A challenge for tissue engineering is producing three-dimensional (3D), vascularized cellular constructs of clinically relevant size, shape and structural integrity. We present an integrated tissue-organ printer (ITOP) that can fabricate stable, human-scale tissue constructs of any shape. Mechanical stability is achieved by printing cell-laden hydrogels together with biodegradable polymers in integrated patterns and anchored on sacrificial hydrogels. The correct shape of the tissue construct is achieved by representing clinical imaging data as a computer model of the anatomical defect and translating the model into a program that controls the motions of the printer nozzles, which dispense cells to discrete locations. The incorporation of microchannels into the tissue constructs facilitates diffusion of nutrients to printed cells, thereby overcoming the diffusion limit of 100-200 μm for cell survival in engineered tissues. We demonstrate capabilities of the ITOP by fabricating mandible and calvarial bone, cartilage and skeletal muscle. Future development of the ITOP is being directed to the production of tissues for human applications and to the building of more complex tissues and solid organs.

Solid-state flexible energy storage devices hold the key to realizing portable and flexible electronic devices. Achieving fully flexible energy storage devices requires that all of the essential components (i.e., electrodes, separator, and electrolyte) with specific electrochemical and interfacial properties are integrated into a single solid-state and mechanically flexible unit. In this study, we describe the fabrication of solid-state flexible asymmetric supercapacitors based on an ionic liquid functionalized-chemically modified graphene (IL-CMG) film (as the negative electrode) and a hydrous RuO(2)-IL-CMG composite film (as the positive electrode), separated with polyvinyl alcohol-H(2)SO(4) electrolyte. The highly ordered macroscopic layer structures of these films arising through direct flow self-assembly make them simultaneously excellent electrical conductors and mechanical supports, allowing them to serve as flexible electrodes and current collectors in supercapacitor devices. Our asymmetric supercapacitors have been optimized with a maximum cell voltage up to 1.8 V and deliver a high energy density (19.7 W h kg(-1)) and power density (6.8 kW g(-1)), higher than those of symmetric supercapacitors based on IL-CMG films. They can operate even under an extremely high rate of 10 A g(-1) with 79.4% retention of specific capacitance. Their superior flexibility and cycling stability are evident in their good performance stability over 2000 cycles under harsh mechanical conditions including twisted and bent states. These solid-state flexible asymmetric supercapacitors with their simple cell configuration could offer new design and fabrication opportunities for flexible energy storage devices that can combine high energy and power densities, high rate capability, and long-term cycling stability.

Numerous approaches have been introduced to regenerate artificial dental tissues. However, conventional approaches are limited when producing a construct with three-dimensional patient-specific shapes and compositions of heterogeneous dental tissue. In this research, bioprinting technology was applied to produce a three-dimensional dentin–pulp complex with patient-specific shapes by inducing localized differentiation of human dental pulp stem cells within a single structure. A fibrin-based bio-ink was designed for bioprinting with the human dental pulp stem cells. The effects of fibrinogen concentration within the bio-ink were investigated in terms of printability, human dental pulp stem cell compatibility, and differentiation. The results show that micro-patterns with human dental pulp stem cells could be achieved with more than 88% viability. Its odontogenic differentiation was also regulated according to the fibrinogen concentration. Based on these results, a dentin–pulp complex having patient-specific shape was produced by co-printing the human dental pulp stem cell–laden bio-inks with polycaprolactone, which is a bio-thermoplastic used for producing the overall shape. After culturing with differentiation medium for 15 days, localized differentiation of human dental pulp stem cells in the outer region of the three-dimensional cellular construct was successfully achieved with localized mineralization. This result demonstrates the possibility to produce patient-specific composite tissues for tooth tissue engineering using three-dimensional bioprinting technology.

Recently, decellularized extracellular matrix-based bio-ink (dECM bio-ink) derived from animal organs is attracting attention because of its excellent biocompatibility. However, its poor 3D printability and weak mechanical properties remain a challenge. Here, we developed a new dECM bio-ink with enhanced 3D printability and mechanical properties. dECM micro-particles of about 13.4 μm in size were prepared by decellularizing a porcine liver followed by freeze-milling. The new bio-ink, named as dECM powder-based bio-ink (dECM pBio-ink), was prepared by loading the dECM micro-particles into a gelatin mixture. The usefulness of the dECM pBio-ink was evaluated by assessing its mechanical properties, printability, and cytocompatibility. The results showed that its mechanical properties and 3D printability were greatly improved. Its elastic modulus increased by up to 9.17 times that of the conventional dECM bio-ink. Micro-patterns with living cells were successfully achieved with 93% cell viability. Above all, the new bio-ink showed superior performance in stacking of layers for 3D printing, whereas the conventional bio-ink could not maintain its shape. Finally, we demonstrated that the dECM pBio-ink possessed comparable cytocompatibility with the conventional dECM bio-ink through in vitro tests with endothelial cells and primary mouse hepatocytes.