Sharper low-power STED nanoscopy by time gating.

Area of Science:

• Biophysics
• Optical Microscopy
• Cell Biology

Background:

• Continuous-wave stimulated emission depletion (CW-STED) microscopy offers super-resolution but can be limited by phototoxicity and contrast.
• Achieving high resolution often requires high light intensities, posing challenges for imaging live specimens.
• Improving signal-to-noise ratio and reducing light exposure are critical for advanced cellular imaging.

Purpose of the Study:

• To enhance the fluorescence on-off contrast in CW-STED microscopy.
• To enable super-resolution fluorescence correlation spectroscopy (SR-FCS) using CW-STED.
• To visualize finer cellular details with reduced light intensities in both fixed and live cells.

Main Methods:

• Implementation of pulsed excitation combined with time-gated detection in CW-STED microscopy.
• Application of the enhanced CW-STED method for imaging fixed and live biological samples.
• Utilizing the developed technique for SR-FCS to study molecular dynamics.

Main Results:

• Significant improvement in fluorescence on-off contrast was achieved.
• Finer cellular details were resolved using moderate light intensities.
• Successful demonstration of SR-FCS for quantifying the dynamics of labeled lipid molecules in living cell plasma membranes.

Conclusions:

• Pulsed excitation and time-gated detection are effective strategies for improving CW-STED performance.
• The enhanced method allows for high-resolution imaging and molecular dynamics studies with reduced light exposure.
• This technique opens new avenues for advanced live-cell super-resolution microscopy and biophysical analysis.