Receptor- and Ligand-Functionalized QDs for Sensing

Chemical sensors based on the competitive binding of sugars to the boronic add ligand have been reported. When 3-aminophenyl boronic acid was covalently linked to GSH-capped CdSe-ZnS QDs, the boronic acid ligand formed boronate esters with 

Different receptor-functionalized QDs were used for the analysis of different substrates, with cyclodextrins, crown-ethers and calixarenes being used as receptor 

The modification of QDs with crown-ethers permitted an analysis of K ions [47]. 

Aggregation of the 15-crown-5-modifled two- (Reproduced with permission of the Royal 

The capping layer of the QDs may act as ligand for the association of metal ions, such that an ET quenching of the QDs luminescence will allow an analysis of the ions. For example, MAA-capped CdS QDs were shown capable ofbinding Hg ions, whereby the fluorescence intensity of the QDs decreased linearly in the range 0.05 X 10 to 4.0 X 10 M of Hg, thus enabling an analysis of the ions with a detection limit of 4.2 x 10 M. Different capping functionalities such as, MPA, 

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