2 research outputs found
Synthesis of Ligand-Stabilized Metal Oxide Nanocrystals and Epitaxial Core/Shell Nanocrystals <i>via</i> a Lower-Temperature Esterification Process
The properties of metal oxide nanocrystals can be tuned by incorporating mixtures of matrix metal elements, adding metal ion dopants, or constructing core/shell structures. However, high-temperature conditions required to synthesize these nanocrystals make it difficult to achieve the desired compositions, doping levels, and structural control. We present a lower temperature synthesis of ligand-stabilized metal oxide nanocrystals that produces crystalline, monodisperse nanocrystals at temperatures well below the thermal decomposition point of the precursors. Slow injection (0.2 mL/min) of an oleic acid solution of the metal oleate complex into an oleyl alcohol solvent at 230 °C results in a rapid esterification reaction and the production of metal oxide nanocrystals. The approach produces high yields of crystalline, monodisperse metal oxide nanoparticles containing manganese, iron, cobalt, zinc, and indium within 20 min. Synthesis of tin-doped indium oxide (ITO) can be accomplished with good control of the tin doping levels. Finally, the method makes it possible to perform epitaxial growth of shells onto nanocrystal cores to produce core/shell nanocrystals
Potential Environmental Impacts and Antimicrobial Efficacy of Silver- and Nanosilver-Containing Textiles
For textiles containing nanosilver,
we assessed benefit (antimicrobial
efficacy) in parallel with potential to release nanosilver (impact)
during multiple life cycle stages. The silver loading and method of
silver attachment to the textile highly influenced the silver release
during washing. Multiple sequential simulated household washing experiments
for fabric swatches in deionized water with or without detergent showed
a range of silver release. The toxicity of washing experiment supernatants
to zebrafish (Danio rerio) embryos
was negligible, with the exception of the very highest Ag releases
(∼1 mg/L Ag). In fact, toxicity tests indicated that residual
detergent exhibited greater adverse response than the released silver.
Although washing the fabrics did release silver, it did not affect
their antimicrobial efficacy, as demonstrated by >99.9% inhibition
of E. coli growth on the textiles,
even for textiles that retained as little as 2 μg/g Ag after
washing. This suggests that very little nanosilver is required to
control bacterial growth in textiles. Visible light irradiation of
the fabrics reduced the extent of Ag release for textiles during subsequent
washings. End-of-life experiments using simulated landfill conditions
showed that silver remaining on the textile is likely to continue
leaching from textiles after disposal in a landfill