Preparation of poly(ethylene glycol) methacrylate coated CuInS2/ZnS quantum dots and their use in cell staining

Abstract

A simple synthesis of poly(ethylene glycol) methacrylate (PEGMA) coated CuInS₂/ZnS quantum dots (QDs) has been developed. X-ray diffraction, transmission electron microscopy, and atomic force microscopy observations demonstrated that uniform CuInS₂/ZnS QDs were successfully prepared. Fourier transform infrared spectroscopy indicated no new peak after the coating process, indicating that only physical interactions occurred during coating and that PEGMA did not disturb the crystal structure of the CuInS₂/ZnS QDs. After PEGMA coating, the photoluminescence spectra of the CuInS₂/ZnS QDs red shifted (from 566 nm to 589 nm) and the QD particle size increased. The concentration and molecular weight of PEGMA play important roles in the water solubility and hydrodynamics of the particles. The PEGMA-coated CuInS₂/ZnS QDs showed stable emissions for up to 3 weeks. As a demonstration of a potential biomedical application, PEGMA-coated CuInS₂-ZnS QDs were used in labeling human liver carcinoma (HepG2) tumor cells.