Multiplexed detection of DNA sequences using a competitive displacement assay in a microfluidic SERRS-based device

Area of Science:

• Analytical Chemistry
• Biotechnology
• Spectroscopy

Background:

• Sensitive detection of specific DNA sequences is crucial for various applications, including diagnostics and research.
• Existing methods often require complex procedures or lack multiplexing capabilities.
• Surface-enhanced resonance Raman spectroscopy (SERRS) offers high sensitivity for molecular detection.

Purpose of the Study:

• To develop a sensitive, multiplexed, and single-step assay for detecting unlabeled DNA sequences.
• To integrate a competitive displacement assay with SERRS in a microfluidic system.
• To enhance SERRS detection sensitivity through optimized nanoparticle-reporter interactions and sample concentration.

Main Methods:

• A competitive displacement assay using DNA probes immobilized on silica beads within a microfluidic channel.
• Displacement of a Raman-labeled reporter sequence by the target DNA sequence.
• Detection via surface-enhanced resonance Raman spectroscopy (SERRS) after concentrating reporter-nanoparticle conjugates in the silica bead matrix.

Main Results:

• Achieved sensitive detection of target DNA sequences down to 100 pM.
• Demonstrated specificity, repeatability, and quantitative performance of the assay.
• Successfully performed multiplexed detection of DNA sequences using the SERRS-based method.

Conclusions:

• The integrated SERRS-based competitive displacement assay provides a sensitive, specific, and multiplexed platform for DNA detection.
• The use of a packed-bead microfluidic column enhances assay sensitivity by eliminating diffusion limitations and concentrating the signal.
• This assay is adaptable for detecting other biological macromolecules, highlighting its broad applicability.