Quantification of bush-cricket acoustic trachea mechanics using Atomic Force Microscopy nanoindentation
Quantification of bush-cricket acoustic trachea mechanics using Atomic Force Microscopy nanoindentation
复制标题
使用原子力显微镜纳米压痕量化灌木蟋蟀声学气管力学
DOI：
10.1016/j.actbio.2022.08.056
复制
发表时间：
2022
影响因子：
9.7
通讯作者：
Montealegre-Z, Fernando
中科院分区：
文献类型：
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作者：
Siamantouras, Eleftherios;Woodrow, Charlie;Celiker, Emine;Cullen, Darron A.;Hills, Claire E.;Squires, Paul E.;Montealegre-Z, Fernando
蟋蟀的声气管（或耳道）是由呼吸气管演变而来的中空管道，用于将外部环境的声音传递到内耳。由于耳朵在前腿的位置，声学气管作为一个结构元件，可以承受运动时的大应力。在这项研究中，我们报告了一种新的原子力显微镜-力光谱（AFM-FS）方法来量化灌木蟋蟀带绦虫的力学。机械性能检查在纵向轴水合带，通过压痕单一纤维使用精密双曲尖端。利用赫兹接触模型分析低应变下的力-位移（F-d）扩展曲线，弹性模量分布在13.9 MPa ~ 26.5 GPa之间，平均值为5.2±7 GPa，中位数为1.03 GPa。虽然几丁质是刚度的主要组成部分，但在纳米尺度上弹性的变化表明，弹性蛋白显著影响单个带绦虫纤维的机械性能（占总数据的38%）。对于高达400nm的压痕，观察到复杂的几丁质-弹性蛋白响应，表明顺应性和刚性之间的结构优化。复合材料的有限元分析表明，复合材料的弹性模量对弹性蛋白和甲壳素含量的百分比、它们的位置和结构构型都很敏感。基于我们的研究结果，我们提出带绦虫纤维的不同模量表明弹性在优化中起关键作用的复杂进化。在蟋蟀和丛林蟋蟀中，前腿的气管已经进化成声道，将声音传送到位于每条腿胫骨上的耳朵。气管由螺旋状的表皮微纤维保持开放，这种微纤维被称为带体，是机械加固的主要成分。我们开发了一种基于原子力显微镜（afm）的方法，在纳米水平上缩进单个带体，以量化听觉研究中的模式物种——长尾矮足蟋蟀（bush-cricketMecopoda elongata）内声道的局部力学特性。将带绦虫纤维固定在坚硬的基底上，压头直接靠近表皮表面。这是首次表征非固定气管带体的纳米结构，并为进一步研究听觉结构的维力学研究铺平了道路。
Derived from the respiratory tracheae, bush-crickets’ acoustic tracheae (or ear canals) are hollow tubes evolved to transmit sounds from the external environment to the interior ear. Due to the location of the ears in the forelegs, the acoustic trachea serves as a structural element that can withstand large stresses during locomotion. In this study, we report a new Atomic Force Microscopy Force Spectroscopy (AFM-FS) approach to quantify the mechanics of taenidia in the bush-cricketMecopoda elongata. Mechanical properties were examined over the longitudinal axis of hydrated taenidia, by indenting single fibres using precision hyperbolic tips. Analysis of the force-displacement (F-d) extension curves at low strains using the Hertzian contact model showed an Elastic modulus distribution between 13.9 MPa to 26.5 GPa, with a mean of 5.2 ± 7 GPa and median 1.03 GPa. Although chitin is the primary component of stiffness, variation of elasticity in the nanoscale suggests that resilin significantly affects the mechanical properties of single taenidia fibres (38% of total data). For indentations up to 400 nm, an intricate chitin-resilin response was observed, suggesting structural optimization between compliance and rigidity. Finite-element analysis on composite materials demonstrated that the Elastic modulus is sensitive to the percentage of resilin and chitin content, their location and structural configuration.Based on our results, we propose that the distinct moduli of taenidia fibres indicate sophisticated evolution with elasticity playing a key role in optimization.Statement of significanceIn crickets and bush-crickets, the foreleg tracheae have evolved into acoustic canals, which transport sound to the ears located on the tibia of each leg. Tracheae are held open by spiral cuticular micro-fibres called taenidia, which are the primary elements of mechanical reinforcement. We developed an AFM-based method to indent individual taenidia at the nanometre level, to quantify local mechanical properties of the interior acoustic canal of the bush-cricketMecopoda elongata, a model species in hearing research. Taenidia fibres were immobilized on a hard substrate and the indenter directly approached the epicuticle surface. This is the first characterization of the nano-structure of unfixed tracheal taenidia, and should pave the way for furtherin vivomechanical investigations of auditory structures.