Issue 33, 2006

A systematic examination of surface coatings on the optical and chemical properties of semiconductor quantum dots

Abstract

A number of procedures are currently available to encapsulate and solubilize hydrophobic semiconductor Quantum Dots (QDs) for biological applications. Most of these procedures are based on the use of small-molecule coordinating ligands, amphiphilic polymers, or amphiphilic lipids. However, it is still not clear how these different surface coating molecules affect the optical, colloidal, and chemical properties of the solubilized QDs. Here we report a systematic study to examine the effects of surface coating chemistry on the hydrodynamic size, fluorescence quantum yield, photostability, chemical stability, and biocompatibility of water-soluble QDs. The results indicate that quantum dots with the smallest hydrodynamic sizes are best prepared by direct ligand exchange with hydrophilic molecules, but the resulting particles are less stable than those encapsulated in amphiphilic polymers. For stability against chemical oxidation, QDs should be protected with a hydrophobic bilayer. For high stability under acidic conditions, the best QDs are prepared by using hyperbranched polyethylenimine. For stability in high salt buffers, it is preferable to have uncharged, sterically-stabilized QDs, like those coated with polyethylene glycol (PEG). These insights are expected to benefit the development of quantum dots and related nanoparticle probes for molecular and cellular imaging applications.

Graphical abstract: A systematic examination of surface coatings on the optical and chemical properties of semiconductor quantum dots

Supplementary files

Article information

Article type
Paper
Submitted
09 May 2006
Accepted
11 Jul 2006
First published
31 Jul 2006

Phys. Chem. Chem. Phys., 2006,8, 3895-3903

A systematic examination of surface coatings on the optical and chemical properties of semiconductor quantum dots

A. M. Smith, H. Duan, M. N. Rhyner, G. Ruan and S. Nie, Phys. Chem. Chem. Phys., 2006, 8, 3895 DOI: 10.1039/B606572B

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