Printing between the Lines: Intricate Biomaterial Structures Fabricated via Negative Embodied Sacrificial Template 3D (NEST3D) Printing

Extrusion printing techniques are widely used across tissue engineering and related fields for producing 3D structures from biocompatible thermoplastics, however the achievable structural complexity and porosity can be limited by the nozzle-based, layer-by-layer deposition process. Here, how this limitation can be overcome through a new technique termed Negative Embodied Sacrificial Template 3D printing is illustrated. It is demonstrated how the negative pattern within a 3D printed object can easily describe geometries that are extremely challenging to extrusion print directly with biomaterials, and at high resolution. Negative patterns in a water-soluble sacrificial template can be "developed" by casting in a secondary material and dissolving the template, creating exquisitely complex 3D structures including hyper-branched dendritic structures and open lattices with stiffnesses tuneable over 3 orders of magnitude. The technique is amenable to a plethora of materials from biodegradable thermoplastics (such as polycaprolactone) to resins (including acrylic and epoxy), silicones (including the Sylgard 184 polydimethylsiloxane formulation), ceramics (including hydroxyapatite composites), hydrogels (including agarose and gelatin methacryloyl), low-melt temperature metal alloys and others. Using an unmodified, consumer-grade printer, NEST3D printing achieves high resolution, intricate biomaterial structures with potential applications in biomedical implants and tissue engineering scaffolds.