Versatile Sensing Platform for Cd²⁺ Detection in Rice Samples and Its Applications in Logic Gate Computation.

Area of Science:

• Biotechnology
• Environmental Science
• Molecular Biology

Background:

• Cadmium (Cd²⁺) is a toxic heavy metal pollutant.
• Accurate detection of Cd²⁺ is crucial for environmental and food safety monitoring.
• Existing detection methods may lack sensitivity, selectivity, or simplicity.

Purpose of the Study:

• To develop a versatile and ultrasensitive sensing platform for Cd²⁺ detection.
• To utilize a Mg²⁺-dependent DNAzyme and toehold-mediated strand replacement for signal amplification.
• To demonstrate the platform's applicability in real-world samples and its potential for constructing logic gates.

Main Methods:

• Design of a sensing platform using a Mg²⁺-dependent DNAzyme and strand replacement mechanism.
• Cd²⁺-aptamer interaction triggers DNAzyme activation and substrate cleavage.
• Cyclic signal amplification via hairpin probes and G-quadruplex DNAzyme formation.
• Fluorescence detection using N-methyl mesoporphyrin IX (NMM).

Main Results:

• Achieved an ultrasensitive detection limit of 2.5 pM for Cd²⁺.
• Demonstrated robustness in complex sample matrices, enabling reliable quantitative analysis in rice.
• Successfully constructed various logic gates (AND, OR, INHIBIT, IMPLICATION, NOR, NAND) using the sensing platform.

Conclusions:

• The developed platform offers a simple, label-free, and enzyme-free method for Cd²⁺ detection.
• High sensitivity, selectivity, and a universal signal amplification mode make it suitable for routine monitoring.
• The platform shows significant promise as a competitive alternative for Cd²⁺ pollution monitoring and advanced molecular computing.