Raman and CARS microspectroscopy of cells and tissues

Abstract

Raman spectroscopy has been recognized to be a powerful tool to study cells and tissues because the method provides molecular information without external markers such as stains or radioactive labels. To overcome the disadvantage of low signal intensities from most biomolecules, enhancement effects are utilized. A non-linear variant of Raman spectroscopy called coherent anti-Stokes Raman spectroscopy (CARS) belongs to the most promising techniques because it combines signal enhancement due to the coherent nature of the process with further advantages such as directional emission, narrow spectral bandwidth and no disturbing interference with autofluorescence. This review describes briefly the principles of the methods and summarizes applications to cells and tissues that are expected to gain significance in the future such as the combination with imaging approaches, microscopy, optical traps and fiber-optic probes.

Towardsin vivointradermal surface enhanced Raman scattering (SERS) measurements: silver coated microneedle based SERS probe

“…These components are buried at 700 mm under the human skin or deeper [2]. Fluorescence spectroscopy, magnetic resonance imaging, ultrasound and other techniques have been developed to probe intradermal layers [3,4]. Among these methods, Raman spectroscopy promises to offer fingerprints related to structures, conformations, and processes in biomolecules below the skin [3].…”

“…Fluorescence spectroscopy, magnetic resonance imaging, ultrasound and other techniques have been developed to probe intradermal layers [3,4]. Among these methods, Raman spectroscopy promises to offer fingerprints related to structures, conformations, and processes in biomolecules below the skin [3]. Although Raman measurements can be achieved from a depth of about 200 mm under the skin [3], the measurements of dermal components deeper than 700 mm is difficult.…”

“…Among these methods, Raman spectroscopy promises to offer fingerprints related to structures, conformations, and processes in biomolecules below the skin [3]. Although Raman measurements can be achieved from a depth of about 200 mm under the skin [3], the measurements of dermal components deeper than 700 mm is difficult. Moreover, the detection sensitivity is limited by the small Raman scattering cross section (10 -29 -10 -32 cm 2 ) of endogenous biomolecules [5].…”

Characterization and Visualization of Vesicles in the Endo-Lysosomal Pathway with Surface-Enhanced Raman Spectroscopy and Chemometrics

“…These challenges have been addressed by applying various chemometric methods, such as principal component (PCA) 10,[14][15][16][17][18] and linear discriminant analysis (LDA), 14,19,20 least square regression 14,21,22 as well as cluster analysis, 17,23,24 which mostly aim at the extraction of representative spectral features for the characterization and/or classification of the sample. 7,14,17,25,26 Furthermore, traditional SERS analysis, including that in the SERS reporter approach, relies on the comparison of spectra from an unknown sample to either: (i) one or more known reference spectral features from a Raman library/literature or (ii) pure samples of expected components.…”

Non-contact, Label-free Monitoring of Cells and Extracellular Matrix using Raman Spectroscopy

“…In this regards, coherent anti-stokes Raman spectroscopy (CARS) is a very interesting technique since it enables faster and more sensitive acquisition of data based on the same vibrational signals utilized in our experiments. 15,16 Other alternative methods including multiphoton-induced autofluorescence and second harmonic generation imaging have been previously proven to be suitable for monitoring biological samples non-or minimal invasively. 17 However, these imaging modalities are associated with very high costs and are limited to autofluorescence-generating molecules.…”