Fluorescent sensor responsive to local viscosity and its application to the imaging of liquid-ordered domain in lipid membranes

A novel fluorescent sensor responsive to local viscosity in the lipid bilayer membranes was designed and synthesized. The sensor changes its fluorescence intensity reflecting the local viscosity of its surrounding medium. The fluorescence measurement showed that the sensor is capable of discriminating between different phase states of lipid bilayer. In addition, the sensor visualized liquid-ordered microdomains on giant vesicles in terms of the microviscosity with a simple fluorescence technique.