One-pot synthesis of ternary CuInS2 quantum dots with near-infrared fluorescence in aqueous solution

In this paper, we present a novel and simple hydrothermal synthesis method for preparing water soluble high quality ternary CuInS2 quantum dots (QDs) with mercaptopropionic acid (MPA) as the stabilizer. The influences of various experimental variables, including the precursor concentrations, reaction time, reaction temperature, pH value, the MPA/Cu molar ratio, as well as the kind of capping ligand used on the luminescent properties of the obtained ternary CuInS2 QDs have been systematically investigated. The stable ternary CuInS2 QDs with good photoluminescence emission properties and narrow size distribution can be obtained under optimum experimental conditions. It was used to label liver cancer cells. The optical features and structure of the obtained CuInS2 QDs have been characterized by UV-vis and fluorescence spectroscopy, TEM, XRD, FT-IR and EDX. The proposed synthesis method was simple, low cost, with comparatively low reaction temperature (150 degrees C), and the as-synthesized near-infrared CuInS2 QDs was proven to have excellent photostability. The synthesized CuInS2 QDs is a promising fluorescent probe for biological and biomedical imaging due to its bandgap in the near infrared and the absence of toxic heavy metal ions.