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Analyzing the feasibility of discriminating between collagen types I and II using polarization‐resolved second harmonic generation
Author(s) -
Romijn Elisabeth I.,
Finnøy Andreas,
Lilledahl Magnus B.
Publication year - 2019
Publication title -
journal of biophotonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.877
H-Index - 66
eISSN - 1864-0648
pISSN - 1864-063X
DOI - 10.1002/jbio.201800090
Subject(s) - collagen fibril , cartilage , second harmonic generation , polarization (electrochemistry) , type ii collagen , fibril , type i collagen , symmetry (geometry) , tendon , chemistry , molecular physics , tensor (intrinsic definition) , biophysics , materials science , optics , anatomy , physics , mathematics , pathology , geometry , biology , biochemistry , medicine , laser
According to previous studies, the nonlinear susceptibility tensor ratio χ 33 / χ 31 obtained from polarization‐resolved second harmonic generation (P‐SHG) under the assumption of cylindrical symmetry can be used to distinguish between fibrillar collagen types. Discriminating between collagen fibrils of types I and II is important in tissue engineering of cartilage. However, cartilage has a random organization of collagen fibrils, and the assumption of cylindrical symmetry may be incorrect. In this study, we simulated the P‐SHG response from different collagen organizations and demonstrated a possible method to exclude areas where cylindrical symmetry is not fulfilled and where fibrils are located in the imaging plane. The χ 33 / χ 31 ‐ratio for collagen type I in tendon and collagen type II in cartilage was estimated to be 1.33 and 1.36, respectively, using this method. These ratios are now much closer than what has been reported previously in the literature, and the larger reported differences between collagen types can be explained by variation in the structural organization.