Despite substantial attention given to the development of osteoregenerative biomaterials, severe deficiencies remain in current products. These limitations include an inability to adequately, rapidly, and reproducibly regenerate new bone; high costs and limited manufacturing capacity; and lack of surgical ease of handling. To address these shortcomings, we generated a new, synthetic osteoregenerative biomaterial, hyperelastic "bone" (HB). HB, which is composed of 90 weight % (wt %) hydroxyapatite and 10 wt % polycaprolactone or poly(lactic-co-glycolic acid), could be rapidly three-dimensionally (3D) printed (up to 275 cm(3)/hour) from room temperature extruded liquid inks. The resulting 3D-printed HB exhibited elastic mechanical properties (~32 to 67% strain to failure, ~4 to 11 MPa elastic modulus), was highly absorbent (50% material porosity), supported cell viability and proliferation, and induced osteogenic differentiation of bone marrow-derived human mesenchymal stem cells cultured in vitro over 4 weeks without any osteo-inducing factors in the medium. We evaluated HB in vivo in a mouse subcutaneous implant model for material biocompatibility (7 and 35 days), in a rat posterolateral spinal fusion model for new bone formation (8 weeks), and in a large, non-human primate calvarial defect case study (4 weeks). HB did not elicit a negative immune response, became vascularized, quickly integrated with surrounding tissues, and rapidly ossified and supported new bone growth without the need for added biological factors.

A bioinspired boron nitride nanosheet (BNNS)/gelatin nanocomposite consisting of hierarchically aligned layered BNNSs bonded with gelatin is fabricated by using electrostatic interactions between the oppositely charged functional groups on gelatin and the BNNSs. To enhance the self‐assembly and interfacial bond strength between these entities, the BNNSs are functionalized using hyperbranched polyglycerol. The 2D alignment of the BNNSs can be controlled by increasing the amount of BNNSs, or by a functionalization process, both of which result in transformation of the nanoscale structure from a randomly oriented to a brick‐and‐mortar structure. The mechanical properties of the resulting nanocomposite material, including the strength and modulus, are controlled by changing the composition of BNNSs and gelatin in the nanocomposite and by modifying the degree of alignment of the BNNSs in the material. This tuning of the mechanical properties yields a material whose performance resembles that of human cortical bone. In vitro cell viability experiments on the BNNSs/gelatin nanocomposite reveal that this artificial nacre supports adhesion, viability, and proliferation of adipose‐derived stem cells, all of which are essential for biomedical applications. Mechanical and biological testing of the material suggests applications of artificial nacre in biomedical fields and for tissue regeneration.

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Graphene nanoplatelets (GNPs), the most important mass‐produced graphene, are fabricated as a mechanical reinforcement for epoxy matrix nanocomposites. Current performance of GNPs as a reinforcing filler is limited by their agglomeration and weak interfacial interaction with certain polymer matrices. Herein, an approach to produce noncovalently functionalized GNPs (F‐GNPs) is reported that can be extended to the industrial level of mass production. The one‐step functionalization process uses melamine, a low‐cost chemical, to improve the interfacial adhesion and dispersion in an epoxy matrix. The mechanical properties of nanocomposites prepared with the F‐GNP flakes are much better (94.3% and 35.3% enhancements in Young's modulus and tensile strength, respectively) than those of the unfilled pure epoxy. Experimental data are analyzed using the Halpin–Tsai model. The fabrication process developed in this paper provides a strategy to use GNPs at the industrial level in lightweight and high‐strength structural applications.

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