Hydrophilic CdSe−ZnS Core−Shell Quantum Dots with Reactive Functional Groups on Their Surface

We synthesized macromolecular ligands for CdSe−ZnS core−shell quantum dots incorporating multiple thiol groups, poly(ethylene glycol) chains, and either carboxylic acids or primary amines along a common poly(methacrylate) backbone. The thiol groups encourage the adsorption of these macromolecular co...

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Bibliographic Details
Published in:Langmuir 2010-07, Vol.26 (13), p.11503-11511
Main Authors: Yildiz, Ibrahim, Deniz, Erhan, McCaughan, Bridgeen, Cruickshank, Stuart F, Callan, John F, Raymo, Françisco M
Format: Article
Language:English
Subjects:
Animals
Cadmium Compounds - adverse effects
Cadmium Compounds - chemistry
Cell Survival
Chemistry
CHO Cells
Colloidal state and disperse state
Cricetinae
Cricetulus
Exact sciences and technology
General and physical chemistry
Materials: Nano-and Mesostructured Materials, Polymers, Gels, Liquid Crystals, Composites
Membranes
Molecular Structure
Nanoparticles - adverse effects
Nanoparticles - chemistry
Nanotechnology
Physical and chemical studies. Granulometry. Electrokinetic phenomena
Quantum Dots
Selenium Compounds - adverse effects
Selenium Compounds - chemistry
Sulfides - adverse effects
Sulfides - chemistry
Surface physical chemistry
Zinc Compounds - adverse effects
Zinc Compounds - chemistry
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Summary:We synthesized macromolecular ligands for CdSe−ZnS core−shell quantum dots incorporating multiple thiol groups, poly(ethylene glycol) chains, and either carboxylic acids or primary amines along a common poly(methacrylate) backbone. The thiol groups encourage the adsorption of these macromolecular constructs on the ZnS shell of the nanoparticles, and the poly(ethylene glycol) chains impose hydrophilic character on the resulting assemblies. Indeed, the coated quantum dots are readily soluble in water and are stable under these conditions for months over a broad pH range (4.0−12.0) and even in the presence of large salt concentrations. In addition, these nanoparticles have relatively small hydrodynamic diameters (17−30 nm) and good quantum yields (0.3−0.4). Furthermore, the pendant carboxylic acids or primary amines of the macromolecular ligands can be exploited to modify the quantum dots after the adsorption of the polymers on their surface. For example, boron dipyrromethene dyes can be connected to the hydrophilic quantum dots on the basis of amide bond formation to encourage the transfer of energy from the luminescent CdSe core to the organic dyes. Our hydrophilic nanoparticles can also cross the membrane of Chinese hamster ovarian cells and accumulate in the cytosol with limited nuclear localization. Moreover, the internalized quantum dots are not cytotoxic and have essentially no influence on cell viability. Thus, our strategy for the preparation of biocompatible quantum dots can evolve into the development of valuable luminescent probes with nanoscaled dimensions and optimal photophysical properties for a diversity of biomedical applications.
ISSN:0743-7463
1520-5827
DOI:10.1021/la1010488