Palombo Marco, Barbetta Andrea, Cametti Cesare, Favero Gabriele, Capuani Silvia
Cardiff University Brain Research Imaging Centre, School of Psychology, Cardiff University, Maindy Road, Cardiff CF24 4HQ, UK.
School of Computer Science and Informatics, Cardiff University, Maindy Road, Cardiff CF24 4HQ, UK.
Gels. 2022 Feb 4;8(2):95. doi: 10.3390/gels8020095.
Considering the current development of new nanostructured and complex materials and gels, it is critical to develop a sub-micro-scale sensitivity tool to quantify experimentally new parameters describing sub-microstructured porous systems. Diffusion NMR, based on the measurement of endogenous water's diffusion displacement, offers unique information on the structural features of materials and tissues. In this paper, we applied anomalous diffusion NMR protocols to quantify the subdiffusion of water and to measure, in an alternative, non-destructive and non-invasive modality, the fractal dimension d of systems characterized by micro and sub-micro geometrical structures. To this end, three highly heterogeneous porous-polymeric matrices were studied. All the three matrices composed of glycidylmethacrylate-divynilbenzene porous monoliths obtained through the High Internal Phase Emulsion technique were characterized by pores of approximately spherical symmetry, with diameters in the range of 2-10 μm. Pores were interconnected by a plurality of window holes present on pore walls, which were characterized by size coverings in the range of 0.5-2 μm. The walls were characterized by a different degree of surface roughness. Moreover, complementary techniques, namely Field Emission Scanning Electron Microscopy (FE-SEM) and dielectric spectroscopy, were used to corroborate the NMR results. The experimental results showed that the anomalous diffusion α parameter that quantifies subdiffusion and d = 2/ changed in parallel to the specific surface area S (or the surface roughness) of the porous matrices, showing a submicroscopic sensitivity. The results reported here suggest that the anomalous diffusion NMR method tested may be a valid experimental tool to corroborate theoretical and simulation results developed and performed for describing highly heterogeneous and complex systems. On the other hand, non-invasive and non-destructive anomalous subdiffusion NMR may be a useful tool to study the characteristic features of new highly heterogeneous nanostructured and complex functional materials and gels useful in cultural heritage applications, as well as scaffolds useful in tissue engineering.
考虑到新型纳米结构材料、复杂材料及凝胶的当前发展情况，开发一种亚微观尺度的灵敏度工具以通过实验量化描述亚微观结构多孔系统的新参数至关重要。基于内源性水扩散位移测量的扩散核磁共振（Diffusion NMR），能提供有关材料和组织结构特征的独特信息。在本文中，我们应用反常扩散核磁共振方法来量化水的亚扩散，并以另一种非破坏性、非侵入性的方式测量具有微观和亚微观几何结构的系统的分形维数d。为此，研究了三种高度非均质的多孔聚合物基质。通过高内相乳液技术获得的所有三种由甲基丙烯酸缩水甘油酯 - 二乙烯基苯多孔整体材料组成的基质，其特征在于具有近似球形对称的孔，直径范围为2 - 10μm。孔通过孔壁上存在的多个窗孔相互连接，这些窗孔的尺寸范围为0.5 - 2μm。孔壁具有不同程度的表面粗糙度。此外，还使用了互补技术，即场发射扫描电子显微镜（FE - SEM）和介电谱，来证实核磁共振结果。实验结果表明，量化亚扩散的反常扩散α参数和d = 2/ 与多孔基质的比表面积S（或表面粗糙度）平行变化，显示出亚微观灵敏度。此处报道的结果表明，所测试的反常扩散核磁共振方法可能是一种有效的实验工具，可用于证实为描述高度非均质和复杂系统而开展的理论和模拟结果。另一方面，非侵入性和非破坏性的反常亚扩散核磁共振可能是一种有用的工具，可用于研究新型高度非均质纳米结构和复杂功能材料及凝胶在文化遗产应用中的特征，以及组织工程中有用的支架。
