Scanning tunnelling microscopy of biomacromolecules

Area of Science:

• Biophysics
• Materials Science
• Microscopy

Background:

• Scanning tunneling microscopy (STM) requires conductive samples for imaging.
• Coating biomacromolecules with conductive layers is a common preparation technique.
• Investigating diverse biomacromolecules aids in understanding their structure and properties.

Purpose of the Study:

• To evaluate the efficacy of platinum/carbon coating for STM imaging of biomacromolecules.
• To compare STM images of a bacterial protein layer and type IV collagen with electron microscopy.
• To demonstrate the versatility of STM in visualizing different biomolecular structures.

Main Methods:

• Specimens of HPI-layer from Deinococcus radiodurans and type IV collagen were prepared.
• Evaporated platinum/carbon was used as a conductive coating film.
• Scanning tunneling microscopy (STM) was employed for high-resolution imaging.

Main Results:

• STM imaging was successful for both the HPI-layer and type IV collagen after coating.
• The HPI-layer, a 2D protein crystal (18 nm period), was clearly visualized.
• Type IV collagen, observed as 1.5 nm diameter triple-helical strands, was also resolved.
• STM images showed strong agreement with conventional electron microscopy data.

Conclusions:

• Platinum/carbon coating is a reliable method for preparing biomacromolecules for STM analysis.
• STM provides high-resolution structural information comparable to electron microscopy for diverse biomolecules.
• This technique expands the application of STM in structural biology and materials science.