Sensitive electrochemical sensor for Cd²⁺ with engineered short high-affinity aptamer undergoing large conformation...

Area of Science:

• Environmental Science
• Analytical Chemistry
• Biosensors

Background:

• Cadmium ion (Cd²⁺) poses significant environmental and health risks.
• Sensitive and rapid detection methods for Cd²⁺ are crucial.

Purpose of the Study:

• To develop a reagent-less aptamer electrochemical sensor for sensitive Cd²⁺ detection.
• To engineer a high-affinity DNA aptamer with a redox tag for enhanced signal transduction.

Main Methods:

• Immobilization of an engineered 15-mer DNA aptamer with methylene blue (MB) redox tag on a gold electrode.
• Utilizing square wave voltammetry (SWV) for electrochemical detection.
• Isothermal titration calorimetry (ITC) for affinity verification.

Main Results:

• The aptamer sensor demonstrated a large conformational change upon Cd²⁺ binding.
• High affinity with K_d ≈ 360 nM was confirmed by ITC.
• Sensitive detection of Cd²⁺ from 0.5 nM to 4 μM with a detection limit of 90 pM.

Conclusions:

• The developed electrochemical aptasensor offers a sensitive, stable, and reusable platform for Cd²⁺ detection.
• The sensor exhibits advantages in easy preparation and rapid response.
• Potential for broad applications in environmental monitoring and health diagnostics.