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Comprehensive mechanical properties (high strength, good fatigue resistance and tunable stiffness) are significant for large and load-bearing implants, but still remain a challenge in practical applications. Polyetheretherketone (PEEK)-Ti6Al4V interpenetrating phase composites (IPCs) with comprehensive mechanical properties were developed using a two-step process: fabricating Ti6Al4V microlattices using powder bed fusion (PBF) and subsequently manufacturing PEEK-Ti6Al4V IPCs using vacuum infiltration. The strut defects in the Ti6Al4V microlattices induced by PBF process were filled with PEEK, and thus excellent interfacial connection was achieved. Mechanical tests, under both quasi-static loading conditions (compression and three-point bending conditions) and dynamic loading condition (three-point bending condition), were carried out on the PEEK-Ti6Al4V composites with low and high modulus (20.0 and 60.0 vol% Ti6Al4V) and the bare Ti6Al4V microlattices of equivalent elastic moduli. It was found that the composites had higher compressive and flexural strengths than the lattices. Moreover, the composites exhibited higher fatigue strength and longer fatigue life than the lattices. The fracture behaviors and the FEM simulation results revealed that the enhancing mechanisms for the PEEK-Ti6Al4V composites can be the alleviation of strut deformation and the resistance to crack propagation. Thus, the PEEK-Ti6Al4V composites can be promising materials for large and load-bearing implants.

The structural organization of natural liver is instrumental in the multifunctionality of hepatocytes, and mimicking these specific architectures in tissue-engineered scaffold plays an important role in the engineering of an implantable liver equivalent in vitro. To achieve this goal, we have developed a novel fabrication process to create chitosan-gelatin hybrid scaffolds with well-organized architectures and highly porous structures by combining rapid prototyping, microreplication and freeze-drying techniques. The scaffolds obtained not only have analogous configurations of portal vein, central vein, flow-channel network and hepatic chambers, but also have high (>90%) porosity, with the mean pore size of 100microm. Swelling and degradation studies showed that the scaffold has excellent properties of hydrophilicity and biodegradability. A hepatocyte culture experiment was conducted to evaluate the efficiency of the well-defined chitosan-gelatin scaffold in facilitating hepatocyte growth in the inner layer of the scaffold in vitro. Scanning electron microscopy and histological analysis showed that hepatocytes could form large colonies in the predefined hepatic chambers, and these cavities could the completely filled with hepatocytes during 7 day culture. Albumin secretion and urea synthesis further indicated that the well-organized scaffolds were more suitable for hepatocyte culture.