A highly sensitive and selective signal-on strategy for microRNA quantification.

Area of Science:

• Biochemistry
• Molecular Biology
• Analytical Chemistry

Background:

• MicroRNAs (miRNAs) are crucial regulators of physiological and pathological processes.
• miRNAs serve as valuable biomarkers for disease diagnosis and monitoring treatment efficacy.
• Accurate and sensitive quantification of miRNAs in biological samples is essential for clinical applications.

Purpose of the Study:

• To develop a simple, cost-effective, and highly sensitive method for quantitative miRNA assay.
• To achieve femtomolar sensitivity and single-base discrimination for miRNA detection.
• To enable direct analysis of miRNAs in complex biological matrices without prior RNA isolation.

Main Methods:

• A novel signal-on strategy involving polyadenylation and 2-Chloroacetaldehyde (CAA) labeling for signal amplification.
• High-performance liquid chromatography with fluorescence detection (HPLC-FD) for separation and quantification.
• Affinity magnetic solid-phase extraction (MSPE) for sample cleanup and enrichment.
• Utilized locked nucleic acid (LNA) probes to enhance assay selectivity.

Main Results:

• Achieved femtomolar sensitivity (limit of detection of 200 fM for miRNA-21) and single-base discrimination.
• Demonstrated a linear calibration curve (R² = 0.999) in the pM to nM range.
• Successfully quantified miRNA-21 in bovine serum and MCF-7 cell lysates with high repeatability (4.0% RSD).
• Eliminated the need for total RNA isolation, simplifying sample preparation.

Conclusions:

• The developed HPLC-FD method provides an accurate, reliable, and cost-effective means for miRNA quantification in biological samples.
• This approach offers significant advantages for disease diagnosis and therapeutic evaluation due to its sensitivity and simplicity.
• The method's ability to bypass RNA isolation broadens its applicability in clinical and research settings.