STABILITY OF WATER-SOLUBLE QUANTUM DOTS UNDER SIMULATED ENVIRONMENTAL CONDITIONS

摘要

Engineered nanomaterials have gained attention as possible emerging contaminants.Fluorescent semiconductor nanocrystals,or quantum dots,are nanometer-sized particles(1-10 nm)that exhibit quantum confinement effects resulting in light emission with broad absorbance and narrow emission wavelengths1.Quantum dots composed of heavy metal chalcogenides(e.g.,CdSe,CdTe)have been well-studied due to relative ease in synthesis and desirable optical properties.Often these materials are encapsulated in a protective shell(e.g.,ZnS)forming a core-shell system.Quantum dots can be made water dispersible by functionalizing the surface with appropriate ligands.Stable water suspensions are commonly referred to as "water-soluble"quantum dots in the literature.Surface functionalization can additionally incorporate biological receptors making quantum dots specific fluorescent tags.Numerous applications have been proposed including medical diagnostics,photovoltaics and anticounterfeiting inks.Realization of any of these applications will result in increased quantum dot fabrication,increasing the potential for environmental release and exposure to receptors.Once released into the environment,quantum dots may be transformed by redox processes altering their toxicity and fate.