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Signal self-enhancement by coordinated assembly of gold nano-particles enables accurate one-step-immunoassays


Current immunoassays are in general performed through time-consuming multi-step procedures that depend on the use of premade signal-producing reporters and often cause assay inaccuracy. Here we report an advanced immunoassay technology that resolves the delayed, complex, and inaccurate assay problems of conventional immunoassays. We have developed an accurate, rapid, simple, and label-free one-step-immunoassay based on the self-enhancement of sensitive immunoassay signals in an assay solution. The nano-scale protein particles (hepatitis B virus capsid and human ferritin heavy chain particles) were genetically engineered to present many well-oriented antibody (or antigen) probes and multi-copies of poly-histidine peptides on their surface, resulting in the construction of 3-dimensional (3D) bioprobes that chemisorb gold ions via coordination bond and sensitively detect both antigen and antibody analytes. Systematic numerical and experimental analyses show that the signal self-enhancement happens through the two coupled reactions under a reducing condition: 1) 3D bioprobe-based sensitive immuno-detection of analytes and 2) coordinated assembly of free and chemisorbed gold nanoparticles around the 3D bioprobe-analyte-associated complexes, which is followed by the quick generation of apparent optical signals. This advanced one-step-immunoassay was successfully applied to the diagnostic assays requiring high accuracy and/or speed, i.e. diagnosis of acute myocardial infarction and hepatitis C through detecting a cardiac protein (troponin I) and anti-hepatitis C virus antibodies in patient sera, indicating it is applicable to the accurate and rapid detection of both antigen and antibody markers of a wide range of diseases.

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Publication details

The article was received on 15 May 2017, accepted on 11 Sep 2017 and first published on 28 Sep 2017

Article type: Paper
DOI: 10.1039/C7NR03453A
Citation: Nanoscale, 2017, Accepted Manuscript
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    Signal self-enhancement by coordinated assembly of gold nano-particles enables accurate one-step-immunoassays

    J. Lee, J. Kwon, H. Kim, J. Lee, R. Kim, M. Heo, J. Shin, H. Lee and Y. J. Cha, Nanoscale, 2017, Accepted Manuscript , DOI: 10.1039/C7NR03453A

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