Selective electrochemical discrimination of 3' isomiRs differing by two nucleotides

Area of Science:

• Biomolecular engineering
• Molecular diagnostics
• Biosensor technology

Background:

• MicroRNAs (miRNAs) and isomiRs are vital biomarkers for disease detection, particularly in oncology.
• Distinguishing between highly similar miRNA and isomiR sequences presents a significant diagnostic challenge.

Purpose of the Study:

• To develop a novel electrochemical biosensor capable of discriminating between miRNAs and isomiRs.
• To create a modular and cost-effective platform for sensitive and specific nucleic acid detection.

Main Methods:

• Design of a five-strand four-way junction (5S-4WJ) electrochemical biosensor.
• Utilized universal reporter strands and target-specific probes for modularity.
• Optimized probe length, mismatches, and hybridization kinetics to differentiate isomiRs.

Main Results:

• The 5S-4WJ biosensor successfully discriminated miR-146b from its isomiR (R + 2).
• Achieved sevenfold higher sensitivity for the isomiR (R + 2) while maintaining specificity at 10-50 nM.
• Demonstrated superior performance compared to existing electrochemical biosensors for targets with length variations.

Conclusions:

• The developed 5S-4WJ sensor enables precise detection of isomiRs, addressing a key limitation in current nucleic acid diagnostics.
• This technology advances the field of molecular diagnostics for early disease detection.
• The modular design offers a low-cost and adaptable solution for biomarker analysis.