Related Experiment Video
Updated: Jul 4, 2026
15:10
From Fast Fluorescence Imaging to Molecular Diffusion Law on Live Cell Membranes in a Commercial Microscope
Published on: October 9, 2014
A guide to accurate measurement of diffusion using fluorescence correlation techniques with blinking quantum dot
Alexia I Bachir1, David L Kolin, Katrin G Heinze
1Department of Chemistry, McGill University, Montreal, Quebec H3A 2K6, Canada.
The Journal of Chemical Physics
|June 17, 2008
Summary
Quantum dot (QD) blinking complicates measurements of biomolecule transport. This study quantifies blinking bias in diffusion measurements and proposes methods to improve accuracy and eliminate errors.
Area of Science:
- Biophysics
- Spectroscopy
- Nanotechnology
Background:
- Fluctuation correlation spectroscopy (FCS) analyzes biomolecule dynamics using fluorescent probes.
- Semiconductor quantum dots (QDs) offer bright, photostable fluorescence but exhibit blinking, a challenge for quantitative measurements.
- QD blinking introduces power-law fluctuations, complicating separation from transport dynamics.
Purpose of the Study:
- To quantify the bias introduced by QD blinking in transport measurements using fluctuation methods.
- To develop methods for accurate diffusion coefficient determination in the presence of blinking.
- To investigate techniques for completely separating blinking and diffusion dynamics.
Main Methods:
- Computer simulations of diffusing point emitters with defined blinking characteristics.
- Analysis of time correlation decays using simple diffusion models.
- Development and application of a blinking-incorporating fitting model.
- Implementation of k-space image correlation spectroscopy (kICS).
Main Results:
- Simple diffusion models systematically overestimate diffusion coefficients due to QD blinking.
- The error magnitude depends on blinking statistics, sampling rate, and data length.
- A blinking-incorporating model improves diffusion coefficient accuracy.
- kICS effectively separates blinking and diffusion dynamics, enabling accurate measurements.
Conclusions:
- QD blinking introduces significant, often unnoticed, bias in standard transport measurements.
- Accurate diffusion measurements require accounting for or eliminating blinking effects.
- kICS offers a robust solution for simultaneous, accurate recovery of diffusion coefficients and blinking parameters.
