Abstract

Small-Molecule Quantification for Point-of-Care Testing Using Paper-based Analytical Devices

Jean-Manuel Segura, Professor, Institute of Life Technologies, University of Applied Sciences and Arts Western Switzerland Valais

Paper offers many advantages as a material to produce point-of-care (POC) diagnostic tests: Paper-based analytical devices (PAD) are cheap, amenable for mass manufacturing, easy to dispose after use and do not require external actuation. Many important biomarkers tested using PADs are small molecules. While some analytes such as glucose can be analyzed using enzymatic assays, most are quantified using competitive immunoassays, which require well-defined concentrations of the reagents (antibodies and tracers). This is not easy to achieve in a POC format, might result in assay variability and renders assay design more complex.  During this talk, I will present two examples how competitive immunoassays can be implemented in paper-based analytical devices for POC applications. In a first example, I will describe the development of a lateral flow assay for salivary cortisol, a biomarker of chronic stress. The low concentration and the stringent requirements on assay precision make the development of such a test challenging. A detailed understanding of the underlying immunoassay mechanism enabled a considerable improvement of the performance. In a second example, I will discuss the development of a vertical flow assay for the antibiotics tobramycin, which requires therapeutic drug monitoring to ensure efficacy while avoiding oto- and nephrotoxicity. A homogeneous competitive immunoassay based on fluorescence polarization was implemented inside paper microzones that enabled both plasma extraction and detection.