Percorrer por autor "Polli, Francesca"
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- Nitrite quantification in processed meat using an enzyme biosensor, a portable reader and a smartphone : a facile and accurate approachPublication . Surace, Luca; Zumpano, Rosaceleste; Polli, Francesca; Gajdar, Július; Mazzei, Franco; Almeida, M. GabrielaThe control of nitrite levels in foodstuff is essential for ensuring human safety. However, the protocols are long and require lab equipment (spectrophotometer and centrifuge) not available in industrial or commercial settings. Herein, we adapted an electrochemical nitrite biosensor utilizing the enzyme cytochrome c nitrite reductase (ccNiR) previously developed in our lab, to meet the analytical requirements of cured meats, and validated it using real samples from different brands. The enzyme was immobilized on a disposable carbon screen-printed electrode (SPE) modified with multi-walled carbon nanotubes (MWCNTs) and connected to a hand-held potentiostat coupled to a smartphone. The carbon nanotubes suspension was optimized using chemically friendly solvents and the SPE surface was electrochemically characterized using ferricyanide as a redox probe, to fine-tune the modification formulation. The nitrite biosensor delivered a sensitivity of 0.0103 μA/μM, a linear range from 5 to 100 μM, and a lower detection limit (LOD) of 3.2 μM. Subsequently, the biosensor was tested for its ability to detect nitrites in various processed meat samples, considering factors such as type and origin. The validation of the electrochemical biosensor was conducted using the gold standard Griess method and HPLC, although the first one failed to detect nitrites in some samples due to matrix interferences. Accordingly, the nitrite biosensor performed well, providing highly accurate and precise results (smaller SD), even in non-centrifuged samples, making it possible to control the meat quality at any point of the chain distribution.
- Optimization of a gold electrodeposited platform for the development of electrochemical immunosensors : the case of study of acute kidney injuryPublication . Polli, Francesca; Zumpano, Rosaceleste; Zanellato, Gianluca; Pereira, Sofia de Azeredo; Fantoni, Alessandro; Almeida, M. GabrielaIn this work, we present a systematic approach for the optimization of a stable and reproducible platform for the development of unlabelled immunosensors based on electrodeposited (ED) gold nanoparticles (AuNPs) on screen-printed carbon electrodes (SPCEs). The modification was performed in a [AuCl4]- solution sweeping the potential between 1.1 V and - 0.1 V vs Ag/AgClsat. The influence of the gold concentration and number of ED scans on surface morphology was investigated through Scanning Electron Microscopy (SEM), Energy dispersive X-ray (EDX), and Cyclic Voltammetry (CV). The results were discussed by considering the average AuNPs diameter determined for each modification and by comparing the features of the realized platforms to those of commercial gold screen-printed electrodes (SPEs). The best performing platform in terms of electrochemical behaviour, stability, and reproducibility was selected for the development of a label-free immunosensor. The target analyte was neutrophil-associated lipocalin (NGAL), a 25 kDa protein that serves as a biomarker for Acute Kidney Injury (AKI), one of the primary causes of in-hospital mortality globally. In contrast to creatinine, NGAL allows for the early prediction of AKI-related clinical events, facilitating timely interventions, which could significantly enhance outcomes in high-risk patients. To this aim, the electrode surface was first modified with a self-assembled monolayer (SAM) of 3-mercaptopropionic acid (MPA) and then functionalized by immobilizing the NGAL antibody via EDC/NHS coupling. The LOD (0.56 μg/mL) and the high sensitivity obtained (21.8 μA mL/μg) were compatible with the diagnostic range required for AKI.