Triple-Bioinspired Burying/Crosslinking Interfacial Coassembly Strategy for Layer-by-Layer Construction of Robust Functional Bioceramic Self-Coatings for Osteointegration Applications

Coating bioceramics of inherent bioactivity onto biometallic implants is a straightforward yet promising solution to address poor osteointegration of the latter. One step further, it would be a nontrivial accomplishment to develop a mild, cheap, and universal route to firmly stabilizing, in principle, any ceramics onto any implant substrate, while imparting expectedly versatile biofunctional performances. Herein, we describe a triple-bioinspired burying/cross-linking interfacial coassembly strategy for enabling such ceramic coatings, which ingeniously fuses bioinspiration from sea rocks (burying assisted particle immobilization), marine mussels (universal adhesion and versatile chemical reactivity), and reef-building oysters (cross-linking rendered cohesion). Specifically, surface functionalized, aqueous dispersed ceramic particles were buried within an substrate-anchored organic matrix of polyelectrolyte multilayers (i.e., (poly(ether imide) (PEI)/poly(sodium-p-styrenesulfonate) (PSS))n), through a new inorganic–organic hybrid layer-by-layer (LBL) coassembly scheme wherein mussel (oyster) inspired adhesive (cohesive) chemistries were exquisitely orchestrated. As a conceptual demonstration, bioactive baghdadite (Ca3ZrSi2O9) was synthesized as model ceramics, with which we constructed on medical titanium robust, biomimetic, and cross-linkable LBL self-assemblies harnessing the said strategy. Intimate substrate contacts and well-defined buried inorganic–organic interfaces were evidently seen, together with good structural and chemical stabilities, especially after cross-linking. Sustained bioactive ion releasing and appreciable biomineralization activity were confirmed in vitro. Subsequently, biological performances of the assemblies were systematically investigated with respect to surface hydrophilicity, protein adsorption, and osteoblast functions. Additionally, nanosilver deposition, which imparted the surfaces with added antibacterial potencies, was used to exemplify the strategy’s versatility in allowing multifunctionality. What’s more, the flexibility of our approach was testified through modifying clinically relevant complicated 3D porous scaffolds. Overall, our strategy basically met the design expectations, boding well for future medical adoption. This study offers the promise of an alternative broadly useful avenue to bioactive and functional surface design of bone implants. It may also provide insights into other multiple-bioinspired materials/interfaces for biological and other applications.