Molecular rotors--fluorescent biosensors for viscosity and flow

Area of Science:

• Biophysics
• Chemical sensing
• Fluorescence spectroscopy

Background:

• Viscosity and fluid flow are critical in biological systems at all scales.
• Traditional methods for measuring viscosity and flow have significant limitations, including cost, time, and sample size constraints.
• Fluorescent dyes offer high sensitivity and resolution for probing microenvironments.

Purpose of the Study:

• To explore the application of molecular rotors as sensitive biosensors for viscosity and fluid flow.
• To address the challenges associated with intensity-based measurements and solvent-specific calibration.
• To enable real-time, microscopic measurements of viscosity and shear stress in biological contexts.

Main Methods:

• Utilizing molecular rotors, which are fluorescent molecules whose emission intensity is dependent on viscosity via twisted intramolecular charge transfer (TICT) states.
• Investigating the viscosity- and shear-stress-dependent photophysical properties of molecular rotors.
• Developing ratiometric measurement systems and incorporating specific recognition groups for targeted sensing.

Main Results:

• Molecular rotors demonstrate viscosity-dependent fluorescence emission due to their TICT state formation.
• The emission intensity of molecular rotors is sensitive to fluid viscosity and shear stress.
• Ratiometric approaches and targeted molecular rotors mitigate challenges of intensity-based measurements and enable specific site sensing.

Conclusions:

• Molecular rotors are emerging as powerful biosensors for microviscosity and fluid shear stress.
• These sensors provide real-time, high-resolution measurements at the microscopic level.
• The technology overcomes limitations of conventional methods, offering broad applicability in biological research.