A sweat sensor for simultaneous detection of multiple thyroid health biomarkers

Thyroid health is conventionally assessed through blood tests, thyroid ultrasound, and fine needle aspiration, none suitable for routine thyroid function monitoring. With the advancement of precision medicine, there is growing demand for portable and non-invasive diagnostic approaches to evaluate thyroid conditions. In this study, an efficient electrochemical sensing system was fabricated to simultaneously detect three thyroid health related indicators in sweat: ascorbic acid (AA), tyrosine (Tyr), and Ca²⁺. The electrode substrate was prepared using a 2D conjugated metal-organic framework material (Ni₃(HITP)₂) with a high electron transfer rate constant and abundant electrochemical reactive site. This material provides a stable foundation for ultra-sensitive detection of trace biomarkers in sweat. Specific sensing components were then deposited on the Ni₃(HITP)₂ electrodes for targeted detection of these biomarkers. To ensure the stability and activity of the enzymes, ascorbate oxidase (AAOx) and tyrosinase were encapsulated within a hydrophilic MAF-7 framework. This universal enzyme protection strategy significantly enhanced their long-term stability meanwhile preserving their high activity. AA and Tyr were detected using amperometric methods based on the catalytic reaction of AAOx and tyrosinase, respectively. Ca²⁺ was analyzed using an open-circuit potential method utilizing ion recognition reactions. The sensing system was successfully tested on real sweat samples collected from volunteers under various daily conditions, demonstrating its capability to simultaneously detect AA, Tyr, and Ca²⁺. The system holds significant promise as a real-time, non-invasive, and personalized tool for routine monitoring of thyroid health.