Preparation and characterisation of fluorescent polystyrene spheres coated with different sized quantum dots

Abstract

Water soluble CdSe quantum dots (QDs) coated polymer sphere with single and multiple fluorescent peaks have been prepared through the layer by layer self-assembly method. Polystyrene (PS) spheres ranging mainly from 330 to 750 nm and from 1·0 to 3·5 μm were used as the templates for deposition of three sized fluorescent QDs. The results of transmission electron microscopy and fluorescent confocal optical slice showed that the PS/CdSe composites were spherical in shape with core–shell structures. Emission colours of the mixture of spheres with single colour signal emitting at different wavelengths stimulated by a single light source could be distinguished clearly. Single spheres with separated, multiple fluorescence peaks could be easily obtained by controlling the ratios of the three sized CdSe QDs.