Investigation of the Lifetime of Electrochemical Immunosensor Based on Immunochromatographic Strip for the Infectious Disease Testing

Lateral flow tests, also known as immunochromatographic assays, are the most popular technique for point-of-care detection. Combined with the advantages of electrochemical immunoassays, portability and quantitative requirements can be met. However, when the sensor’s reproducibility and mass production are of more importance for practical applications, antibody activity retention is the most critical factor. Once adsorbed to a solid surface, antibodies do not always retain the activity and performance during storage. Although some antibody stabilizers in solution such as sucrose, azide, can be used, their effects might be limited in novel conditions such as in electrochemical assays 1 . Therefore, finding additional methods for improving the long-term stability of antibodies is crucial for these novel devices. Blocking agents not only prevent non-specific binding but also stabilize the immobilized reactant by sterical support 2 . Herein, Bovine serum albumin (BSA), Polyvinylpyrrolidone (PVP), and Casein are investigated and optimized as blocking agents. 3% casein under 2 hours of treatment by homogenizer showed the lowest background and minimum loss of charge after 3 days of storage in less than 10% low humidity (-16% whereas PVP lost -55%). Their performance was corroborated by testing a Dengue virus electrochemical immunosensor with 3,3’,5,5’-Tetramethylbenzidine (TMB) as electrochemical reagent for horseradish peroxidase (HRP). A sandwich immunoreaction was performed on the immunochromatographic strip and the oxidized TMB was measured amperometrically with a screen-printed electrode, which is embedded close to the capture antibody area. As antibody systems derived from other assays such as ELISA do not maintain their reactivity in lateral flow tests and other alternatives prove to be limited, our strategy becomes a potential approach that can be applied in extensive combinations with other existing methods. EMD Millipore. Rapid Lateral Flow Test Strips - Considerations for Product Development; EMD Millipore Corporation , 2013 . Jitsukawa, T.; Nakajima, S.; Sugawara, I.; Watanabe, H. Increased Coating Efficiency of Antigens and Preservation of Original Antigenic Structure after Coating in ELISA. Immunol. Methods 1989 , 116 (2), 251–257.