Surface Enhanced Raman Scattering

This note describes an application demonstrating the capability of Surface Enhanced Raman Scattering (SERS). For a detailed review of the SERS and its mechanism, we recommend an excellent review article by Dr. Alan Campion and Patanjali Kambhampati, titled, “Surface Enhanced Raman Scattering” in Chemical Society Reviews, 1998, Volume 27, Page 241.

SERS of Isoniazid

Isoniazid is used as a first-line treatment for tuberculosis (TB) in combination with other drugs for the treatment of active disease. Isoniazid is also used for prevention of TB in people who have been exposed to active disease but have no symptoms.

The chemical structure of Isoniazid is

Raman spectrum of Isoniazid powder, recorded on Raman Systems R-3000 instrument is shown below:

A solution of Isoniazid in de-ionized water was made. The concentration of the solute is 0.0000126% w/w. This concentration is beyond the limit of detection of conventional Raman scattering, as seen in the spectrum below. This is a spectrum of the above solution, recorded on the R-3000.

A few drops of the above solution were then added to a solution of gold colloid, 20nm diameter (obtained from Sigma-Aldrich). The following spectrum is obtained. The peaks in this spectrum match up exactly with the Isoniazid spectrum shown above, indicating surface enhancement.

This application can then be further extended to quantify the amount of Isoniazid in solution, thus making SERS a very powerful tool for quantitative analysis of trace quantities.