A 3D-Printed Assemblable Bespoke Scaffold as a Versatile Microcryogel Carrier for Site-Specific Regenerative Medicine.

Advances in additive manufacturing have led to diverse patient-specific implant designs utilizing computed tomography, but this requires intensive work and financial implications. Here, Digital Light Processing is used to fabricate a hive-structured assemblable bespoke scaffold (HIVE). HIVE can be manually assembled in any shape/size with ease, so a surgeon can create a scaffold that will best fit a defect before implantation. Simultaneously, it can have site-specific treatments by working as a carrier filled with microcryogels (MC) incorporating different biological factors in different pockets of HIVE. After characterization, possible site-specific applications are investigated by utilizing HIVE as a versatile carrier with incorporated treatments such as growth factors (GF), bioceramic, or cells. HIVE as a GF-carrier shows a controlled release of bone morphogenetic protein/vascular endothelial growth factor (BMP/VEGF) and induced osteogenesis/angiogenesis from human mesenchymal stem cells (hMSC)/human umbilical vein endothelial cells (HUVECs). Furthermore, as a bioceramic-carrier, HIVE demonstrates enhanced mineralization and osteogenesis, and as a HUVEC carrier, it upregulates both osteogenic and angiogenic gene expression of hMSCs. HIVE with different combinations of MCs yields a distinct local effect and successful cell migration is confirmed within assembled HIVEs. Finally, an in vivo rat subcutaneous implantation demonstrates site-specific osteogenesis and angiogenesis.

Three-dimensional printing of photonic colloidal glasses into objects with isotropic structural color.

Structural color is frequently exploited by living organisms for biological functions and has also been translated into synthetic materials as a more durable and less hazardous alternative to conventional pigments. Additive manufacturing approaches were recently exploited for the fabrication of exquisite photonic objects, but the angle-dependence observed limits a broader application of structural color in synthetic systems. Here, we propose a manufacturing platform for the 3D printing of complex-shaped objects that display isotropic structural color generated from photonic colloidal glasses. Structurally colored objects are printed from aqueous colloidal inks containing monodisperse silica particles, carbon black, and a gel-forming copolymer. Rheology and Small-Angle-X-Ray-Scattering measurements are performed to identify the processing conditions leading to printed objects with tunable structural colors. Multimaterial printing is eventually used to create complex-shaped objects with multiple structural colors using silica and carbon as abundant and sustainable building blocks.

Digital Light 3D Printed Bioresorbable and NIR-Responsive Devices with Photothermal and Shape-Memory Functions.

Digital light processing (DLP) 3D printing is a promising technique for the rapid manufacturing of customized medical devices with high precision. To be successfully translated to a clinical setting, challenges in the development of suitable photopolymerizable materials have yet to be overcome. Besides biocompatibility, it is often desirable for the printed devices to be biodegradable, elastic, and with a therapeutic function. Here, a multifunctional DLP printed material system based on the composite of gold nanorods and polyester copolymer is reported. The material demonstrates robust near-infrared (NIR) responsiveness, allowing rapid and stable photothermal effect leading to the time-dependent cell death. NIR light-triggerable shape transformation is demonstrated, resulting in a facilitated insertion and expansion of DLP printed stent ex vivo. The proposed strategy opens a promising avenue for the design of multifunctional therapeutic devices based on nanoparticle-polymer composites.

Light-Based Printing of Leachable Salt Molds for Facile Shaping of Complex Structures.

3D printing is a powerful manufacturing technology for shaping materials into complex structures. While the palette of printable materials continues to expand, the rheological and chemical requisites for printing are not always easy to fulfill. Here, a universal manufacturing platform is reported for shaping materials into intricate geometries without the need for their printability, but instead using light-based printed salt structures as leachable molds. The salt structures are printed using photocurable resins loaded with NaCl particles. The printing, debinding, and sintering steps involved in the process are systematically investigated to identify ink formulations enabling the preparation of crack-free salt templates. The experiments reveal that the formation of a load-bearing network of salt particles is essential to prevent cracking of the mold during the process. By infiltrating the sintered salt molds and leaching the template in water, complex-shaped architectures are created from diverse compositions such as biomedical silicone, chocolate, light metals, degradable elastomers, and fiber composites, thus demonstrating the universal, cost-effective, and sustainable nature of this new manufacturing platform.

Hierarchical porous materials made by stereolithographic printing of photo-curable emulsions.

Porous materials are relevant for a broad range of technologies from catalysis and filtration, to tissue engineering and lightweight structures. Controlling the porosity of these materials over multiple length scales often leads to enticing new functionalities and higher efficiency but has been limited by manufacturing challenges and the poor understanding of the properties of hierarchical structures. Here, we report an experimental platform for the design and manufacturing of hierarchical porous materials via the stereolithographic printing of stable photo-curable Pickering emulsions. In the printing process, the micron-sized droplets of the emulsified resins work as soft templates for the incorporation of microscale porosity within sequentially photo-polymerized layers. The light patterns used to polymerize each layer on the building stage further generate controlled pores with bespoke three-dimensional geometries at the millimetre scale. Using this combined fabrication approach, we create architectured lattices with mechanical properties tuneable over several orders of magnitude and large complex-shaped inorganic objects with unprecedented porous designs.

3D Printed Scaffolds for Monolithic Aerogel Photocatalysts with Complex Geometries.

Monolithic aerogels composed of crystalline nanoparticles enable photocatalysis in three dimensions, but they suffer from low mechanical stability and it is difficult to produce them with complex geometries. Here, an approach to control the geometry of the photocatalysts to optimize their photocatalytic performance by introducing carefully designed 3D printed polymeric scaffolds into the aerogel monoliths is reported. This allows to systematically study and improve fundamental parameters in gas phase photocatalysis, such as the gas flow through and the ultraviolet light penetration into the aerogel and to customize its geometric shape to a continuous gas flow reactor. Using photocatalytic methanol reforming as a model reaction, it is shown that the optimization of these parameters leads to an increase of the hydrogen production rate by a factor of three from 400 to 1200 µmol g-1 h-1 . The rigid scaffolds also enhance the mechanical stability of the aerogels, lowering the number of rejects during synthesis and facilitating handling during operation. The combination of nanoparticle-based aerogels with 3D printed polymeric scaffolds opens up new opportunities to tailor the geometry of the photocatalysts for the photocatalytic reaction and for the reactor to maximize overall performance without necessarily changing the material composition.

Digital light 3D printing of customized bioresorbable airway stents with elastomeric properties.

Central airway obstruction is a life-threatening disorder causing a high physical and psychological burden to patients. Standard-of-care airway stents are silicone tubes, which provide immediate relief but are prone to migration. Thus, they require additional surgeries to be removed, which may cause tissue damage. Customized bioresorbable airway stents produced by 3D printing would be highly needed in the management of this disorder. However, biocompatible and biodegradable materials for 3D printing of elastic medical implants are still lacking. Here, we report dual-polymer photoinks for digital light 3D printing of customized and bioresorbable airway stents. These stents exhibit tunable elastomeric properties with suitable biodegradability. In vivo study in healthy rabbits confirmed biocompatibility and showed that the stents stayed in place for 7 weeks after which they became radiographically invisible. This work opens promising perspectives for the rapid manufacturing of the customized medical devices for which high precision, elasticity, and degradability are sought.

3D Printing of Salt as a Template for Magnesium with Structured Porosity.

Porosity is an essential feature in a wide range of applications that combine light weight with high surface area and tunable density. Porous materials can be easily prepared with a vast variety of chemistries using the salt-leaching technique. However, this templating approach has so far been limited to the fabrication of structures with random porosity and relatively simple macroscopic shapes. Here, a technique is reported that combines the ease of salt leaching with the complex shaping possibilities given by additive manufacturing (AM). By tuning the composition of surfactant and solvent, the salt-based paste is rheologically engineered and printed via direct ink writing into grid-like structures displaying structured pores that span from the sub-millimeter to the macroscopic scale. As a proof of concept, dried and sintered NaCl templates are infiltrated with magnesium (Mg), which is typically highly challenging to process by conventional AM techniques due to its highly oxidative nature and high vapor pressure. Mg scaffolds with well-controlled, ordered porosity are obtained after salt removal. The tunable mechanical properties and the potential to be predictably bioresorbed by the human body make these Mg scaffolds attractive for biomedical implants and demonstrate the great potential of this additive technique.