Freeze-fracture of 3T3 cells for high-resolution scanning electron microscopy

Area of Science:

• Cell Biology
• Microscopy Techniques
• Materials Science

Background:

• Field-emission scanning electron microscopy (FE-SEM) offers high resolution for biological samples.
• Freeze-fracture techniques reveal cellular ultrastructure by fracturing cells along their natural planes.
• Low-voltage SEM imaging can minimize sample damage and enhance surface detail.

Purpose of the Study:

• To evaluate the performance of a Hitachi S-900 FE-SEM for imaging biological samples.
• To assess the feasibility of obtaining high-resolution images of freeze-fractured cells at low beam voltages.
• To compare FE-SEM results with transmission electron microscopy (TEM) of deep-etch replicas.

Main Methods:

• Cells (3T3) were extracted with Triton and freeze-fractured.
• Samples were lightly coated with platinum (1.5-3 nm thickness) via rotary deposition.
• Imaging was performed using a Hitachi S-900 FE-SEM at low accelerating voltages (1.5-5 kV).

Main Results:

• High-resolution images of unstained, glutaraldehyde-fixed 3T3 cells were obtained.
• Optimal imaging was achieved at accelerating voltages between 1.5-5 kV.
• The FE-SEM performance was evaluated under low beam voltage conditions.

Conclusions:

• Low-voltage FE-SEM is effective for high-resolution imaging of freeze-fractured biological samples.
• The technique provides detailed visualization of cellular structures without the need for staining.
• FE-SEM imaging at low voltages presents a viable alternative to TEM for certain ultrastructural studies.