Herein, a colorimetric paper-based analytical device (PAD) is proposed for the direct determination of glutathione (GSH) in saliva. The device's sensing ability is based on the GSH-induced inhibition of the peroxidase (POD)-like activity of transition metal dichalcogenide (TMD) 2D-nanoflakes integrated on paper. TMDs (i.e., MoS2, WS2, MoSe2, and WSe2) were nanostructured via sonochemical exfoliation in water using sodium cholate as stabilizing agent, and, for the first time, their POD-like activity was comprehensively studied on paper towards TMB (3,3',5,5'-tetramethylbenzidine) oxidation. The nanozymatic activity of the four TMDs was carefully tested on six different papers under various TMD loading conditions. MoS2 proved to be the most effective 2D-TMD when combined with Whatman 602H paper. The MoS2-PAD was then used to develop a smartphone-based colorimetric method that relies on GSH-mediated inhibition of catalytic TMB oxidation, resulting in a blue colour switch-off. The MoS2-PAD, shown in Figure 1, was conceived to host a 3-point 'control calibration' and sample analysis in triplicate. Its manufacturing relies on the printing of hydrophobic barriers on paper to define the sensing spots, which also act as MoS2 and TMB reservoirs; this was performed using a simple, portable wax printer. The MoS2-PAD smartphone-based colorimetric assay consists of two straightforward steps, i.e., (i) saliva and H2O2 loading, (ii) smartphone readout after 10 min. The GSH matrix matched calibration returned a linear range enclosed between 0.5 and 10 μM (R² = 0.991) with a LOD of 0.14 μM, showing a suitable inter-batch reproducibility (RSD ≤ 4%, n = 3). The device reliability was demonstrated through GSH determination in 17 real saliva samples, obtaining accurate (recovery: 81-117%) and reproducible data (RSD ≤ 16%, n=3), correlated with the Ellman-reference method (r = 0.972). Summing up, the proposed PAD enables GSH determination at physiologically relevant levels, requiring only 3 μL of sample, representing a step toward point-of-care devices based on nanozymatic functional materials.
Integrated paper/transition metal dichalcogenides colorimetric device for the nanozymatic-sensing of glutathione in saliva
Annalisa Scroccarello;Paolo Di Battista;Flavio Della Pelle;Dounia El Fadil;Dario Compagnone
2025-01-01
Abstract
Herein, a colorimetric paper-based analytical device (PAD) is proposed for the direct determination of glutathione (GSH) in saliva. The device's sensing ability is based on the GSH-induced inhibition of the peroxidase (POD)-like activity of transition metal dichalcogenide (TMD) 2D-nanoflakes integrated on paper. TMDs (i.e., MoS2, WS2, MoSe2, and WSe2) were nanostructured via sonochemical exfoliation in water using sodium cholate as stabilizing agent, and, for the first time, their POD-like activity was comprehensively studied on paper towards TMB (3,3',5,5'-tetramethylbenzidine) oxidation. The nanozymatic activity of the four TMDs was carefully tested on six different papers under various TMD loading conditions. MoS2 proved to be the most effective 2D-TMD when combined with Whatman 602H paper. The MoS2-PAD was then used to develop a smartphone-based colorimetric method that relies on GSH-mediated inhibition of catalytic TMB oxidation, resulting in a blue colour switch-off. The MoS2-PAD, shown in Figure 1, was conceived to host a 3-point 'control calibration' and sample analysis in triplicate. Its manufacturing relies on the printing of hydrophobic barriers on paper to define the sensing spots, which also act as MoS2 and TMB reservoirs; this was performed using a simple, portable wax printer. The MoS2-PAD smartphone-based colorimetric assay consists of two straightforward steps, i.e., (i) saliva and H2O2 loading, (ii) smartphone readout after 10 min. The GSH matrix matched calibration returned a linear range enclosed between 0.5 and 10 μM (R² = 0.991) with a LOD of 0.14 μM, showing a suitable inter-batch reproducibility (RSD ≤ 4%, n = 3). The device reliability was demonstrated through GSH determination in 17 real saliva samples, obtaining accurate (recovery: 81-117%) and reproducible data (RSD ≤ 16%, n=3), correlated with the Ellman-reference method (r = 0.972). Summing up, the proposed PAD enables GSH determination at physiologically relevant levels, requiring only 3 μL of sample, representing a step toward point-of-care devices based on nanozymatic functional materials.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
