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Fluorescence detection methods for microfluidic droplet platforms
Published on: December 10, 2011
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Fluorescence Monitored Voltammetry of Single Attoliter Droplets
Christopher Batchelor-McAuley1, Christopher A Little1, Stanislav V Sokolov1
1Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University , South Parks Road, Oxford OX1 3QZ, U.K.
Analytical Chemistry
|October 18, 2016
Summary
Researchers developed a method to track and electrochemically control individual emulsion droplets using Nile Red dye. This technique allows for in situ monitoring and analysis of droplet behavior at the single-particle level.
Area of Science:
- Analytical Chemistry
- Electrochemistry
- Materials Science
Background:
- Organic-in-water emulsions are crucial in various chemical processes.
- Real-time monitoring of individual emulsion droplets is challenging.
- Electrochemical control offers a novel way to manipulate and study these systems.
Purpose of the Study:
- To develop a method for fluorescent and electrochemical labeling of individual emulsion droplets.
- To enable in situ tracking and sizing of suspended particles.
- To investigate the electrochemical switching of dye fluorescence and confined volume voltammetry.
Main Methods:
- Utilized the lipid-soluble fluorophore Nile Red for labeling.
- Employed a combined thin-layer optical/electrochemical cell.
- Monitored droplet accumulation on a carbon fiber electrode.
- Applied potentiostatic control to switch dye fluorescence.
- Performed single-particle fluorescence intensity measurements versus applied potential.
Main Results:
- Successfully enabled optical detection and in situ tracking/sizing of individual emulsion droplets (average diameter 530 nm).
- Demonstrated irreversible droplet accumulation at the electrode.
- Achieved electrochemical switching of Nile Red fluorescence via redox control.
- Constructed dynamic cyclic voltammograms of individual particles.
- Observed asymmetric redox switching kinetics, suggesting chemical gating in the organic phase.
Conclusions:
- The developed technique allows for precise electrochemical control and analysis of individual emulsion droplets.
- Confined volume voltammetry provides insights into single-particle redox processes.
- The findings suggest a chemically gated mechanism for dye reformation in the organic phase, impacting fluorescence.
- This method opens new avenues for studying interfacial phenomena in emulsions.
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