A label-free fluorescence detection strategy for lysozyme assay using CuInS2 quantum dots.

We have developed a simple and efficient fluorescence detection system for lysozyme utilizing I–III–VI type Cu–In–S ternary quantum dots (CuInS₂ QDs) as the probe. Water-soluble near-infrared CuInS₂ QDs capped with 3-mercaptopropionic acid were directly synthesized by using a hydrothermal method. Poly(dimethyl diallyl ammonium chloride), as a cationic polyelectrolyte, could bind to 3-mercaptopropionic acid-capped CuInS₂ QDs via electrostatic interactions that would lead to fluorescence quenching of CuInS₂ QDs. And the addition of a lysozyme aptamer could effectively turn on the quenched fluorescence due to the stronger interaction between the cationic polyelectrolyte and negatively charged aptamer. The addition of lysozyme would result in fluorescence quenching of CuInS₂ QDs again due to the specific binding between lysozyme and the lysozyme aptamer. Therefore, this label-free fluorescence system could be applied to selectively detect lysozyme. [ABSTRACT FROM AUTHOR]