Department of Physics, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.
J Biophotonics. 2019 Jan;12(1):e201800090. doi: 10.1002/jbio.201800090. Epub 2018 Aug 20.
According to previous studies, the nonlinear susceptibility tensor ratio χ /χ 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 /χ -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.
根据以往的研究，在圆柱对称性假设下，从偏振分辨二次谐波产生（P-SHG）中获得的非线性极化率张量比 χ/χ 可用于区分纤维状胶原蛋白类型。区分 I 型和 II 型胶原纤维在软骨组织工程中很重要。然而，软骨中的胶原纤维具有随机的组织方式，圆柱对称性的假设可能不正确。在这项研究中，我们模拟了来自不同胶原组织的 P-SHG 响应，并展示了一种可能的方法来排除圆柱对称性不满足的区域以及纤维位于成像平面的区域。使用这种方法，估计肌腱中的 I 型胶原和软骨中的 II 型胶原的 χ/χ 比分别为 1.33 和 1.36。这些比率现在比以前文献中报道的要接近得多，而且胶原类型之间报道的更大差异可以通过结构组织的变化来解释。
