Near-Infrared Dye-Aptamer Assay for Small Molecule Detection in Complex Specimens

Area of Science:

• Biotechnology
• Analytical Chemistry
• Biosensing Technology

Background:

• Aptamers are in vitro selected oligonucleotides with high target affinity, widely used in biosensors.
• Aptamer dye-displacement assays offer label-free, sensitive, simple, and rapid detection.
• Interferents in biospecimens often impair the sensitivity of UV-vis based aptamer assays.

Purpose of the Study:

• To develop a robust aptamer-based biosensor assay overcoming limitations of traditional methods in complex biospecimens.
• To utilize near-infrared (NIR) dye signatures for enhanced sensitivity and reduced interference.
• To demonstrate the assay's utility for detecting small-molecule analytes in clinical samples.

Main Methods:

• Employed 3,3'-diethylthiadicarbocyanine iodide (Cy5) dye, which complexes with aptamers.
• Utilized aptamer-target binding to displace Cy5, inducing J-aggregate formation for NIR signal generation.
• Validated the assay by detecting three small-molecule analytes in serum and urine using specific DNA aptamers.

Main Results:

• The NIR dye-displacement assay successfully detected analytes in complex matrices like serum and urine.
• The method demonstrated high sensitivity, enabling detection at clinically relevant concentrations.
• The formation of Cy5 J-aggregates provided a distinct and detectable NIR signal.

Conclusions:

• The developed dye-aptamer NIR biosensor effectively overcomes interference issues present in biospecimens.
• This platform offers a sensitive, label-free, and rapid method for high-throughput analyte detection.
• The assay shows significant potential for clinical diagnostics and analysis of biological samples.