Localized Bicirculating DNAzyme Self-Feedback Amplification Strategy for Ultra-Sensitive Fluorescence Biosensing of...

Area of Science:

• Biotechnology
• Molecular Biology
• Nanotechnology

Background:

• DNAzyme-based cascade networks enable ultrasensitive microRNA (miRNA) detection but are complex, costly, and time-consuming.
• Existing methods often require intricate designs and lengthy procedures, limiting their practical application.

Purpose of the Study:

• To design a novel, simple, non-cascade DNAzyme network for ultrasensitive miRNA detection.
• To develop a cost-effective, rapid, and efficient biosensor with improved amplification capabilities.

Main Methods:

• A nonenzymatic, isothermal, bicirculating amplification network was developed using two toehold-mediated strand-displacement reactions.
• A localized DNAzyme amplification strategy was employed, utilizing superparamagnetic Fe3O4@SiO2 particles for DNAzyme localization and signal probe separation.
• The system was tested for microRNA-122 detection using fluorescence.

Main Results:

• The novel network demonstrated amplification comparable or superior to cascading designs.
• An ultrasensitive fluorescence biosensor achieved a detection limit of 84 zmol L⁻¹ for microRNA-122, an 8-order-of-magnitude improvement over non-amplification methods.
• The biosensor exhibited specificity, speed, thermal stability, and low cost.

Conclusions:

• The bicirculating DNAzyme amplification network provides a simple yet effective strategy for ultrasensitive bioassays.
• This approach offers a new pathway for developing advanced biosensors, DNA logic gates, and DNA computers.
• The design overcomes limitations of traditional cascade networks, presenting a more practical and efficient solution.