A single-bead telomere sensor based on fluorescence resonance energy transfer

Area of Science:

• Biotechnology
• Nanotechnology
• Molecular Biology

Background:

• Accurate detection of single DNA molecules is crucial for molecular diagnostics.
• Current methods often require labeled targets or complex protocols.
• Developing sensitive and rapid detection systems remains a significant challenge.

Purpose of the Study:

• To develop a highly sensitive, single-bead sensor for detecting unlabeled DNA molecules.
• To utilize fluorescence resonance energy transfer (FRET) for real-time DNA detection.
• To introduce a new quantitative parameter for bio-sensor quality assessment.

Main Methods:

• Fabrication of a 200 nm single-bead sensor using Alexa 488 (donor) and Crimson 625 (acceptor) dyes.
• Utilizing G-quadruplex formation and stretching upon target DNA binding to modulate FRET efficiency.
• Employing a polydimethylsiloxane microfluidic device for controlled sample delivery and rapid analysis.
• Quantifying sensor performance using a novel parameter, sensor-sample ratio (RS).

Main Results:

• Demonstrated detection of single, unlabeled DNA molecules with a sensitivity of 1 fM.
• Observed a decrease in FRET efficiency upon target DNA binding, indicating G-quadruplex stretching.
• Achieved a sensing experiment completion time of 5 minutes under optimized microfluidic conditions.
• Proposed and validated the RS parameter for bio-sensor quality evaluation, with an optimal value of 10.

Conclusions:

• The developed single-bead sensor offers a sensitive and rapid method for detecting unlabeled DNA.
• The FRET-based mechanism effectively quantifies DNA binding events.
• The novel RS parameter provides a reliable metric for assessing bio-sensor performance and optimization.