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The authors report the preparation of silica nanotubes by a simple two-stage thermal evaporation of ZnSe and SiO powders. Firstly, nanocables with single crystalline ZnSe nanowire cores and amorphous SiO2 shells were formed by a combined vapor-liquid-solid and SiO-assisted growth process. The ZnSe cores were then evaporated at high temperatures leaving behind SiO2 nanotubes. As-fabricated SiO2 nanotubes were studied with scanning electron microscopy, transmission electron microscopy, energy-dispersive x-ray spectroscopic analysis, and photoluminescence measurement. The SiO2 nanotubes were found to be amorphous, diameter uniform, smooth, and rigid. This method can be used to prepare other materials and morphology-controlled nanotubes. [ABSTRACT FROM AUTHOR]

Large-scale uniform silicon nanowires (SiNWs) array was fabricated by chemical etching on n-Si(111) wafer. Silver nanoparticles (AgNPs) were loaded on their surfaces. The AgNPs on SiNWs (AgNPs@SiNWs) array exhibit strong surface-enhanced Raman effect. On the substrate surfaces, characteristic Raman signals are generated with trace amount of mouse immunoglobulin G (mIgG), goat-anti-mouse immunoglobulin G (gamIgG), and immune complexes formed from 4 ng each of mIgG and gamIgG. The shifted positions and changed intensities in Raman bands indicate the occurrence of immunoreactions. This AgNPs@SiNWs array is a unique substrate for surface-enhanced Raman spectroscopy to show the immune reagents and immunoreactions at higher sensitivity. [ABSTRACT FROM AUTHOR]