Photo-Assisted Room Temperature Synthesis of Brightly Fluoresce ZnSe Quantum Dots in Aqueous Medium

Abstract

The ZnSe quantum dots (QDs) have gained considerable research interest as an alternative to heavy-metal-based QDs and are non-toxic, have strong emission in UV-blue region, and with wider band gap are suitable for doping various ions to tune their optical and electronics properties. For biological applications, aqueous stability of QDs is an indispensable prerequisite. Mercapto-carboxylic acids such as mercaptopropionic acids (MPA), thioglycolic acids (TGA), etc., are commonly used for providing aqueous stability to the QDs. They also provide surface functional groups suitable for bioconjugation as well as restrict size of QDs during synthesis. Photo-assisted synthesis of ZnSe QDs has been studied previously but requires refluxing of QDs at relatively high temperatures for longer durations. Here, the authors report a photo-assisted synthesis of ZnSe QDs capped with either MPA or TGA at room temperature in aqueous medium. The as-synthesized QDs were probed for their structural, optical and chemical properties through various characterization techniques. The synthesized QDs were ca 2–3 nm in diameter; surface functionalized with carboxylic group and showed bright fluorescence in UV-blue region.
Keywords: ZnSe quantum dots, Fluorescence, Aqueous medium, Nanocrystals