Target-activated multivalent sensing platform for improving the sensitivity and selectivity of Hg²⁺ detection

Area of Science:

• Biochemistry
• Analytical Chemistry
• Nanotechnology

Background:

• Sensor performance relies heavily on sensitivity and selectivity, posing challenges for trace detection.
• Developing sensors with simultaneous high sensitivity and selectivity remains a key research area.
• Mercury ions (Hg²⁺) are toxic and require sensitive detection methods.

Purpose of the Study:

• To explore multivalency's role in enhancing analytical sensitivity and selectivity for target detection using a DNAzyme-based sensor.
• To develop a target-activated dual Mg²⁺-dependent DNAzyme (MNAzyme) for mercury ion sensing.
• To investigate the improved binding stability and catalytic efficiency of the dual MNAzyme.

Main Methods:

• Design and synthesis of a target-activated dual Mg²⁺-dependent DNAzyme (MNAzyme).
• Utilizing the thymine-Hg²⁺-thymine structure for target recognition and MNAzyme formation.
• Characterization of MNAzyme catalytic activity and comparison with monomeric counterparts.
• Application of the MNAzyme in a sensor for mercury ion detection using UV-vis spectrophotometry and naked-eye observation.

Main Results:

• The dual MNAzyme demonstrated a theoretically 1.60-fold higher catalytic rate constant compared to the monomer.
• Achieved 4.50-fold enhancement in sensitivity and 1.44-fold enhancement in selectivity for mercury ion detection.
• Established a limit of detection of 0.04 nM (UV-vis) and 0.2 nM (naked eye) for mercury ions.
• Exhibited desirable selectivity for Hg²⁺ over other metal ions.

Conclusions:

• The developed dual MNAzyme platform offers a simple, highly sensitive, and selective method for mercury ion detection.
• Multivalency significantly enhances the analytical performance of DNAzyme-based sensors.
• This versatile sensing platform holds potential for on-site detection of various low-abundance analytes.