Novel water-soluble chitosan derivatives/quantum dots nanocomposite: synthesis, characterization and...

Water-soluble biocompatible and monodisperse ZnS, CdS, CdSe quantum dots (QDs) were synthesized using natural chitosan derivatives as stabilizers. TEM, XRD, SAED and UV-vis confirmed the formation of nanoparticles with average size of 3-5 nm, and the resulted ZnS, CdS nanocrystals were shown to be of cubic and blended phase. It was found that the molecular structure of chitosan stabilizer had a large influence on the optical and crystalline properties of the QDs. Through refluxing, the surface defects of the nanoparticles were passivated and the photoluminescence were enhanced. The particle size and the photoluminescence intensity can be controlled through altering the concentration of precursor ions and stabilizer solution, the molar ratio of metal ions/[S2-] and refluxing time. The resulting biopolymer/QD composite can be potentially applied as biosensor or fluorescence tags in biological systems.