International Nano Letters
Volume:2 Issue: 1, Jan 2012

Synthesis and application of Mesoporous silicate nanoparticles is important area of research in many fields such as drug delivery, medicine, catalysis and optic. The method of synthesis strongly affects the properties of product. In this work, mesoporous silica nanoparticles were synthesized synthesized by means of a hydrogel. The obtained product was characterized by X-ray diffraction, scanning electron microscopy and nitrogen physisorption. The results show that highly ordered mesoporous silica nanoparticles were synthesized by means of a hydrogel.

In this article, Ru(4,4’-dicarboxy-2,2’-bipyridine)2(NCS)2 dye (N3) and some derivatives were investigated using DFT calculations in solution to elucidate the influence of the environment and substituted groups on the electronic properties. Full geometry optimization and investigation electronic properties of N3 dye and some derivatives were performed using DFT and HF calculations. The singlet ground state geometries were fully optimized at the B3LYP/3-21G** level of theory through Gaussian 98 program. Based on the computed results, the optoelectronic properties are sensitive to chemical solvent environments. Moreover, the properties of anatase cluster (TiO2) models have been investigated and then N3 dyes have been adsorbed on TiO2 nano-particle with diprotonated states. The modified N3 dyes highly affected electronic structure. This leads to significant changes in the absorption spectra as compared to the N3 dyes. Through hybrid methods the properties of interfacial electronic coupling of the combined system were estimated. The results of some combined systems showed that the electronic coupling, lowest LUMOs and the TiO2 conduction band resided in the visible region.

Nanocrystalline CuAlO2 was synthesized by mechanical alloying of Cu2O and α-Al2O3 powders in the molar ratio of 1:1 for 20 h in toluene medium with tungsten carbide balls and vials using planetary ball mill. The ball milling was carried out at 300 rpm with a ball to powder weight ratio of 10:1 and then annealed at 1373 K in a platinum crucible for 20 h to get CuAlO2 phase with average crystallite size 45 nm. Complex impedance spectroscopic measurement in the frequency region 1 Hz to 10 MHz between the temperatures 333 to 474 K was carried out for nanocrystalline CuAlO2 sample. The obtained complex impedance data was analyzed for that of AC conductivities, correlations between DC and AC conductivities and crossover frequencies (fco) for all the measured temperatures. Barton, Nakajima and Namikawa (BNN) relation was applied to understand the correlation between DC and AC conductivities. The observed experimental results were discussed in the paper.

The present study is aimed to investigating the formulation and in vitro anticancer activities of solid lipid nanoparticles of 5 Fluorouracil (5-FU) prepared using glyceryl monostearate (GMS) and cetyl palmitate (CP) through hot homogenization method. The lipids were selected based on the partition coefficient of 5-FU in lipids. The lipid nanoparticles were optimized for process and formulation parameters. The optimized nanoparticles were characterized for their zeta potential, morphology, release kinetics, and anti-cancer activity. Higher entrapments were achieved using a combination of emulsifiers. Zeta potential of the optimized CP and GMS SLN formulation were -8.26 and -9.35 mV, respectively. Both the optimized formulations were spherical. The in vitro release studies of SLNs of both the lipid carriers followed peppas-korsenmayer equation when carried out at pH 3.5 and pH 7.4. The Chemosensitivity assay carried out in B16F10 cell lines revealed that CP SLNs had better cytotoxicity than 5-FU solution and GMS SLNs at 48 hours of incubation. Sub-toxic concentration of 5-FU loaded CP SLNs (0.12 µg/mL) possessed comparable anti-migrational activity, colony inhibition activity and cytopathic as that of 5-FU solution effects. The results indicated that encapsulating 5-FU in CP would be a promising delivery system for delivering 5-FU.

A novel, simple, less time-consuming and cost-effective sol-gel method has been developed to synthesize Nano Titania-Silica with poly vinyl alcohol composite relatively at low temperature in acidic pH. Titania sol was prepared by hydrolysis of titanium tetrachloride and was mixed with silicic acid and tetrahydrofuran mixture. The reaction was carried out under vigorous stirring for 6 hours and dried at room temperature with addition of PVA solution. The resulting powders were characterized by X-ray diffraction, scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared (FT-IR), UV–Visible spectroscopy and thermal techniques. The grain size of the particles was calculated by X-ray diffraction, surface morphology and chemical composition was determined from scanning electron microscopy–energy dispersive spectroscopy, metal oxide stretching was confirmed from FT-IR spectroscopy, band gap was calculated using UV-Visible spectroscopy and thermal stability of the prepared composite was determined by thermo gravimetric/differential thermal analysis (TG/DTA). Since TiO2 got agglomerated on the surface of SiO2, effective adsorptive sites increase which in turn increased the photo catalytic efficiency of the resulting composite.

During the past decade, much attention has been paid to the replacement of homogeneous catalysts by solid acid catalysts. Friedel-Crafts benzylation of toluene with benzyl chloride (BC) in liquid phase was carried out over highly active, nano crystalline sulfated titania systems. These catalysts were prepared by sol gel method. Modification was done by loading 3% of transition metal oxides over sulfated titania. Reaction parameters such as, catalyst mass, molar ratio, temperature and time have been studied. More than 80% conversion of benzyl chloride and 100% selectivity are shown by all the catalysts under the optimum conditions. Catalytic activity is correlated with Lewis acidity obtained from perylene adsorption studies. The reaction appears to proceed by an electrophile, which involves the reaction of BC with the acidic titania catalyst. The catalyst was regenerated and reused up to four reaction cycles with equal efficiency as in the first run. The prepared systems are environmentally friendly and are easy to handle.

Platinum oxide nanoparticles were prepared by a simple hydrothermal route and chemical reduction using carbohydrates (Fructose and sucrose) as the reducing and stabilizing agents. In comparison with other metals, platinum oxide causes less environmental pollution; therefore, it is considered an appropriate candidate to deal with environmental pathogens. The crystallite size of these nanoparticles was evaluated from X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microscopy (TEM) and was found to be 10 nm, which is the demonstration of EM bright field and transmission electron microscopy. The effect of carbohydrates on the morphology of the nanoparticles was studied through TEM. The nanoparticles were administered to the Pseudomonas Stutzeri and Lactobacillus cultures and the incubation was done at 37 oC for 24 hours. The nanocomposites exhibited interesting inhibitory as well as bactericidal activity against P. Stutzeri and and Lactobacillus species. Incorporation of nanoparticles also increased the thermal stability of the carbohydrates. The results of this paper showed that carbohydrates can serve as a carrier for platinum oxide nanoparticles and the nanocomposites can have potential biological applications.

This paper demonstrates the synthesis of SnO2 nanoparticles using a simple hydrothermal route in the presence of the surfactant hydrazine at 100oC for 12 h. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) were employed to characterize the as-prepared product and optical property was studied by UV–vis diffuse reflectance spectroscopy (DRS). The X-ray diffraction (XRD) pattern of the as-prepared sample is indexed to the tetragonal structure of SnO2 and the calculated particle size is 22.4 nm, which is further confirmed by TEM. The selected area electron diffraction (SAED) patterns showed continuous ring patterns without any additional diffraction spots and rings of secondary phases revealing their crystalline structure. Analysis of the DRS spectrum showed the band gap of the synthesized SnO2 to be 3.6 eV. The anionic surfactant hydrazine plays a key role in the formation of the SnO2 nanostructures. A probable reaction for the formation of SnO2 nanoparticles is proposed.

Bromothymol blue (BTB) thin films were prepared by depositing a thin layer of a sol containing tetraorthosilicate (TEOS) and bromothymol blue (BTB) pH-indicator in the presence of surfactants, namely cetyltrimethylammonium bromide C19H42BrN (CTAB) or dodecyldimethyl amino-oxide C14H31NO (69%), C16H35NO (11%), Genaminox LA, (GLA) onto a glass slide substrate. CTAB or GLA surfactants were used to improve the mesostructure of the host material and to increase its porosity. Optical BTB thin films were found to be sensitive against pH, and behave as free BTB. This provides evidence for weak interactions between the BTB molecules and the host silica matrix. The effects of the sol mixture on the stability and reproducibility and the colourmetric response to solutions of different pH were examined and pKa values were determined. The BTB thin film sensors showed an advantage over the encapsulated monolithic sensors in which the thin film sensors exhibit a faster response time than the monolithic discs. These pH sensors showed reproducibility and high stability behavior.

Copper oxide nanoparticles were prepared and subsequently deposited onto the surface of cotton fiber by ultrasonic irradiation. The structure and morphology of the coated and un-coated cottons were examined by XRD and SEM/EDX analysis. These methods revealed that CuO nanoparticles are crystalline and corresponds to the monoclinic phase, and that these nanoparticles are physically adsorbed onto the cotton fiber surface. They have an average size of 10 nm, and the physical and chemical properties of the treated cotton fibers are markedly different from those of the untreated cotton fibers. The CuO-cotton fiber nano-composite tested against Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive) cultures showed a significant antimicrobial activity, whereas its analogous CuS-coated cotton material formed by the reaction CuO coated cotton fibers with H2S, showed no activity.