Electrochemical detection of single-nucleotide mismatches using an electrode microarray.

Area of Science:

• Electrochemistry
• Molecular Biology
• Biosensing

Background:

• Accurate detection of DNA sequence variations is crucial for diagnostics.
• Electrochemical impedance spectroscopy (EIS) offers a label-free method for analyzing biomolecular interactions.
• Distinguishing single-nucleotide mismatches in DNA remains a challenge.

Purpose of the Study:

• To develop and validate an EIS-based method for detecting single-nucleotide mismatches in DNA.
• To evaluate the sensitivity and specificity of the proposed method.
• To assess the impact of impurities on DNA detection.

Main Methods:

• Utilized gold electrode arrays for electrochemical measurements.
• Employed electrochemical impedance spectroscopy (EIS) to analyze DNA hybridization.
• Applied Randles equivalent circuits to interpret impedance data based on DNA conformation changes induced by Zn(2+).

Main Results:

• Achieved unequivocal detection of eight single-nucleotide mismatches in 20-mer DNA sequences.
• Demonstrated discrimination of single-nucleotide mismatches at target strand concentrations as low as 10 femtomolar (fM).
• Showed that nontarget DNA does not interfere, maintaining the 10 fM detection limit, while protein impurities affect detection.

Conclusions:

• The developed EIS method provides a sensitive and specific approach for detecting single-nucleotide DNA mismatches.
• The technique is robust against nontarget DNA, highlighting its potential for genetic analysis.
• Further optimization may be needed to mitigate interference from protein impurities.