UV-induced transformation and physicochemical property changes of quantum dots in the presence of air.

Engineered nanomaterials (ENMs) can be released to the environment during their lifecycles. The potential uptake by biological systems, along with uncertain distribution pathways, makes this class of materials important to study from a perspective of potential impacts to the environment and people. In this study, colloidal quantum dots (Q-dots), with diameter around 3 nm and passivated with CH chains (oleic acid), were used, as a model system, to investigate the fate and the transformations of ENMs under UV irradiation in the presence of air. Before and after the UV light irradiation, the changes of the Q-dots on DNA interaction potency, and UV-Vis and fluorescence spectra are compared. When the Q-dots were exposed to UV light, the formation of water-soluble products was confirmed by UV-Vis and fluorescence spectra collected from aqueous dispersions and by the mass loss. Both the UV irradiation time and intensity were found to influence the amount of water-soluble products produced. However, before and after UV irradiation, the Q-dots exhibited little change of their DNA interaction potency. Therefore, it seems that the Q-dot surface chemical reactivity to DNA changed little, in conjunction with photo-oxidization of the surface passivation ligand. [ABSTRACT FROM AUTHOR]