Journal of Nano Research Vol. 20

Abstract: The hierarchical structure of flabellate Bi₂Mo_0.5W_0.5O₆ solid solution has been successfully synthesized by a facile hydrothermal method in the presence of a surfactant of PEG6000. The as-synthesized products are composed of nanosheets with similar orthorhombic Aurivillius layered structures. The flabellate Bi₂Mo_0.5W_0.5O₆ solid solution has an average length of 4~5μmand width of 3~4μm and is composed of oblong nanosheets which has a length of several hundred nanometers, a width of ~600nm and a thickness of ~50nm. FT-IR spectra suggest that PEG6000 plays a vital role in the formation process of the flabellate Bi₂Mo_0.5W_0.5O₆ hierarchical structures. UV-vis spectra indicate that the flabellate Bi₂Mo_0.5W_0.5O₆ solid solution possessed photo absorption properties in the visible light region. The flabellate Bi₂Mo_0.5W_0.5O₆ solid solution exhibits highly efficient visible-light-driven activity for degradation of Rhodamine-B (RhB) under the 500W Xe lamp light irradiation.

Abstract: Gold nanoparticles (GNP) were synthesized, characterized and their antifungal activities investigated against three pathogenic fungi of different genera and species (Fusarium verticillioides, Penicillium citrinum and Aspergillus flavus). The anti-fungi treatments efficiency of the GNP (concentrations: 0, 0.05, 0.1 and 0.2 mg L^-1 in PDA media) were evaluated at 2, 4, 6 and 8 days after incubation by measuring the diameter of fungal colonies and investigating fungi structure alterations by scanning electron microscopy (SEM). It was observed that the GNP concentration increased, fungal colony growth diameter reduced. However, the highest GNP concentration applied in the experiment was not able to completely inhibit fungal growth. The SEM analysis of the fungi structure Au treated showed damaged hyphae and unusual bulges that were not observed in fungi that growth on medium without treatment (Control). Although up to the highest concentration of GNP media applied did not completely inhibited fungi growth, the hyphae modifications led growth reduction which could influence the toxins production by these fungi.

Abstract: The use of metal chelators is becoming increasingly important in the development of new tracers for molecular imaging. With the rise of the field of nanotechnology, the fusion of both technologies has shown great potential for clinical applications. The pharmacokinetcs of nanoparticles can be monitored via positron emission tomography (PET) after surface modification and radiolabeling with positron emitting radionuclides. Different metal ion chelators can be used to facilitate labeling of the radionuclides and as a prerequisite, optimized radiolabeling procedure is necessary to prevent nanoparticle aggregation and degradation. However, the effects of chelator modification on nanoparticle pharmacokinetic properties have not been well studied and currently no studies to date have compared the biological effects of the use of different chelators in the surface modification of nanoparticles.

Abstract: In this work, an interesting phenomenon demonstrating the similarities between the results from both Surface Enhanced Raman Spectroscopy (SERS) and Surface Enhanced Fluoresence (SEF) for rhodamine B (RhB) molecules adsorbed on gold nanoparticles was reported. By changing the deposition time, porous Au nanoparticle films with various densities and sizes were deposited. Via thermal annealing, the densities and sizes were modified. It is concluded from the results that the intensity of SERS and SEF varied in parallel with different Au nanoparticle films: different sizes and different densities. We believe that the results obtained can provide us with a reference when developing bio-chemical sensors based on Surface Enhanced Raman Spectroscopy and Surface Enhanced Fluorescence.

Abstract: The novel nanoflower precursors were successfully fabricated via microwave hydrothermal process in the presence of an anion surfactant Poly (N-vinyl-2-pyrrolidone). Nickel oxide (NiO) with the similar morphology of precursors was also obtained by a simple thermal decomposition of the as-prepared precursors at 400 °C for 2 h in air. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. The synthesized NiO nanoclusters have a cubic structure with an average size 500-1000 nm. The specific capacitance of NiO is about 208.4 F/g.

Abstract: Nanostructured MnO_x/Ni (OH)₂ composites have been electrodeposited on Ni foam for synthesis of a binder-free electrode for electrochemical capacitors with high specific capacitance and stable electrochemical properties. The microstructure, morphology and chemical composition were characterized by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. Cyclic voltammetry and galvanostatic charge/discharge measurements were applied to investigate the electrochemical capacitance of the electrode active materials. The results indicated that MnO_x acted as a template for growth of Ni (OH)₂ with an inter-connected 3D porous network nanostructure. A maximum capacitance value of 2334 F/g at current density of 5 A/g in 1 M KOH electrolyte was achieved, much higher than that of pure Ni (OH)₂ and MnO_x (992 and 179 F/g, respectively). Moreover, in the charge/discharge process at even larger current density of 20 A/g, the electrode could maintain 82.8 % of the initial specific capacitance after 500 cycles, higher than that of pure Ni (OH)₂ (only 46.6% remains). The enhanced capacitance performance was attributed to the synergic effect between the respective single oxides.

Abstract: Nitric oxide (NO) is involved in several physiological processes, such as the control of vascular tone, the inhibition of platelet aggregation, smooth muscle cell replication, immune response and neuronal communication. Several pathologies have been associated to dysfunctions in the endogenous NO production. Thus, there is a great interest in the development of NO-releasing drugs and in matrices which are able to stabilize and release NO locally in different tissues. In this scenario, the preparation of NO-releasing nanomaterials, such as dendrimers, liposomes, metallic, silica, and polymeric nanoparticles, zeolites and metal organic frameworks, is a promising strategy for delivering NO in diverse applications, as discussed in this work.

Abstract: The silver nanoparticles production (~8 nm) by Fusarium oxysporum was evidenced by the presence of the plasmon absorption band. These particles were stable by several months due to protein capping originated by the biogenic process as observed by transmission electron microscopy (TEM). The cytotoxicity of silver nanoparticles was assayed on V79 fibroblast cell line and were evaluated by tetrazolium reduction and neutral red uptake giving an IC₅₀ of 22 μM. Silver nanoparticles impregnation in textile fabrics was made through the padding method and their impregnation was confirmed by SEM-EDS. The antimicrobial tests on the textile fabric were done with different bacteria. These fabrics showed antimicrobial activity against all the studied bacteria. The antimicrobial activity was maintained until the 30ª washes showing the high adhesion of these nanoparticles on the fabric fibers probably due to interaction between protein capping and fibers. Then, it was demonstrated an efficient method of stable silver nanoparticles production and their high adhesion on the textile fabrics.

Abstract: The simple and industrially adjustable process of silver nanoparticles deposition on cotton fabric followed by coating with γ-methacryloxypropyl trimethoxysilane (MPS), as well as the properties of obtained nanocomposite has been investigated. Silver nanoparticles were prepared through the reduction of silver nitrate with sodium borohydrate and deposited on cellulose fabric. In order to stabilize obtained nanostructured material and improve its properties, the fabric was treated by immersion in cross linkable MPS. The morphology of the finished fabrics was characterized by Scanning Electron Microscopy (SEM). It has been determined that process does not impair nanocharacter of silver particles and yield uniform distribution throughout the fabric surface. The concentration of Ag in the fabric samples was determined by Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). The average deposited amount of nanoparticles was found to be 63 ppm and 48 ppm for samples without and those with MPS, respectively. The character of obtained polysiloxane coating was examined using Fourier Transform Infrared (FTIR) spectroscopy. The presence of SiOSi bonds on the cellulose surface pointed out to self-condensation between silanol groups. Differential Thermal and Thermo-Gravimetric Analysis (DTA/TGA) revealed that MPS deposited on fabric provided modification of thermal properties. The change of the surface properties after the modification was ascertained by contact angle measurements. The antimicrobial activity of the antibacterial finish on the cotton fabric, expressed as bacterial reduction efficiency, has been determined. Bacterial reduction of at least 88.5% against both, Staphylococcus aureus and Escherichia coli, has been obtained.

Abstract: Many efforts in these last years have dedicated in the development of new drugs due to an increase of microbial organisms resistant to multiple antibiotics, and silver nanoparticles appears as a novel antimicrobial agent. The aim of our work was to evaluate the in vitro and in vivo antileishmanial activity of the silver nanoparticles prepared by chemical process and by biosynthesis from Fusarium oxysporum. In vitro antipromastigote activity of L. amazonensis showed that silver nanoparticles chemically synthesized (AgCHEM), biogenic silver nanoparticles (AgBIO) and amphotericin B decreased the parasite load up to 13%, 61%, and 68%, respectively. The IC₅₀ of AgCHEM and AgBIO was 103.5 ± 11.5 μM and 31.6 ± 8.2 μM respectively. The assay of antileishmanial effect of these nanoparticles was evaluated in vivo (BALB/c mice) against L. amazonensis. The mice infected with promastigotes of L. amazonensis in the ear showed that after 10 days of treatment (twice a week for four weeks) the wound in the control (mice treated with PBS solution) was large, while the wound of the mice treated with amphotericin B (positive control) exhibited low size of lesion. The same parasitemia inhibition with amphotericin B was observed when AgBIO were used at 300 fold lower concentration, and 100 fold less concentration of AgCHEM than amphotericin B. Thus, these nanoparticles can be used in wound helping like cutaneous leishmaniasis.