Towards a real-time, label-free, diamond-based DNA sensor.

Area of Science:

• Nanomaterials Science
• Biotechnology
• Analytical Chemistry

Background:

• Distinguishing single-mismatch DNA from fully complementary DNA is crucial for DNA sensor development.
• Current methods face challenges in reliably identifying single-base mismatches.
• Nanocrystalline diamond (NCD) offers a promising platform for biosensing applications.

Purpose of the Study:

• To develop a real-time method for differentiating single-mismatch target DNA from fully complementary target DNA using impedance spectroscopy.
• To investigate the hybridization and denaturation dynamics of DNA on NCD surfaces.
• To optimize buffer conditions and temperatures for enhanced DNA discrimination.

Main Methods:

• Impedance spectroscopy was performed on DNA-functionalized NCD layers.
• Real-time hybridization and denaturation experiments were conducted.
• Data was fitted to an electrical circuit model to analyze changes in the diamond's space charge region.
• Experiments were varied across different buffer solutions and temperatures (20-80°C).

Main Results:

• Real-time hybridization showed a significant impedance decrease at low frequencies for complementary DNA, but not for 1-mismatch DNA.
• Real-time denaturation allowed differentiation at higher frequencies, with complementary DNA exhibiting longer impedance decay times than 1-mismatch DNA.
• Optimal conditions included Microhyb buffer at 80°C for hybridization and 0.1 M NaOH above 40°C for denaturation.

Conclusions:

• The combination of real-time hybridization and denaturation spectra provides critical information for target DNA identification.
• This impedance spectroscopy approach on NCD enables reliable identification of DNA mismatch sequences.
• The findings contribute to the advancement of sensitive and specific DNA detection technologies.