Flotation Immunoassay: Masking the Signal from Free Reporters in Sandwich Immunoassays

Abstract

In this work, we demonstrate that signal-masking reagents together with appropriate capture antibody carriers can eliminate the washing steps in sandwich immunoassays. A flotation immunoassay (FI) platform was developed with horseradish peroxidase chemiluminescence as the reporter system, the dye Brilliant Blue FCF as the signal-masking reagent, and buoyant silica micro-bubbles as the capture antibody carriers. Only reporters captured on micro-bubbles float above the dye and become visible in an analyte-dependent manner. These FIs are capable of detecting proteins down to attomole levels and as few as 106 virus particles. This signal-masking strategy represents a novel approach to simple, sensitive and quantitative immunoassays in both laboratory and point-of-care settings.

Surface enhanced Raman scattering for the multiplexed detection of pathogenic microorganisms: towards point-of-use applications

“…A testing strategy is considered POU if it provides rapid ‘on-site’ results at the site of care delivery, production, or in resource limited settings, supporting timely and proper preventative action. 18 These inherent constraints are being circumvented by the rise of biosensor technology because it has the potential to provide sensitive, specific and reliable data comparable to conventional techniques, but with shorter analysis times and less restrictions on field deployability. 19 Whilst there are a number of POU biochemical tests available for the detection of pathogenic organisms, such as adenosine triphosphate (ATP) bioluminescence and colorimetric lateral flow assays (LFA), they currently suffer from technical challenges pertaining to a lack of specificity and sensitivity compared to the more traditional detection techniques.…”

Optical Glass Microsphere Enabled Rapid Single‐Molecular Fluoroimmunoassay

“…[ 3a ] Considering the portability and the cost of the immunoassay, various immunoassays had been developed besides the classic immunoassay on the microwell plate. Hereinto, the most popular and portable immunoassay could be regarded as the lateral flow/strip immunoassay that was performed on a filter paper [ 6c,17 ] the printed paper substrate had been adopted to obtain the sensitive sandwich immunoassay to detect 54 µ m IgG. [ 18 ] In addition, tons of portable immunoassays for the point‐of‐care (POC) had been constructed to implement the immunoassays on‐site based on microfluidics and paper pads.…”

Point of care testing for infectious diseases

“…While central clinical laboratories offer sensitive and specific assays, such as blood culture, high-throughput immunoassays, polymerase chain reaction (PCR) and mass spectrometry (MS) tests, they are often time and labor intensive, costly, and dependent on sophisticated instruments and well trained operators. On the other hand, point-of-care (POC) tests provide rapid 'on-site' results at the site of care delivery, and in resource-limited settings, supporting timely and proper treatment [3]. According to the World Health Organization (WHO), POC tests that address infectious disease control needs, especially for the developing countries, should follow "ASSURED" criteria: (1) affordable, (2) sensitive, (3) specific, (4) user-friendly, (5) rapid and robust, (6) equipment-free and (7) deliverable to end-users [4].…”