Thiol-coated alloyed quantum dots: comparison of approaches to modification.

Abstract

Quantum dots (QDs) are luminescent semiconductor nanocrystals. Their main feature is the size effect: the nanocrystal size and shape impact on the optical properties. This provides a prospect for the application of QDs in optics, microelectronics, optoelectronics, medicine, biology, printing industry, and energetics. There are cases where it is necessary to use nanostructures with uniform size and different optical properties.
Multicomponent alloyed QDs are the promising alternative to heterostructural QDs. The alloyed QDs synthesis procedure makes it possible to adjust optical properties by changing composition and inner nanoparticle structure without nanocrystal size variation. Hydrophilicity is a key requirement in QDs applications to the analysis of polar solutions (including biological fluids). Their stability in a polar solution can be provided by hydrophilization. The ligand exchange method is optimal for the alloyed QDs, since the size of the nanoparticles after modification practically does not change, which makes it possible to maximize the advantage of this nanostructure. The described method allows the use of thiols as ligands. The nanoparticles obtained by this technique are applicable in bioanalysis due to the acid's terminal carboxyl groups necessary for bioconjugation.
In this work we present the results of the CdZnSeS/ZnS alloyed QDs hydrophilization by the ligand exchange method and considers the following hydrophilizing agents: dihydrolipoic acid, thioglycolic acid, mercaptopropionic acid, 2-mercaptoethanol. The effect of hydrophilizing agents on the alloyed QDs optical properties (quantum yield, position and full width at half maximum of the luminescence peak), their stability and toxicity were studied in order to select the optimal modifier and further use the obtained nanostructures in bioanalysis.


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Speaker

Pavel Strokin
Saratov State University
Russia

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