Probing the 3D structure of cornea-like collagen liquid crystals with polarization-resolved SHG microscopy

Claire Teulon (1) , Aurélien Tidu (2) , François Portier (2) , Gervaise Mosser (2) , Marie-Claire Schanne-Klein (1)

1 LOB - Laboratoire d'Optique et Biosciences
2 LCMCP - Laboratoire de Chimie de la Matière Condensée de Paris

This work aims at characterizing the three-dimensional organization of liquid crystals composed of collagen, in order to determine the physico-chemical conditions leading to highly organized structures found in biological tissues such as cornea. To that end, we use second-harmonic generation (SHG) microscopy, since aligned collagen structures have been shown to exhibit intrinsic SHG signals. We combine polarization-resolved SHG experiments (P-SHG) with the theoretical derivation of the SHG signal of collagen molecules tilted with respect to the focal plane. Our P-SHG images exhibit striated patterns with variable contrast, as expected from our analytical and numerical calculations for plywood-like nematic structures similar to the ones found in the cornea. This study demonstrates the benefits of P-SHG microscopy for in situ characterization of highly organized biopolymers at micrometer scale, and the unique sensitivity of this nonlinear optical technique to the orientation of collagen molecules.

Mots clés: Nonlinear microscopy; Harmonic generation and mixing; Polarimetry; Light propagation in tissues; Tissue characterization References and links 1 D Hulmes

Domaines: Imagerie; Optique [physics.optics]

Claire Teulon, Aurélien Tidu, François Portier, Gervaise Mosser, Marie-Claire Schanne-Klein. Probing the 3D structure of cornea-like collagen liquid crystals with polarization-resolved SHG microscopy. Optics Express, 2016, 24, pp.16084 - 10. ⟨10.1364/OE.24.016084.v001⟩. ⟨hal-01421625⟩