Developments in Raman microspectroscopy; rapid, sensitive and specific sensing.

I’ll outline methods we are developing to enhance the detection of molecules, nanoparticles, pharmaceuticals and identifying single cells using Raman microspectroscopy. Raman spectroscopy provides a molecular fingerprint of a sample. It is inherently a weak process in that only one in every million scattered photons is Raman scattered, but with lasers and microscopes very high power densities can be delivered to samples. However, this may result in sample degradation or fluorescence, so we have been investigating methods to enhance the Raman signal from molecules and cells.
We are fabricating SERS (surface enhanced Raman scattering) substrates using laser inscription by photoreduction of silver solution and testing the substrates for signal enhancement with a view to reducing the Raman excitation power required, reducing the signal acquisition time and reducing the limit of detection of the molecule. We have also made optical tweezers on the tip of an optical fibre in order to lift single cells away from fluorescent substrates such as borosilicate glass, and collect the Raman signal from single cells.
I’ll give examples of applications of Raman micro spectroscopy in the areas of nanotoxicology, pharmaceuticals and disease signature detection.