DNA Nanodevices Group, Fraunhofer Institute for Cell Therapy and Immunology, Perlickstr. 1, 04103 Leipzig, Germany.
Soft Matter Physics Division, Peter Debye Institute, Faculty of Physics and Earth Sciences, Leipzig University, Linnéstr. 5, 04103 Leipzig, Germany.
Nanoscale. 2023 Apr 27;15(16):7374-7383. doi: 10.1039/d2nr05615a.
In order to understand and predict the mechanical behaviours of complex, soft biomaterials such as cells or stimuli-responsive hydrogels, it is important to connect how the nanoscale properties of their constituent components impact those of the bulk material. Crosslinked networks of semiflexible polymers are particularly ubiquitous, being underlying mechanical components of biological systems such as cells or ECM, as well as many synthetic or biomimetic materials. Cell-derived components such as filamentous biopolymers or protein crosslinkers are readily available and well-studied model systems. However, as evolutionarily derived materials, they are constrained to a fixed set of structural parameters such as the rigidity and size of the filaments, or the valency and strength of binding of crosslinkers forming inter-filament connections. By implementing a synthetic model system based on the self-assembly of DNA oligonucleotides into nanometer-scale tubes and simple crosslinking constructs, we used the thermodynamic programmability of DNA hybridization to explore the impact of binding affinity on bulk mechanical response. Stepwise tuning the crosslinking affinity over a range from transient to thermodynamically stable shows an according change in viscoelastic behaviour from loosely entangled to elastic, consistent with models accounting for generalized inter-filament interactions. While characteristic signatures of concentration-dependent changes in network morphology found in some other natural and synthetic filament-crosslinker systems were not apparent, the presence of a distinct elasticity increase within a narrow range of conditions points towards potential subtle alterations of crosslink-filament architecture. Here, we demonstrate a new synthetic approach for gaining a deeper understanding of both biological as well as engineered hydrogel systems.
为了理解和预测复杂的软生物材料（如细胞或响应刺激的水凝胶）的力学行为，了解其组成成分的纳米级特性如何影响整体材料的特性非常重要。半刚性聚合物的交联网络尤为普遍，它们是细胞或细胞外基质等生物系统以及许多合成或仿生材料的基础力学成分。细胞衍生的成分，如丝状生物聚合物或蛋白质交联剂，是现成的且经过充分研究的模型系统。然而，作为进化衍生的材料，它们受到固定结构参数的限制，例如纤维的刚性和尺寸，或者形成纤维间连接的交联剂的结合价和强度。通过实现基于 DNA 寡核苷酸自组装成纳米级管和简单交联结构的合成模型系统，我们利用 DNA 杂交的热力学可编程性来探索结合亲和力对整体力学响应的影响。在从瞬时到热力学稳定的范围内逐步调整交联亲和力，会导致粘弹性行为从松散缠结到弹性发生相应变化，这与考虑广义纤维间相互作用的模型一致。虽然在一些其他天然和合成纤维交联剂系统中发现的网络形态浓度依赖性变化的特征特征不明显，但在狭窄条件范围内存在明显的弹性增加，表明交联纤维结构可能存在潜在的细微变化。在这里，我们展示了一种新的合成方法，用于更深入地了解生物和工程水凝胶系统。
