DNAzyme-mediated fluorescence sensor based on covalent organic framework for Pb²⁺ detection

Area of Science:

• Analytical Chemistry
• Materials Science
• Biotechnology

Background:

• Lead ions (Pb²⁺) pose significant environmental and health risks.
• Accurate detection of Pb²⁺ is crucial for environmental monitoring and public health.
• Existing detection methods often face challenges with sensitivity, selectivity, or complexity.

Purpose of the Study:

• To develop a novel "signal-on" fluorescence sensing strategy for sensitive and selective detection of lead ions (Pb²⁺).
• To utilize a covalent organic framework (COF) as an efficient fluorescence quencher and GR5 DNAzyme as a Pb²⁺-responsive element.

Main Methods:

• Synthesis of a stable covalent organic framework (COF) with high fluorescence quenching efficiency.
• Immobilization of GR5 DNAzyme on the COF surface, leading to fluorescence quenching of an attached fluorophore.
• Detection of Pb²⁺ through the specific cleavage of GR5 DNAzyme, releasing the fluorophore and causing fluorescence recovery.

Main Results:

• The developed sensor exhibits a "signal-on" fluorescence response upon Pb²⁺ detection.
• High sensitivity was achieved with a low detection limit of 0.067 nM for Pb²⁺.
• The method demonstrated excellent selectivity and was successfully applied to detect Pb²⁺ in real water samples with high recovery rates (89.58%–112.70%).

Conclusions:

• The COF/GR5 DNAzyme system provides a simple, sensitive, and reliable platform for Pb²⁺ detection.
• Covalent organic frameworks show great potential as efficient fluorescence quenchers in nucleic acid-based biosensing applications.
• This work offers a promising approach for environmental monitoring and the detection of toxic heavy metal ions.