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Point-of-care testing of nitrite in oral medicine : application and validation of an enzymatic biosensor in human saliva

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Resumo:Periodontal 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.
Autores principais:Gaspar, Sara Rodrigues
Outros Autores:Proença, Luís; Alves, Ricardo; Almeida, Maria Gabriela
Assunto:periodontal disease saliva nitrite biosensors point-of-care test
Ano:2025
País:Portugal
Tipo de documento:contribuição para revista
Tipo de acesso:acesso aberto
Instituição associada:Egas Moniz - Cooperativa de Ensino Superior, CRL
Idioma:inglês
Origem:Egas Moniz - Cooperativa de Ensino Superior, CRL

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