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Fluorescence Lifetime Imaging of Molecular Rotors in Living Cells
Published on: February 9, 2012
Imaging of flow patterns with fluorescent molecular rotors
Adnan Mustafic1, Hsuan-Ming Huang, Emmanuel A Theodorakis
1Faculty of Engineering, Driftmier Engineering Center, University of Georgia, Athens, GA 30602, USA.
Journal of Fluorescence
|April 21, 2010
Summary
Shear-sensitive molecular rotors can visualize fluid flow patterns in microfluidic devices. Their fluorescence intensity changes with flow rate, enabling precise flow measurement and control.
Area of Science:
- Photochemistry
- Fluid Dynamics
- Materials Science
Background:
- Molecular rotors are fluorescent molecules forming twisted intramolecular charge transfer states (TICT) upon photoexcitation.
- Their fluorescence quantum yield is typically low in low-viscosity solvents but increases with viscosity.
- A novel mechanism shows rotor fluorescence also depends on solvent shear stress.
Purpose of the Study:
- To investigate the application of shear-sensitive molecular rotors for imaging flow patterns in microfluidic chambers.
- To assess the sensitivity and resolution of this technique for flow measurement.
- To compare experimental results with computational fluid dynamics (CFD) simulations.
Main Methods:
- Constructed flow chambers from polycarbonate and acrylic with varying geometries.
- Injected molecular rotor solutions in ethylene glycol into chambers at controlled flow rates.
- Utilized LED-induced fluorescence (LIF) imaging and digital cameras to capture flow patterns.
- Analyzed intensity differences between flow and no-flow images and compared with CFD simulations.
Main Results:
- Detectable intensity differences observed at average flow rates as low as 0.1 mm/s.
- An exponential relationship was found between flow rate and fluorescence intensity increase.
- Qualitative agreement was observed between experimental imaging and CFD simulations.
- Prolonged light exposure led to reduced emission intensity.
Conclusions:
- Shear-sensitive molecular rotors offer a sensitive method for imaging microfluidic flow patterns.
- This technique provides high spatial and temporal resolution for flow visualization.
- Potential applications include microfluidics, flow measurement, and process control.
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