Ionic Strength Investigation on the Interaction Between miR-155 and a PNA-Based Probe by Atomic Force Spectroscopy

Area of Science:

• Biochemistry
• Molecular Biology
• Biophysics

Background:

• Peptide nucleic acids (PNAs) are synthetic DNA/RNA analogues.
• PNAs lack phosphate groups, making them less sensitive to ionic strength.
• MicroRNAs (miRNAs), like miR-155, are implicated in various diseases, including cancer.

Purpose of the Study:

• To investigate the interaction forces between PNA and microRNA-155 (miR-155).
• To analyze the influence of ionic strength on PNA-miR-155 binding kinetics and thermodynamics.
• To assess the potential of PNA as a diagnostic and therapeutic tool.

Main Methods:

• Atomic Force Spectroscopy (AFS) was employed to measure unbinding forces.
• Experiments were conducted in fluid across a range of ionic strengths (50-300 mM).
• The Bell-Evans model was used to analyze the force-loading rate data.

Main Results:

• Unbinding forces between PNA and miR-155 at 150 mM ionic strength followed the Bell-Evans model.
• This allowed for the extraction of kinetic and thermodynamic properties of the PNA-miR-155 duplex.
• Binding forces and recognition times were largely independent of ionic strength between 50-300 mM.

Conclusions:

• PNA-miR-155 interactions are robust and stable across a physiologically relevant ionic strength range.
• The findings support the utility of PNAs in biosensors for disease diagnostics and therapeutics.
• PNAs offer a promising platform for in situ molecular detection and intervention.