Surface-enhanced Raman Scattering-based Competitive Immunoassay of Poly-gamma-D-Glutamic Acid for Highly Sensitive Detection of Anthrax Biomarker

Abstract

Anthrax is a highly acute disease caused by the bacterium Bacillus anthracis. In this article, we report a highly sensitive detection technique for pathogenic B. anthracis, based on the use of a surface-enhanced Raman scattering (SERS)-active magnetic sensor. Gold nanoparticles (GNPs) and magnetic beads were used as SERS nanotags and supporting substrates, respectively. Here, an SERS-based competitive immunoassay platform is described for the quantitative evaluation of the anthrax marker. Poly-gamma-D-glutamic acid (PGA) capsules were used as a target biomarker for the highly sensitive detection of B. anthracis becausePGAis known to be closely associated with the pathogenesis of B. anthracis infection. The SERS-based competitive assay reveals an extraordinarily high sensitivity for PGA with a limit of detection of similar to 1.0 ng/mL. This work provides a conceptually new immunoassay prototype for fast and sensitive detection of PGA markers.