title: The Impact of Collagen Fibril Polarity on Second Harmonic Generation Microscopy.
abstract: In this work, we report the implementation of interferometric second harmonic generation (SHG) microscopy with femtosecond pulses. As a proof of concept, we imaged the phase distribution of SHG signal from the complex collagen architecture of juvenile equine growth cartilage. The results are analyzed in respect to numerical simulations to extract the relative orientation of collagen fibrils within the tissue. Our results reveal large domains of constant phase together with regions of quasi-random phase, which are correlated to respectively high- and low-intensity regions in the standard SHG images. A comparison with polarization-resolved SHG highlights the crucial role of relative fibril polarity in determining the SHG signal intensity. Indeed, it appears that even a well-organized noncentrosymmetric structure emits low SHG signal intensity if it has no predominant local polarity. This work illustrates how the complex architecture of noncentrosymmetric scatterers at the nanoscale governs the coherent building of SHG signal within the focal volume and is a key advance toward a complete understanding of the structural origin of SHG signals from tissues.
authors.affiliation: Institut National de la Recherche Scientifique, Centre Énergie Matériaux Télécommunications, Varennes, Quebec, Canada.
authors.forename: Charles-André
authors.initials: CA
authors.lastname: Couture
authors.affiliation: Institut National de la Recherche Scientifique, Centre Énergie Matériaux Télécommunications, Varennes, Quebec, Canada.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Bancelin
authors.affiliation: Department of Physics, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Jarno
authors.initials: J
authors.lastname: Van der Kolk
authors.affiliation: Department of Physics, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Konstantin
authors.initials: K
authors.lastname: Popov
authors.affiliation: Institut National de la Recherche Scientifique, Centre Énergie Matériaux Télécommunications, Varennes, Quebec, Canada.
authors.forename: Maxime
authors.initials: M
authors.lastname: Rivard
authors.affiliation: Institut National de la Recherche Scientifique, Centre Énergie Matériaux Télécommunications, Varennes, Quebec, Canada.
authors.forename: Katherine
authors.initials: K
authors.lastname: Légaré
authors.affiliation: Comparative Orthopaedic Research Laboratory, Faculté de Médecine Vétérinaire, University of Montreal, Sainte Hyacinthe, Quebec, Canada.
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Martel
authors.affiliation: Comparative Orthopaedic Research Laboratory, Faculté de Médecine Vétérinaire, University of Montreal, Sainte Hyacinthe, Quebec, Canada.
authors.forename: Hélène
authors.initials: H
authors.lastname: Richard
authors.affiliation: University of Oxford, Botnar Research Center, NDORMS, Oxford, United Kingdom.
authors.forename: Cameron
authors.initials: C
authors.lastname: Brown
authors.affiliation: Comparative Orthopaedic Research Laboratory, Faculté de Médecine Vétérinaire, University of Montreal, Sainte Hyacinthe, Quebec, Canada.
authors.forename: Sheila
authors.initials: S
authors.lastname: Laverty
authors.affiliation: Department of Physics, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Lora
authors.initials: L
authors.lastname: Ramunno
authors.affiliation: Institut National de la Recherche Scientifique, Centre Énergie Matériaux Télécommunications, Varennes, Quebec, Canada. Electronic address: legare@emt.inrs.ca.
authors.forename: François
authors.initials: F
authors.lastname: Légaré
mesh_terms: D000818:Animals; D002356:Cartilage / Q000737:chemistry; D003094:Collagen / Q000737:chemistry*; D006736:Horses; D008853:Microscopy; D008954:Models, Biological; D055503:Protein Multimerization; D017433:Protein Structure, Secondary
chemical_list: D003094:Collagen