Pure and Applied Biomineralisation Group, Institute of Biophysics, University of Bremen, Bremen, Germany.
Micron. 2012 Dec;43(12):1351-63. doi: 10.1016/j.micron.2012.03.014. Epub 2012 Apr 6.
Mimicry of the tough natural composite nacre in future bioengineering requires knowledge of the biomineralisation process. The insoluble organic matrix isolated from the shell of the gastropod Haliotis laevigata was characterised by protein chemistry, topographical and mechanical measurements. Demineralisation of nacre in dilute acetic acid or ethylenediaminetetraacetic acid revealed a set of soluble proteins and the insoluble matrix. The insoluble matrix contains a chitin core and firmly attached proteins, which could be removed by sodium dodecyl sulfate and glycerol indicating a hydrophobic interaction. Atomic force microscopy images of the native insoluble matrix showed a filamentous network with pores or holes, where the filaments showed globular attachments of different sizes, possibly the attached protein molecules. During direct observation of protein degradation imaged by atomic force microscopy the insoluble matrix gets smooth and flat indicating the removal of the attached proteins by proteases. We propose a model of protein coated chitin filaments for the insoluble matrix of nacre. Mechanical measurements by force mapping revealed a Young's modulus depending on the hydration state of the organic layers. The fully hydrated organic matrix has an elastic modulus below 1 MPa comparable to some hydrogels.
未来生物工程中对坚韧天然复合珍珠母的模拟需要了解生物矿化过程。从腹足纲软体动物 Haliotis laevigata 的壳中分离出的不溶性有机基质通过蛋白质化学、形貌和机械测量进行了表征。在稀乙酸或乙二胺四乙酸中脱矿化珍珠母揭示了一组可溶性蛋白质和不溶性基质。不溶性基质含有甲壳素核心和牢固附着的蛋白质，这些蛋白质可以通过十二烷基硫酸钠和甘油去除，表明存在疏水相互作用。天然不溶性基质的原子力显微镜图像显示出具有孔或洞的丝状网络，其中丝状结构显示出不同大小的球形附着，可能是附着的蛋白质分子。在原子力显微镜直接观察蛋白质降解的过程中，不溶性基质变得光滑和平坦，表明蛋白酶去除了附着的蛋白质。我们提出了一种蛋白质涂覆的壳素纤维不溶性基质模型。通过力映射进行的机械测量表明，有机层的水合状态决定了杨氏模量。完全水合的有机基质的弹性模量低于 1 MPa，类似于一些水凝胶。
