3D Construction of Biologically Derived Materials

Current scaffold designs and materials do not provide all of the appropriate cues necessary to mimic in-vivo conditions for tissue engineering and stem cell engineering applications. It has been hypothesized that many biomaterials, such as bone, muscle, brain and heart tissue exhibit piezoelectric and ferroelectric properties. Typical cell seeding environments incorporate biochemical cues and more recently mechanical stimuli, however, electrical cues have just recently been incorporated in standard in-vitro examinations. In order to develop their potential further, novel scaffolds are required to provide adequate cues in the in-vitro environment to direct stem cells to differentiate down controlled pathways or develop novel tissue constructs. This invention is for a scaffold that provides for such cues by mimicking the native biological environment, including biochemical, topographical, mechanical and electrical cues.

Fabrication of the biocapsule is accomplished by the use of a perforated mold, which allows CNTs in suspension or solution to be deposited by vacuum filtration. Other methods of creating a pressure differential between the outside of the mold and the inside of the mold can be used to drive the CNT deposition process. The mesh builds up gradually, over the course of minutes, so the thickness of the mesh can be controlled by the time of deposition. The fabrication procedure results in a mesh that is held together entirely by entanglement and non-covalent interaction between the CNTs. Filtration of CNTs onto the surface of a mold as the method of biocapsule fabrication is superior to other methods of fabrication that require assembly from multiple pieces of buckypaper, since these methods require seams in order to create a closed container. Seams result in weakness of the biocapsule and can result in leakage of the transplanted cells outside the container, which defeats the immune-shielding function of the biocapsule. The perforated mold/filtration method makes biocapsule manufacture more efficient, and makes possible a wider range of shapes of the biocapsule, to facilitate transplantation into a wider range of sites in the body. The perforated mold/filtration method also allows small beads to be incorporated into the wall of the biocapsule. Small beads, functionalized with bioactive materials, may be used to maintain the health or enhance the function of the cells inside the biocapsule, or may be used to enhance biocompatibility. The pores of the biocapsule permit gas exchange (oxygen, carbon dioxide), as well as free diffusion of metabolites, proteins and other cell products, which keep the cells healthy, and may provide useful therapeutics. Tissue or tissue fragments, and micro or nanoscale medical devices can also be placed inside the biocapsule to facilitate their implantation into the body.

NASA's new technique for generating recyclable feedstocks for on-demand additive manufacturing employs the high-yield reversibility of the Diels-Alder reaction between maleimide and furan functionalities, utilizing the exceedingly favorable interaction between specific chemical functionalities, often termed "click reactions" due to their rapid rate and high efficiency. Integration of these moieties within a polymer coating on epoxy microparticle enables reversible assembly into macroscopic, free-standing articles. This click chemistry can be activated and reversed through the application of heat. Monomer species can be used to incorporate these functionalities into polyimide materials, which provide excellent mechanical, thermal, and electrical properties for space applications. Copoly (carbonate urethane) has been shown to be a viable coating material in the generation of polymer-coated epoxy microparticle systems and is amenable to being processed through a variety of approaches (e.g., filaments and slurries for 3D printing, compression molding, etc.). The polymeric materials are grown from the surfaces of in-house fabricated epoxy microparticles. The thermal and mechanical properties of the microparticles can be readily tuned by changes in composition. There are a number of potential applications for this NASA technology ranging from use of these materials for recyclable/repurpose-able articles (structural, decorative, etc.) to simple children's toys. More demanding uses such as for replacement parts in complex industrial systems are also possible. For long term space missions, it is envisioned that these feedstocks would be integrated into secondary spacecraft structures such that no additional concerns would be introduced due to in-space chemical reactions and no additional mass would be required.

The technology is a method to increase automation of Additive Manufacturing (AM) through augmentation of the Fused Filament Fabrication (FFF) process. It can significantly increase the speed of 3D printing by automating the removal of printed components from the build platform without the need for additional hardware, which increases printing throughput. The method can also be leveraged to perform automated object testing and characterization. The method includes embedding into the manufacturing instructions methods to fabricate directly onto the build platform an actuator tool, such as a linear spring. The deposition head can be leveraged as a robotic manipulator of the actuator tool to bend, cock, and release the linear spring to strike the target manufactured object and move it off the build platform of the machine they were manufactured on. The ability for an object to 'fly off of the machine that made it' essentially enables automated clearing of the processed build volume. The technology can also be used for testing the AM machine or the feedstock material by successively fabricating prototypes of the manufactured object, and taking measurements from sensors as the actuator strikes the prototype. This provides automated testing for quality control, machine calibration, material origins, and counterfeit detection.

The technology uses additive print manufacturing to produce hierarchical and integrated structural and functional elements into large-area thin-film structures. Adding these structural and functional elements has the potential to enable very lightweight, large-scale thin-films with improved damage tolerance, self-deployment capability, flexibility, and multifunctional (optical, thermal, electrical) connectivity and interrogation capabilities. Based on simple and proven additive manufacturing concepts, advanced geometrical, biomimetic (insect wing), and hierarchical structures could be applied to, or eventually with further development integrated within the bulk of large-area thin films using roll-to-roll processing techniques for a potentially low-cost manufacturing approach. The subject technology potentially addresses many of the disadvantages of current large-scale membrane material systems, which are prone to damage or require extensive deployment and support structures.