Gaspar, Sara RodriguesProença, LuísAlves, RicardoAlmeida, Maria Gabriela2025-09-052025-09-052025-082214-1804PURE: 128750520PURE UUID: 04b93e0e-3cc5-45ef-b35b-02832785287cScopus: 105012628995http://hdl.handle.net/10362/187605Funding Information: This work is financed by national funds through the FCT – Foundation for Science and Technology, I.P., under the projects UIDB/04585/2020 (Research Center - CiiEM), UIDP/04378/2020 and UIDB/04378/2020 (Research Unit on Applied Molecular Biosciences - UCIBIO), and LA/P/0140/2020 (Associate Laboratory Institute for Health and Bioeconomy - i4HB), and for the research project 2022.04940.PTDC. The authors acknowledge Nuno Costa from Laboratório de Análises/REQUIMTE/LAQV at NOVA FCT, Portugal, for the acquisition of the ion chromatography data. Publisher Copyright: © 2025 The AuthorsPeriodontal disease (PD) is a chronic inflammatory condition triggered by bacterial biofilms and progresses through two main stages: gingivitis and periodontitis. The existing diagnostic methods remain time-consuming and require clinical expertise. Salivary nitrite, a stable end-product of nitric oxide produced during inflammation, has emerged as a promising biomarker for PD. However, its reliable quantification in saliva typically relies on laboratory-based assays that are unsuited to clinical workflows. This study aimed to test and validate a new nitrite point-of-care test (POCT) for oral medicine. Building on previous research, we developed a biosensing platform based on screen-printed carbon electrodes modified with a selective enzyme, the cytochrome c nitrite reductase. To adapt bioelectrodes for salivary analysis, they were further modified with a poly(vinyl) alcohol coating and a biochemical oxygen scavenger system (ascorbate oxidase and ascorbate). The nitrite biosensor achieved a suitable linear range of 5–300 μM, with a sensitivity of 0.015 μM−1, validated against the gold-standard Griess method. Unlike the Griess reaction, the biosensor was unaffected by sample turbidity, rendering centrifugation unnecessary. Additionally, we observed that sample freezing altered nitrite concentrations, increasing levels in non-centrifuged samples, while decreasing them in previously clarified samples. These findings highlight the need for real-time analysis and call into question the reliability of previously published data that overlooked these variables. Therefore, our results demonstrate the potential of the nitrite biosensor as a novel salivary POCT and emphasize the critical need for standardized sample-handling protocols.104871062engBiosensorsNitritePeriodontal diseasePoint-of-care testSalivaBiotechnologyElectronic, Optical and Magnetic MaterialsAnalytical ChemistrySignal ProcessingElectrical and Electronic EngineeringSDG 3 - Good Health and Well-beingjournal article10.1016/j.sbsr.2025.100860https://www.scopus.com/pages/publications/105012628995