Highly Sensitive MicroRNA Detection by Coupling Nicking-Enhanced Rolling Circle Amplification with MoS₂ Quantum Dots

Area of Science:

• Biochemistry
• Analytical Chemistry
• Molecular Biology

Background:

• MicroRNAs (miRNAs) are crucial biomarkers for various diseases.
• Sensitive and selective detection methods for miRNAs are essential for early diagnosis.
• Existing methods often face challenges with sensitivity, selectivity, or complexity.

Purpose of the Study:

• To develop a label-free and highly sensitive fluorescence assay for microRNA detection.
• To utilize nicking-enhanced rolling circle amplification (RCA) and molybdenum disulfide quantum dots (MoS2 QDs) for signal amplification and detection.
• To demonstrate the assay's efficacy in detecting microRNA let-7a in biological samples.

Main Methods:

• Construction of a padlock probe for microRNA recognition and RCA initiation.
• Coupling of G-quadruplex formation-induced nicking with RCA for signal amplification.
• Integration of inner filter effect (IFE) based quenching of MoS2 QDs by hemin/G-quadruplex DNAzymes.
• Detection of microRNA let-7a using the fluorescence quenching signal.

Main Results:

• The assay demonstrated high sensitivity for microRNA let-7a detection with a limit of detection as low as 4.6 fM.
• The method exhibited high selectivity for the target microRNA.
• Successful application of the sensor for detecting microRNA let-7a in dilute human serum samples with satisfactory recovery rates.

Conclusions:

• The developed fluorescence assay offers a sensitive and selective platform for microRNA detection.
• The combination of RCA and MoS2 QDs provides an effective strategy for signal amplification and fluorescence quenching.
• The assay holds significant potential for clinical diagnosis of miRNA-associated diseases and biochemical research.