Department of Biomedical Engineering, The Iby and Aladar Fleischman Faculty of Engineering, Tel-Aviv University, Tel-Aviv 69978, Israel.
Department of Biomedical Engineering, The Iby and Aladar Fleischman Faculty of Engineering, Tel-Aviv University, Tel-Aviv 69978, Israel.
Acta Biomater. 2014 Jun;10(6):2762-8. doi: 10.1016/j.actbio.2014.02.014. Epub 2014 Feb 15.
Pore size distribution (PSD) within porous biomaterials is an important microstructural feature for assessing their biocompatibility, longevity and drug release kinetics. Scanning electron microscopy (SEM) is the most common method used to obtain the PSD of soft biomaterials. The method is highly invasive and user dependent, since it requires fracturing of the sample and then considers only the small portion that the user had acquired in the image. In the current study we present a novel nuclear magnetic resonance (NMR) method as an alternative method for estimation of PSD in soft porous materials. This noninvasive 3-D diffusion NMR method considers the entire volume of the specimen and eliminates the user's need to choose a specific field of view. Moreover, NMR does not involve exposure to ionizing radiation and can potentially have preclinical and clinical uses. The method was applied on four porous 50/50 poly(dl-lactic-co-glycolic acid) bioresorbable films with different porosities, which were created using the freeze-drying of inverted emulsions technique. We show that the proposed NMR method is able to address the main limitations associated with SEM-based PSD estimations by being non-destructive, depicting the full volume of the specimens and not being dependent on the magnification factor. Upon comparison, both methods yielded a similar PSD in the smaller pore size range (1-25μm), while the NMR-based method provided additional information on the larger pores (25-50μm).
多孔生物材料中的孔径分布（PSD）是评估其生物相容性、耐久性和药物释放动力学的重要微观结构特征。扫描电子显微镜（SEM）是获取软生物材料 PSD 的最常用方法。该方法具有高度的侵入性和用户依赖性，因为它需要对样品进行断裂，然后仅考虑用户在图像中获取的一小部分。在当前的研究中，我们提出了一种新的核磁共振（NMR）方法，作为估计软多孔材料 PSD 的替代方法。这种非侵入性的 3D 扩散 NMR 方法考虑了样品的整个体积，并消除了用户选择特定视场的需要。此外，NMR 不涉及电离辐射的暴露，并且具有潜在的临床前和临床用途。该方法应用于四种不同孔隙率的 50/50 聚（DL-丙交酯-共-乙交酯）可生物降解薄膜，这些薄膜是通过反相乳液冷冻干燥技术制备的。我们表明，所提出的 NMR 方法通过非破坏性、描绘样品的整个体积以及不依赖于放大倍数，能够解决与 SEM 基 PSD 估计相关的主要限制。通过比较，两种方法在较小的孔径范围（1-25μm）中都产生了相似的 PSD，而基于 NMR 的方法则提供了关于较大孔径（25-50μm）的附加信息。
