la703746w_si_006.pdf (15.91 kB)

Light-Induced Aggregation of Colloidal Gold Nanoparticles Capped by Thymine Derivatives

Download (15.91 kB)
journal contribution
posted on 06.05.2008 by Jingfang Zhou, Rossen Sedev, David Beattie, John Ralston
The colloid stability of thymine-coated gold nanoparticles under light irradiation as a function of particle size, surface charge, and exposure time was investigated in alkaline, aqueous solutions as well as in a 0.5 vol % of DMF in H2O mixture. With increasing exposure to light irradiation at 280 nm, more and more particles coagulated. Light-induced aggregation of colloidal gold nanoparticles was attributed to reorientation of thymine terminal groups tethered on gold particle surfaces. A smaller particle size and negatively charged surface reduced the rate of photodimerization or even inhibited the photoreaction. UV−vis and FTIR spectroscopy confirmed the photodimerization of terminal thymine molecules under 280 nm light irradiation. The reaction kinetics of thymine photodimerization appears to be a combination of first-order reactions, each having different rates, reflecting the inhomogeneity and high curvature of the gold nanoparticle surfaces.