Mouthguard type biosensor for wireless measurement of salivary uric acid

The number of hyperuricemia patients has been increasing. It is important that keep normal uric acid (UA) levels to prevent complicating disease of hyperuricemia. The current standard of UA tests uses a blood sample. However, it is not suitable for self-monitoring of UA level because it involves the burden of puncture and the risk of infection by taking a blood sample. Personal UA sensor is expected to monitor diurnal variation without invasiveness in a casual manner. In this study, we fabricated and evaluated a uricase-based biosensor toward the non-invasive continuous measurement of salivary UA concentration in the oral cavity. Uricase catalyzed UA and produced H2O2 in an enzyme-immobilized membrane on a Pt electrode. Then, generated H2O2 concentration which is correlated to the UA concentration was measured by the chronoamperometry technique. As a result, not only a wide dynamic range (0.1–10 μmol/L) but also high selectivity for UA was observed. In the future, the developed UA biosensor would allow monitoring UA levels non-invasively and continuously.