Silver-Based Supramolecular Hydrogel for the Development of Smartphone-Enabled Alkaline Phosphatase Sensor

16 August 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Alkaline phosphatase (ALP) is an important protein responsible for various conditions related to hepatobiliary, osteopenia, pregnancy, and certain cancers. Developing an easy-to-use paper-based sensor for ALP would provide a point-of-care diagnostic device. A silver-coordinated cytidine hydrogel is a potential candidate to show responses under different concentrations of ALP. Herein, we prepared and characterized a three-component hydrogel system comprising cytidine, boric acid, and silver nitrate. The gelation occurs rapidly within a minute at room temperature and atmospheric pressure, which makes the system more convenient to use. Reduction of Ag+ by the in situ generated ascorbic acid by ALP allows the development of colorimetric sensor based on the gel-coated paper, enabling quantification of ALP concentration. This portable sensor works efficiently on a smartphone color-scanning app, making point-of-care detection easier. RGB values obtained from scanning indicate the ALP concentration in the range of 1-100 nM, which is independent of mobile cameras. The hydrogel exhibits excellent solvo-reversibility and enables naked-eye colorimetric detection of ALP with a detection limit of 0.23 nM (0.016 U/L). The sensing strategy works well in spiked human serum with a detection limit of 0.34 nM (0.023 U/L) in solution and paper-based sensors. Overall, the cytidine-based gel system presents an effective point-of-care diagnostic system for detecting ALP with high sensitivity.


alkaline phosphatase
cytidine gel
mobile scanning
paper-based sensor

Supplementary materials

Supplementary Information
Additional figures, methods, and dataset


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