A simple and effective sample preparation method for atomic force microscopy visualization of individual DNA...

Area of Science:

• Biophysics
• Materials Science
• Nanotechnology

Background:

• Atomic force microscopy (AFM) is a powerful tool for visualizing biological molecules at the nanoscale.
• Imaging individual DNA molecules in aqueous solution presents challenges in sample preparation and stability.
• Existing methods often require specific buffer conditions that can interfere with biological interactions.

Purpose of the Study:

• To develop a simple, controllable, and effective sample preparation method for AFM imaging of individual DNA molecules in aqueous solution.
• To enable high-resolution, reproducible, and stable AFM imaging of DNA in various buffer conditions.
• To facilitate in situ investigation of DNA molecular interactions and DNA/chitosan complexes for gene delivery applications.

Main Methods:

• Immobilization of DNA molecules onto mica surfaces using magnesium ions (Mg(2+)) as a positively charged bridge at concentrations of 5.0-10.0 mM.
• Utilizing Mg(2+)-modified mica for AFM imaging of DNA in buffers lacking magnesium ions.
• Employing AFM to capture high-resolution images of DNA molecules in solution.

Main Results:

• Successful AFM imaging of individual DNA molecules in aqueous solution was achieved.
• The method demonstrated good resolution, reproducibility, and stability of DNA imaging.
• The prepared samples allowed for in situ investigation of DNA molecular interactions and DNA/chitosan complexes.

Conclusions:

• A robust and versatile sample preparation method for AFM analysis of DNA in solution has been established.
• This technique overcomes limitations of previous methods, allowing imaging in diverse buffer environments.
• The method has significant implications for studying DNA behavior and its applications in gene delivery systems.