Surface‐enhanced Raman Scattering‐based Competitive Immunoassay of Poly‐γ‐d‐Glutamic Acid for Highly Sensitive Detection of Anthrax Biomarker#

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‐γ‐ d ‐glutamic acid ( PGA ) capsules were used as a target biomarker for the highly sensitive detection of B. anthracis because PGA is 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 ~1.0 ng/ mL . This work provides a conceptually new immunoassay prototype for fast and sensitive detection of PGA markers.