Background: The development of portable easy-to-use devices to selectively determine antioxidants still represents an open issue; antioxidants, in fact, often coexist and have similar redox reactivity. In this framework, ensuring selective colorimetric reactivity in Paper-based Analytical Devices (PAD) for a single antioxidant compound is a challenge, and the selective determination still requires time-consuming and cumbersome methods. Results: A disposable paper-based device (Flip-PAD) for the rapid and selective colorimetric determination of ascorbic acid (AA) is proposed. The Flip-PAD is equipped with a platinum nanostructured (L-nPt) catalytic paper realized using a CO2 laser, able to oxidize 3,3′,5,5′-tetramethylbenzidine (TMB); the selective inhibition of the reaction by AA gives the analytical signal. The L-nPt paper in the Flip-PAD is coupled with fiberglass loaded with TMB, and assembled in an array format to allow the simultaneous analysis of 5 samples in 1 min; a smartphone camera is used for the RGB signal acquisition. The L-nPt CO2-laser-based synthesis was carefully optimized to maximize the nanozyme (oxidase-mimicking) activity; TMB-catalytic conversion and AA-mediated inhibition were carefully studied via colorimetric, spectroscopic and microscopical analysis. The catalytic conversion of uncolored-TMB in blue-colored TMBox occurs in 1 min, with no additional reagent needed; the AA-induced TMB-catalytic conversion inhibition results in a dye conversion ‘switch-off’ employed as analytical signal. Significance: AA dose-response signal resulted linear from 31 to 250 mg kg−1 (R2 = 0.992), showing a LOD of 6 mg kg−1; analytical performance resulted constant over 6 weeks (RSD = 4 %). The Flip-PAD exploitability was proved for the AA determination in different foods and pharmaceutical samples, returning accurate (recoveries 92−114 %; relative error −11/+4 %) and reproducible (RSD ≤10 %; n = 3) data. The proposed laser-based approach opens new paths for PADs and nanostructured systems development.
Flip-PAD integrating laser-scribed platinum-nanozyme for rapid smartphone-based colorimetric determination of ascorbic acid
Scroccarello, Annalisa;Della Pelle, Flavio;Fiori, Selene;Del Carlo, Michele;Compagnone, Dario
2025-01-01
Abstract
Background: The development of portable easy-to-use devices to selectively determine antioxidants still represents an open issue; antioxidants, in fact, often coexist and have similar redox reactivity. In this framework, ensuring selective colorimetric reactivity in Paper-based Analytical Devices (PAD) for a single antioxidant compound is a challenge, and the selective determination still requires time-consuming and cumbersome methods. Results: A disposable paper-based device (Flip-PAD) for the rapid and selective colorimetric determination of ascorbic acid (AA) is proposed. The Flip-PAD is equipped with a platinum nanostructured (L-nPt) catalytic paper realized using a CO2 laser, able to oxidize 3,3′,5,5′-tetramethylbenzidine (TMB); the selective inhibition of the reaction by AA gives the analytical signal. The L-nPt paper in the Flip-PAD is coupled with fiberglass loaded with TMB, and assembled in an array format to allow the simultaneous analysis of 5 samples in 1 min; a smartphone camera is used for the RGB signal acquisition. The L-nPt CO2-laser-based synthesis was carefully optimized to maximize the nanozyme (oxidase-mimicking) activity; TMB-catalytic conversion and AA-mediated inhibition were carefully studied via colorimetric, spectroscopic and microscopical analysis. The catalytic conversion of uncolored-TMB in blue-colored TMBox occurs in 1 min, with no additional reagent needed; the AA-induced TMB-catalytic conversion inhibition results in a dye conversion ‘switch-off’ employed as analytical signal. Significance: AA dose-response signal resulted linear from 31 to 250 mg kg−1 (R2 = 0.992), showing a LOD of 6 mg kg−1; analytical performance resulted constant over 6 weeks (RSD = 4 %). The Flip-PAD exploitability was proved for the AA determination in different foods and pharmaceutical samples, returning accurate (recoveries 92−114 %; relative error −11/+4 %) and reproducible (RSD ≤10 %; n = 3) data. The proposed laser-based approach opens new paths for PADs and nanostructured systems development.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
