Applications of Raman spectroscopy in cancer diagnosis

Abstract

Novel approaches toward understanding the evolution of disease can lead to the discovery of biomarkers that will enable better management of disease progression and improve prognostic evaluation. Raman spectroscopy is a promising investigative and diagnostic tool that can assist in uncovering the molecular basis of disease and provide objective, quantifiable molecular information for diagnosis and treatment evaluation. This technique probes molecular vibrations/rotations associated with chemical bonds in a sample to obtain information on molecular structure, composition, and intermolecular interactions. Raman scattering occurs when light interacts with a molecular vibration/rotation and a change in polarizability takes place during molecular motion. This results in light being scattered at an optical frequency shifted (up or down) from the incident light. By monitoring the intensity profile of the inelastically scattered light as a function of frequency, the unique spectroscopic fingerprint of a tissue sample is obtained. Since each sample has a unique composition, the spectroscopic profile arising from Raman-active functional groups of nucleic acids, proteins, lipids, and carbohydrates allows for the evaluation, characterization, and discrimination of tissue type. This review provides an overview of the theory of Raman spectroscopy, instrumentation used for measurement, and variation of Raman spectroscopic techniques for clinical applications in cancer, including detection of brain, ovarian, breast, prostate, and pancreatic cancers and circulating tumor cells.

Raman spectral discrimination in human liquid biopsies of oesophageal transformation to adenocarcinoma

“…Ribose sugars are precursors to biosynthetic pathways generated by the Warburg effect, which is responsible for keeping cancer cells alive by generating energy through glycolysis, where glucose is converted to lactose for energy followed by lactate fermentation even when oxygen is available . Amide III vibrations attributed to β‐sheet and α‐helix conformation in proteins are highly associated to cancer ; as well as DNA methylation, which is an enzyme‐induced chemical modification to the DNA structure where a methyl group is covalently bonded to the cytosine base, and abnormalities in this phenomenon are related to carcinogenesis . Shifts in the Amide I peak are known to be associated with transformation to cancer due to alterations in protein backbone conformation .…”

Mammalian cell and tissue imaging using Raman and coherent Raman microscopy

“…Higher Raman signal intensities and peaks indicate a greater concentration of bonds with certain vibrational frequencies. The theory of RS is well documented and reviewed by Prince, Frontiera, & Potma, 2017, Jones, Hooper, Zhang, Wolverson, & Valev, 2019, and Auner et al, 2018 At the atomic level, electrons of the analyte are placed in a short-lived virtual energy state, inducing a dipole moment as a simple consequence of electron repulsion. Since RS depends on the polarizability of a molecular bond, in contrast to how polar a bond may already be, as in the case of infrared (IR) spectroscopy, molecules with a weaker IR signal may have a stronger RS signal (Bernath, 2005).…”

A Miniature Fibre-Optic Raman Probe Fabricated by Ultrafast Laser-Assisted Etching

“…Collectively, a group of photons scattered inelastically by tissue carry a spectral "fingerprint" that infers the molecular makeup of the tissue. Since tissue is molecularly complex, very subtle variations between tissues can be detected by performing multivariate analysis on the Raman-shifted spectra, and, therefore, normal tissue can be distinguished from precancer and cancer tissue [9][10][11].…”