Gröger Christian, Lutz Katharina, Brunner Eike
Institute of Biophysics and Physical Biochemistry, University of Regensburg, Regensburg, Germany.
Cell Biochem Biophys. 2008;50(1):23-39. doi: 10.1007/s12013-007-9003-2. Epub 2007 Oct 11.
Biomineralization, which means the formation of inorganic materials by biological processes, currently finds increasing research interest. It involves the synthesis of calcium-based minerals such as bones and teeth in vertebrates, and of shells. Silica biomineralization occurs, for example, in diatoms and silica sponges. Usually, biominerals are made up of amorphous compounds or small microcrystalline domains embedded into an amorphous matrix. Nevertheless, they exhibit very regular shapes and, as in the case of diatoms, intricate nanopatterns of amazing beauty. It is, therefore, commonly assumed that biominerals are formed under the structure-directing influence of templates. However, single molecules are by far too small to direct the formation of the observed shapes and patterns. Instead, supramolecular aggregates are shown to be involved in the formation of templating superstructures relevant in biomineralization. Specific biomolecules were identified in both diatoms and silica sponges, which elegantly combine two indispensable functions: on the one hand, the molecules are capable of inducing silica precipitation from precursor compounds. On the other hand, these molecules are capable of self-assembling into larger, structure-directing template aggregates. Such molecules are the silaffins in the case of diatoms and the silicateins in sponges. Long-chain polyamines of similar composition have meanwhile been discovered in both organisms. The present review is especially devoted to the discussion of the self-assembly behavior of these molecules. Physico-chemical studies on a model compound, poly(allylamine), are discussed in detail in order to elucidate the nature of the interactions responsible for self-assembly of long-chain polyamines and the parameters controlling this process. Numerous biomimetic silica synthesis experiments are discussed and evaluated with respect to the observations made on the aforementioned "natural" biomolecules.
生物矿化是指通过生物过程形成无机材料，目前越来越受到研究关注。它涉及脊椎动物中钙基矿物质如骨骼和牙齿以及贝壳的合成。例如，硅藻和硅质海绵中会发生二氧化硅生物矿化。通常，生物矿化产物由无定形化合物或嵌入无定形基质中的小微晶域组成。然而，它们呈现出非常规则的形状，就像硅藻的情况一样，还有令人惊叹的美丽复杂纳米图案。因此，人们普遍认为生物矿化产物是在模板的结构导向影响下形成的。然而，单个分子太小，远不足以指导观察到的形状和图案的形成。相反，超分子聚集体被证明参与了生物矿化中相关模板超结构的形成。在硅藻和硅质海绵中都鉴定出了特定的生物分子，这些分子巧妙地结合了两个不可或缺的功能：一方面，这些分子能够从前体化合物中诱导二氧化硅沉淀。另一方面，这些分子能够自组装成更大的、具有结构导向作用的模板聚集体。在硅藻中这类分子是硅蛋白，在海绵中是硅酸酶。同时，在这两种生物中都发现了组成相似的长链多胺。本综述特别致力于讨论这些分子的自组装行为。详细讨论了对模型化合物聚烯丙胺的物理化学研究，以阐明负责长链多胺自组装的相互作用的性质以及控制这一过程的参数。针对上述“天然”生物分子的观察结果，对众多仿生二氧化硅合成实验进行了讨论和评估。
