Helium Ion Microscopy Visualizes Lipid Nanodomains in Mammalian Cells

Area of Science:

• Cell biology
• Microscopy techniques
• Biophysics

Background:

• Cell membranes feature dynamic lipid micro- and nanodomains crucial for signal transduction.
• The small size of these nanodomains (10-200 nm) hinders direct imaging with conventional light microscopy.

Purpose of the Study:

• To present helium ion microscopy (HIM) as a novel method for direct visualization of cell membrane nanodomains.
• To demonstrate HIM's capability to image biological specimens without conductive coating at high resolution.

Main Methods:

• Helium ion microscopy (HIM) for direct visualization of cell membrane nanodomains.
• Specimen preparation involving fixation of unsaturated fatty acids and selective removal of saturated fatty acids.
• Corroboration using atomic force microscopy, fluorescence microscopy, 3D structured illumination microscopy, and direct stochastic optical reconstruction microscopy.

Main Results:

• HIM achieves 1.5 nm resolution, enabling clear identification of nanodomains in cell membrane ultrastructure.
• Observed nanodomains average 20 nm in diameter and are densely packed with a minimal nearest neighbor distance of approximately 15 nm.
• HIM images preserve nanodomain shape, supported by complementary microscopy techniques.

Conclusions:

• Helium ion microscopy is a powerful tool for high-resolution imaging of cell membrane nanodomains.
• The findings provide new insights into the ultrastructure and arrangement of membrane nanodomains.
• This technique advances the study of lipid organization and its role in cellular signaling.