Confocal Raman Microscopy (Micro-Spectroscopy, RA-MSP) permits the acquisition of complete Raman spectra from volume elements (voxels) as small as 300 x 300 x 500 nm3, or about 50 femtograms of sample. The main advantage of this technology is that the complete biochemical composition of the voxel is sampled.

We collect 10,000 to 20,000 individual Raman spectra, acquired in mapping mode from one human cell, to construct pseudo-color maps of that cell that reproduce the chemical composition of cellular compartments. These maps are constructed by methods of mul-tivariate statistics, and are completely objective. They reveal sub-cellular organization at the sub-micrometer level, and permit the identification of nuclei, nucleoli, and internal membrane structures.

Confocal Raman microscopy is similar to confocal fluorescence microscopy or two-photon microscopy in that 3-dimensional pictures of an object, such as a cell, can be constructed. The main advantage of RA-MSP over other techniques is that it can be carried out on live cells without any stains or contrast agents.