Magnetic bead-based reverse colorimetric immunoassay strategy for sensing biomolecules

Area of Science:

• Biotechnology
• Analytical Chemistry
• Nanotechnology

Background:

• Prostate-specific antigen (PSA) is a key biomarker for prostate cancer detection.
• Sensitive and reliable detection methods for low-abundance PSA are crucial for early diagnosis.
• Existing colorimetric immunoassays may have limitations in sensitivity and specificity.

Purpose of the Study:

• To develop a novel reverse colorimetric immunoassay (RCIA) for sensitive PSA detection.
• To couple catalase with magnetic bead-based peroxidase mimics for enhanced detection.
• To validate the RCIA method for biological fluid and clinical serum analysis.

Main Methods:

• Synthesis and functionalization of magnetic beads and gold nanoparticles with antibodies.
• Development of a sandwich-type immunoassay using functionalized nanostructures.
• Utilizing catalase to modulate hydrogen peroxide levels and influence colorimetric signal.
• Quantification of residual hydrogen peroxide for PSA determination.

Main Results:

• The RCIA achieved a wide dynamic range of 0.05-20 ng mL(-1) for PSA.
• A low detection limit of 0.03 ng mL(-1) was obtained.
• High precision with intra- and interassay coefficients of variation below 6.1% and 9.3%.
• Clinical serum specimens showed good agreement with ELISA results.

Conclusions:

• The developed RCIA is a sensitive and reliable method for PSA detection in biological fluids.
• The strategy effectively utilizes catalase and magnetic beads for enhanced immunoassay performance.
• The RCIA shows potential for clinical application in prostate cancer diagnostics.