Journal of Nano Research Vol. 66

Abstract: In this work, the effect of carbon on the electrochemical properties of multi-walled carbon nanotube (MWCNT) functionalized Lithium iron manganese phosphate was studied. In an attempt to provide insight into the structural and electronic properties of optimized electrode materials a systematic study based on a combination of structural and spectroscopic techniques. The phosphor-olivine LiFe_0.5Mn_0.5PO₄, was synthesized via a simple microwave synthesis using LiFePO₄ and LiMnPO₄ as precursors. Cyclic voltammetry was used to evaluate the electrochemical parameters (electron transfer and ionic diffusivity) of the LiFe_0.5Mn_0.5PO₄ redox couples. The redox potentials show two separate distinct redox peaks that correspond to Mn²⁺/Mn³⁺ (4.1 V vs Li/Li⁺) and Fe²⁺/Fe³⁺ (3.5 V vs Li/Li⁺) due to interaction arrangement of Fe-O-Mn in the olivine lattice. The electrochemical impedance spectroscopy (EIS) results showed LiFe_0.5Mn_0.5PO₄-MWCNTs having high conductivity with reduced charge resistance. This result demonstrates that MWCNTs stimulates faster electron transfer and stability for the LiFe_0.5Mn_0.5PO₄ framework, which demonstrates favorable as a host material for Li⁺ ions.

Abstract: Introduction of metallic nanoparticles into glasses can obviously improve the up-conversion luminescence efficiency through surface plasmon resonance (SPR). In this research, the Er³⁺/Yb³⁺ co-doped TeO₂-ZnO-Bi₂O₃ glasses containing silver nanoparticles and nanocrystals were prepared by direct current(DC) electric field assisted heat treatment, to study the effect of silver nanoparticles on the up-conversion luminescence properties of Er³⁺. The results show that, although the introduction of AgNO₃ will weaken the thermal stability of TZB-ErYb to some extent, the number and size of silver nanoparticles can be increased after DC electric field treated at 100°C for 10 minutes. Meanwhile, the nanocrystals do not grow too large to affect the up-conversion emission intensity of Er³⁺. The up-conversion emission intensity of Er³⁺ in TZB-ErYb-6AgNO₃-100°C-150V-10min is 43 times stronger than that of TZB-ErYb. These results indicate that DC electric field assisted heat treatment can synergistically adjust the silver nanoparticles and nanocrystals and is a promising method to improve the luminescence properties of tellurite glasses.

Abstract: The bis (O-n-propyldithiocarbonato) diphenyl of tin (IV) [Ph₂Sn (S₂COⁿPr)₂] was synthesized as a precursor for the preparation of SnS nanoparticles. The complex was characterized by X-ray single crystal diffraction, thermogravimetric analyses (TGA), nuclear magnetic resonance (NMR) and IR spectroscopy. Hot injection method was used to synthesize the SnS nanoparticles under nitrogen atmosphere at 260 °C. The SnS nanoparticles formed were studied by powder X-ray diffraction, Raman spectroscopy and transmission electron microscopy (TEM). The phase was found to be polycrystalline, orthorhombic SnS with a strong (111) preferred orientation. The band gap of SnS nanoparticles is 1.28eV.

Abstract: For the development of complex calcium sulfonate grease containing ultrafine SiO₂/MoS₂ powders with self-reparing performance. On the basis of the dispersion of the nanoSiO₂ particles, the effects of particle size,addition amount,load and the mass ratio of nanoSiO₂ to ultrafine MoS₂ powders on the tribological properties of commercial No.2 complex calcium sulfonate grease were systematically studied by four ball friction and wear tester. The results show that suitable particle size and addition amount of single SiO₂ and MoS₂ powders can significantly reduce the coefficient of friction (COF) and the wear scar diameter (WSD) of the grease. The composite of nanoSiO₂ and MoS₂ powder can broaden the load range of base grease and further improve the tribological properties of complex calcium sulfonate grease. When the mass ratio of nanoSiO₂ powder to MoS₂ powder is 3:7 and the total addition amount is 0.8wt%, the COF and the WSD of the grease are decreased by 53.64% and 27.08%, respectively, compared with the base grease. The two powders in the composite grease have synergy effect for improving the tribological performance and the friction stability of the grease during the process of long friction.

Abstract: In this study, silver nanoparticles (AgNPs) were synthesized using methanol extract of Semenovia. suffruticosa. The prepared AgNPs (SS-AgNPs) were examined by ultraviolet-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-raydiffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscope (SEM). Afterward, biological activities including cytotoxicity, ability to generate reactive oxygen species (ROS), antileishmanial and antibacterial effects were investigated. According to the UV-Vis spectroscopy, absorption peak at 430 nm indicates the synthesis of AgNPs. TEM and SEM image of AgNPs shows spherical shape with size range of 20–70 nm. FTIR analysis displayed the involvement of phytochemical constituents in synthesized nanoparticles. The X-ray diffraction analysis confirmed the synthesis of highly pure AgNPs with high crystallinity and Cubic shape with crystalline size of 21.4 nm. SS-AgNPs were cytotoxic on cell lines with IC₅₀ values of 15, 20, 20 and 26 µg/mL in HEK 293, Caco-2, SH-SY5Y and MDA-MD-231 cells, respectively. DCFH-DA assay showed that 24 h exposure to 25, 50, 100, 200 µg/mL concentrations of SS-AgNPs significantly increased production of ROS in cells that indicate oxidative stress induction by SS-AgNPs. Annexin V-PE/7-AAD staining analysis revealed a combination of apoptosis and necrosis following the exposure of Ag NPs to cells. SS-AgNPs displayed a notable bactericidal activity against Gram-negative bacterial strains. SS-AgNPs revealed remarkable antileishmanial activity against the promastigote and amastigote stages of Leishmania. major. IC₅₀ values of SS-AgNPs were 16.17 and 6.35 using promastigote and amastigotes assay respectively. Conclusively, phytosynthesized AgNPs is effective in antileishmanial, antimicrobial and cytotoxic activities.

Abstract: The principal aim of this research is using biosynthesized ZnO-CaO nanoparticles (NPs) for preparation of indole derivatives. ZnO-CaO NPs have been prepared using Zn(CH₃COO)₂ and eggshell waste powder in solvent-free conditions. Morphology and structure of NPs were determined by FT-IR, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy dispersive spectra (EDS). It was used as a highly efficient catalyst for the synthesis of indole derivatives. Some indole derivatives were synthesized by the reaction of indole, formaldehyde, aromatic and aliphatic amines in the presence of ZnO-CaO NPs (5 mol%) in ethanol under reflux conditions. The assigned structure was further established by CHN analyses, NMR, and FT-IR spectra. Because of excellent capacity, the exceedingly simple workup and good yield, eco-friendly catalyst ZnO-CaO NPs were proved to be a good catalyst for this reaction.

Abstract: Electrospray technique has received increasing attentions for intracellular gene delivery as well as production of nanoparticles. In this study, chitosan/pDNA nanoparticles with N/P ratio of 5 were prepared and transferred to HEK293T cells by electrospray technique. Physicochemical characterization of prepared nanoparticles, including size, zeta potential and entrapment efficiency was performed and attachment of pDNA to chitosan was confirmed by gel agarose electrophoresis. Moreover, transfection efficiency was investigated using flow cytometry. MTT assay was performed for cell viability studies. Nanoparticles were prepared at three pDNA concentrations of 10, 55 and 100 μg/ml in fixed N/P ratio. Size of nanoparticles was obtained as 110, 188 and 240 nm, using DLS. SEM showed size of 102.34 ± 10.66 nm for samples having 55 μg/ml pDNA. Zeta potential and entrapment efficiency were +25 mv and 85±4%m respectively. The effect of pDNA concentration, electrospray time and incubation time on transfection efficiency was investigated using Box-Behnken design. Percent of GFP-positive cells was 41.05 ± 3.04% which was taken as an indicator of transfection efficiency. Transfection efficiency of this method was then compared with that of calcium phosphate (31.1 ± 2.4%), showing improved efficiency. Considering the fact that electrospray is an easy, low cost, one-step process which makes low damage to cells and produces monodispersed nanoparticles, the method is introduced as a fascinating approach in gene transfection.

Abstract: A series of PEGylated active carbon nanoparticles were fabricated with improved dispersity in water and were explored for their ability for carrying drugs and potential application in lymphatic targeted tracing and chemotherapy of colorectal cancer. The active carbon nanoparticles were oxidized in a mild condition with 30% H₂O₂ solution and then mPEG-NH₂ was grafted to the nanoparticles. Compared with the original carbon nanoparticles, the oxidized and PEGylated nanoparticles all present improved stability and initial solubility in water and the PEGylated nanoparticles perform best. Size of the nanoparticles was well controlled in a rational area which can fulfill the requirement for lymphatic targeting. The PEGylated nanoparticles have excellent drug loading properties and allow for sustained release under physiological conditions. The MTT results show the drug-loaded nanoparticles can effectively kill SW480 cells (Human Colon Cancer Cells). These characteristics make the PEGylated nanoparticles become a promising candidate for using as drug-loaded powder for both lymphatic targeted tracing and chemo-therapy without using suspending agent in tumor treatment.

Abstract: We report the preparation, structural, electrochemical and photocatalytic studies of monodispersed cadmium sulphide quantum dots from didecylaminyl dithiocarbamate and 4-chloro-3-(trifluoromethyl) anilinyl dithiocarbamate cadmium(II) complexes. Powder X-ray diffraction pattern confirms hexagonal crystalline phases for the as-preapred CdS quantum dots irrespective of the precursor used with particle size of 3.39-5.51 nm. Optical absorption band edges of 515 nm were observed for the cadmium sulfide quantum dots with energy band gaps estimated from the Tauc plots of 1.97 eV for OLM-CdS1 prepared from Cd(II) didecylaminyl dithiocarbamate and 1.92 eV for OLM-CdS2 prepared from Cd(II) 4-chloro-3-(trifluoromethyl) anilinyl dithiocarbamate. These energy band gaps are blue shifted with respect to the bulk cadmium sulphide. The calculated electrochemical band gap of 2.34 V and 3.30 V are higher than band gap energy. The as-prepared CdS quantum dots were used as photocatalysts for the photocatalytic decomposition of methylene blue (MB) with efficiency of 61 % and 55 %.

Abstract: The effects of pre-heating temperature and thickness of layers on (002) preferred orientation of ZnO thin films and their photocatalytic activity are reported. All films crystallize into a Zincite-type structure. With increasing pre-heating temperature, the evolution from (002) to (101) diffraction peaks indicates change in growth mode of ZnO films. Pre-heating at 100°C is the most favourable for highly oriented ZnO thin films along (002) plane whereas all films deposited with different number of layers are oriented along (101) plane. The crystallite size is found to be in the range 20 - 32 nm. The observed average optical transmittance for these films is higher than 90% in the visible range. The energy band gap decreases with increasing number of layers but increases with increasing pre-heating temperatures_. Wettability tests of ZnO thin films surface show a hydrophobic aspect for all films. The film pre-heated at 400°C with 223nm of thickness exhibits the highest degradation of methyl blue dye of 94% with high levels of photostability over five cycles.