Fluorescence lifetime probe for solvent microviscosity utilizing anilinonaphthalene sulfonate

Area of Science:

• Photophysics and Spectroscopy
• Biophysical Chemistry
• Materials Science

Background:

• Anilinonaphthalene sulfonate (ANS) is a fluorescent probe used to study local hydrophobicity.
• The fluorescence intensity of ANS changes significantly with its environment.
• Understanding the relationship between ANS fluorescence and microviscosity is crucial for its application.

Purpose of the Study:

• To investigate the correlation between the fluorescent dynamics of excited ANS and solvent microviscosity.
• To determine how the molecular structure of ANS affects its sensitivity to microviscosity.
• To apply ANS fluorescence to measure microviscosity in biological systems.

Main Methods:

• Time-resolved fluorescence spectroscopy was employed to study ANS.
• The fluorescence lifetime of ANS in the charge transfer (CT) state was measured.
• Comparative analysis of 2,6-ANS and 1,8-ANS sensitivity to microviscosity was performed.

Main Results:

• The fluorescence lifetime of ANS in the CT state is a sensitive indicator of microviscosity.
• 2,6-ANS exhibits higher sensitivity to microviscosity than 1,8-ANS.
• The rotational freedom of the phenylamino group in ANS influences its sensitivity.
• Microviscosity measurements were successfully conducted in aqueous solutions of hyaluronan, gellan gum, and gelatin.

Conclusions:

• ANS fluorescence lifetime can accurately estimate solvent microviscosity.
• The molecular structure of ANS, specifically the phenylamino group's rotational freedom, dictates its sensitivity.
• ANS is a valuable probe for microviscosity measurements in biological systems and fluorescence lifetime imaging microscopy.