Percorrer por autor "Gaspar, Sara Rodrigues"
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- Point-of-care testing of nitrite in oral medicine : application and validation of an enzymatic biosensor in human salivaPublication . Gaspar, Sara Rodrigues; Proença, Luís; Alves, Ricardo; Almeida, Maria GabrielaPeriodontal 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.
- Trends in nitrite detection : recent advances in electrochemical sensor technologiesPublication . Gajdár, Július; Gaspar, Sara Rodrigues; Almeida, M. GabrielaNitrite has become increasingly significant analyte in analytical chemistry, with its monitoring being essential in various industrial sectors, environmental studies, and healthcare applications. The importance of nitrite detection is evident in the growing number of research publications focused on this topic in recent years. This review specifically concentrates on the development and application of electrochemical sensors. Herein, we provide a comprehensive overview of the methodologies used for nitrite determination, including approaches based on nitrite reduction and oxidation, as well as the use of nitrite biosensors and potentiometric sensors. We attempt to highlight the progress and innovations made in this field since 2010, aiming to give readers a broad understanding of the current state of research and its future directions.