We have developed an interferometric implementation of coherent anti-Stokes Raman scattering which enables broadband coherent Raman spectroscopy free from the nonresonant background, with a signal strength proportional to concentration. Spectra encode mode symmetry information into the amplitude response, which can be directly compared to polarized spontaneous Raman spectra. The method requires only passive polarization optics and is suitable for a wide range of laser linewidths and pulse durations. The method's application to Raman spectral imaging is demonstrated.

The incidence of obesity is rising at an alarming rate. Despite its recognition as an urgent healthcare concern, obesity remains largely an unsolved medical problem. A comprehensive screen for functional dietary phytochemicals identified proanthocyanidins as putative targets to ameliorate obesity. A full-scale purification of oligomeric proanthocyanidins (OPCs) derived from grape seed extract yielded pure OPC dimer, trimer, tetramer, and their gallates (pOPCs). Forward chemical screening conducted in suggested that pOPCs reduced the activity of lipase and triglyceride storage capacity Proanthocyanidin trimer gallate in particular modified lipid desaturation in, revealed by hyperspectral coherent anti-Stokes Raman scattering microscopy. Exposure to trimer gallate resulted in the transcriptional down-regulation of (an ortholog of the human peroxisome proliferator-activated receptor-α), and a key regulator of fat metabolism, and 2 downstream genes: and A combination exposure of 2 or 3 pOPCs (dimer gallate, trimer and/or trimer gallate) suggested the absence of synergistic potential. By using the whole-organism coupled with versatile biochemical, biophysical, and genetic tools, we provide an account of the composition and bioactivity of individual OPCs and more generally highlight the potential of traditional Chinese medicine-derived drug leads.-Nie, Y., Littleton, B., Kavanagh, T., Abbate, V., Bansal, S. S., Richards, D., Hylands, P., Sturzenbaum, S. R. Proanthocyanidin trimer gallate modulates lipid deposition and fatty acid desaturation in .

Broadband coherent anti‐Stokes Raman scattering (B‐CARS), excited through intrapulse three‐color processes in which both the pump and Stokes photons are derived from a broadband beam, enable diffraction‐limited hyperspectral Raman imaging over the entire fingerprint spectral region with a speed and sensitivity far superior to that possible with conventional spontaneous Raman confocal microspectroscopy. We extend the theory of spectral interferometric polarization coherent anti‐Stokes Raman scattering (SIP‐CARS) to include three‐color excitation processes. This allows for the B‐CARS measurement of polarized Raman‐equivalent spectra free of the nonresonant background, without the requirement for post‐acquisition computational processing. We demonstrate the simultaneous measurement of both three‐color and two‐color SIP‐CARS, at low and high Raman shifts, respectively, in good agreement with theory. These proof of concept results pave the way for photon‐efficient SIP‐CARS signal generation with ultrafast lasers, for all‐optical, fast, quantitative Raman hyperspectral imaging.

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We have developed an interferometric implementation of coherent anti-Stokes Raman scattering (CARS) which enables broadband coherent Raman spectroscopy free from non-resonant background (NRB), with a signal strength proportional to concentration. Spectra encode mode symmetry information into the amplitude response which can be directly compared to polarised spontaneous Raman spectra. The method requires only passive polarisation optics and is suitable for a wide range of laser linewidths and pulse durations.