Silver Nanocolloid Research Articles

One-Pot Synthesis and Characterization of Poly(Alkoxysilane)s Promoted by Silver Colloidal Nanoparticles

Si-Si/Si-O dehydrocoupling of hydrosilanes with alcohols (1:1.5 mole ratio), catalyzed by AgNO3 which converted to Ag(0) colloidal nanoparticles, gave poly(alkoxysilane)s in one-pot in moderate to high yield. The hydrosilanes include p-X-C6H4SiH3 (X = H, CH3, OCH3, F), PhCH2SiH3, and (PhSiH2)2. The alcohols include MeOH, EtOH, (i)PrOH, PhOH, and CF3(CF2)2CH2OH. The weight average molecular weight and polydispersity of the poly(alkoxysilane)s were in the range of 1,600 approximately 8,000 Dalton and 1.4 approximately 3.5. The dehydrocoupling reactions of phenylsilane with ethanol (1:3 mole ratio) in the presence of the silver nanocolloid catalyst produced only triethoxyphenylsilane as product.

The effect of silver nanoparticles on splenocyte activity and selected cytokine levels in the mouse serum at early stage of experimental endotoxemia

The objective of this study was to determine the effect of a nonionic silver nanocolloid administered orally for 7 or 14 days at three concentration levels (25 ppm, 2.5 ppm, and 0.25 ppm) on the phagocytic activity and mitogenic response of splenocytes and selected cytokine serum levels (IL-1beta, IL-6, IL-10, IL-12 p70, TNF-alpha) in NMRI mice at the early stage of experimental endotoxemia induced with single 30 microg/mouse dose of bacterial LPS. Regardless of the period of administration, silver nanoparticles enhanced the production of proinflammatory cytokines and anti-inflammatory cytokine IL-10, and they inhibited IL-12 p70 levels in response to LPS challenge. The studied nanoparticles' effect on splenocyte activity was determined by the period of administration. After 7 days of use, silver nanoparticles enhanced the phagocytic activity, and doses of 2.5 ppm stimulated the mitogenic response of splenocytes. After 14 days of administration, silver nanoparticles lowered the phagocytic activity regardless of the dose applied. Although the results obtained are ambiguous, they suggest that silver nanoparticles administered via the alimentary tract are more likely to increase an inflammatory response of an organism than offer protection after LPS challenge.

Preparation of Ag/PVP Nanocomposites as a Solid Precursor for Silver Nanocolloids Solution

A polyvinylpyrrolidone (PVP)/Ag nanocomposites was prepared by the simultaneous thermal reduction and radical polymerization route. The in situ synthesis of the Ag/PVP nanocomposites is based on the finding that the silver n-propylcarbamate (Ag-PCB) complex can be directly dissolved in the NVP monomer, and decomposed by only heat treatment in the range of 110 to to form silver metal. Silver nanoparticles with a narrow size distribution (5 - 40 nm) were obtained, which were well dispersed in the PVP matrix. A successful synthesis of Ag/PVP nanocomposites then proceeded upon heat treatment as low as . Moreover, important advantages of the in situ synthesis of Ag/PVP composites include that no additives (e.g. solvent, surface-active agent, or reductant of metallic ions) are used, and that the stable silver nanocolloid solution can be directly prepared in high concentration simply by dissolving the Ag/PVP nanocomposites in water or organic solvent.

Design and evaluation of single nozzle with a non-conductive tip for reducing applied voltage and pattern width in electrohydrodynamic jet printing (EHDP)

We investigated the effect of a non-conductive tip inserted into a capillary nozzle (inner diameter of 860 µm) on jet formation and pattern width in electrohydrodynamic jet printing. Simulated and experimental results showed that the non-conductive tip stabilized the jet, and reduced the effective nozzle diameter and the onset voltage needed for the cone-jet mode, by eliminating the backflow near the apex of the liquid cone while a tiny backflow away from the apex of the liquid cone still remained. Silver nanocolloid patterns with an average width of 18.5 µm (standard deviation: 1.5 µm) were obtained with an applied voltage of 2.7 kV, a flow rate of 3 µl min−1 and a stage velocity of 200 mm s−1.

Thermo optical response and optical limiting in Ag and Au nanocolloid prepared by laser ablation

Optical limiting of the gold and silver nanocolloids has been studied under CW illumination at 532 nm. Nonlinear and thermo optical properties of the samples were investigated using CW Z-scan experiments. Sign of nonlinear refraction coefficient of colloids are negative at this condition. Negative sign implying thermal self defocusing is the most important mechanism of nonlinearity in our experiments. Diffraction pattern and greater magnitude of nonlinearities shows that gold nanocolloid is a better optical limiter than silver nanocolloid in the same experimental condition. Also thermo optical coefficient and limiting threshold of the samples have been determined.

Surface-enhanced Raman scattering study of benzyl mercaptide and benzyl isocyanide on gold and silver nanocolloid surfaces

The adsorption structure and binding of benzyl mercaptide (BZM) and benzyl isocyanide (BZI) on gold and silver nanocolloid surfaces have been comparatively investigated by means of surface-enhanced Raman scattering (SERS). The appearance of the ring ν(CH) band denoted a standing geometry of the phenyl ring of BZI. On gold, the CNC bonds appeared to have a largely parallel orientation as evidenced by the disappearance of the ν as(CH 2) vibrations. On the other hand, a prominent ν as(CH 2) band in the SERS spectra suggests a rather linear bond angle of CNC: on silver.