Label-free DNA quantification using isothermal amplification on an exposed core optical fiber microfluidic platform

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Optoelectronics

Background:

• Isothermal amplification offers efficient DNA detection compatible with portable devices.
• The COVID-19 pandemic highlighted the need for rapid, widespread diagnostic tools.
• Existing methods may lack the sensitivity, speed, or portability required for field applications.

Purpose of the Study:

• To develop and demonstrate a novel, label-free isothermal deoxyribonucleic acid (DNA) amplification method.
• To integrate optical fiber sensing with microfluidics for real-time DNA quantification.
• To achieve highly sensitive and selective DNA detection using refractive index (RI) changes.

Main Methods:

• Fabrication of a Mach-Zehnder (MZ) interference structure using exposed-core fiber (ECF).
• Integration of a microfluidic channel for sample and amplification solution delivery.
• Real-time monitoring of solution RI changes during isothermal DNA amplification.

Main Results:

• Successful demonstration of a label-free, real-time quantitative measurement of DNA amplification.
• Detection of ultra-low DNA concentrations (0.16 aM) using the proposed platform.
• Validation of the system's high sensitivity, selectivity, and portability.

Conclusions:

• The developed optical fiber-based platform provides a breakthrough for label-free DNA detection and quantification.
• This method meets the demand for simple, rapid, portable, and highly sensitive diagnostic tools.
• Potential applications include point-of-care diagnostics and environmental monitoring.