Résumé
The high chemical specificity, minimal sample preparationand the ability to use advanced optical technologies in thevisible or near-infrared spectral range have led in the lastyears to an increase in the biomedical applications of Ramanspectroscopy. Raman spectroscopy measures the inelasticscattering of light by vibrating molecules, providing thechemical fingerprints of cells, tissues or biofluids. However,as Raman scattering efficiency is quite low, requiringrelatively long acquisition times, new technologies based onBroadband Coherent Anti-Stokes Raman scattering(BCARS) was proposed [1]. This coherent Raman imagingtechnique is based on the detection of the fingerprint regionof molecules (500-1800 cm-1), as well as the higher-energyCH-/OH-stretch region (~2,700 cm−1 to 3,300 cm−1) andcould probe multiple Raman transitions simultaneously toallow imaging of biological tissues with improved molecularcontrast. When compared to spontaneous Ramanmicroscopy, BCARS microscopy provided 10-100x fasterimage acquisition for quantitative and qualitative assessmentof pharmaceuticals at much higher spatiochemical resolutionand with spectra of much higher signal-to noise ratio [2]. Inthis talk, I will present the principles of the BCARSmicroscopy we’ve developed in our laboratory and someexamples of biological applications. BCARS imaging is usedto evaluate changes underlying the lesion of a spinal cordinjury in a murine model. After injury the axonalregeneration in spinal cord is inhibited by a glial and afibrous scar, acting as a physical and chemical barrier.Recently we have reported that the signal exhibited byfibrillar collagen enabled to specifically monitor it as abiomarker of a spinal cord lesion [3]. However, the injuryand the scarring process involves also other elements as themyelin sheets, microglia, astrocytes and extracellular matrixcomponents. We demonstrate the versatility of BCARSimaging to assess the additional structural and metabolicmodifications of the injured tissue in excised murine spinalcord samples at different time points (1, 2, 4, 6 weeks) afterinjury.1) Camp Jr CH et al. Nat. Photonics 8(8), 627 (2014).2) Hartshorn CM et al. Anal. Chem. 85(17), 8102 (2013)3) C. Manesco, et al. Nanomedicine: Nanotechnology,Biology, and Medicine 53 (2023) 102699.