Colloidal gold, a useful marker for transmission and scanning electron microscopy

Area of Science:

• Biotechnology
• Microscopy
• Nanotechnology

Background:

• Accurate visualization of cellular structures and molecules is crucial in biological research.
• Existing electron microscopy techniques can be limited by marker size and specificity.

Purpose of the Study:

• To develop and optimize electron-dense markers for transmission electron microscopy (TEM) and scanning electron microscopy (SEM).
• To demonstrate the utility of these markers for localizing specific macromolecules on cell surfaces and within cells.

Main Methods:

• Preparation of gold granules labeled with a monolayer of specific macromolecules (polysaccharides, proteins).
• Optimization of marker preparation conditions for simplicity and speed.
• Application of the gold labeling technique to yeast cell walls, erythrocyte membranes, yeast cells, and intact erythrocytes.
• Utilizing TEM and SEM for imaging.
• Employing spectrophotometric measurements to quantify marker adsorption.

Main Results:

• Successfully prepared electron-dense gold markers suitable for TEM and SEM.
• Demonstrated the general applicability of the method for labeling polysaccharides and proteins.
• Achieved good spatial resolution in localizing target macromolecules.
• Showcased suitability for double-labeling experiments due to the availability of different gold granule sizes.
• Validated the method for both surface and thin-section labeling.

Conclusions:

• A simple, rapid, and versatile method for preparing gold nanoparticle markers for electron microscopy has been established.
• This technique offers high spatial resolution for visualizing specific macromolecules in various biological samples.
• The method is suitable for diverse applications, including double-labeling and thin-section analysis.