CdSe/ZnS core/shell quantum dots for bio-application

N. Dai; J. Chen

doi:10.1117/12.667661

23 January 2006 CdSe/ZnS core/shell quantum dots for bio-application

N. Dai, J. Chen

Proceedings Volume 6029, ICO20: Materials and Nanostructures; 602904 (2006) https://doi.org/10.1117/12.667661
Event: ICO20:Optical Devices and Instruments, 2005, Changchun, China

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.

Citation Download Citation

N. Dai and J. Chen "CdSe/ZnS core/shell quantum dots for bio-application", Proc. SPIE 6029, ICO20: Materials and Nanostructures, 602904 (23 January 2006); https://doi.org/10.1117/12.667661

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