Using the layer-by-layer (LbL) assembly technique to deposit mechanically reinforcing coatings onto porous templates is a route for fabricating engineered bone scaffold materials with a combination of high porosity, strength, and stiffness. LbL assembly involves the sequential deposition of nano- to micro-scale multilayer coatings from aqueous solutions. Here, a design of experiments (DOE) approach was used to evaluate LbL assembly of polyethyleneimine (PEI), polyacrylic acid (PAA), and nanoclay coatings onto open-cell polyurethane foam templates. The thickness of the coatings, and the porosity, elastic modulus and collapse stress of coated foam templates were most strongly affected by the pH of PAA solutions, salt concentration, and interactions between these factors. The mechanical properties of coated foams correlated with the thickness of the coatings, but were also ascribed to changes in the coating properties due to the different assembly conditions. A DOE optimization aimed to balance the trade-off between higher mechanical properties but lower porosity of foam templates with increasing coating thickness. Micromechanical modeling predicted that deposition of 116 QLs would achieve mechanical properties of cancellous bone (>0.05 GPa stiffness and >2 MPa strength) at a suitable porosity of >70%. When capped with a final layer of PAA and cross-linked via thermal treatment, the PEI/PAA/PEI/nanoclay coatings exhibited good indirect cytotoxicity with mesenchymal stem cells. The ability of LbL assembly to deposit a wide range of functional constituents within multilayer-structured coatings makes the general strategy of templated LbL assembly a powerful route for fabricating engineered tissue scaffolds that can be applied onto various porous template materials to achieve a wide range of properties, pore structures, and multifunctionality.

中文翻译：

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用于工程骨支架的纳米复合涂层多孔模板：逐层组装条件的参数研究。

使用逐层（LbL）组装技术将机械增强涂层沉积到多孔模板上是一条制造具有高孔隙率，强度和刚度的工程骨支架材料的途径。LbL组装涉及从水溶液中依次沉积纳米级至微米级多层涂层。在这里，实验设计（DOE）方法用于评估聚乙烯亚胺（PEI），聚丙烯酸（PAA）和纳米粘土涂料在开孔聚氨酯泡沫模板上的LbL组装。PAA溶液的pH值，盐浓度以及这些因素之间的相互作用对涂层的厚度以及涂层泡沫模板的孔隙率，弹性模量和坍塌应力的影响最大。涂层泡沫的机械性能与涂层的厚度相关，但也归因于不同的组装条件导致涂层性能的变化。DOE优化旨在平衡泡沫模板的较高机械性能与较低孔隙率之间的权衡，同时增加涂层厚度。微机械建模预测，在适当的孔隙率> 70％的情况下，沉积116个QL会获得松质骨的机械性能（> 0.05 GPa的刚度和> 2 MPa的强度）。当用PAA的最后一层覆盖并通过热处理交联时，PEI / PAA / PEI /纳米粘土涂层对间充质干细胞表现出良好的间接细胞毒性。