Macromolecular Orientation in Biological Tissues Using a Four-Polarization Method in FT-IR Imaging

Abstract

Fourier transform infrared spectroscopy has emerged as a powerful tool for tissue specimen investigation. Its nondestructive and label-free character enables direct determination of biochemical composition of samples. Furthermore, the introduction of polarization enriches this technique by the possibility of molecular orientation study apart from purely quantitative analysis. Most of the molecular orientation studies focused on polymer samples with a well-defined molecular axis. Here, a four-polarization approach for Herman’s in-plane orientation function and azimuthal angle determination was applied to a human tissue sample investigation for the first time. Attention was focused on fibrous tissues rich in collagen because of their cylindrical shape and established amide bond vibrations. Despite the fact that the tissue specimen contains a variety of molecules, the presented results of molecular ordering and orientation agree with the theoretical prediction based on sample composition and vibration directions.

Super-Resolved 3D Mapping of Molecular Orientation Using Vibrational Techniques

“…The first applications of IR imaging with 4P on polymeric systems 11 − 14 were followed by active compound visualization 15 and recently by human tissue microarray analysis by Koziol et al in 2020. 16 , 17 …”

Fourier Transform Infrared Polarization Contrast Imaging Recognizes Proteins Degradation in Lungs upon Metastasis from Breast Cancer

“…For anisotropic samples the absorption of polarized light varies and depends on its direction, creates an effect of linear dichroism represented by dichroic ratio (D) is defined as D=A ‖(0⁰) /A Ʇ(90⁰) where A ‖ and A Ʇ represent absorbances for parallel and perpendicular radiation, respectively. Values of this ratio give the insights about the dipole moment orientation distribution with regards to the orientation axis as well as might be used for Herman’s orientation function (f) also called in-plane orientation function [ 27 ]. The latter describes the degree or extent of orientation of the chain axes (polymers, fibers) relative to some other axis of interest and is expressed by the equation below: where α is an angle between the transition dipole moment and main molecular axis [ 26 ].…”

Hyperspectral Molecular Orientation Mapping in Metamaterials

“…Only the data from fits with a regression coefficient R 2 > 96% were selected for plotting as in previous the study [21]. The four polarisation method was used for characterisation of biopolymers and tissue [18,22].…”