Single-mismatch position-sensitive detection of DNA based on a bifunctional ruthenium complex

Area of Science:

• Electrochemistry
• Biochemistry
• Nanotechnology

Background:

• Ruthenium complexes offer dual functionality for sensing applications.
• DNA biosensors require sensitive and selective detection methods.
• Intercalative binding enhances DNA-analyte interactions.

Purpose of the Study:

• To develop a sensitive and selective electrochemical DNA biosensor using a novel ruthenium complex.
• To investigate the binding interactions between the ruthenium complex and DNA.
• To quantify target DNA sequences from Helicobacter pylori.

Main Methods:

• Synthesis and in situ generation of a bifunctional ruthenium complex (RuL).
• Spectroscopic and electrochemical techniques to study DNA binding.
• Immobilization of a thiolated capture probe onto gold electrodes for biosensor fabrication.
• Electrochemical detection of hybridized DNA targets.

Main Results:

• The ruthenium complex exhibits selective intercalative binding to double-stranded DNA (dsDNA).
• The complex functions as both a redox probe and a fluorescent tag.
• The developed DNA biosensor accurately quantifies Helicobacter pylori DNA sequences from 106 to 708 pmol.
• A low detection limit of 92+/-0.4 pmol and high linearity (R=0.995) were achieved.
• The biosensor successfully detected single DNA mismatches and their positions without suppressors.

Conclusions:

• The bifunctional ruthenium complex is a highly effective indicator for DNA sensing.
• The developed electrochemical biosensor offers sensitive, selective, and specific detection of pathogenic DNA.
• This approach enables precise DNA sequence analysis, including mismatch identification, crucial for diagnostics.