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Flip-PAD integrating laser-scribed platinum-nanozyme for rapid smartphone-based colorimetric determination of ascorbic acid

Year: 2025
Type: article
Abstract: 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. 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 CO 2 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, assembled in an array format to allow the simultaneous analysis of 5 samples in 1 minute; a smartphone camera is used for the RGB signal acquisition. The L-nPt CO 2 -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 TMB ox 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. AA dose-response signal resulted linear from 31 to 250 mg Kg -1 (R 2 = 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. • A Flip-PAD for rapid and selective determination of ascorbic acid (AA) is proposed • Flip-PAD operation relies on a CO 2 laser-scribed paper/nanoplatinum catalytic layer • AA smartphone-based sensing relies on TMB-catalytic conversion selective inhibition • Flip-PAD AA determination needs 1 min and no additional reagents • Flip-PAD allows selective and accurate AA determination in food and pharmaceuticals
DOI: 10.1016/j.aca.2025.344150
Language: English
Open Access status: hybrid
Estimated APC paid: $4,270
OpenAlex ID: W4410022518
FWCI: 0.705
Cites: 43
Cited by: 3
Related to: 10