A Label-free Simple Biosensor for Pb²⁺ Detection Based on G-quadruplex DNA and Exonuclease III

Area of Science:

• Biotechnology
• Environmental Science
• Analytical Chemistry

Background:

• Heavy metal ions, particularly lead ions (Pb²⁺), present significant risks to human health and ecosystems.
• Developing sensitive and effective detection methods for Pb²⁺ is crucial for environmental monitoring and public health.

Purpose of the Study:

• To develop a label-free biosensor for the detection of lead ions (Pb²⁺).
• To utilize G-quadruplex DNA (G4-DNA) and Exonuclease III (Exo III) for a novel Pb²⁺ detection strategy.

Main Methods:

• A label-free biosensor was constructed using G4-DNA and Exo III.
• Pb²⁺ ions induce G4-DNA to form a cage-like structure, inhibiting Exo III cleavage of DNA.
• Fluorescence signal generation via DNA dye (SG I) upon inhibition of cleavage.

Main Results:

• The biosensor demonstrated a broad linear detection range for Pb²⁺ from 10 nM to 20 µM.
• A low limit of detection (LOD) of 7.3 nM was achieved.
• The biosensor exhibited high specificity for Pb²⁺ and good recovery rates (91.4%-109.7%) in pond water samples.

Conclusions:

• The developed G4-DNA/Exo III-based biosensor provides a simple, sensitive, and specific method for detecting Pb²⁺.
• This biosensor shows potential for practical application in environmental water quality monitoring.