Method for orienting DNA molecules on mica surfaces in one direction for atomic force microscopy imaging

Area of Science:

• Biophysics
• Molecular Biology
• Surface Science

Background:

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

Purpose of the Study:

• To develop an efficient method for stretching DNA molecules on a flat surface for AFM imaging.
• To enable precise immobilization and stretching of single DNA molecules.
• To facilitate high-resolution imaging of DNA structure and conformation.

Main Methods:

• DNA molecules were functionalized with thiol groups at their 5' ends using Polymerase Chain Reaction (PCR).
• A heterobifunctional cross-linker, N-Succinimidyl6-[3'-(2-pyridyldithio) propionamido]hexanoate (LC-SPDP), was used for conjugation.
• Thiolated DNA was immobilized onto amino-silanized mica surfaces via cross-linker reaction and surface amine coupling.

Main Results:

• DNA molecules were successfully anchored to the mica surface via their 5' ends.
• The method resulted in fully stretched DNA molecules oriented in one direction.
• AFM imaging confirmed the successful stretching and immobilization of DNA.

Conclusions:

• The developed method provides an efficient way to stretch and immobilize DNA for AFM.
• This technique allows for high-resolution imaging of single DNA molecules.
• The approach is valuable for nanoscale biophysical studies and DNA analysis.