Molecular imaging with CARS micro-spectroscopy

After more than a decade of instrument and method development, broadband coherent anti-Stokes Raman scattering (CARS) micro-spectroscopy is beginning to live up to its potential as a label-free imaging modality that can rapidly generate high resolution images with full vibrational spectra at each image pixel. Presently these instruments are able to obtain quantitative, spatially resolved information on lipids from the CH stretch region of the Raman spectrum, and some instrument designs facilitate acquisition of high quality fingerprint spectra, containing information on a host of molecular species including structural proteins, nucleotides, and metabolites. While most of the existing instruments are research projects themselves, it appears that the relevant technologies are maturing so that commercially available instruments may not be too far in the future, making this remarkable imaging modality widely available.