Surface-Enhanced Raman spectral analysis of substrates for salivary based disease detection

Raman Spectroscopy is a mean to study the molecular structure property of solid, liquid and gases from its scattering spectrum. It offers a detailed biochemical fingerprint for identifying the unknown molecule. Since the amount of inelastic scattering is infinitesimally small relative to that of the elastic scattering, the Raman signal emitted is extremely weak, rendering limited applications. Surface Enhanced Raman Spectroscopy augments the detection sensitivity of Raman spectroscopy with nano-sensing chip as substrate, enabling amplification of Raman signal by a factor of 10⁴ to 10⁹. This innovation is made possible with the integration of the latest in optical sensing technology and nanotechnology. With this improvement, SERS has shown its niche in tracing molecular structure, especially in marking abnormal biological molecules such as cancer, conjunctivitis, AIDS. The quality of spectrum is highly dependent on the substrate type and laser wavelength. Our work here examines the spectral characteristics of 3 candidate substrate types and wavelength for application in salivary based disease detection. The spectrum intensity enhancement, oxidation and fluorescence effects are also investigated. This study finds that adoption of gold or Klarite^® as substrate and 785nm as wavelength are appropriate for salivary based disease detection using SERS technique. The latter will be preferred if cost effectiveness is important.