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Enzyme-catalyzed Ag Growth on Au Nanoparticle-assembled Structure for Highly Sensitive Colorimetric Immunoassay.

ABSTRACT: We have developed a sensitive colorimetric immunoassay with broad dynamic range using enzyme-catalyzed Ag growth on gold nanoparticle (NP)-assembled silica (SiO₂@Au@Ag). To reduce Ag⁺ ion content and promote Ag growth on the assembled Au NPs, alkaline phosphatase (AP)-based enzymatic amplification was incorporated, which considerably increased the colorimetric read-out. As a model study, sandwich enzyme-linked immunosorbent assay (ELISA) was used to quantify target IgG. The immune complexes capture the Ab-IgG-AP-labeled detection Ab and trigger the enzyme-catalyzed reaction to convert 2-phospho-L-ascorbic acid to ascorbic acid in the presence of the target IgG. Ascorbic acid reduced Ag⁺ to Ag, which formed Ag shells on the surface of SiO₂@Au and enhanced the absorbance of the SiO₂@Au@Ag solution. Plasmonic immunoassay showed a significant linear relationship between absorbance and the logarithm of IgG concentration in the range of ca. 7 × 10^-13 M to 7 × 10^-11 M. The detection limit was at 1.4 × 10^-13 M, which is several hundred folds higher than that of any conventional colorimetric immunoassay. Thus, our novel approach of signal-amplification can be used for highly sensitive in vitro diagnostics and detection of target proteins with the naked eye without using any sophisticated instrument.

SUBMITTER: Pham XH

PROVIDER: S-EPMC5908853 | biostudies-literature | 2018 Apr

REPOSITORIES: biostudies-literature

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Enzyme-catalyzed Ag Growth on Au Nanoparticle-assembled Structure for Highly Sensitive Colorimetric Immunoassay.

Pham Xuan-Hung XH Hahm Eunil E Kim Tae Han TH Kim Hyung-Mo HM Lee Sang Hun SH Lee Yoon-Sik YS Jeong Dae Hong DH Jun Bong-Hyun BH

Scientific reports 20180419 1

We have developed a sensitive colorimetric immunoassay with broad dynamic range using enzyme-catalyzed Ag growth on gold nanoparticle (NP)-assembled silica (SiO<sub>2</sub>@Au@Ag). To reduce Ag<sup>+</sup> ion content and promote Ag growth on the assembled Au NPs, alkaline phosphatase (AP)-based enzymatic amplification was incorporated, which considerably increased the colorimetric read-out. As a model study, sandwich enzyme-linked immunosorbent assay (ELISA) was used to quantify target IgG. The ...[more]

PMID: 29674713

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Dataset Information

Enzyme-catalyzed Ag Growth on Au Nanoparticle-assembled Structure for Highly Sensitive Colorimetric Immunoassay.

Publications

Enzyme-catalyzed Ag Growth on Au Nanoparticle-assembled Structure for Highly Sensitive Colorimetric Immunoassay.

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