Multiscale modeling of calcified polymer hydrogels

钙化聚合物水凝胶的多尺度建模

• 批准号: 420794479
• 负责人: Professorin Dr.-Ing. Sandra Klinge
• 金额: --
• 依托单位: Fachgebiet Strukturmechanik und Strukturberechnung
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/420794479?language=en
• 关键词: Multiscale; modeling; calcified; polymer; hydrogels

Hydrogels, a significant group of highly hydrated polymers, represent the best choice for the potential application to bone fracture regeneration, which goes back to their bioactivity, affinity for biologically active proteins and compatibility with the bone tissue. However, this kind of materials also shows a serious disadvantage, namely, it loses its mechanical strength through swelling. This makes its straightforward usage difficult and motivates the development of different enhancement procedures. One of the most modern techniques for this purpose is calcification or, in a more general sense, mineralization. This method is inspired by the natural process of the bone growth where the enzyme alkaline phosphatase causes mineralization of the bone by cleavage of the phosphate from organic molecules. An analogous process induces homogeneous mineralization of a hydrogel and increases its mechanical strength. Recently, optical and electron microscopy has revealed that calcification yields different types of microstructure dependent on the type of the underlying polymer, and thus has clearly indicated that computational modeling can significantly contribute to the targeted investigation of effective behavior and material parameters. Fracture energy and diffusivity are two particularly important aspects in this context. The former is taken as the main measure of material ductility and represents a weak point of calcified hydrogels. In order to solve this challenging problem, inspiration once more comes from natural materials and their hierarchical microstructure. The study of diffusion in macromolecular solutions is motivated by many biomedical applications as well as by its key role for protein assembly and interstitial transport. The project furthermore studies the design of the mineralization process which includes two essential steps: the understanding of the mechanisms governing the microstructure development and subsequently their optimization. The investigation of the diffusivity and of mineralization requires a profound knowledge on the processes on the nanoscale. This of course strongly substantiates computer simulations, since this kind of processes is yet non-accessible even by the most modern microscopy techniques. The spectrum of applicable methods encompasses the multiscale finite element method, the phase field method, the model reduction strategy and the finite difference method.

水凝胶是一类重要的高水合聚合物，由于其生物活性、对生物活性蛋白的亲和力以及与骨组织的相容性，是潜在应用于骨折再生的最佳选择。然而，这种材料也显示出一个严重的缺点，即它通过膨胀而失去机械强度。这使得它的直接使用变得困难，并促使开发不同的增强过程。用于这一目的的最现代技术之一是钙化，或者在更广泛的意义上，矿化。这种方法的灵感来自于骨骼生长的自然过程，在这种过程中，碱性磷酸酶通过从有机分子中分解磷酸盐而导致骨骼矿化。类似的过程会导致水凝胶的均匀矿化，并增加其机械强度。最近，光学和电子显微镜揭示了钙化作用产生的不同类型的微结构取决于底层聚合物的类型，因此清楚地表明，计算模拟可以显著有助于对有效行为和材料参数的有针对性的研究。在这种情况下，断裂能和扩散率是两个特别重要的方面。前者被认为是衡量材料延展性的主要指标，代表了钙化水凝胶的一个弱点。为了解决这一具有挑战性的问题，灵感再次来自天然材料及其层次化的微观结构。大分子溶液中扩散的研究受到许多生物医学应用的推动，以及它在蛋白质组装和间质运输中的关键作用。该项目还研究了矿化过程的设计，其中包括两个基本步骤：了解支配微结构发展的机制，并随后对其进行优化。对扩散和矿化的研究需要对纳米尺度上的过程有深刻的了解。这当然有力地证实了计算机模拟，因为即使用最现代的显微镜技术，这种过程也是无法获得的。适用的方法包括多尺度有限元方法、相场法、模型降阶策略和有限差分法。