WEB Printing life - Bio-selective Hydrogels and novel composite inks for biofabrication
Inspired by three decades of substantial research in the field of material-cell interaction combined with the availability of novel 3D-printing techniques, biofabrication displays a highly promising strategy to generate spatially organized cell-loaded biologically functional matrices. Previous limitations of mimicking native tissues by cell seeding on readily structured constructs should be overcome applying bioprinting/bioassembly to precisely place cells, factors and materials in a 3D structure and program the subsequent maturation process towards functional tissue. Simultaneously bringing materials, cells and processing into symbiosis is a challenging task, that requires consideration of multiple aspects, starting with bioink design, processing behavior and final construct properties.
Here, we applied a biotechnological production strategy to design spider silk-based materials to be used as bioinks. Strikingly, besides excellent cytocompatibility, we demonstrated a secondary effect, that is subjected to be a highly useful artefact from the natural blueprint of our materials – spider silk in nature displays bacterial and fungal repellent properties. These properties could be reproduced in the artificial system and we were able to unravel the structure-property-relationship on the mesoscale, which is responsible for these outstanding properties. Furthermore, targeted modification of recombinant spider silk proteins enabled us to generate bio-selective properties allowing mammalian cells to adhere and proliferate on 2D such as within 3D structures, while simultaneously effectively inhibiting bacterial and fungal adhesion without the need of any antimicrobial agents. Besides these biofunctional features, another important aspect to be considered is the suitability of such bioinks for 3D-printing. Usually, high gel concentrations are required to achieve good resolution and shape fidelity of the printed constructs. Unfortunately, increasing concentrations result in higher shear forces upon bioprinting, which might be on the expense of cell viability. To bypass this problem, we established a platform technology to produce fiber fragments which can be applied to adapt rheological properties and reinforce hydrogels, thereby mechanically supporting cells and providing biomimetic fibrous structures. Being applicable for various existing bioinks, this strategy might play a key role to overcome limitations in the printability of biologically attractive hydrogels.