The US Navy seeks to commercialize through licensing an easy-to-make, versatile substrate for Surface Enhanced Raman Spectroscopy (SERS). Even though SERS has been investigated for sensing purposes since 1974, the lack of off-the-shelf substrates and reproducibility have been the two key weak points that have prevented this useful technique from being more widely practiced. This recent Navy innovation helps to overcome these problems and, at the same time, provides for lower detection limits.
SERS active metal colloids are immobilized onto functionalized magnetic particles to form SERS active capture matrices (ACM). An appropriate reagent is introduced to form a self assembled monolayer, SAM, (in the above example the reagent is RSH), onto the ACMs. The resultant SAM-ACM is used to extract analytes. A magnet is used to concentrate the microparticles onto the side of the sample vial, allowing analyte detection by SERS. The SAM itself exhibits a SERS spectrum, which can be used advantageously for normalization purposes. The innovation enables the sensitivity of SERS to be more fully utilized for detection of analytes.
- Reproducible – The normalization procedure which leverages a SAM peak as an internal standard increases the precision of the analyte signal by more than 1 order of magnitude
- Low detection limit – Magnetic particles are a common enrichment tool in the biosciences. Inventors report the detection limit for naphthalene with PCTP – gold colloid on magnetic particles to be 0.3μg mL-1 compared with 1.5 μg mL-1 using PCTP – gold on glass (the more traditional technique).
- Conducive to manufacturing – Magnetic microparticles with various functional groups including amines and carboxylic acids are readily available. A broad array of off-the-shelf SAMs have been demonstrated to be useful for the detection of analytes of interest including explosives, narcotics, and chemical warfare agents. Colloids have been used to probe the SERS phenomenon for better than 20 years.
- Inventors may be available for consultation and collaboration
- Two US Patents: 7,879,625; 9,470,671