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A high-resolution colorimetric immunoassay platform realized by coupling enzymatic multicolor generation with smartphone readout

Abstract

A high-resolution colorimetric immunoassay platform has been developed based on enzyme-catalyzed multicolor generation and smartphone-assisted signal readout. The multi-color generation is accomplished in this system through the urease-catalyzed urea hydrolysis-induced color change of the pH indicator phenol red, changing from yellow to orange to red over pH 6.6 to 8.0. The color change is easily tailored by controlling urease activity via the inhibitor silver ion (Ag+), of which the amount is in turn adjusted by alkaline phosphatase (ALP)-catalyzed ascorbic acid (AA) production. An ALP-linked colorimetric immunoassay is readily realized based on the above urease catalyzed multicolor generation system. Under optimal condition, a limit of detection (LOD) at 1.73ng mL-1 and a dynamic range from 0 to 18ng mL-1 are achieved with rabbit IgG as a model analyte. A colored picture for each test is directly taken by a smartphone and then quantitatively analyzed with the free software Image J, eliminating the use of expensive and desktop equipment. The dose-dependent multicolor display is easier to be distinguished by the naked eye for qualitative or semiquantitative detection over the traditional one-color system. The developed immunoassay scheme provides a promising platform for on-site testing or applications in resource-poor areas.

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Publication details

The article was received on 28 Feb 2018, accepted on 04 May 2018 and first published on 05 May 2018


Article type: Paper
DOI: 10.1039/C8AN00382C
Citation: Analyst, 2018, Accepted Manuscript
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    A high-resolution colorimetric immunoassay platform realized by coupling enzymatic multicolor generation with smartphone readout

    W. Xie, L. Lei, M. Tian, Z. Zhang and Y. Liu, Analyst, 2018, Accepted Manuscript , DOI: 10.1039/C8AN00382C

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