A Handheld Saliva Analyzer Employing Homogeneous Nanogrid Film for Noninvasive on‐Site Detection Periodontitis and Salivary Gland Tumor

Saliva is a non-invasive, easily collected fluid ideal for health monitoring, but its ultralow metabolite concentrations make accurate detection challenging for current analytical tools, limiting its clinical diagnostic use. Here, a homogeneous nanogrid film composed of Prussian blue/Au nanogrid (PB/AuNG) to fabricate salivary biosensors for diagnosing oral diseases is fabricated. The PB/AuNG nanogrid film allows for the uniform immobilization of oxidase enzymes or antibodies, thereby substantially enhancing the detection sensitivity for trace salivary biomarkers. Then it is designed biosensing chips modified with PB/AuNG to respectively detect the lactate (potential biomarkers of periodontitis) and interleukin (IL)-6 (potential biomarkers of salivary gland tumor). The microchips have achieved the ultra-low limit of 6.5 µM to lactate within 5 s and 0.14 fg mL^-1 to IL-6 within 20 min. After comprehensive performance evaluation and feasibility validation, a handheld saliva analyzer integrated with PB/AuNG-based microchips for portable, non-hospital-based monitoring is developed. The device is subsequently employed to analyze real saliva samples from periodontitis and salivary gland tumor patients, successfully distinguishing between the two groups based on differences in lactate and IL-6 concentrations. This study presents a diagnostic platform for early detection of saliva metabolites, aiming to promote proactive, personalized health management.