Structural Modification of DNA Studied by Scanning Tunneling Microscopy.

Area of Science:

• Molecular Biology
• Nanotechnology
• Biophysics

Background:

• Deoxyribonucleic acid (DNA) typically exists in a double-helix structure.
• Theoretical models predict alternative DNA conformations, including cross and T-shaped structures.
• Direct visualization techniques are crucial for identifying non-canonical DNA structures.

Purpose of the Study:

• To investigate DNA structural variants beyond the canonical double helix.
• To directly visualize individual DNA molecules using advanced microscopy.
• To confirm the existence of predicted DNA structural anomalies.

Main Methods:

• Electrospray deposition of DNA onto a Au(111) surface.
• Analysis of DNA structures using low-temperature scanning tunneling microscopy (LT-STM).
• High-resolution imaging to identify molecular conformations.

Main Results:

• Detailed visualization of various DNA structures on the Au(111) surface.
• Observation of double-stranded DNA partially unraveling into single strands.
• Confirmation of T-shaped DNA structures, aligning with theoretical predictions.

Conclusions:

• Scanning tunneling microscopy can effectively visualize individual DNA molecules and their structures.
• The study provides direct experimental evidence for T-shaped DNA formations.
• Findings support the existence of structural polymorphism in DNA under specific conditions.