The Immunoprobe Aggregation State is Central to Dipstick Immunoassay Performance

Area of Science:

• Nanotechnology
• Biomedical Engineering
• Immunodiagnostics

Background:

• Infectious disease outbreaks necessitate rapid diagnostic tools.
• Paper-based immunoassays offer advantages in cost and scalability but face sensitivity challenges.
• Understanding molecular mechanisms can enhance immunoassay development.

Purpose of the Study:

• To investigate how synthesis strategy and surface chemistry affect nanoparticle-antibody immunoprobes in paper immunoassays.
• To quantify the impact of these factors on antigen binding affinity and immunoprobe distribution.
• To identify key factors influencing immunoassay performance.

Main Methods:

• Conjugation of gold nanoparticles to antibodies (anti-IgG, anti-Zika NS1) via electrostatic adsorption, NHS, and Hz chemistries.
• Utilizing these immunoprobes in paper dipstick immunoassays.
• Quantifying effective antigen affinity and immunoprobe distribution on test lines.

Main Results:

• Nanoparticle colloidal stability is a critical factor influencing immunoassay results.
• Instability post-synthesis and during antigen binding leads to reduced or lost assay signals.
• Surface chemistry and synthesis strategy directly impact immunoprobe behavior and assay sensitivity.

Conclusions:

• Optimizing nanoparticle colloidal stability is essential for improving paper-based immunoassay performance.
• Understanding immunoprobe behavior at the molecular level can accelerate diagnostic test development.
• This research provides insights for creating more sensitive and reliable rapid diagnostic tools.