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Aqueous Synthesis and Fluorescence-Imaging Application of CdTe/ZnSe Core/Shell Quantum Dots with High Stability and Low Cytotoxicity
KTH, School of Biotechnology (BIO). KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
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2010 (English)In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, Vol. 10, no 3, 1741-1746 p.Article in journal (Refereed) Published
Abstract [en]

CdTe/ZnSe core/shell quantum dots were directly synthesized in an aqueous condition by heating a mixed solution of ZnCl2, NaHSe and CdTe QDs in the presence of mercaptosuccinic acid as a stabilizer. By controlling the size and composition, the CdTe/ZnSe QDs with emission wavelength ranging from 540 to 630 nm, high quantum yield (44%) and narrow full width at half maximum (FWHM) could be obtained. Characterization results with HRTEM, XRD and EDX have shown that the synthesized CdTe/ZnSe ON have good monodispersity and a nice crystal structure, and exhibited better stability and less cytotoxicity as compared with CdTe QDs. Furthermore, luminescent QD-IgG bioprobes were produced to detect the breast cancer marker Her2 on the surface of fixed MCF-7 cancer cells for their optical imaging.

Place, publisher, year, edition, pages
2010. Vol. 10, no 3, 1741-1746 p.
Keyword [en]
Optical Imaging, Quantum Dots, Aqueous Synthesis, Cytotoxicity, Stability, Fluorescence, Core-Shell Structure, cdte nanocrystals, in-vivo, room-temperature, size series, photoluminescence, photostability, nanoparticles, therapy, vitro
National Category
Chemical Sciences Materials Engineering Condensed Matter Physics
URN: urn:nbn:se:kth:diva-19153DOI: 10.1166/jnn.2010.2049ISI: 000273984800037ScopusID: 2-s2.0-77950955285OAI: diva2:337200
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2013-11-19Bibliographically approved
In thesis
1. Rational design of nanoparticles for biomedical imaging and photovoltaic applications
Open this publication in new window or tab >>Rational design of nanoparticles for biomedical imaging and photovoltaic applications
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis aims to rationally design nanoparticles and promote their applications in biomedical imaging and photovoltaic cells.

Quantum dots (QDs) are promising fluorescent probes for biomedical imaging. We have fabricated two types of MSA capped QDs: CdTe/ZnSe core/shell QDs synthesized via an aqueous method and CdTe QDs via a hydrothermal method. They present high quantum yields (QYs), narrow emission band widths, high photo- and pH-stability, and low cytotoxicity. QD-IgG probes were produced and applied for labeling breast cancer marker HER2 proteins on MCF-7 cells.

For the purpose of single molecule tracking using QDs as fluorescent probes, we use small affibodies instead of antibodies to produce QD-affibody probes. Smaller QD-target protein complexes are obtained using a direct immunofluorescence approach. These QD-affibody probes are developed to study the dynamic motion of single HER2 proteins on A431 cell membranes.

Fluorescence blinking in single QDs is harmful for dynamic tracking due to information loss. We have experimentally studied the blinking phenomenon and the mechanism behind. We have discovered an emission bunching effect that two nearby QDs tend to emit light synchronously. The long-range Coulomb potential induced by the negative charge on the QD surface is found to be the major cause for the single QD blinking and the emission bunching in QD pairs.

We have studied the in vitro cytotoxicity of CdTe QDs to human umbilical vein endothelial cells (HUVECs). The QDs treatment increases the intracellular reactive oxygen species (ROS) level and disrupts the mitochondrial membrane potential. The protein expression levels indicate that the mitochondria apoptosis is the main cause of HUVCEs apoptosis induced by CdTe QDs.

Gold nanorods (GNRs) are scattering probes due to their tunable surface plasmon resonance (SPR) enhanced scattering spectrum. In order to control the yield and morphology of GNRs, we have systematically studied the effects of composition and concentration in the growth solution on the quality of the GNRs produced via a seed-mediated method. The aspect ratios of GNRs were found to be linearly depended on the concentration ratio of silver ions and CTAB. The high quality GNRs obtained were adsorbed to COS-7 cell membranes for dark field imaging.

We have rationally designed two types of QDs by wave function engineering so as to improve the efficiency of QD-sensitized solar cells. A reversed type-I CdS/CdSe QD confines excitons in the shell region, whereas a type-II ZnSe/CdS QD separates electrons in the shell and holes in the core. Their absorbed photon-to-current efficiencies (APCE) are as high as 40% and 60% respectively.

In conclusion, rationally designed nanoparticles are proven a high potential for applications as probes in biomedical labeling, imaging and molecule tracking, and as sensitizers for photovoltaic cells.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011
National Category
Theoretical Chemistry
urn:nbn:se:kth:diva-33346 (URN)978-91-7415-973-8 (ISBN)
Public defence
2011-05-24, FB52, AlbaNova, Roslagstullsbacken, Stockholm, 14:00 (English)
QC 20110511Available from: 2011-05-11 Created: 2011-05-03 Last updated: 2011-05-11Bibliographically approved

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