On-Particle Rolling Circle Amplification-Based Core-Satellite Magnetic Superstructures for MicroRNA Detection

Area of Science:

• Biotechnology
• Nanotechnology
• Molecular Biology

Background:

• DNA-assembled core-satellite superstructures are increasingly used in biosensing due to their tunable properties.
• The number of magnetic nanoparticle (MNP) satellites influences signal intensity in response to stimuli.
• Efficient methods for preparing high-load, responsive superstructures are needed for advanced biosensing applications.

Purpose of the Study:

• To develop a novel, rapidly responsive core-satellite magnetic superstructure for sensitive microRNA detection.
• To utilize on-particle rolling circle amplification (RCA) for high MNP loading and duplex-specific nuclease-assisted target recycling for enhanced sensitivity.

Main Methods:

• On-particle rolling circle amplification (RCA) was used to create DNA scaffolds with high magnetic nanoparticle (MNP) loading.
• Duplex-specific nuclease (DSN) was employed for target-triggered MNP release via scaffold hydrolysis.
• Optomagnetic sensing quantified released MNPs for microRNA detection.

Main Results:

• The developed biosensor demonstrated a wide linear detection range of approximately 5 orders of magnitude for let-7b microRNA.
• A high sensitivity of 1 femtomolar (fM) was achieved for let-7b detection.
• The biosensor successfully discriminated single-nucleotide mismatches and detected let-7b in complex biological samples like cell extracts and serum.

Conclusions:

• The proposed DNA-assembled core-satellite magnetic superstructure offers a sensitive and rapid platform for microRNA detection.
• The biosensor's ability to detect microRNA in clinical samples highlights its potential for early disease diagnosis and monitoring.
• This approach provides a robust and versatile tool for nucleic acid sensing with broad applicability in diagnostics.