Colorimetric detection of D-dimer in a paper-based immunodetection device

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Immunodiagnostics

Background:

• D-dimer is a critical blood biomarker for diagnosing thrombotic events.
• Current diagnostic methods can be time-consuming and expensive.
• There is a need for rapid, point-of-care diagnostic tools for D-dimer detection.

Purpose of the Study:

• To develop and validate a microfluidic paper-based analytical device (μPAD) for D-dimer detection.
• To assess the sensitivity and linearity of the μPAD immunoassay.
• To evaluate the potential clinical utility of the μPAD for D-dimer screening.

Main Methods:

• Fabrication of μPADs using wax printing on chromatographic paper.
• Immobilization of anti-D-dimer capture antibodies.
• Conjugation of anti-D-dimer antibodies with 40 nm gold nanoparticles for signal amplification.
• Testing of buffer and simulated plasma samples with varying D-dimer concentrations.

Main Results:

• Successful detection of D-dimer in samples down to 15 ng/mL.
• Observed linear correlation between signal intensity and D-dimer concentration up to 100 ng/mL.
• Demonstrated potential for clinical relevance by achieving positive results above 250-500 ng/mL with appropriate dilution.

Conclusions:

• μPADs offer a promising platform for sensitive and specific D-dimer detection.
• The developed immunoassay demonstrates potential for cost-effective, point-of-care diagnostics.
• Further comparison with lateral flow devices is warranted to fully understand the merits and pitfalls.