicated the surface adsorption of biomolecules containing asymmetric and symmetric CH2 stretch bands. TEM image showed different sizes of GNPs with an average of 12 ± 3.7 nm and shape such as polygonal, cylindrical and prism-shaped GNPs. Conclusion: This method avoids the use of toxic chemicals; hence possesses immense prospect in vivid biomedical applications.

Background: Electrochemistry technique has attracted significant attention over the past decade as a potential candidate for the highly sensitive detection of analyte species. Objective: The goal of the present work is to fabricate a novel electrochemical non-enzymatic glucose sensor based on the nickel-copper/graphene oxide-modified glassy carbon electrode (Ni- Cu/GO/GCE). Method: A bare GCE was coated with graphene oxide, and then immersed in a deoxygenated solution containing 50 mM NiCl2 and 50 mM CuCl2 for the electrodeposition at -0.6 V for 100 s. The modified electrode's morphology and electrochemical performance were characterized using scanning electron microscopy and cyclic voltammetry, respectively. Results: The Ni-Cu/GO/GCE was found to exhibit a higher electrocatalytic activity for glucose oxidation than did a nickel/graphene oxide-modified GCE in an alkaline solution. When used as a glucose sensor, the electrode exhibited a sensitivity of 160.37 μA mM^-1 cm^-2 for glucose oxidation with a linear range from 15 μM to 1030 μM and a detection limit of 2 μM. The sensor was highly selective for glucose even in the presence of common interfering species such as ascorbic acid, uric acid, and dopamine. As a demonstration of its practicality, the Ni-Cu/GO/GCE was used to measure glucose in fetal bovine serum. Conclusion: A non-enzymatic glucose sensor based on the Ni-Cu/GO/GCE with high sensitivity and improved specificity was developed and characterized. Selective detection of glucose in a linear concentration range of 15-1030 μM was obtained. The proposed method has potential to be applied for accurate measurement of glucose level in real samples.

Background: Tuberculosis bacilli has a highly lipoidal cell, which makes penetration of drugs into the cells difficult leading to the development of resistance, which can be overcome by the use of nanonized niosomal delivery system. Many plants of genus Spermacoce have exhibited antibuberculosis activity, which has not been tested for S. hispida. Objective: The aim of the present study was to study the antituberculosis activity of Spermacoce hispida extracts and develop novel nano noisome based drug delivery system for the extract of Spermacoce hispida to enhance antituberculosis activity. Method: Thin film hydration technique was employed for the preparation of herbal nano niosomes using different non-ionic surfactants (Span 40 and span 60), cholesterol and suitable solvents. Characterization of niosomes was done using photo micrographs, transmission electron microscopy (TEM), entrapment efficiency, in vitro drug release, physical stability and in vitro antituberculosis activity. Results: Nano niosomes were found to be spherical in shape, which was confirmed by photomicrograph. In the preparation of calibration curve, the extract was found to obey Beer’s law in range of 20- 50 μg/ mL. Transmission electron micrographs were obtained for selected batches (SCE3, SCE5, SCE6). The vesicles were of varying size 2-3 μm, 1-2 μm and 3-4 μm, respectively. The drug entrapment efficiency for niosomes was observed in the range of 23.4±0.404 to 82.5±0.472 percent. In the sedimentation studies, the niosomes of three batches (SCE4, SCE5 and SCE6) took 75 days to settle. The release of drug from niosomes containing Span 40 was 51% and Span 60 was 53% in 200 min. It was observed that formulation SCE 3 (71±0.351-50±0.528), showed higher stability over the formulation SCE 5 (57±0.432-49±0.642), SCE 6 (59±0.565-33±0.212). Colour changes were not found in all formulations after twelve weeks. In the in vitro antituberculosis activity, formulations SCE3 and SCE6 were effective at 12.5 μg/mL, while SCE5 was effective at 25 μg/mL, which was better than the chloroform extract. Conclusion: The developed niosomal nano-carrier system exhibited prolonged release of drug and enhanced the in vitro antituberculosis activity of Spermacoce hispida extract.

Background: Atomic force microscopy (AFM) is a modern and one the most advanced techniques used in the morphological screening of nanoparticles and other nano and micro biomaterials. Objective: In this research, we tried to identify the problems and the reasons behind the failed artefacts of the transfersomes made of raloxifene HCl as a model drug, and sodium deoxycholate (anionic), Span 80 and Span 85 (non-ionic) as the surfactants during their characterization by AFM. Method: The critical approach in preparing the test samples for AFM was studied on the mica cover slip. Dynamic light scattering was used to determine the hydrodynamic diameter and zeta potential of the lipid vesicles while high-resolution transmission electron microscopy (HRTEM) was used to measure/determine the particle size. The methods used in the preparation of slides for the lipid-based nano-samples were also summarised in addition to the different materials also used. Results: Hydrodynamic diameter of the formulations was reported as Z-Average values. TSD and TSP-80 formulations showed an average size of 79.96±0.63 and 128.00±0.15 nm, with a PDI of 0.195 and 0.101 with the zeta-potential recorded -17.10±0.21mV and +35.00±0.25mV, respectively. We also observed that the AFM images show a close proximity with HRTEM. AFM shows that external factors such as dilution, selection of slides and preparation of sample led to alteration in the results. Conclusion: AFM characterization was carried out in order to visualise the collapsed and failed artefact due to the use of undefined substrate and methodology. The 3-D images of successful artefact viewed after using suitable conditions clearly showed a distinguished appearance when compared with failed artefact.

Background: Tosylate indicates to the anion of p-toluenesulfonic acid, the tosyl group is also useful as protecting group for amines, it is abbreviated as Ts or Tos. Objective: In this study geometry optimization, infrared spectra, and some electronical properties have been achieved. Method: All the calculations have been based on the density functional theory (DFT) at the 3-21G basis set B3LYP level throughout Gaussian 09 package. Results: geometrical structure, HOMO surfaces, LUMO surfaces, contour maps, total energy, energy gap have been produced throughout the geometry optimization. Conclusion: The values of energy gap very appropriate to some electronic devices that need semiconductor energy gap approximate to (4.1eV), all molecules owe anti-ferromagnetic material properties because it have beta orbitals at energy levels, that is to say there is new available levels may be occupied.

Background: We report for the first time that there is a considerable effect on the morphology and optical properties of hematite (α-Fe2O3) nanoparticles by varying the precursor concentrations from 1mmol to 3mmol. The nanoparticles were synthesized by combustion route using ferric nitrate, citric acid and ammonia as precursors at an annealing temperature range of 600°C. Phase purity, morphological studies and optical properties of the products were studied by powder X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Raman spectroscopy and UV Visible spectroscopy. The as-synthesized hematite nanoparticles have a mesoporous granular and somewhat spherical structure with a bulk density ranging from 0.11 to 0.59gmcm^-3. Conclusion: The band gap of the as-synthesized(α-Fe2O3) nanoparticles decreases from 1.96eV-1.77eV with the decrease in the precursor concentration. Raman spectroscopy confirmed the formation of a hematite phase of iron oxide nanoparticles. Practical percentage yield of the products increased from 47% to 65% with decrease in precursor concentrations.

Background: Recently, manganese dioxide MnO2 has attracted renewed attention of investigators. This is primarily due to its low cost, making it a potential material for various applications. Objective: The goal of the present work was to synthesize MnO2 nanorods and study their optical and electrochemical properties. Method: The method involves refluxing of potassium permanganate (KMnO4) and manganese chloride (Mncl2) mixture in isopropyl alcohol (IPA)-water system. The surface morphology, vibrational response and structural parameters were characterized using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman Spectroscopy, Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA) and BET surface area measurements. The optical properties of the synthesized material were investigated using PL and UV-Vis. Spectroscopy. Electrochemical properties of resulting product (as an electrode) were studied in two-electrode cell assembly, employing galvanostatic charge/discharge (GCD), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) techniques. Results: FESEM and TEM images show that material is in the form of nanorods. XRD analysis showed the tetragonal structure of synthesized product. Thermal stability up to 400 °C has been observed for the sample. The BET analysis of the sample showed the existence of large and small pores. A direct band-gap of 4.1 eV was observed. Specific capacitance of value 108.2 F g^-1 was measured for 1 M Na2SO4 electrolyte solution, at current density of 1 mA cm^-2. Conclusion: MnO2 nanorods were successfully prepared using chemical refluxing technique. The electrochemical studies show that MnO2 can be profitably used for energy storage applications.

Background: The nanoscale junction represents one of the most active classes of materials, and they have been widely used as active materials for nanoelectronic applications. Objective: In this study, we theoretically analyzed the transfer characteristics for a single molecule in nanoscale junctions at room temperature. Method: All the calculations are based on Anderson model with electron-phonon interactions. The molecule transfer in the junction is viewed as a potential barrier crossing problem which is described by a truncated harmonic oscillator and the inelastic electron tunneling. Results: The transfer was done by overcoming the associated potential barrier due to a gain in energy from the tunneling electrons. The transfer behavior of the molecule between tow leads became more clearly visible by studying the transfer rate characteristics, which led to the numerical calculations. Characteristic features of this study include a power-law dependence of the transfer rate with the applied bias voltage and crossover from current-driven to thermally activated transfer by decreasing the vibrational mode energy or increasing the temperature of the junctions. Conclusion: Our analysis may present insight to understand the physical and chemical mechanisms of motion and reaction of single molecule induced by inelastic tunneling electrons.

Background: ‘Plasmonics’ dealing with localized surface plasmon resonances in metal nanoparticles (nanostructures) and planar metal-dielectric interfaces is a rapidly developing field and is under recent intensive investigations owing to fundamental interests and numerous potential applications. In this regard, the polarization properties of scattered light from plasmonic systems are of paramount importance for gaining fundamental understanding on a number of interesting and intricate polarization optical effects and for their potential applications. Coupling and inter-conversion between the spin (SAM, circular / elliptical polarization) and orbital angular momentum (OAM, phase vortex) degrees of freedom of light leading to the so-called spin orbit interaction (SOI) of light, is one such intriguing spin (polarization) optical effect that has recently been observed in diverse plasmonic systems. These have received particular attention because of their potential applications towards development of novel spin-controlled nanophotonic devices. Objective: Here, we briefly review the basic concepts of SOI, the resulting spin optical effects and their manifestations in diverse nano-plasmonic systems. Method: Mueller matrix spectroscopic system is developed and utilized for probing and tuning spindependent plasmonics effects. Results: We provide illustrative results on controlled enhancement of the SOI effects in plasmonic nanostructures. The specifics of a novel dark field Mueller matrix spectroscopic experimental system and the representative results of studies using this system on the SOI and other spin-based plasmonics effects are presented. Conclusion: The implications of these results towards spin-controlled photonic applications are discussed.