In Situ Construction of Morphologically Different Hydroxyapatite-Mineralized Structures on a Three-Dimensional Bionic Chitin Scaffold

Slow healing at the tendon–bone interface is a prominent factor in the failure of tendon repair surgeries. The development of functional biomaterials with 3D gradient structures is urgently needed to improve tendon–bone integration. The crystalline form of hydroxyapatite (HAP) has a crucial impact on cell behavior, which directly influences protein adsorption, such as bone morphogenetic protein 2, the adhesion, proliferation, and osteogenic differentiation with cells. This work aimed to generate gradient mineral structures in situ by stabilizing calcium and phosphate ions using a polymer-induced liquid precursor process. To regulate the crystalline growth of HAP at the interface of β-chitin, this work made use of the surface properties of the organic matrix found in cuttlefish bone. These techniques allowed us to prepare an organic–inorganic composite gradient scaffold comprising plate-like HAP mineralized in situ on the surface of the scaffold and fibrous HAP in the scaffold’s interior. Organic–inorganic composite gradient materials are anticipated for use in tendon–bone healing produced via the in situ construction of gradient-distributed HAP mineralization layers having varying crystalline morphologies on chitin scaffolds that possess a three-dimensional bionic structure.