The many facets of Raman spectroscopy for biomedical analysis

A critical review is presented to the use of linear and nonlinear Raman microspectroscopies in biomedical diagnostics of bacteria, cells and tissues. Linear Raman spectroscopy offers a wealth of chemical and molecular information. Its routine clinical application poses a challenge due to relatively weak signal intensities and confounding overlapping effects. Nonlinear variants of Raman spectroscopy such as coherent anti-Stokes Raman scattering (CARS) and stimulated Raman scattering (SRS) have been recognized as tools for rapid image acquisition. Imaging applications benefit from the fact that contrast is based on the chemical composition and molecular structures in a label-free and non-destructive manner. The current state of the art is evaluated, illustrative examples are given, future developments are pointed out, and important reviews and references to the current literature are selected. The topics are identification of bacteria and single cells, imaging of single cells, Raman activated cell sorting, diagnosis of tissue sections, fiber optic Raman spectroscopy, and progress in coherent Raman scattering in tissue diagnosis. The roles of networks – such as Raman4clinics on a European level – and early adopters are discussed to translate, disseminate and validate new methods.