Controlled growth of gold nanocrystals on biogenic As–S nanotubes by galvanic displacement

Abstract

Traditional methods for fabricating nanoscale arrays are usually based on lithographic techniques while alternative new approaches rely on the use of nanoscale templates made of synthetic or biological materials. Here, gold (Au) nanocrystals were grown on the surface of the microbiologically formed As-S nanotubes through the process of galvanic displacement. The size and organization of the synthesized Au nanocrystals were affected by the pH dependent speciation of HAuCl precursors as well as the initial ratio of As-S/HAuCl. We found that as pH increased, the Au nanocrystals grown on As-S nanotubes had smaller sizes but were more likely to assemble in one-dimension along the nanotubes. At a proper initial ratio of As-S/HAuCl, Au nanotubes were formed at pH 6.0. The mechanism of Au nanostructures formation and the synthesis process at different pHs were proposed. The resulting Au nanoparticle/As-S nanotube and Au nanotube/As-S nanotube hetero-structures may provide important properties to be used for novel nano-electronic devices.

Magnetic mesoporous Fe3O4@nSiO2@mSiO2 nanoparticles for high-throughput mass spectrometry detection of hydrolyzed products of organophosphorus nerve agents

“…72-2303) without other spurious peaks, and the red curve of Fe 3 O 4 @nSiO 2 @mSiO 2 displayed a broad diffraction peak near the diffraction angle of 22.5°, which is attributed to amorphous SiO 2 diffraction peaks. 22 Meanwhile, the results indicate that the prepared magnetic nanocore Fe 3 O 4 is pure phase, and magnetic nanomaterial Fe 3 O 4 @nSiO 2 @mSiO 2 was successfully coated with SiO 2 on the surface of Fe 3 O 4 . Fig.…”

Role of gold nanoparticles in advanced biomedical applications

“…Interestingly, a seed mediated multistep method can also be used to produce nanocrystals with different aspect ratios. 124 In the rst step, the growth solution was prepared by mixing HAuCl 4 , cetyl-tri-methyl ammonium bromide (CTAB), cyclohexane, and acetone. In the second step, gold seeds with very ne size were produced using conventional reducing agents, e.g., sodium citrate and sodium borohydride.…”

“…124,125 The size and shape of the resulted GNP crystals depend upon the amount of seed, concentration of gold salt, and purity of the CTAB. 124,126 In seed mediated synthesis, gold nanostructures with different shapes and sizes such as bipyramids, stars, cubes, and dodecahedrons can be prepared by varying the concentration of gold precursor, ascorbic acid, capping agent, and seed. 53,127 Likewise, the photochemical process is also effective for the seed mediated synthesis of gold nanoparticles.…”