Electrochemical DNA sensors based on nanostructured organic dyes/DNA/polyelectrolyte complexes

Area of Science:

• Electrochemistry
• Materials Science
• Biochemistry

Background:

• Phenothiazine dyes like Methylene Blue and Methylene Green are electroactive.
• Layer-by-layer assembly is a versatile technique for creating functional thin films.
• DNA integrity and redox status are crucial in biological and environmental contexts.

Purpose of the Study:

• To synthesize and characterize novel polyelectrolyte complexes on electrode surfaces.
• To investigate the electrochemical behavior of these complexes.
• To explore their potential for detecting DNA damage and changes in dye redox states.

Main Methods:

• Electropolymerization of phenothiazine dyes.
• Layer-by-layer assembly on glassy carbon electrodes.
• Electrochemical characterization using direct current voltammetry and electrochemical impedance spectroscopy.

Main Results:

• Successful formation of polyelectrolyte complexes involving Methylene Blue, Methylene Green, poly(allylamine hydrochloride), polystyrene sulfonate, and salmon sperm DNA.
• Electrochemical impedance spectroscopy revealed changes in charge transfer resistance and capacitance correlated with layer structure and DNA presence.
• The Fenton reagent's impact on interfacial resistance varied, with Methylene Green-based coatings showing a maximal effect.
• Poly(Methylene Blue)-based coatings exhibited higher selectivity for response detection.

Conclusions:

• The developed polyelectrolyte complexes offer a platform for electrochemical sensing.
• The distinct electrochemical responses allow for distinguishing between DNA damage and alterations in the polyphenothiazine redox state.
• The study highlights the tunability of these complexes for specific sensing applications.