Noninvasive assessment of collagen gel microstructure and mechanics using multiphoton Microscopy
Noninvasive assessment of collagen gel microstructure and mechanics using multiphoton Microscopy
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DOI：
10.1529/biophysj.106.097998
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发表时间：
2007-03-15
影响因子：
3.4
通讯作者：
George, Steven C.
中科院分区：
文献类型：
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作者：
Raub, Christopher B.;Suresh, Vinod;George, Steven C.
胶原蛋白水凝胶的多光子显微镜产生二次谐波产生（SHG）和双光子荧光（TPF）图像，其可用于在深度（类似于1 mm）非侵入性地研究凝胶微观结构。微结构也是凝胶机械性能的主要决定因素;因此，我们假设，SHG和TPF）可以用来预测胶原水凝胶的整体力学性能。我们利用聚合温度（4-37摄氏度）和戊二醛来操纵胶原蛋白水凝胶纤维直径、空间填充特性和交联密度。多光子显微镜和扫描电子显微镜显示，随着聚合温度降低（37-4 ℃），纤维直径和孔径增加，而水凝胶储能模量（G '，分别从23 +/- 63 Pa至0.28 +/- 0.16 Pa，平均值+/- SE）和平均SHG降低（TPF的最小变化）。相比之下，戊二醛显著增加了平均TPF信号（不影响SHG信号）和储能模量（交联前为16 +/- 3.5 Pa，交联后为138 +/- 40 Pa，平均值+/- SD）。我们的结论是，SHG和TPF可以表征差异的胶原蛋白水凝胶的微观特征，与散装机械性能强相关。因此，光学成像可能是一个有用的非侵入性工具，以评估组织力学。
Multiphoton microscopy of collagen hydrogels produces second harmonic generation (SHG) and two-photon fluorescence (TPF) images, which can be used to noninvasively study gel microstructure at depth (similar to 1 mm). The microstructure is also a primary determinate of the mechanical properties of the gel; thus, we hypothesized that bulk optical properties (i.e., SHG and TPF) could be used to predict bulk mechanical properties of collagen hydrogels. We utilized polymerization temperature (4-37 degrees C) and glutaraldehyde to manipulate collagen hydrogel fiber diameter, space-filling properties, and cross-link density. Multiphoton microscopy and scanning electron microscopy reveal that as polymerization temperature decreases (37-4 degrees C) fiber diameter and pore size increase, whereas hydrogel storage modulus (G', from 23 +/- 63 Pa to 0.28 +/- 0.16 Pa, respectively, mean +/- SE) and mean SHG decrease (minimal change in TPF). In contrast, glutaraldehyde significantly increases the mean TPF signal (without impacting the SHG signal) and the storage modulus (16 +/- 3.5 Pa before to 138 +/- 40 Pa after cross-linking, mean +/- SD). We conclude that SHG and TPF can characterize differential microscopic features of the collagen hydrogel that are strongly correlated with bulk mechanical properties. Thus, optical imaging may be a useful noninvasive tool to assess tissue mechanics.