KAO European Research Laboratories, KAO Germany GmbH, D-64297 Darmstadt, Germany.
Institut de Sciences des Matériaux de Mulhouse-IS2M, CNRS UMR 7361, F-68057 Mulhouse, France; Lomonosov Moscow State University, GSP-1, Leninskie Gory, Moscow 119991, Russian Federation; Moscow Institute of Physics and Technology (State University), Institutskiy per. 9, Dolgoprudny, Russian Federation; Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russian Federation.
J Struct Biol. 2021 Mar;213(1):107679. doi: 10.1016/j.jsb.2020.107679. Epub 2020 Dec 10.
Utilising the AFM nanoindentation technique for the study of hair cross- and longitudinal sections, the mechanical anisotropy of human hair fibres affected by a rare congenital condition, Monilethrix, has been investigated for the first time. Supported by X-ray microdiffraction data, and applying a model based on an ideal composite material consisting of rods (KIFs) and matrix (KAPs) to Monilethrix affected fibres, it has been shown that the results could be grouped into clearly different classes, namely: almost isotropic behaviour for Monilethrix affected hairs and anisotropic behaviour for Control hair. Moreover, AFM nanoindentation of hair cross sections has demonstrated, also for the first time that hairs affected by Monilethrix have a continuous, and not periodic, weakness within the cortex. This has been attributed to disruptions in the KIF-KIF, KIF-intermacrofibrillar matrix or KIF-desmosome complexes within the hair shaft, as suggested by X-ray microdiffraction examination. Hairs from a patient exhibiting no obvious phenotype exhibited similar mechanical weakness despite the otherwise normal visual appearance of the fibre. This further supports a hypothesis that the beaded appearance of Monilethrix hair is a secondary factor, unrelated to the inherent structural weakness.
利用原子力显微镜纳米压痕技术研究头发的横切面和纵切面，首次研究了受罕见先天性疾病多发性外生性骨疣影响的人发纤维的机械各向异性。该研究得到了 X 射线微衍射数据的支持，并将基于由棒（KIFs）和基质（KAPs）组成的理想复合材料的模型应用于受多发性外生性骨疣影响的纤维，结果表明可以将其分为明显不同的两类，即：多发性外生性骨疣影响的头发几乎各向同性，而对照头发表现出各向异性。此外，头发横切面的原子力显微镜纳米压痕也首次表明，多发性外生性骨疣影响的头发在皮质内存在连续而非周期性的弱点。这归因于头发轴内 KIF-KIF、KIF-细胞间基质或 KIF-桥粒复合体的破坏，正如 X 射线微衍射检查所表明的那样。尽管纤维的外观正常，但一位表现出无明显表型的患者的头发也表现出类似的机械弱点。这进一步支持了这样一种假设，即多发性外生性骨疣头发的珠状外观是一种与固有结构弱点无关的次要因素。
