The cross between doctors and workers in pharyngitis-macromolecular crowding agent improves the sensitivity of lateral flow immunoassay.

Lateral flow immunoassay (LFIA) is widely used in the fields of health, environment and food, and is used for low-cost, simple and rapid on-demand testing. Usually, users only need to add samples without any other intervention from the sample application. A striking challenge and persistent pursuit in LFIA is to improve the detection sensitivity without affecting simplicity and practicality. We report that the addition of water-soluble macromolecular crowding agent leads to the improvement of sensitivity, which is attributed to the exposure of antibodies and micro/nano-particle conjugates to macromolecular crowding environment, and at the same time, it migrates through the restricted pores of the strip-through the capillary force pad, promoting the interaction responsible for analyte recognition and signal generation. Streptococcus pyogenes is related to pharyngitis. In order to immediately prove that the sensitivity is enhanced, we work directly on the commercially available equipment that has been optimized in terms of reagents and conditions. Among the crowers used, ficoll, Mr 400000 and ficoll, Mr 70000 improve the signal by 5-10 times without affecting the background. Because the addition of macromolecular crowding agent is a supplement to other strategies to enhance sensitivity, such as the design of new labels and the introduction of signal amplification, we expect that the proposed modulation will be extended to many analytes with various reporter genes and LFIA configurations.

Innovations: 1. Introducing water-soluble macromolecular crowding agent as a new strategy to improve the sensitivity of lateral flow immunoassay is a breakthrough method. Traditionally, improving the sensitivity of LFIA often requires complex technical improvement, and this study provides a relatively simple solution; 2. The study reveals the positive influence of the crowded environment of macromolecules on the interaction between antibodies and micro/nano-particle conjugates, which provides a new theoretical perspective for bioanalysis technology; 3. Without changing the basic structure and operation simplicity of LFIA, the detection sensitivity was significantly improved by adding crowding agent, and the original advantages of rapid detection were maintained.

 Scientific research inspiration: 1. The mechanism of macromolecular crowding agent inspires us to rethink the environmental factors of the interaction between biomolecules, especially the crowding effect on the behavior of biomolecules; 2. The research shows that the regulation of micro-environment can be an important way to improve the detection sensitivity, which provides a new idea for the improvement of other bioanalysis technologies; 3. By simply adjusting additives, the detection performance can be improved without increasing complexity, and this strategy has a wide range of potential application values; 4. The differential influence of Ficoll molecular weight on sensitivity improvement is revealed, which provides a theoretical basis for further optimizing the selection of crowding agent. Extension of ideas: 1. This research method can be extended to other lateral flow immunoassay systems, and may even be applicable to different types of biosensing technologies, such as enzyme-linked immunosorbent assay (ELISA); 2. We can explore different types of macromolecular crowding agents and study their influence mechanism on biomolecule interaction and detection sensitivity; 3. Combining this method with the existing signal amplification and new labeling technology, it is possible to achieve more significant sensitivity improvement; 4. This method has an important application prospect for fields that need high sensitivity and rapid detection, such as infectious disease diagnosis, food safety and environmental monitoring; 5. Further study on the influence of crowded environment on biomolecular dynamics may open up a new research direction for biotechnology and medical diagnosis; 6. Explore the influence of crowding agents with different molecular weights and chemical properties on detection performance, and provide theoretical support for personalized and accurate bioanalysis methods; 7. Consider interdisciplinary integration of this technology with other emerging detection technologies (such as nanotechnology and microfluidic technology) to develop more advanced diagnostic tools. 

Similar research ideas: 1. By adding specific viscosity regulators (such as polyethylene glycol, dextran, etc.) to study its influence on the sensitivity of immunoassay. 2. Explore the regulation of natural polysaccharides with different molecular weights and concentrations (such as hyaluronic acid and chitosan) as crowding agents on the detection effect. 3. Using protein-protein interaction enhancer (such as ammonium sulfate and citrate) to improve the antigen-antibody binding efficiency. 4. To study the synergistic effect of surfactant and macromolecular crowding agent on the migration rate of immunochromatography. 5. Develop an intelligent crowded environment based on temperature responsive polymers to achieve a controllable immune response enhancement effect.

DOI : 10.1016/j.bios.2022.114737