title: SERS immunoassay based on the capture and concentration of antigen-assembled gold nanoparticles.
abstract: A simple, rapid, and sensitive immunoassay has been developed based on antigen-mediated aggregation of gold nanoparticles (AuNP) and surface-enhanced Raman spectroscopy (SERS). Central to this platform is the extrinsic Raman label (ERL), which consists of a gold nanoparticle modified with a mixed monolayer of a Raman active molecule and an antibody. ERLs are mixed with sample, and antigen induces the aggregation of the ERLs. A membrane filter is then used to isolate and concentrate the ERL aggregates for SERS analysis. Preliminary work to establish proof-of-principle of the platform technology utilized mouse IgG as a model antigen. The effects of membrane pore diameter and AuNP size on the analytical performance of the assay were systematically investigated, and it was determined that a pore diameter of 200 nm and AuNP diameter of 80 nm provide maximum sensitivity while minimizing signal from blank samples. Optimization of the assay provided a detection limit of 1.9 ng/mL, 20-fold better than the detection limit achieved by an ELISA employing the same antibody-antigen system. Furthermore, this assay required only 60 min compared to 24h for the ELISA. To validate this assay, mouse serum was directly analyzed to accurately quantify IgG. Collectively, these results demonstrate the potential advantages of this technology over current diagnostic tests for protein biomarkers with respect to time, simplicity, and detection limits. Thus, this approach provides a framework for prospective development of new and more powerful tools that can be designed for point-of-care diagnostic or point-of-need detection.
authors.affiliation: Department of Chemistry, Illinois State University, Normal, IL 61790, USA.
authors.forename: Arielle
authors.initials: A
authors.lastname: Lopez
authors.affiliation: Department of Chemistry, Illinois State University, Normal, IL 61790, USA.
authors.forename: Francis
authors.initials: F
authors.lastname: Lovato
authors.affiliation: Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA.
authors.forename: Soon Hwan
authors.initials: SH
authors.lastname: Oh
authors.affiliation: Department of Chemistry, Illinois State University, Normal, IL 61790, USA.
authors.forename: Yen H
authors.initials: YH
authors.lastname: Lai
authors.affiliation: Department of Chemistry, Illinois State University, Normal, IL 61790, USA.
authors.forename: Seth
authors.initials: S
authors.lastname: Filbrun
authors.affiliation: Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Driskell
authors.affiliation: Department of Chemistry, Illinois State University, Normal, IL 61790, USA. Electronic address: jdriske@ilstu.edu.
authors.forename: Jeremy D
authors.initials: JD
authors.lastname: Driskell
mesh_terms: D000818:Animals; D000941:Antigens / Q000737:chemistry* / Q000276:immunology; D006046:Gold / Q000737:chemistry*; D007118:Immunoassay / Q000379:methods*; D007074:Immunoglobulin G / Q000097:blood; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry*; D051379:Mice; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013997:Time Factors
chemical_list: D000941:Antigens; D007074:Immunoglobulin G; D006046:Gold
keywords: Dynamic light scattering; Gold nanoparticles; Immunoassay; Surface-enhanced Raman spectroscopy