Next Article in Journal
A Novel Flower-Like Ag/AgCl/BiOCOOH Ternary Heterojunction Photocatalyst: Facile Construction and Its Superior Photocatalytic Performance for the Removal of Toxic Pollutants
Previous Article in Journal
NaYF4 Microstructure, beyond Their Well-Shaped Morphology
Previous Article in Special Issue
Electrochemical DNA Biosensors Based on Labeling with Nanoparticles
Open AccessFeature PaperArticle

Design and Simple Assembly of Gold Nanostar Bioconjugates for Surface-Enhanced Raman Spectroscopy Immunoassays

1
UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
2
CENIMAT-I3N, Departamento de Ciência dos Materiais, Faculdade de Ciências e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
3
REQUIMTE/LAQV, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, 4169-007 Porto, Portugal
4
FOCAS Research Institute, Technological University Dublin, Kevin Street, Dublin 8, Ireland
*
Authors to whom correspondence should be addressed.
Nanomaterials 2019, 9(11), 1561; https://doi.org/10.3390/nano9111561
Received: 15 October 2019 / Revised: 24 October 2019 / Accepted: 30 October 2019 / Published: 4 November 2019
(This article belongs to the Special Issue Nanomaterials for Immunosensors and DNA Sensors)
Immunoassays using Surface-Enhanced Raman Spectroscopy are especially interesting on account not only of their increased sensitivity, but also due to its easy translation to point-of-care formats. The bases for these assays are bioconjugates of polyclonal antibodies and anisotropic gold nanoparticles functionalized with a Raman reporter. These bioconjugates, once loaded with the antigen analyte, can react on a sandwich format with the same antibodies immobilized on a surface. This surface can then be used for detection, on a microfluidics or immunochromatographic platform. Here, we have assembled bioconjugates of gold nanostars functionalized with 4-mercaptobenzoic acid, and anti-horseradish peroxidase antibodies. The assembly was by simple incubation, and agarose gel electrophoresis determined a high gold nanostar to antibody binding constant. The functionality of the bioconjugates is easy to determine since the respective antigen presents peroxidase enzymatic activity. Furthermore, the chosen antibody is a generic immunoglobulin G (IgG) antibody, opening the application of these principles to other antibody-antigen systems. Surface-Enhanced Raman Spectroscopy analysis of these bioconjugates indicated antigen detection down to 50 µU of peroxidase activity. All steps of conjugation were fully characterized by ultraviolet-visible spectroscopy, dynamic light scattering, ζ -Potential, scanning electron microscopy, and agarose gel electrophoresis. Based on the latter technique, a proof-of-concept was established for the proposed immunoassay. View Full-Text
Keywords: surface enhanced Raman spectroscopy Surface; Enhanced Raman Spectroscopy; gold nanostars; gold nanoparticles; immunoconjugates; immunoassay; horseradish peroxidase; Raman reporter; agarose gel electrophoresis; dynamic light scattering surface enhanced Raman spectroscopy Surface; Enhanced Raman Spectroscopy; gold nanostars; gold nanoparticles; immunoconjugates; immunoassay; horseradish peroxidase; Raman reporter; agarose gel electrophoresis; dynamic light scattering
Show Figures

Graphical abstract

MDPI and ACS Style

Oliveira, M.J.; P. de Almeida, M.; Nunes, D.; Fortunato, E.; Martins, R.; Pereira, E.; J. Byrne, H.; Águas, H.; Franco, R. Design and Simple Assembly of Gold Nanostar Bioconjugates for Surface-Enhanced Raman Spectroscopy Immunoassays. Nanomaterials 2019, 9, 1561.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop