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|Title:||Measurement of the hydrodynamic radius of quantum dots by fluorescence correlation spectroscopy excluding blinking|
|Author:||Thomaz, A. A. de|
Almeida, D. B.
Pelegati, V. B.
Carvalho, H. F.
Cesar, C. L.
|Abstract:||Fluorescence Correlation Spectroscopy (FCS) is an optical technique that allows the measurement of the diffusion coefficient of molecules in a diluted sample. From the diffusion coefficient it is possible to calculate the hydrodynamic radius of the molecules. For colloidal quantum dots (QDs) the hydrodynamic radius is valuable information to study interactions with other molecules or other QDs. In this chapter we describe the main aspects of the technique and how to use it to calculate the hydrodynamic radius of quantum dots (QDs). © 2014 Springer Science+Business Media New York.|
One of the most important properties of quantum dots (QDs) is their size. Their size will determine optical properties and in a colloidal medium their range of interaction. The most common techniques used to measure QD size are transmission electron microscopy (TEM) and X-ray diffraction. However, these techniques demand the sample to be dried and under a vacuum. This way any hydrodynamic information is excluded and the preparation process may alter even the size of the QDs. Fluorescence correlation spectroscopy (FCS) is an optical technique with single molecule sensitivity capable of extracting the hydrodynamic radius (HR) of the QDs. The main drawback of FCS is the blinking phenomenon that alters the correlation function implicating in a QD apparent size smaller than it really is. In this work, we developed a method to exclude blinking of the FCS and measured the HR of colloidal QDs. We compared our results with TEM images, and the HR obtained by FCS is higher than the radius measured by TEM. We attribute this difference to the cap layer of the QD that cannot be seen in the TEM images.
|Editor:||American Chemical Society|
|Citation:||Methods In Molecular Biology. Humana Press Inc., v. 1199, n. , p. 85 - 91, 2014.|
|Appears in Collections:||IFGW - Artigos e Outros Documentos|
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