Centro de Nanociencias y Micro y Nanotecnologías, Instituto Politécnico Nacional, Luis Enrique Erro s/n, Zacatenco, 07738, Ciudad de México, Mexico.
Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Prolongación de Carpio y Plan de Ayala s/n, Santo Tomás, 11340, Ciudad de México, Mexico.
Plant Physiol Biochem. 2022 Jan 1;170:249-254. doi: 10.1016/j.plaphy.2021.12.011. Epub 2021 Dec 13.
The objective of this study was to evaluate the effect of the presence of calcium oxalate (CaOx) crystals on the micromechanical properties of sclerenchyma tissue from the pecan nutshell (Carya illinoinensis). The microstructure of the cross-section nutshell was examined using light microscopy (LM) and atomic force microscopy (AFM). Using an instrumented indentation system, indentation tests with maximum loads of 500 mN were made on the biological material where the variables studied were the number of crystals present in the evaluated area and the size of individual crystals. Microscopic analysis revealed that the pecan nutshell consists of sclerenchyma tissue with multiple CaOx crystals randomly distributed throughout the material, exhibiting prismatic shapes and various sizes. The results of the indentation tests showed that the examined areas where there were crystals (1, 2 or up to 3) presented values of hardness and elastic modulus significantly higher (P < 0.05) compared to the sclerenchyma (without crystals). Likewise, there were no significant differences (P > 0.05) between the values of the micromechanical properties of the areas evaluated as a function of the number of crystals. On the other hand, it was observed that the size of the crystals did not show a direct correlation with the mechanical properties evaluated as expected. In conclusion, the biomineralization phenomenon is a successful strategy designed by nature to improve the rigidity of the pecan nutshell, where the CaOx crystals strengthen the structure by increasing the micromechanical properties.
本研究的目的是评估草酸钙 (CaOx) 晶体的存在对山核桃壳（Carya illinoinensis）韧皮组织的微机械性能的影响。使用光学显微镜 (LM) 和原子力显微镜 (AFM) 检查横截面壳的微观结构。使用仪器化压痕系统，在生物材料上进行最大载荷为 500 mN 的压痕试验，研究的变量是评估区域中存在的晶体数量和单个晶体的大小。微观分析表明，山核桃壳由韧皮组织组成，其中随机分布着多个 CaOx 晶体，呈现出棱柱形和各种大小。压痕试验的结果表明，存在晶体的检查区域（1、2 或多达 3 个）的硬度和弹性模量值明显高于（P < 0.05）无晶体的韧皮组织。同样，评估区域的微机械性能值与晶体数量之间没有显著差异（P > 0.05）。另一方面，观察到晶体的大小与预期的机械性能没有直接相关性。总之，生物矿化现象是大自然设计的一种成功策略，旨在提高山核桃壳的刚性，其中 CaOx 晶体通过增加微机械性能来增强结构。
