Basic Study
Copyright ©The Author(s) 2018. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Dec 21, 2018; 24(47): 5379-5390
Published online Dec 21, 2018. doi: 10.3748/wjg.v24.i47.5379
Novel screening test for celiac disease using peptide functionalised gold nanoparticles
Anantdeep Kaur, Olga Shimoni, Michael Wallach
Anantdeep Kaur, Olga Shimoni, Institute for Biomedical Materials and Devices, Faculty of Science, University of Technology Sydney, Sydney 2007, Australia
Michael Wallach, School of Life Sciences, Faculty of Science, University of Technology Sydney, Sydney 2007, Australia
Author contributions: Shimoni O and Wallach M designed research; Kaur A performed research, analysed data; Kaur A wrote the paper with critical revisions related to the intellectual content of the manuscript from Shimoni O and Wallach M; all authors approved the final version of the article to be published.
Supported by the Australian Government Research Training Program Scholarship, No. IH150100028; and Olga Shimoni acknowledges the Australian Research Council and National Health and Medical Research Council for financial support, No. APP1101258.
Institutional review board statement: This study was reviewed and approved by the University of Technology Sydney Research Ethics committee (UTS HREC ETH16 - 0841). The clinical samples were collected with informed consent and approval of Melbourne Health and WEHI Human Research Ethic Committees (2003.009 and 03/04) respectively.
Conflict-of-interest statement: The authors declare that they have no conflict of interest.
Data sharing statement: No additional data are available
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Corresponding author to: Olga Shimoni, BSc, MSc, PhD, Senior Lecturer, Institute for Biomedical Materials and Devices, Faculty of Science, University of Technology Sydney, PO Box 123, 15 Broadway, Ultimo, New South Wales, Sydney 2007, Australia.
Telephone: +61-2-95142842
Received: July 13, 2018
Peer-review started: July 13, 2018
First decision: August 27, 2018
Revised: September 1, 2018
Accepted: October 5, 2018
Article in press: October 5, 2018
Published online: December 21, 2018
Research background

Celiac disease is a chronic immune mediated disorder of the small intestine caused by consuming the protein gluten present in wheat and some other cereals. Following the activation of the innate immune system, a number of cytokines as well as antibodies are released in celiac patients that can be used as specific biomarkers to develop diagnostic tests. Over the years, a number of diagnostic tests have been developed, however, in spite of the good initial results in terms of sensitivity and specificity, when these tests are used on a large scale they have lowered predictive values. In the present study, a novel assay using peptide functionalised gold nanoparticles was developed that can be useful in an exclusion based diagnostic strategy.

Research motivation

The number of celiac disease sufferers are rapidly increasing throughout the world, and there is an increased need for newer detection methods that are easy to use, accurate as well as cheaper to enable early identification of the disease. The present study addresses this issue through the development of a novel assay combining the unique properties of gold nanoparticles with the specificity of the antibodies. The developed assay shows great potential to be developed as a point-of-care test that would be beneficial for large scale screening of celiac disease.

Research objectives

In order to develop a celiac diagnostic assay based on the properties of the gold nanoparticles combined with the specificity of the antibodies from serum the following aims have been addressed in this work: (1) To develop method for the binding and adsorption of peptide derived from gliadin, the main antigenic protein causing celiac disease on the surface of gold nanoparticles; (2) to detect and measure the concentrations of antibodies to be used as biomarkers in serum; (3) to test and validate the developed test on real patient serum samples.

Research methods

The peptide coated gold nanoparticles were characterized using UV-vis spectra, dynamic light scattering and transmission electron microscopy. The UV-vis absorbance readings of peptide coated AuNPs following interactions with AGA and IgG from rabbit serum (control antibody) were used to calculate the percentage absorbance values. The students t-test was used to compare the sets of quantitative data that were collected independently of one another to calculate the p value and determine statistical significance. The assay sensitivity was determined based on the colorimetric response values.

The clinical accuracy of the peptide coated AuNPs was determined using a selected, varied set of thirty human serum samples obtained from patients with celiac disease or controls without celiac disease. The results for the thirty clinical samples were recorded after the visual examination of precipitate formation and the determination of a shift or change in absorbance values using a UV-vis spectrophotometer. The assay sensitivity was determined based on the colorimetric response values obtained for each serum sample.

Research results

The peptide sequence was successfully coated to the AuNP and characterization methods indicated that a stable colloidal suspension of the peptide coated AuNPs was achieved that was sustained by the high affinity biotin-avidin interactions.

The addition of anti-gliadin antibody to peptide coated AuNPs as well as in spiked serum at a threshold level resulted in lowering as well as a shift of absorbance peaks that indicated the aggregation of AuNPs. On the other hand, in the presence of a non-specific, normal IgG antibody there was no interaction between the peptide coated AuNPs, with no reduction in color or shift in wavelength or aggregation of AuNPs.

The clinical accuracy of the peptide coated AuNPs was tested using 30 clinical samples, where 26 samples were shown to have the same analysis as that obtained with existing serology and histology, however, 2 false positive results and 2 false negative results were also obtained using the AuNP-peptide-AGA assay giving the AuNP-peptide-AGA assay an overall accuracy of 86.6%.

Research conclusions

In this study, we demonstrate the potential of peptide functionalised gold nanoparticles as a colorimetric sensor for screening celiac disease. The AuNP-peptide assay seems promising for development as a point-of-care test, this is because it is based on the formation of a precipitate as well as a reduction in color for a positive sample in the presence of a celiac disease specific autoantibody, thereby, eliminating the need for secondary antibody. This greatly reduces the cost of development for the assay and would be a step in the direction of one-step detection for celiac disease based on single antibody detection.

Research perspectives

The AuNP-Peptide based approach shows great potential and would be particularly useful in aiding large-scale screening of the general population, particularly in the pre-selection of young Celiac disease (CD) sufferers which can be then confirmed by mucosal biopsy. A positive result would strengthen the possibility of CD while a negative test would help avoid unnecessary intestinal biopsy thereby reducing the economic burden on healthcare resources resulting in cost savings.