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Direct single-molecule counting for immunoassay applications.

Patrick J Macdonald1, Qiaoqiao Ruan1, Sergey Y Tetin1

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This summary is machine-generated.

Single-molecule counting using TIRF enhances immunoassay sensitivity and specificity. This method enables a universal platform for diverse diagnostic and blood screening assays, including HIV detection.

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Digital immunoassaysFluorescence microscopySingle-molecule imagingTIRF

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Area of Science:

  • Biotechnology
  • Analytical Chemistry
  • Biophysics

Background:

  • Single-molecule methods provide high specificity and sensitivity for complex biological systems.
  • Immunoassays are crucial for diagnostics but can benefit from enhanced detection techniques.

Purpose of the Study:

  • To apply single-molecule total internal reflection fluorescence (TIRF) microscopy to immunoassays for improved target molecule counting.
  • To develop a universal detection platform for various diagnostic and blood screening applications.

Main Methods:

  • Utilizing single-molecule counting on eluted detection conjugates after capture and sandwich formation on microparticles.
  • Employing a sample reloading approach to concentrate analytes on the detection surface, leveraging the streptavidin-biotin interaction.
  • Demonstrating the method on a model system and an HIV p24 antigen assay.

Main Results:

  • Successfully applied single-molecule counting to immunoassays, demonstrating high sensitivity and specificity.
  • Validated the utility of eluted detection conjugate counting for robust immunoassay performance.
  • Showcased the effectiveness of sample reloading for analyte concentration in low-volume samples.

Conclusions:

  • Single-molecule detection in immunoassays is powerful, flexible, and does not require complex instrumentation.
  • The developed approach offers a simple, effective, and universal platform for diverse diagnostic needs.
  • This method holds significant potential for advancing immunoassay diagnostics, including blood screening and infectious disease detection.