Silver Azide Nanoparticles Embedded into Silica as Energetic Nano-materials

Silver azide is a primary high explosive that can be initiated by different means. In this work, silver azide nanoparticles were obtained, embedded into silica, and further derivatized with biotin. TEM, DLS, and IR measurements were used to characterize the hybrid energetic nanoparticles. The hybrid nanoparticles are made from an explosive core (silver azide) and a shell (silica), to which has been attached through an organic linker a biological target vectot (biotin).These hybrid nanoparticles can be used as models to study smart energetic nano-materials.DOI: http://dx.doi.org/10.5755/j01.ms.21.3.6926</p

ZN(II)/AU(I) AND ZN(II)/AG(I) COMPLEXES WITH SALEN SCHIFF BASE EXPRESS PROMISING CYTOTOXIC ACTIVITY IN HUMAN CANCER CELLS

Objective: The aim of our study was to evaluate the influence of two complexes of Zn(II)/Au(I) and Zn(II)/Ag(I) with Schiff base ligand (H2Salen) obtained from the condensation reaction between salicylaldehyde and ethylenediamine (abbreviated ZnSalenAu, ZnSalenAg) on viability and proliferation of cultured human cancer cells.Methods: The following cell lines were used as model systems: Human cervical carcinoma (cervical carcinoma), A549 (non-small cell lung cancer [NSCLC]), glioblastoma multiforme (8MGBA), and A431 (squamous cell carcinoma) and its multidrug-resistant (MDR) clones A431-MDR, A431-MRP, and A431-ABCG2 that express mdr1, mrp1, or abcg2 gene, respectively. The investigations were performed by thiazolyl blue tetrazolium bromide test, neutral red uptake cytotoxicity assay, crystal violet staining, hematoxylin and eosin staining, double staining with acridine orange, and propidium iodide in short-term experiments (12–72 h, with monolayer cell cultures) as well as colony-forming method in long-term experiments (25 days, with three dimensional cancer cell colonies).Results: The results obtained revealed that ZnSalenAu and ZnSalenAg decreased significantly viability and proliferation of the treated cells in a time- and concentration-dependent manner being more active as compared to the free ligand H2Salen.Conclusion: The present study demonstrates for the 1st time the ability of two heterometallic complexes ZnSalenAu and ZnSalenAg to decrease significantly viability and proliferation of cultured cell lines established from some of the most common and aggressive human cancers (NSCLC, carcinoma of uterine cancer, 8MGBA, and squamous cell carcinoma) as well as MDR cancer cells

Chromium Substituted Cobalt Ferrites by Glycine-Nitrates Process

Chromium substituted cobalt ferrites (CoFe2–xCrxO4, 0 ≤ x ≤ 2) were synthesized through solution combustion method using glycine as fuel, named glycine-nitrates process (GNP). As evidenced by X-ray diffraction data (XRD), single cubic spinel phase was formed for all CoFe2–xCrxO4 (0 ≤ x ≤ 2) series. The cubic lattice parameter (a) decreases with increasing chromium content. Room temperature 57Fe Mössbauer spectra revealed the Fe3+ and Cr3+ site occupancy, the local hyperfine magnetic fields and the substitution of Fe3+ by Cr3+ in the lattice. Scanning electron microscopy (SEM) showed a refinement of particle size with the increase of Cr3+ content. Magnetic measurements from 5 K to 120 K have shown a dropping in the saturation magnetization as the chromium content increases. This behaviour has been explained in terms of substitution of Fe3+ by Cr3+ in the cubic lattice of cobalt ferrite

Atomic scale insight into the decomposition of nanocrystalline zinc hydroxynitrate toward ZnO using Mn2+ paramagnetic probes

Layered zinc hydroxynitrate (ZHN), with the chemical formula Zn5 (OH)8 (NO3)2·2H2O, exhibits a range of special properties such as anion-exchange and intercalation capacity, as well as biocompatibility, making it attractive for a large variety of applications in fields from nanotechnology to healthcare and agriculture. In this study nanocrystalline ZHN doped with 1,000 ppm Mn2+ was prepared by two synthesis methods (coprecipitation and solid state reaction) using similar environment-friendly precursors. The complex morpho-structural [X-ray diffraction, scanning and transmission electron microscopy, textural analysis] and spectroscopic [Fourier transform infrared and electron paramagnetic resonance (EPR)] characterization of the two ZHN nanopowders showed similar crystalline structures with Mn2+ ions localized in the nanocrystals volume, but with differences in their morphological and textural characteristics, as well as in the doping efficiency. ZHN obtained by coprecipitation consists of larger nanoplatelets with more than two times larger specific surface area and pore volume, as well as a dopant concentration than in the ZHN sample obtained by solid state reaction. The thermal stability and the on-set of the structural phase transformation have been investigated at atomic scale with high accuracy by EPR, using Mn2+ as paramagnetic probes. The on-set of the ZHN structural phase transformation toward ZnO was observed by EPR to take place at 110°C and 130°C for the samples prepared by coprecipitation and solid state reaction, respectively, evidencing a manganese induced local decrease of the transformation temperature. Our results contribute to the selection of the most appropriate ZHN synthesis method for specific applications and in the development of new green, cost-effective synthesis routes for Mn2+ doped nano-ZnO

TiO2-Ag Photocatalysts for Degradation of Dyes and Antibiotics from Aqueous Solution

Titanium dioxide, TiO2, plays an important role due to its catalytic properties and high chemical [...

Mesoporous Bioactive Glass Nanoparticles in the SiO2-P2O5-CaO-MO (M=Mg, Zn) System: Synthesis and Properties

Mesoporous bioactive glass nanoparticles (MBGNs) are widely recognized for their ability to bond to hard tissue, while the ions released from the BG structure enhance specific cellular pathways. In this study, the SiO2-P2O5-CaO-MgO-ZnO system was used to successfully synthesize MBGNs by a microemulsion-assisted sol-gel method. The MBGNs calcinated at 600 &deg;C/3 h had a typical phosphosilicate structure together with a poorly crystalline hydroxyapatite (HAp). The addition of ZnO not only led to a higher degree of crystallinity of HAp but also induced a higher porosity of the particles. All MBGNs had a mesoporous structure with an interconnected network of slit shape pores. For each type of composition, two families of highly dispersed spherical nanoparticles could be identified. In vitro tests in simulated body fluid (SBF) proved that after only 3 days of immersion all the materials were covered with a layer of brushite whose degree of crystallinity decreases in the presence of Zn2+. The antibacterial assay revealed a strong inhibitory effect for all samples after 40 h of contact. Simultaneously, MBGNs did not increase the intracellular oxidative stress while it stimulated the cell proliferation process

Formation and Stabilization of Gold Nanoparticles in Bovine Serum Albumin Solution

The formation and growth of gold nanoparticles (AuNPs) were investigated in pH 7 buffer solution of bovine serum albumin (BSA) at room temperature. The processes were monitored by UV-Vis, circular dichroism, Raman and electron paramagnetic resonance (EPR) spectroscopies. TEM microscopy and dynamic light scattering (DLS) measurements were used to evidence changes in particle size during nanoparticle formation and growth. The formation of AuNPs at pH 7 in the absence of BSA was not observed, which proves that the albumin is involved in the first step of Au(III) reduction. Changes in the EPR spectral features of two spin probes, CAT16 and DIS3, with affinity for BSA and AuNPs, respectively, allowed us to monitor the particle growth and to demonstrate the protective role of BSA for AuNPs. The size of AuNPs formed in BSA solution increases slowly with time, resulting in nanoparticles of different morphologies, as revealed by TEM. Raman spectra of BSA indicate the interaction of albumin with AuNPs through sulfur-containing amino acid residues. This study shows that albumins act as both reducing agents and protective corona of AuNPs

Structural, Morphological, and Optical Properties of Single and Mixed Ni-Co Aluminates Nanoparticles

A series including single and mixed Ni-Co aluminates was obtained using the precursor method, with malic acid as a ligand. The malate precursors (polynuclear coordination compounds) were isolated and characterized by Fourier Transform Infrared (FTIR), Ultraviolet/Visible/Near Infrared (UV–Vis–NIR) spectroscopy, and thermal analysis. The UV–Vis–NIR spectra of the synthesized complex compounds highlighted the presence of Co2+ and Ni2+ in an octahedral environment. The thermal decomposition of these precursors led to Co1−xNixAl2O4 (x = 0, 0.1, 0.25, 0.5, 0.75, 0.9, and 1) spinels. The effect of Ni2+ substitution on the structure, morphology, and optical properties of the obtained oxides was studied with the help of different characterization tools. XRD, FTIR, and Raman spectra evidenced the formation of the spinel phase. The size of the crystallites and the agglomeration degree of the particles decrease when the nickel content increases. The band gap (BG) value is not significantly influenced by the Ni substitution. The fluorescence spectra recorded for all samples show a similar pattern, but different intensities of the emission bands

Lipoic Acid Gold Nanoparticles Functionalized with Organic Compounds as Bioactive Materials

Water soluble gold nanoparticles protected by lipoic acid were obtained and further functionalized by standard coupling reaction with 1-naphtylamine, 4-aminoantipyrine, and 4′-aminobenzo-15-crown-5 ether. Derivatives of lipoic acid with 1-naphtylamine, 4-aminoantipyrine, and 4′-aminobenzo-15-crown-5 ether were also obtained and characterized. All these were tested for their antimicrobial activity, as well as for their influence on mammalian cell viability and cellular cycle. In all cases a decreased antimicrobial activity of the obtained bioactive nanoparticles was observed as compared with the organic compounds, proving that a possible inactivation of the bioactive groups could occur during functionalization. However, both the gold nanoparticles as well as the functionalized bioactive nanosystems proved to be biocompatible at concentrations lower than 50 µg/mL, as revealed by the cellular viability and cell cycle assay, demonstrating their potential for the development of novel antimicrobial agents