A novel method to make hydrophilic quantum dots and its application on biodetection

We developed a novel method to water-solubilize hydrophobic quantum dots (QDs) in water via ultrasonic emulsification method. This structural procedure was simple and one-step. Analysis with transmission electron microscopy (TEM), ultraviolet–visible (UV–vis) absorption spectroscopy, X-ray powder diffraction (XRD), photoluminescence (PL) measurement, and fluorescence microscopy demonstrated that the as-prepared samples were uniform in size distribution with ca. 40 nm, and had good optical properties. QDs were conjugated with antibodies. Then, gel filtration chromatography was used to separate QD–antibody bioconjugates. Antibodies were fluorescently labelled with polymer-coated QDs nanoparticles via the conjugation procedure and their immunoassay activity confirmed covalent conjugation. These results indicate that QDs can serve as substitutes for traditional organic dyes in the field of biodetection.