Surface Modified Chitosan with Cadmium Sulfide Quantum Dots as Luminescent Probe for Detection of Silver Ions

In present work, the surface modified cadmium sulfide quantum dots (CdS QDs) was synthesized with chitosan for the detection of silver ions. Chitosan was employed as matrix medium to fabricate CdS QDs, resulting in the formation of novel QDs/chitosan composite. The CdS quantum dots surface coated with chitosan were analyzed using UV-vis spectrophotometer, X-ray diffraction and transmission electron microscope. The chitosan + CdS QDs exhibited high aqueous solubility with better steadiness. By using chitosan + CdS, the silver ions were not only detected but also reduced to nanosize due to the reducing property of chitosan. The mechanism of fluorescence quenching of chitosan + CdS by Ag+ was investigated using photoluminescence spectroscopy.