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Updated: Aug 14, 2026
Fluorescence Lifetime Imaging of Molecular Rotors in Living Cells
Published on: February 9, 2012
Interaction of fluorescent molecular rotors with blood plasma proteins
Walter J Akers1, Jay M Cupps, Mark A Haidekker
1Department of Biological Engineering, University of Missouri-Columbia, Columbia, MO 65211, USA.
Abstract:
Many disease states have associated blood viscosity changes. Molecular rotors, fluorescent molecules with viscosity sensitive quantum yields, have recently been investigated as a new method for biofluid viscosity measurement. Current viscometer measurements are complicated by proteins adhering to surfaces and forming air-surface layers. It is unknown at this time what effects proteins may have on biofluid viscosity measurements using molecular rotors. To answer this question, binding affinities to blood plasma proteins were investigated by equilibrium dialysis for four hydrophilic molecular rotors. Aqueous solutions of 9-[(2-cyano-2-hydroxy-carbonyl)vinyl]julolidine (CCVJ) and three derivatives were prepared and dialyzed against solutions of bovine source albumin, fibrinogen and immunoglobulin G approximating normal physiologic concentrations and fresh-frozen human plasma. After equilibration, dye concentration on each side of the dialysis membrane was assessed by spectrophotometry. The relative binding affinity of the four dyes to the proteins and to the plasma was compared. Affinity of all dyes was highest for albumin. The bound dye fraction showed little change in relation to protein concentration in the physiological concentration range. Diol, the most hydrophilic molecular rotor tested showed the lowest affinity for albumin. This study indicates that hydrophilic molecular rotors are well-suited for biofluid viscosity measurement.
Insights
Hydrophilic molecular rotors show promise for measuring biofluid viscosity, even in the presence of blood plasma proteins. Their binding affinities to proteins like albumin were assessed, indicating suitability for viscosity measurements.
Area of Science:
- Biochemistry
- Biophysics
- Analytical Chemistry
Background:
- Blood viscosity changes are linked to various disease states.
- Molecular rotors are fluorescent probes sensitive to viscosity, offering a novel biofluid measurement approach.
- Existing viscometry methods face challenges due to protein adsorption and air-surface layer formation.
Purpose of the Study:
- To investigate the impact of blood plasma proteins on biofluid viscosity measurements using molecular rotors.
- To determine the binding affinities of hydrophilic molecular rotors to key blood plasma proteins.
Main Methods:
- Four hydrophilic molecular rotors, including 9-[(2-cyano-2-hydroxy-carbonyl)vinyl]julolidine (CCVJ), were studied.
- Equilibrium dialysis was employed to assess binding affinities against bovine albumin, fibrinogen, immunoglobulin G, and human plasma.
- Dye concentrations were measured using spectrophotometry after equilibration.
Main Results:
- All tested molecular rotors exhibited the highest binding affinity to albumin.
- The fraction of bound dye remained relatively stable across physiological protein concentration ranges.
- Diol, the most hydrophilic rotor, displayed the lowest affinity for albumin.
Conclusions:
- Hydrophilic molecular rotors demonstrate suitability for biofluid viscosity measurements.
- Protein binding effects do not significantly impede the use of these rotors in biofluid analysis.
- This technology holds potential for improved diagnostics and monitoring of viscosity-related diseases.
