Abstract Composite biomaterials are of great interest in tissue engineering and regenerative medicine. Composites partially exhibit the properties of their starting materials but, through rational design, they can be endowed with synergistic effects, overcoming the limitations of the single components. Calcium phosphate/polyvinyl alcohol (CaP/PVA) composites are archetypical examples of composite biomaterials, where a soft elastic biologically inert gel is combined with a bioactive inorganic phase, radically improving the mechanical properties. The combination allows engineering a material which better resembles the tissue architecture, for example, osteochondral defects, where organic-inorganic interfaces and gradient properties are present. The combination of components with opposite properties such as polyvinyl alcohol (PVA) and calcium phosphates (CaP) for creating synergistic properties is a grand challenge for the material engineer, where the know-how on PVA preparation must be adapted to the necessity of incorporating a phase with the appropriate size, aspect ratio, chemical composition, homogeneity or even pre-determined composition gradients. In this review, we report how these design challenges were overcome and how different design parameters involved in CaP/PVA influence each other. The review is organized as follows. First, the general properties of organic/inorganic composites and PVA hydrogels are briefly summarized. Then, CaP/PVA composites are described according to their preparation methods, discussing how parameters such as polymer deacetylation degree, tacticity, molecular weight, freeze-thawing parameters, CaP content or CaP addition or in situ preparation modality influence the composite’s properties such as friction, boundary lubrication, porosity, and osteointegration. Finally, open research questions and future and desirable developments are given.

中文翻译：

---

磷酸钙/聚乙烯醇复合水凝胶：冻融合成方法及其在再生医学中的应用综述

摘要 复合生物材料在组织工程和再生医学领域具有重要意义。复合材料部分地展示了其原材料的特性，但通过合理的设计，它们可以被赋予协同效应，克服单一成分的局限性。磷酸钙/聚乙烯醇 (CaP/PVA) 复合材料是复合生物材料的典型例子，其中软弹性生物惰性凝胶与生物活性无机相结合，从根本上提高了机械性能。这种组合允许设计一种更类似于组织结构的材料，例如骨软骨缺损，其中存在有机-无机界面和梯度特性。将具有相反特性的组分（如聚乙烯醇 (PVA) 和磷酸钙 (CaP)）组合以产生协同特性对材料工程师来说是一个巨大的挑战，其中 PVA 制备的专业知识必须适应结合相具有适当的尺寸、纵横比、化学成分、均匀性或什至预先确定的成分梯度。在这篇综述中，我们报告了如何克服这些设计挑战以及 CaP/PVA 中涉及的不同设计参数如何相互影响。审查安排如下。首先，简要总结了有机/无机复合材料和 PVA 水凝胶的一般特性。然后，根据其制备方法描述了 CaP/PVA 复合材料，讨论了聚合物脱乙酰度、立构规整度、分子量、冻融参数、CaP 含量或 CaP 添加或原位制备方式会影响复合材料的特性，如摩擦、边界润滑、孔隙率和骨整合。最后，给出了开放的研究问题以及未来和理想的发展。