Measuring the Hydrodynamic Radius of Colloidal Quantum Dots by Fluorescence Correlation Spectroscopy

Area of Science:

• Biophysics
• Materials Science
• Nanotechnology

Background:

• Colloidal quantum dots (QDs) possess versatile optoelectronic properties valuable in life sciences.
• Their application in fluorescence-based techniques spans over two decades.
• Accurate structural characterization, including size, is essential for QD bioconjugation.

Purpose of the Study:

• To detail the Fluorescence Correlation Spectroscopy (FCS) technique.
• To explain how FCS can be utilized to determine the hydrodynamic radius of QDs.
• To highlight the importance of hydrodynamic radius for bioconjugated QDs in life science applications.

Main Methods:

• Fluorescence Correlation Spectroscopy (FCS) measures fluorophore light emission.
• FCS analyzes fluorescence intensity autocorrelation to determine diffusion coefficients.
• Hydrodynamic radius is calculated from the diffusion coefficient.

Main Results:

• FCS provides a method to measure the hydrodynamic radius of QDs and their bioconjugates.
• This technique is suitable for studying bioconjugated QDs in suspension.
• It offers an alternative to light scattering or crystalline structure analysis.

Conclusions:

• FCS is an effective optical technique for characterizing the size of bioconjugated QDs.
• Understanding the hydrodynamic radius is paramount for optimizing QD performance in life science applications.
• The chapter provides a guide to applying FCS for QD size determination.