Electrochemical Detection of Single-Stranded DNA Using Polymer-Modified Electrodes.

Area of Science:

• Electrochemistry
• Materials Science
• Biotechnology

Background:

• Development of modified electrodes for enhanced electrochemical sensing.
• Investigating the catalytic properties of ruthenium-based polymers.
• Understanding electron transfer mechanisms in modified electrode systems.

Purpose of the Study:

• To prepare and characterize glassy carbon electrodes modified with poly[Ru(vbpy)3(2+)] and poly[Ru(vbpy)3(2+)/vba] films.
• To evaluate the catalytic activity of these modified electrodes for the oxidation of guanosine 5'-monophosphate (GMP) and polyguanosine (poly[G]).
• To assess the potential of these modified electrodes for detecting DNA with guanine bases.

Main Methods:

• Reductive electropolymerization of ruthenium complexes on glassy carbon electrodes.
• Electrochemical characterization of polymer films in aqueous and non-aqueous solutions.
• Cyclic voltammetry to study the catalytic oxidation of GMP, poly[G], and DNA.

Main Results:

• Polymer films exhibited reversible Ru(III/II) couples in non-aqueous but irreversible in aqueous media.
• Catalyzed oxidation of GMP and poly[G] with current enhancement attributed to electrostatic condensation and facilitated electron transfer.
• Detection of single-stranded DNA with enhanced current (8-13 µA) for 8 pmol of attached DNA, indicating 65% current efficiency for guanine oxidation.

Conclusions:

• Glassy carbon electrodes modified with poly[Ru(vbpy)3(2+)] and its copolymer show significant catalytic activity for guanine oxidation.
• The modified electrodes demonstrate potential for sensitive electrochemical detection of DNA and related biomolecules.
• The study highlights the role of electrostatic interactions and electron transfer kinetics in the observed catalytic enhancement.