A Colorimetric Biosensing Platform with Aptamers, Rolling Circle Amplification and Urease-Mediated Litmus Test

Area of Science:

• Biotechnology
• Analytical Chemistry
• Biosensing

Background:

• Developing sensitive and versatile detection methods is crucial for diagnostics.
• Existing platforms may lack amplification power or simplicity.
• Colorimetric assays offer visual detection but often require enhancement.

Purpose of the Study:

• To develop an ultra-sensitive colorimetric sensing platform.
• To integrate rolling circle amplification (RCA) with a urease-mediated litmus test.
• To demonstrate the platform's versatility for detecting various targets, including pathogens and biomarkers.

Main Methods:

• Utilized rolling circle amplification (RCA) for signal amplification.
• Employed urease-labeled DNA hybridized to RCA products and immobilized on magnetic beads.
• Detected target presence via urease-catalyzed urea hydrolysis and subsequent pH change measured by a litmus test.
• Integrated structure-switching aptamers for thrombin and PDGF detection, and a spike-binding aptamer for SARS-CoV-2 detection.

Main Results:

• Achieved ultra-sensitive colorimetric detection of targets.
• Demonstrated successful detection of human thrombin, PDGF, and SARS-CoV-2 in saliva.
• Showcased the platform's adaptability for diverse aptamer-based sensing applications.
• Confirmed the feasibility of integrating the platform into a paper-based device for point-of-care applications.

Conclusions:

• The developed platform offers a highly sensitive and efficient method for colorimetric detection.
• The combination of RCA and urease-mediated detection provides a robust sensing strategy.
• The platform's adaptability and integration into paper-based devices highlight its potential for widespread diagnostic applications.