Raman Spectroscopy Methods to Characterize the Mechanical Response of Soft Biomaterials

Abstract

Raman spectroscopy has been used extensively to characterize the influence of mechanical deformation on microstructure changes in biomaterials. While traditional piezo-spectroscopy has been successful in assessing internal stresses of hard biomaterials by tracking prominent peak shifts, peak shifts due to applied loads are near or below the resolution limit of the spectrometer for soft biomaterials with moduli in the kilo- to mega-Pascal range. In this Review, in addition to peak shifts, other spectral features (e.g., polarized intensity and intensity ratio) that provide quantitative assessments of microstructural orientation and secondary structure in soft biomaterials and their strain dependence are discussed. We provide specific examples for each method and classify sensitive Raman characteristic bands common across natural (e.g., soft tissue) and synthetic (e.g., polymeric scaffolds) soft biomaterials upon mechanical deformation. This Review can provide guidance for researchers aiming to analyze micromechanics of soft tissues and engineered tissue constructs by Raman spectroscopy.

Human extracellular matrix (ECM)-like collagen and its bioactivity

“…Hence, it could result in a smaller percentage of alpha and triple helix in hCol with a certain amount of type III collagen as seen in Figure 3C and D . For other regions, although the Raman positions of peaks in C–C, C–S stretching region, amide III and C–H bending position were different to some degree between bCol I and hCol, it could attributed to spectral variability and broad spectral features in biological samples [ 59 , 60 ]. For fibrillar structure, SEM and TEM showed a 68-nm D-periodicity of collagen fibril in hCol.…”

Raman Spectroscopy and Mapping Analysis of Low-Dimensional Nanostructured Materials and Systems

“…The L a values are 18.2, 11.2, 9.6, 15.6, 14.0, and 13.7 nm for the different graphene oxides (from S-1 to S-6), and these values are lesser than the L a of graphite (122 nm). These results indicated that there is no linear relation to quantify the amounts of sp 3 and sp 2 domains present in graphene oxide with different oxidation degrees. Altogether, the Raman analysis showed the occurrence crystalline to amorphous transition with disruption of stacking order when graphite is oxidized into graphene oxide.…”

“…Raman spectroscopy is a promising non-destructive testing of materials to understand their crystallinity, chemical bonding vibrations and effects of surface defects [1,2]. The Raman spectroscopy becomes an important technique for the characterization of nanostructured materials, especially the two-dimensional (2D) materials (such as graphene, MoS 2 , siloxene, metalenes), biomaterials, composites, and for understanding energy-conversion process in the recent years [3][4][5]. Additionally, these techniques are useful for criminological & forensic applications, biomedical applications, and as well as bio-sensors for health care sectors [6][7][8].…”

Label-Free Quantification of Microscopic Alignment in Engineered Tissue Scaffolds by Polarized Raman Spectroscopy

“…Polarized Raman spectroscopy (PRS) can overcome the above limitation because it can detect alignment at the molecular level as it is based on vibrational light-scattering technique in which the intensity of the signal relies on the orientation of vibrating molecules relative to the laser polarization direction . Hence, PRS can extract structural information not only about collagen but all other biomacromolecules, such as multiple proteins and other cell components . Since PRS can be performed in aqueous environments, it holds a distinct advantage over polarized Fourier-transform infrared spectroscopy in probing highly hydrated tissue samples .…”

“…14 Hence, PRS can extract structural information not only about collagen but all other biomacromolecules, such as multiple proteins and other cell components. 15 Since PRS can be performed in aqueous environments, it holds a distinct advantage over polarized Fourier-transform infrared spectroscopy in probing highly hydrated tissue samples. 16 In our own 17 and other studies, 18−20 PRS has been used to characterize the organization of matrix in native tissue.…”