Spectroscopy firm Wasatch Photonics has partnered with nanoparticle coating specialist Nikalyte to facilitate the evaluation and testing of a novel surface-enhanced Raman spectroscopy (SERS) substrate for trace detection of materials.
The substrate will have applications in narcotics, food safety, pharmaceuticals, environmental, and biological analysis.
SERS is a specialised form of Raman spectroscopy in which the analyte of interest interacts with gold or silver nanostructures to significantly enhance the Raman signal.
It enables Raman spectroscopy, a technique most often used for the identification of bulk materials, to be applied to the detection of trace quantities of potentially harmful or biologically relevant compounds.
Nikalyte, a supplier of nanoparticle coating equipment and services, has developed a new form of substrate for SERS analysis. It incorporates the ease of use of a solid SERS substrate with the reproducibility of liquid SERS at a cost-effective price point, thus overcoming previous limitations to widespread use of the SERS technique.
Conventional wet-deposited SERS substrates offer convenient sample preparation in that they employ an absorbent pad mounted to a microscope slide, but often display significant spatial inhomogeneities, resulting in low signal reproducibility. SERS using colloidal gold nanoparticles in aqueous solution, in contrast, yield very reproducible signals, but require handling of solutions that is not conducive to field use by non-experts.
Surface Enhanced Raman Spectroscopy (SERS) using gold nanoparticles. (Image:Nikalyte)
The Nikalyte SERS substrate approach is innovative in that it uses gold nanoparticles generated and deposited in a vacuum, ensuring that they are ultra-pure and highly uniformly distributed. As no chemicals are used in the synthesis of the nanoparticles, the SERS substrates are free of contamination, delivering superior sensitivity and specificity.
Together, Nikalyte and Wasatch Photonics have been evaluating the performance of these new substrates for use in a variety of relevant applications. As a manufacturer of high sensitivity, field-portable Raman spectrometers at wavelengths spanning 248-1,064nm, Wasatch Photonics is well-positioned to evaluate the performance of the SERS substrates. To date, the use of 785nm and 830nm excitation has been assessed for trace detection of a representative drug analyte, demonstrating a 1,000x increase in the limit of detection using the Nikalyte SERS substrates. The results of this study have been published here.
'Surface enhanced Raman is an exciting and rapidly growing field,’ said Dr Vicky Broadley, Nikalyte sales and marketing director. ‘We are very excited to be working with Wasatch Photonics to evaluate and develop our SERS technology and to push the limits of what current SERS sensors can offer,'
Future work will focus on improving the limit of detection further, and on studies of other analytes relevant for promising SERS applications, according to the partners.
