Development of Mn²⁺-Specific Biosensor Using G-Quadruplex-Based DNA

Area of Science:

• Biochemistry
• Molecular Biology
• Nanotechnology

Background:

• Metal ions are integral to biological systems and materials, but their excess can lead to health issues and environmental damage.
• Developing sensitive and selective metal ion detection methods is crucial for monitoring and mitigating risks.
• DNA's unique structural properties, particularly guanine-rich sequences forming G-quadruplexes, offer potential for novel sensor applications.

Purpose of the Study:

• To screen for and characterize a DNA molecule capable of detecting manganese ions (Mn²⁺) with high sensitivity and selectivity.
• To investigate the structural and stability changes of the DNA molecule in response to Mn²⁺.
• To establish a Förster resonance energy transfer (FRET) based system for quantifying Mn²⁺ concentration.

Main Methods:

• Screening of an IRDAptamer library for Mn²⁺-binding sequences.
• Circular dichroism and Thioflavin T fluorescence assays to analyze G-quadruplex formation.
• Serum resistance and thermostability assays to assess molecular stability.
• Förster resonance energy transfer (FRET) system utilizing fluorescently labeled DNA termini.

Main Results:

• Identification of MnG4C1, a guanine-rich DNA sequence forming a non-canonical G-quadruplex structure in the presence of Mn²⁺.
• MnG4C1 exhibited enhanced serum resistance and thermostability in a Mn²⁺-dependent manner.
• A FRET-based system demonstrated effective Mn²⁺ detection with a limit of detection (LOD) of 0.76 µM.
• Mn²⁺-dependent conformational changes in MnG4C1 were successfully detected via FRET.

Conclusions:

• The identified DNA sequence, MnG4C1, functions as a sensitive and selective sensor for Mn²⁺.
• MnG4C1's stability and conformational changes are modulated by Mn²⁺ concentration.
• This DNA-based sensor offers a promising tool for monitoring Mn²⁺, relevant to neurodegenerative disease research and environmental monitoring.