AFRL-Sponsored Technology Enables Surface-Enhanced Raman Detection of Hazardous Chemicals

  • Published
  • By Plans and Programs Directorate
  • AFRL/XP
Surface-enhanced Raman spectroscopy (SERS) is a technology that enables scientists to detect the presence of chemicals at extremely low levels of concentration (potentially as low as the single-molecule level). This technology applies both to national security--particularly for the identification of threatening chemical and biological agents--and to the medical field (e.g., for glucose monitoring).
AFRL sponsored the research and development of a reliable, robust substrate that greatly enhances hazardous species detection. Under the Multidisciplinary University Research Initiative, Northwestern University scientists developed metal-film-over-nanosphere substrates, which enable SERS-based rapid detection of an anthrax biomarker. By effectively targeting the anthrax biomarker calcium dipicolinate, the SERS method permits detection of anthrax spores present in an extremely small sample size (smaller than a regular aspirin tablet) in approximately 10 minutes. Most importantly, this method enables detection of anthrax at 1/4 the lethal dosage. The scientists also demonstrated SERS detection of Bacillus spores. The team successfully transitioned these laboratory-developed sensing capabilities to a portable Raman spectrometer for use as a commercially available
(via DeltaNu, LLC), field-deployable device.
The SERS demonstration results indicate that the team's efforts improved the detection sensitivity for molecular species by a factor of 10 million. This remarkable surface enhancement results from plasmon resonances that can arise when a molecule is between (or in the immediate vicinity) of various metallic nanostructures. Recent advances in the ability to fabricate and control nanostructures enable the development of techniques and methods for using SERS for control and reproduction purposes; these capabilities will enhance the detection sensitivity of molecular and biomolecular species. An 11-minute procedure can detect ≤2,600 spores, far below the anthrax infectious dose of 10,000 spores. The SERS sensing technology's speed and sensitivity make it a viable option for field analysis of potentially harmful bioagents.
AFRL continues to lead the effort to develop this exciting new technology. A Small Business Technology Transfer project is currently under way to further explore ways to use SERS nanotechnology to identify and detect biomolecular and biological entities, including trace amounts of chemical and biological agents, toxic species, and biological species such as proteins.