Li Naitao, Duan Xiaoman, Ding Xiao Fan, Zhu Ning, Chen Xiongbiao
Division of Biomedical Engineering, College of Engineering, University of Saskatchewan, Saskatoon, SK, S7N 5A9, Canada.
Division of Biomedical Engineering, College of Engineering, University of Saskatchewan, Saskatoon, SK, S7N 5A9, Canada; Canadian Light Source, Saskatoon, S7N 2V3, SK, Canada; Department of Chemical and Biological Engineering, College of Engineering, University of Saskatchewan, Saskatoon, SK, S7N 5A9, Canada.
J Mech Behav Biomed Mater. 2025 Mar;163:106844. doi: 10.1016/j.jmbbm.2024.106844. Epub 2024 Nov 29.
Hydrogel-based scaffolds have been widely used in soft tissue regeneration due to their biocompatible and tissue-like environment for maintaining cellular functions and tissue regeneration. Understanding the mechanical properties and internal microstructure of hydrogel-based scaffold, once implanted, is imperative in tissue engineering applications and longitudinal studies. Notably, this has been challenging to date as various conventional characterization methods by, for example, mechanical testing (for mechanical properties) and microscope (for internal microstructure) are destructive as they require removing scaffolds from the implantation site and processing samples for characterization. Synchrotron radiation propagation-based imaging-computed tomography (SR-PBI-CT) is feasible and promising for non-destructive visualizing of hydrogel scaffolds. As inspired, this study aimed to perform a study on the characterization of mechanical properties and microstructure of hydrogel scaffolds based on the SR-PBI-CT. In this study, hydrogel biomaterial inks composed of 3% w/v alginate and 1% w/v gelatin were printed to form scaffolds, with some scaffolds being degraded over 3 days. Both degraded and undegraded scaffolds underwent compressive testing, with the strains being controlled at the preset values; meanwhile stresses within scaffolds were measuring, resulting the stress-strain curves. Concurrently, the scaffolds were also imaged and examined by SR-PBI-CT at Canadian Light Source (CLS). During the imaging process, the scaffolds were mechanically loaded, respectively, with the strains same as the ones in the aforementioned compressive testing, and at each strain, the scaffold was scanned with a pixel size of 13 μm. From the stress-strain curves obtained in the compression testing, the Young's modulus was evaluated to characterize the elastic behavior of scaffolds: with the range between around 5-25 kPa. From the images captured by SR-PBI-CT, the scaffolds microstructures were examined in terms of the strand cross-section area, pore size, and hydrogel volume. Further, from the SR-PBI-CT images, the stress within hydrogel of scaffolds were evaluated, showing the agreement with those obtained from compression testing. These results have illustrated that the mechanical properties and microstructures of scaffolds, ether being degraded or not, can be examined and characterized by the SR-PBI-CT imaging, in a non-destructive manner. This would represent a significant advance for facilitating longitudinal studies on the scaffolds once implanted in-vivo.
基于水凝胶的支架因其生物相容性和类似组织的环境，能够维持细胞功能和组织再生，已被广泛应用于软组织再生。了解植入后基于水凝胶的支架的力学性能和内部微观结构，在组织工程应用和纵向研究中至关重要。值得注意的是，由于各种传统表征方法，例如用于力学性能的力学测试和用于内部微观结构的显微镜检查，都具有破坏性，因为它们需要从植入部位取出支架并处理样品进行表征，所以迄今为止这一直是一项挑战。基于同步辐射传播的成像计算机断层扫描（SR-PBI-CT）对于水凝胶支架的无损可视化是可行且有前景的。受此启发，本研究旨在基于SR-PBI-CT对水凝胶支架的力学性能和微观结构进行表征研究。在本研究中，由3% w/v海藻酸盐和1% w/v明胶组成的水凝胶生物材料墨水被打印成支架，其中一些支架在3天内降解。降解和未降解的支架都进行了压缩测试，应变被控制在预设值；同时测量支架内的应力，得到应力-应变曲线。同时，这些支架也在加拿大光源（CLS）通过SR-PBI-CT进行成像和检查。在成像过程中，分别对支架施加与上述压缩测试中相同应变的机械载荷，并且在每个应变下，以13μm的像素尺寸对支架进行扫描。从压缩测试获得的应力-应变曲线中，评估杨氏模量以表征支架的弹性行为：范围在大约5-25 kPa之间。从SR-PBI-CT捕获的图像中，根据股线横截面积、孔径和水凝胶体积检查支架的微观结构。此外，从SR-PBI-CT图像中评估支架水凝胶内的应力，结果与压缩测试获得的结果一致。这些结果表明，无论支架是否降解，其力学性能和微观结构都可以通过SR-PBI-CT成像以无损方式进行检查和表征。这将代表在促进对体内植入后的支架进行纵向研究方面取得重大进展。
