سال:1393 | دوره: | شماره: |تعداد مقالات:9

Nanoparticles of azithromycin are prepared using solvent/antisolvent precipitation method. The solubility of drug in water and the oral bioavailability are increased with decreasing particle size. The effect of type and concentration of surfactant and feed drug concentration are evaluated on the precipitated particle size. The nanoazithromycin in range 200–400 nm is obtained by the addition of absolute ethanol as solvent, water as antisolvent in presence of TweenÒ 80 as surfactant. The prepared nanoparticles are characterized by infra-red spectra, particle size distribution, scanning electron microscopy, X-ray diffraction and differential scanning calorimetry. The chemical structure of nanosized azithromycin does not show any change but the crystallinity reduces in comparison with raw drug. Dissolution of azithromycin nanoparticles in purified water and buffer phosphate (pH of 6.0) is 2.93 and 3.36, respectively, times of raw drug in 30 min.

A kind of water–oil separation material was fabricated by depositing the mesoporous microspheres (MS) on filter paper. MS had been prepared via surfactant-template method and modified by octyltriethoxysilane. The diameter of microspheres was in the range of 200–800 nm. There were uniform mesopores in the microspheres, and the surface area of microspheres was more than 1, 000 m2 g-1. The thin film, showing both hydrophobicity and lipophilicity, had a high contact angle for water (greater than 130o) and a low one for n-hexane (about 0o). Meanwhile, the film presented excellent separating efficiency between water and oil, which could reach 98.8%. Good selectivity and simple preparation procedure might lead the material to be highly valuable on water–oil separation.

The broadband optical absorption properties of silicon nanowire films fabricated by electroless metal deposition technique followed by HF/Fe (NO3) 3 solution-based chemical etching at room temperature on p-type silicon substrates have been measured and found absorption higher than that of the solid thin films of equivalent thickness. The observed behavior is effectively explained by light scattering and light trapping though some of the observed absorption is due to a high density of surface states in the nanowires films. Synthesized structures absorbed more than 82% of incident radiation in case of Cu-deposited silicon nanowires, whereas for Ag it was maximum 83%, which is much greater than that of the bulk silicon as they absorbed maximum 43% of the radiation.

In the present study, zinc (Zn), magnesium (Mg) and titanium (Ti) nanoparticles synthesized using fungus by employing various precursor salts of sulfate salts, nitrate salts, chloride salts and oxide salts. To access the nanoparticle production potential, over a hundreds of fungi were isolated from the soil and tested with precursor salts of the Zn, Mg and Ti. Out of which, only 14 fungal isolates were identified, having potential to reduce metal salt into metal nanoparticles. Upon molecular identification, six were identified as Aspergillus flavus, two each as Aspergillus terreus and Aspergillus tubingensis and one each as Aspergillus niger, Rhizoctonia bataticola, Aspergillus fumigatus, and Aspergillus oryzae. Factors responsible for more production of monodispersed Zn, Mg and Ti nanoparticles were optimized. It was concluded that 0.01 mM precursor salt concentration, 72 h of incubation at pH 5.5 and temperature 28oC resulted smaller nanoparticles obtained. The biosynthesized functional Zn and Ti nanoparticles can be stored up to 90 days and Mg nanoparticles up to 105 days in its nanoform. Bio-transformed products were analyzed using valid characterization technique i.e. dynamic light scattering, transmission electron microscopy, atomic force microscopy, energy dispersive X-ray spectroscopy to confirm size, shape, surface morphology and elemental composition. It was found that the average size of developed nano Zn was 8.2 nm, with surface charge of-5.70 mV and 98% particles were of Zn metal only. Similarly, the average size of Mg nanoparticles was 6.4 nm with surface charge of-6.66 and 97.4% Mg metal yield, whereas, Ti nanoparticles size were found in the ranges between 1.5 and 30 nm with surface charge of-6.25 mV and 98.6% Ti metal yield.

The hydrothermal synthesis and optical properties of Nb5+-doped lithium metasilicate and lithium disilicate nanomaterials were investigated. The microstructures and morphologies of the synthesized Li2-2x-Nb2xSiO3+d and Li2-2xNb2xSi2O5+d nanomaterials were studied with powder X-ray diffraction and scanning electron microscopy techniques, respectively. The synthesized niobium-doped lithium metasilicate and lithium disilicate nanomaterials, respectively, are isostructural with the standard bulk Li2SiO3 (space group Cmc21) and Li2Si2O5 (space group Ccc2) materials. Photoluminescence spectra of the synthesized materials are studied. The measured optical properties show dependence on the dopant amounts in the structure.

In this paper, we report N2, CH4 and CO2 adsorption in single-walled silicon carbon nanotubes (SiCNTs) using grand canonical Monte-Carlo and calculate the isosteric heat of gas adsorption. The results demonstrate that at ambient temperature and high pressure, gas adsorption in these nanotubes is in the order of CO2>CH4>N2 and nanotubes’ order is (10, 10)<(20, 20)<(40, 40), while this order of adsorptivity of nanotubes will be inverted for N2 when the pressure is very low. Then, we fit our simulation results to Langmuir and Langmuir–Freundlich equations to illustrate the mechanism of gas adsorptivity. The fitting exhibits that the simulation data obtained are very close to Langmuir–Freundlich behavior, which emphasizes that the dominant adsorptivity has occurred in multi-layer adsorption. Moreover, the comparison between our simulation results and other reports, which studied these gases’ adsorption on different nanoporous materials, experimentally and theoretically, is presented to illustrate that SiCNTs still have the best gas adsorptivity ability at ambient temperature and low/high pressure.

In this work, nanocomposite low-density polyethylene films with carbon nanotube base were prepared by solution casting from boiling xylene. Fresh Mazafati dates were placed on the packages obtained from films and stored at ambient temperature. In addition, the fungal growth and sensory attributes were monitored on the 0th, 30th, 60th, and 90th days of storage. Although films containing carbon nanotube increased shelf life of Mazafati dates compared to controls, some of the characteristics of sensory were lost.

The field of nanotechnology now has pivotal roles in electronics, biology and medicine. Its application can be appraised, as it involves the materials to be designed at atomic and molecular level. Due to the advantage of their size, nanospheres have been shown to be robust drug delivery systems and may be useful for encapsulating drugs and enabling more precise targeting with a controlled release. In this review specifically, we highlight the recent advances of this technology for medicine and drug delivery systems.

Polyaniline as a conductive polymer and chitosan as a natural polymer have been reacted with formaldehyde as grafting agent and potassium persulfate as an initiator. The effect of using specific primer, different ratio of monomers and the solubility of synthesized copolymer has been studied and analyzed. Characterization of this new copolymer were occurred by Fourier transform infrared spectroscopy, UV–visible, scanning electron microscopy and differential scanning calorimetry technique.