© Fraunhofer IGB
Novel additive manufacturing processes are currently being worked on in a variety of research fields. Among the established printing techniques, inkjet printing offers a highly attractive technique for creating two-dimensional or three-dimensional structures that are previously designed on a computer.
Our work focuses on the development of suitable ink formulations to process diverse functional components such as hydrogels, nano- and microparticles, proteins and cells.
Biological materials for 3D printing
For 2D/3D printing, Fraunhofer IGB develops e.g. initiator-free crosslinking biocompatible hydrogels and equips biopolymers with crosslinkable groups or functionalities by chemical modification. This allows the solubility properties and viscosity to be controlled and an adaptation to the different requirements of additive processes such as inkjet printing or pneumatic dispensing to be made possible.
We want to enable biopolymers such as gelatin, hyaluronic acid and chondroitin sulfate to modify surfaces and build three-dimensional tissue models. To control the physicochemical properties of biomolecules and hydrogels, we couple chemical functions such as crosslinkable methacrylic groups, thiol groups and benzophenones to the biopolymers and mask functional groups responsible for gelling of the materials.
In cooperation with the IGVP at the University of Stuttgart, we are also developing printable and crosslinkable cell-compatible polyethylene glycols.
If the inks contain biological materials such as biomolecules, cells, tissue preparations or biocompatible materials, the printed structures can perform a biological function. The biomaterial in its non-crosslinked, printable form is referred to as a bioink. The composition of these inks depends on the subsequent application. Thus, bioinks can be formulated with and without cells.
Bioinks for tissue engineering applications are optimized for the printing process and at the same time for the promotion of tissue-specific functions through targeted variation of the composition. We have already successfully produced "bone inks" and "vascularization inks" based on the available material construction kit. Both bioinks are dispersions of biomolecules and tissue-specific cells that can be stably formed into a 3D structure via dispensing processes.
Protein-containing bioinks should be processable while maintaining the native functionality of the proteins. We achieve this by using water-soluble and protein-compatible components. These inks can be used, for example, to make specific areas on a substrate attractive for adhesion of different cell types.
Nanoparticles have the potential to transport a variety of functions: Both the properties of the particle shell, such as being equipped with certain chemical groups and the loading of the particle core with dyes or active components, which are released after printing, for example in contact with water, can contribute to the systematic design of material properties. We are developing inkjet-compatible formulations at the Fraunhofer IGB, for the targeted and structured application of suspensions of functional nanoparticles. For example, we have developed a water-based ink for coating surfaces with charged nanoparticles. These inks could find their application in the production of sensitive rapid tests based on nucleic acid microarrays.
Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB