Rapid detection of an anthrax biomarker by surface-enhanced Raman spectroscopy

Xiaoyu Zhang, Matthew A. Young, Olga Lyandres, Richard P. Van Duyne*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

666 Scopus citations


A rapid detection protocol suitable for use by first-responders to detect anthrax spores using a low-cost, battery-powered, portable Raman spectrometer has been developed. Bacillus subtilis spores, harmless simulants for Bacillus anthracis, were studied using surface-enhanced Raman spectroscopy (SERS) on silver film over nanosphere (AgFON) substrates. Calcium dipicolinate (CaDPA), a biomarker for bacillus spores, was efficiently extracted by sonication in nitric acid and rapidly detected by SERS. AgFON surfaces optimized for 750 nm laser excitation have been fabricated and characterized by UV-vis diffuse reflectance spectroscopy and SERS. The SERS signal from extracted CaDPA was measured over the spore concentration range of 10-14-10-12 M to determine the saturation binding capacity of the AgFON surface and to calculate the adsorption constant (Kspore = 1.7 × 1013 M -1). At present, an 11 min procedure is capable of achieving a limit of detection (LOD) of ∼2.6 × 103 spores, below the anthrax infectious dose of 104 spores. The data presented herein also demonstrate that the shelf life of prefabricated AgFON substrates can be as long as 40 days prior to use. Finally, these sensing capabilities have been successfully transitioned from a laboratory spectrometer to a field-portable instrument. Using this technology, 104 bacillus spores were detected with a 5 s data acquisition period on a 1 month old AgFON substrate. The speed and sensitivity of this SERS sensor indicate that this technology can be used as a viable option for the field analysis of potentially harmful environmental samples.

Original languageEnglish (US)
Pages (from-to)4484-4489
Number of pages6
JournalJournal of the American Chemical Society
Issue number12
StatePublished - Mar 30 2005

ASJC Scopus subject areas

  • General Chemistry
  • Biochemistry
  • Catalysis
  • Colloid and Surface Chemistry


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