Cellular imaging using total internal reflection fluorescence microscopy: theory and instrumentation.

Area of Science:

• Cell Biology
• Microscopy Techniques
• Biophysics

Background:

• Live cell fluorescent microscopy is crucial for understanding dynamic cellular processes like signaling and trafficking.
• High spatiotemporal resolution and sensitivity are key for observing transient intermediate states at the single-molecule or organelle level.
• Confocal microscopy offers improved contrast and axial resolution, while Total Internal Reflection Fluorescence Microscopy (TIRFM) achieves thinner optical sections.

Purpose of the Study:

• To discuss the optical principles and setup of TIRFM.
• To highlight the utility of TIRFM for high-sensitivity imaging of cellular events near the cell cortex.
• To explore the integration of TIRFM with other imaging modalities for comprehensive biological insights.

Main Methods:

• Explanation of the evanescent field principle in TIRFM for selective fluorophore excitation.
• Discussion of TIRFM setup components, including high numerical-aperture (NA) objective lenses.
• Consideration of quantitative TIRFM applications and complementary genetic/molecular techniques.

Main Results:

• TIRFM generates a thin excitation field (<100 nm), enabling exquisite sensitivity for processes at the cell cortex.
• Recent advancements in objective lenses and commercial systems have increased TIRFM accessibility for biologists.
• TIRFM is particularly effective for studying dynamic events at the cell membrane interface.

Conclusions:

• TIRFM is a powerful, accessible technique for high-resolution live-cell imaging of near-membrane cellular dynamics.
• Quantitative TIRFM, combined with other methods, provides deep insights into complex cellular processes.
• The technique is well-suited for elucidating mechanisms in cell signaling, membrane trafficking, and cytoskeleton remodeling.