β-Cyclodextrin controlled assembling nanostructures from gold nanoparticles to gold nanowires

In this Letter, β-cyclodextrin (β-CD) was employed as stabilizer in the synthesis of gold nanoparticles. Gold nanoparticles were synthesized by the reduction of HAuCl4 by NaBH4 in the presence of β-CD. Varying the ratio of β-CD to HAuCl4, isolated gold nanoparticles could be assembled into nanowires. The nanoparticles and nanowires were characterized by transmission electron microscopy, UV/visible spectroscopy, infrared spectroscopy and X-ray photoelectron spectroscopy. The decreased relative intensity of skeletal and ring vibration in FT-IR spectra and the negative shift of the Au4f7/2 binding energy in XPS spectra confirmed that β-CD was chemisorped on Au nanoparticles via hydroxyl group.