Polyelectrolyte Brush-Decorated Polystyrene Nanoparticles for Sensitive Antigen Detection via Enhancing Spatial Capture Efficiency in a Lateral Flow Immunochromatographic Assay

High Resolution Image Download MS PowerPoint Slide Rapid detection is crucial for the control and management of infectious diseases. The lateral flow immunochromatographic assay (LFIA) is a prevalent method for quick diagnostics. However, its sensitivity remains a significant limitation. In this study, we report the development of an enhanced test line for LFIA, incorporating spherical polyelectrolyte brushes (SPBs) to create a nanoparticle (NP)-based 3D antigen capture matrix, resulting in increased sensitivity for the detection of SARS-CoV-2 antigens and inactivated viruses. SPBs, characterized by their densely charged polymer-decorated polystyrene NPs, enable efficient immobilization of capture antibodies. By sufficiently utilizing this nanoscale feature of SPBs, a robust “antigen capture matrix” through the volumetric layering of SPBs NPs was established on the LFIA test line. This modification, denoted as the LFIA-SPB strip, retains the foundational architecture and signal interpretation duration of standard LFIA while significantly improving its analytical performance. The limit of detection (LOD) value for detection of SARS-CoV-2 recombinant antigen was improved from 255.90 pg/mL of traditional LFIA to 81.33 pg/mL of LFIA-SPB. It also demonstrated exceptional specificity for SARS-CoV-2 in the presence of other respiratory viruses, achieving a LOD of 0.26 TCID 50 /mL and a cutoff limit of 0.62 TCID 50 /mL by naked eye for the inactivated wild type variant. The proposed LFIA-SPB combines high sensitivity and specificity, offering an innovative and straightforward approach to overcome the current limitations of commercial LFIA products. With the benefits of simple production and cost effectiveness, this approach holds significant promise for widespread practical applications in rapid disease diagnostics.