Method for stretching DNA molecules on mica surface in one direction for AFM imaging

Area of Science:

• Biophysics
• Molecular Biology
• Surface Science

Background:

• Atomic Force Microscopy (AFM) is crucial for nanoscale imaging.
• Stretching DNA molecules is essential for accurate AFM analysis.
• Existing methods for DNA stretching and immobilization can be complex or inefficient.

Purpose of the Study:

• To develop an efficient method for stretching DNA molecules on a surface for AFM imaging.
• To enable precise immobilization of DNA via its 5' end.
• To achieve uniformly stretched DNA conformations for high-resolution imaging.

Main Methods:

• DNA molecules were functionalized with thiol groups at the 5' end using Polymerase Chain Reaction (PCR).
• A heterobifunctional cross-linker, N-Succinimidyl6-[3'-(2-pyridyldithio) propionamido]hexanoate (LC-SPDP), was used for conjugation.
• Immobilization was achieved by anchoring thiolated DNA to amino-silanized mica surfaces via the cross-linker's reactive groups.
• Samples were washed and dried to prepare for AFM imaging.

Main Results:

• DNA molecules were successfully anchored to the atomically flat mica surface via their 5' ends.
• The cross-linking and immobilization strategy resulted in uniformly stretched DNA molecules.
• AFM imaging confirmed the successful stretching and high-quality visualization of the DNA strands.

Conclusions:

• The developed method provides an efficient and reliable way to stretch and immobilize DNA for AFM.
• This technique facilitates high-resolution imaging of single DNA molecules in a stretched conformation.
• The approach has potential applications in nanoscale biophysics and molecular diagnostics.