Morpho-mechanics of human collagen superstructures revealed by all-optical correlative micro-spectroscopies

Abstract

In every biological tissue, morphological and topological properties strongly affect its mechanical features and behaviour, so that ultrastructure, composition and mechanical parameters are intimately connected. Overall, it is their correct interplay that guarantees the tissue functionality. The development of experimental methods able to correlate these properties would open new opportunities both in the biological and the biomedical fields. Here, we report a correlative study intended to map supramolecular morphology, biochemical composition and viscoelastic parameters of collagen by all-optical microscopies. In particular, using human corneal tissue as a benchmark, we correlate Second-Harmonic Generation maps with mechanical and biochemical imaging obtained by Brillouin and Raman micro-spectroscopy. The study highlights how subtle variations in supramolecular organization originate the peculiar mechanical behavior of different subtypes of corneal lamellae. The presented methodology paves the way to the non-invasive assessment of tissue morpho-mechanics in biological as well as synthetic materials.

Mechano-chemistry of human femoral diaphysis revealed by correlative Brillouin–Raman microspectroscopy

“…This technique gives global information on bone elasticity but does not allow one to investigate the microscale level because of the limited spatial resolution. Recently, a new method has been proposed to measure the mechanical properties of biological tissues, based on Brillouin micro-spectroscopy 2 – 7 The technique is based on the inelastic scattering of light from thermally activated acoustic waves propagating through the sample at GHz frequencies. Based on the light-scattering process, it has the great advantage of being non-destructive and contactless, since it does not need external probes but light.…”

Self‐assembling amyloid‐like peptides as exogenous second harmonic probes for bioimaging applications

“…In particular, collagen I and collagen II have been proven to efficiently produce SHG signals . SHG has been applied to investigate rat and human corneal samples . Collagen fibrils in cornea were observed under SHG microscopy without any labelling.…”

Polarization‐dependent second‐harmonic generation for collagen‐based differentiation of breast cancer samples

“…A recent work demonstrated that a more generalized model, considering both cylindrical and trigonal symmetry, could be used to describe the organization of collagen structure. 47 Such approach could provide improved results in human breast samples. 48 Following the experimental approach described herein, which was based on the calculation of the integrated anisotropy parameter values of different collagen types, the discrimination between benign and malignant cancer tissue samples could be achieved.…”