Analytical Sciences

Wax-Assisted One-Step Enzyme-Linked Immunosorbent Assay on Lateral Flow Test Devices

Masanori ISHII,* Pattarachaya PREECHAKASEDKIT,** Kentaro YAMADA,* Orawon CHAILAPAKUL,*** Koji SUZUKI,* and Daniel CITTERIO*

*Department of Applied Chemistry, Keio University, 3-14-1 Hiyoshi, Kohoku, Yokohama 223-8522, Japan
**Program in Biotechnology, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand
***Electrochemistry and Optical Spectroscopy Center of Excellence (EOSCE), Department of Chemistry, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand

Lateral flow tests (LFTs) are widely used analytical tools characterized by portability, operator simplicity and short analysis times. A remaining challenge is their limited analytical sensitivity, which in classical immunoassay formats is overcome by enzyme-linked immunosorbent assay (ELISA) formats. The implementation of ELISA to an LFT format however, is hampered by the complexity of the procedure requiring the enzyme substrate addition after sample addition. In this work, a simple method for automation of this procedure without user interference is presented. Originally used sample pads of LFTs have been replaced by hydrophobic wax-modified filter paper-based sample pads to realize a delayed flow a pre-deposited colorimetric ELISA substrate without other alterations to the classical lateral-flow immunoassay format. The performance of the system has been characterized by visualizing flow behavior and final proof-of-concept is provided by a model mouse IgG assay, achieving a limit of detection of 15.8 ng mL⁻¹ from just a single application of the sample solution.

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