Fishing plasma-circulating autoantibodies with magnetic pseudo-platelets for rapid optomagnetic quantification

Area of Science:

• Biomedical Engineering
• Immunology
• Analytical Chemistry

Background:

• Accurate detection of anti-platelet autoantibodies is critical for diagnosing immune thrombocytopenia (ITP).
• Conventional assays are limited by detecting surface-bound antibodies, being labor-intensive, semi-quantitative, and affected by low platelet counts.

Purpose of the Study:

• To develop and validate a novel magnetic pseudo-platelet-based optomagnetic sensing system for detecting plasma-circulating anti-platelet autoantibodies.
• To compare homogeneous and heterogeneous detection formats for sensitivity, specificity, and diagnostic accuracy in ITP patients.

Main Methods:

• Fabrication of magnetic pseudo-platelets to capture circulating autoantibodies.
• Establishment of an optomagnetic sensing system based on antibody-induced particle agglutination.
• Systematic comparison of homogeneous (real-time immuno-agglutination) and heterogeneous (secondary signal amplification) formats.

Main Results:

• The heterogeneous format achieved limits of detection of 0.83 ng/mL in buffer and 5.3 ng/mL in 10% plasma.
• The homogeneous format had limits of detection of 6.1 ng/mL in buffer and 130 ng/mL in 10% plasma.
• The biosensor demonstrated excellent discrimination between ITP patients and healthy controls, comparable in accuracy to flow cytometry.

Conclusions:

• The magnetic pseudo-platelet biosensor provides a rapid (∼11 min), platelet count-independent method for detecting anti-platelet autoantibodies.
• This technology is suitable for point-of-care testing and offers a versatile platform for screening blood protein biomarkers.
• The developed assay offers complementary diagnostic information for immune thrombocytopenia.