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Proceedings Paper

CdSe/ZnS core/shell quantum dots for bio-application
Author(s): N. Dai; J. Chen
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Paper Abstract

Quantum dots, with functional group on surfaces, can be attached to bio-molecules to form quantum-dots/bio-molecule complex. With their excellent photo-electronic properties, quantum dots are now widely used to label the bio-molecules and highlight a cell's nucleus and microtubule fibers. They may also be used to control and operate the bio-molecules. We investigate the synthesis of the CdSe/ZnS core- shell quantum dots. To make the quantum dots water-soluble, the TOPO, TOPSe, and HAD ligands on the surface of CdSe/ZnS QDs were replaced by mercaptoundecanoic acid (MUA). The MUA-coated quantum dots are dispersible in water. For the use in biology, it is required that the quantum dots, when surrounded by a bio-environment, have high quantum yield and long fluorescence lifetime. Our study indicates that quantum yield of the core-shell quantum dots exceeds 60% and fluorescence lifetime of the electrons in the excited state is around 20 nano seconds. The CdSe/ZnS core/shell structure is very stable. No significant fluorescence decay is observed with a prolong excitation by a 365 nm ultro-violet light source of 30 mW. Here the function of the ZnS is two-fold: as both the barrier and the passivation layer for the CdSe quantum dots. In addition, the S-2 bonds are bio-active, which form stable bonding to bio-molecules.

Paper Details

Date Published: 23 January 2006
PDF: 6 pages
Proc. SPIE 6029, ICO20: Materials and Nanostructures, 602904 (23 January 2006); doi: 10.1117/12.667661
Show Author Affiliations
N. Dai, Shanghai Institute of Technical Physics (China)
J. Chen, Shanghai Institute of Technical Physics (China)

Published in SPIE Proceedings Vol. 6029:
ICO20: Materials and Nanostructures
Wei Lu; Jeff Young, Editor(s)

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