%0 Journal Article %A Zhou, Jingfang %A Sedev, Rossen %A Beattie, David %A Ralston, John %D 2008 %T Light-Induced Aggregation of Colloidal Gold Nanoparticles Capped by Thymine Derivatives %U https://acs.figshare.com/articles/journal_contribution/Light_Induced_Aggregation_of_Colloidal_Gold_Nanoparticles_Capped_by_Thymine_Derivatives/2940634 %R 10.1021/la703746w.s006 %2 https://acs.figshare.com/ndownloader/files/4639348 %K UV %K light irradiation %K H 2O mixture %K terminal thymine molecules %K DMF %K gold nanoparticle surfaces %K FTIR %K thymine terminal groups %K photodimerization %K particle size %K gold particle surfaces %K exposure %K Thymine DerivativesThe colloid stability %K 280 nm light irradiation %K Colloidal Gold Nanoparticles Capped %X 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. %I ACS Publications