A DNA biosensor based on peptide nucleic acids on gold surfaces

Area of Science:

• Surface Chemistry
• Biomolecular Engineering
• Analytical Chemistry

Background:

• Peptide nucleic acid (PNA) molecules can form self-assembled monolayers (SAMs) with optimal structural configuration for DNA recognition.
• Previous research indicates PNA SAMs on gold surfaces maintain DNA binding capabilities.

Purpose of the Study:

• To develop and characterize a DNA biosensor utilizing PNA SAMs on gold.
• To demonstrate the detection and spectroscopic analysis of PNA-DNA hybridization without fluorescence labeling.

Main Methods:

• Fabrication of PNA SAMs on gold surfaces.
• Utilized PM-RAIRS (Polarization Modulation-Reflection Absorption Infrared Spectroscopy) for surface characterization.
• Employed synchrotron radiation XPS (X-ray Photoelectron Spectroscopy) for molecular detection and hybridization analysis.

Main Results:

• Spectroscopic features, including those linked to the DNA backbone's phosphate groups, confirmed PNA-DNA heteroduplex formation.
• XPS N(1s) core level peaks were decomposed, with components assigned to different chemical species post-hybridization.
• Demonstrated unambiguous signatures of DNA hybridization on the PNA-functionalized gold surface.

Conclusions:

• The combined use of PM-RAIRS and XPS provides powerful, label-free characterization of PNA-DNA hybridization.
• PNA-based biosensors show significant promise for detecting DNA molecules in natural samples.
• The developed spectroscopic methods offer robust validation for PNA-DNA interactions.