In:
Scientific Reports, Springer Science and Business Media LLC, Vol. 8, No. 1 ( 2018-04-19)
Abstract:
We have developed a sensitive colorimetric immunoassay with broad dynamic range using enzyme-catalyzed Ag growth on gold nanoparticle (NP)-assembled silica (SiO 2 @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 SiO 2 @Au and enhanced the absorbance of the SiO 2 @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.
Type of Medium:
Online Resource
ISSN:
2045-2322
DOI:
10.1038/s41598-018-24664-w
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
2018
detail.hit.zdb_id:
2615211-3
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