A two-layer circuit cascade-based DNA machine for highly sensitive miRNA imaging in living cells

Area of Science:

• Biotechnology
• Molecular Biology
• Nanotechnology

Background:

• MicroRNAs (miRNAs) are vital biomarkers for cancer diagnosis.
• Low miRNA expression levels necessitate ultrasensitive detection methods.
• Existing methods often lack the sensitivity and selectivity required for clinical applications.

Purpose of the Study:

• To develop an ultrasensitive and highly selective DNA machine for detecting and imaging low-abundance miRNA in living cells.
• To create a cascade system for amplified miRNA detection based on toehold-mediated strand displacement reactions (TMSDR).
• To establish a sensitive platform for quantifying specific miRNA biomarkers like miR-203.

Main Methods:

• Construction of a two-layer, enzyme-free DNA machine utilizing TMSDR.
• Integration of two DNA circuits in a cascade system for signal amplification.
• Transfection of the DNA machine into breast cancer cells for in situ miRNA detection and fluorescence imaging via FRET.

Main Results:

• Achieved a detection limit as low as 4 fM for miR-203 quantification.
• Demonstrated a 10,000-fold improvement in amplification efficiency compared to single circuits.
• Successfully performed amplified analysis and imaging of low-abundance miRNA in living cells.

Conclusions:

• The developed two-layer cascade DNA machine offers a highly sensitive platform for analyzing low-abundance miRNAs.
• This technology holds significant promise for advancing biomedical and clinical research, particularly in cancer diagnostics.
• The enzyme-free, isothermal nature of the DNA machine enhances its applicability in various settings.