Fabrication of chitosan–CdSe/CdS/ZnS multilayer films by electrostatic self-assembly method

The l-cysteine-modified CdSe/CdS/ZnS nanocrystals were synthesized in aqueous solution by using l-cysteine as stabilizer. The chitosan–CdSe/CdS/ZnS ultrathin multilayer films were fabricated on the pretreated quartz substrate by layer-by-layer electrostatic self-assembly method. The CdSe/CdS/ZnS nanocrystals were characterized by X-ray power diffraction (XRD), fluorescence spectrum and UV–vis spectrum. The UV–vis spectrum, fluorescence spectrum, IR spectrum, contact angle analysis and atomic force microscope analysis were used to characterize the chitosan–CdSe/CdS/ZnS ultrathin multilayer films. The results indicate that chitosan and CdSe/CdS/ZnS nanocrystals are alternatively deposited on the quartz surface, resulting in the buildup of a high quality chitosan–CdSe/CdS/ZnS multilayer films. The prepared ultrathin films of chitosan–CdSe/CdS/ZnS show good fluorescent property, which have potential application in biosensor.