Bionic hierarchically ordered structured organic–inorganic composites (BOICs): From materials manufacturing to tissue regeneration engineering

Biominerals, such as bones and teeth, are typically natural organic–inorganic composites characterized by hierarchically ordered structures and exceptional mechanical properties. In contrast, synthetic organic–inorganic composites exhibit inferior structural order, mechanical performance, and bioactivity, which restricts their clinical applicability. Researchers have been inspired to precisely regulate the integration and spatial arrangement of organic matrix (e.g., collagen, chitosan) and inorganic units (e.g., calcium phosphate) via mimicking the process of biomineralization to fabricate bionic hierarchically ordered structured organic–inorganic composites (BOICs). These BOICs demonstrate distinguished mechanical properties and biocompatibility, and even perform novel functions, including the bionic bone scaffolds for hard tissue regeneration, bionic mandibular scaffolds for gradient repair, and even as substitutes for tendons. Furthermore, BOICs offer opportunities to study the structural ordering and mechanical properties of artificially enhanced organic–inorganic composites and their effects on biological behaviors of cells. This review systematically summarizes the hierarchically ordered structures and mechanical characteristics of bones and teeth, details current BOICs construction strategies, and highlights their applications in tissue repair. Finally, the current challenges in the development and clinical implementation of BOICs are discussed, with the aim of stimulating innovative ideas and encouraging further developments in tissue regeneration engineering.