Biofabrication

Biofabrication is the “the automated generation of biologically functional products with structural organization from living cells, bioactive molecules, biomaterials, cell aggregates such as micro-tissues, or hybrid cell-material constructs, through bioprinting or bioassembly and subsequent tissue maturation processes.” (Groll et al. 2016) The FMZ is mainly focusing on bioprinting approaches. These are e.g. processing of cell-instructive scaffolds from biomaterial inks or the fabrication of cell-containing constructs made from bioinks. The Biofabrication platform is thus divided in melt electrowriting (MEW), a novel fabrication approach to make fine structured scaffolds, and in Bioprinting where also hydrogel based Bioinks are developed in-house.

Melt Electrowriting

Melt electrowriting is a 3D printing technology that electrostatically sustains a molten fluid jet  over a translating collector stage. MEW allows the 3D printing of new biomaterials with nano- and microscale structures for a variety of applications, including biomedical. The MEW printers are custom-built research level devices. They can fabricate fine structured scaffolds using a broad range of polymers.

MEW is particularly pertinent to biomedical engineers as materials for clinical, research and in vitro applications. It produces fine and flexible lattices that are cell invasive and unique, and incredibly variable. For further information on this technology, feel free to read the increasing literature listed below.

Contact:
Prof Dr. Paul Dalton
Telephone +49(0)931 201-74081
paul.dalton@fmz.uni-wuerzburg.de

Group Leader

Paul Dalton is a Professor at the University of Würzburg, Germany with over 20 years’ of interdisciplinary experience in biomedical materials, including polymer processing,  nanotechnology and hydrogels. He pioneered melt electrowriting (MEW) and is interested in how materials can advance neuroscience. MEW is now recognized as a distinct class of additive manufacturing for the manufacture of biomedical materials. Paul has published over 100 research articles in journals including Advanced Materials, Progress in Polymer Science and Nature Materials.

Figure 1: The diameter of MEW fibers is substantially smaller than conventional extruders. This SEM image shows MEW fibers direct-written in 5µm increments, from 5µm to 30µm. Reproduced from Hrynevich et al.

Figure 2: A “spheroid-catching” MEW scaffold with a gradient of fiber diameters, made with a single nozzle in a single print. Shown upside down, white fibers indicate the embossing of the first, fiber that lands on the collector. This 40µm diameter fiber is indicated in blue, while the 4µm diameter fiber is in red. Two catching fibers are visible. Reproduced from Hrynevich et al. (Supplementary Information).

Bioink Synthesis and Development

A bioink is defined as “a formulation of cells suitable for processing by an automated biofabrication technology that may also contain biologically active components and biomaterials” (Groll et al. 2019). The automated fabrication technology the FMZ is mainly utilizing is extrusion-based bioprinting. Bioink development at the FMZ (approach see figure 3) is focused on the combination of cells and biomaterials, more specifically the synthesis of hydrogel-based inks made from fully synthetic as well as modified natural polymers. According to the chosen polymers the applied synthetic techniques include cationic and anionic polymerizations of glycidols and polyoxazolines and subsequent polymer analogue sidechain modifications. For the natural polymers, different polysaccharides and proteins are used as starting materials to introduce further cross-linkable side functions. All synthesized and modified polymers are chemically characterized using the in-house available techniques (e.g. NMR, GPC, FT-IR, Raman, MALDI-TOF) to determine molecular weights, degree of modification and degradation or the branching geometry of synthesized materials.

After their synthesis the materials are investigated for their suitability as bioink components for the different below described techniques. This means that the hydrogel forming materials are crosslinked via radical polymerization, thiol-ene chemistry or reversible imine formation and then studied for their mechanical stability as well as swelling and degradation properties. Techniques applied for this are dynamic mechanical analysis, gravimetric evaluation as well as oscillation rheology.

Overall strategies for our bioink development are the investigation of new materials for bioinks, the optimization of existing materials using macromolecular chemistry and the development of materials for new printing approaches, as described below.

Contact:
Prof Dr. Jürgen Groll
Telephone +49(0)931 201-73510
juergen.groll@fmz.uni-wuerzburg.de

Dr. habil Jörg Tessmar
Telephone +49(0)931 201-73720
joerg.tessmar@fmz.uni-wuerzburg.de

Figure 3: Overview of bioink development at FMZ

Bioprinting

In bioprinting additive manufacturing is used to make bioengineered structures from living and non-living materials. The three most frequently applied techniques are inkjet printing, laser induced forward transfer and extrusion-based bioprinting. The main focus of the department is on extrusion-based bioprinting where biomaterials inks or hydrogel-based bioinks are processed. In most of our printers, the material is loaded into a cartridge and dispensed through a fine needle tip using pressurized air. The printer can be programmed to coordinate cartridge movement and dispensing in a way that 3D constructs can be fabricated in a layer-by-layer fashion. At the FMZ we have a variety of commercially available bioprinters that are used to access the printability of bioinks and biomaterial inks and to develop tissue models.

Besides using commercially available systems we also modify printers and develop new bioprinting techniques. One example is the convergence of microfluidics and bioprinting for the design of new printing approaches.

A big challenge in bioprinting is the online evaluation of the process. We addressed it in a collaboration with the University of Lübeck that is sponsored by the BMBF. Besides the print fidelity also information about the chemical structure and the status of the cells are analyzed via optical coherence tomography and RAMAN spectroscopy. Ideally, we are aiming to achieve information about e.g. cell viability using non-invasive techniques like optical coherence microscopy.

Contact:
Dr. Tomasz Jüngst
Telephone +49(0)931 201-73590
tomasz.juengst@fmz.uni-wuerzburg.de

Figure 4: Extrusion-based bioprinting of hydrogel-based inks

Prof Dr. Jürgen Groll
Telephone +49(0)931 201-73510
juergen.groll@fmz.uni-wuerzburg.de

Prof Dr. Paul Dalton
Telephone +49(0)931 201-74081
paul.dalton@fmz.uni-wuerzburg.de

Dr. habil Jörg Tessmar
Telephone +49(0)931 201-73720
joerg.tessmar@fmz.uni-wuerzburg.de

Dr. Tomasz Jüngst
Telephone +49(0)931 201-73590
tomasz.juengst@fmz.uni-wuerzburg.de

M. Sc. Ezgi Bakirci
Designing melt electrowritten structures for neural applications
+49(0)931 201-73462
ezgi.bakirci@fmz.uni-wuerzburg.de

M. Sc. Christoph Böhm
Thermal degradation during melt electrowriting
+49(0)931 201-73462
christoph.c.boehm@fmz.uni-wuerzburg.de

M. Sc. Leonard Forster
Hyaluronic acid hydrogels for bioprinting
+49(0)931 201-73530
leonard.forster@fmz.uni-wuerzburg.de

M. Sc. Johannes Herbig
Development of a micro particle sensor system to establish correlations between mechanical stress and cell functionality during biofabrication
+49(0)931 31 – 80696
johannes.herbig@fmz.uni-wuerzburg.de

Dipl.-Ing. Andrei Hrynevich
Melt electrowriting design concepts
+49(0)931 201-73462
Andrei.hrynevich@fmz.uni-wuerzburg.de

M. Sc. Juliane Kade
Melt electrowriting of electroactive polymers
+49(0)931 201-73462
juliane.kade@stud-mail.uni-wuerzburg.de

M. Sc. Ali Nadernezhad
Pre-endothelialized perfusable microvascular networks for biofabrication of standardized in vitro tissue models.
+49(0)931 201-73552
ali.nadernezhad@fmz.uni-wuerzburg.de

M. Sc. Daniel Nahm
Melt electrowriting of hydrogel fibers
+49(0)931 201-73462
daniel.nahm@uni-wuerzburg.de

M. Sc. Ilona Paulus
Multifunctional POx-based building blocks for bioinks
+49(0)931 201-73462
ilona.paulus@fmz.uni-wuerzburg.de

M. Sc. Junwen Shan
Biopolymer based hydrogels for bioprinting
+49(0)931 201-73462
junwen.shan@fmz.uni-wuerzburg.de

M. Sc. Ruben Gerrit Scheuring
3D printing of vascular structures from vascular wall-resident stem cells
+49(0)931 201-73552
ruben.scheuring@fmz.uni-wuerzburg.de

MB BCh, M. Sc. Almoatazbellah Youssef
Melt electrowriting of medical implants
+49(0)931 201-73462
moataz.youssef@fmz.uni-wuerzburg.de

Full list of colleagues

J. Groll, J.A. Burdick, D.W. Cho, B. Derby, M. Gelinsky, S.C. Heilshorn, T. Jüngst, J. Malda, V.A. Mironov, K. Nakayama, A. Ovsianikov, W. Sun, S. Takeuchi, J.J. Yoo, T.B.F. Woodfield. A definition of bioinks and their distinction from biomaterial inks. Biofabrication. 2018 Nov 23;11 (1), 013001

M. Weis, J. Shan, M. Kuhlmann, T. Jungst, J. Tessmar, J. Groll. Evaluation of Hydrogels Based on Oxidized Hyaluronic Acid for Bioprinting, Gels. 2018 Oct 9;4(4).

A. Hrynevich, B. Şen Elçi, J.N. Haigh, R. McMaster, A. Youssef, C. Blum, T. Blunk, G. Hochleitner, J. Groll, P.D. Dalton. Dimension-based design of melt electrowritten scaffolds. Small, 2018. 14, 1800232.

E. McColl, J. Groll, T. Jungst, P.D. Dalton. Design and fabrication of melt electrowritten tubes using intuitive software. Materials and Design, 2018. 155, 46-58.

E. Petcu, R. Midha, E. McColl, A. Popa-Wagner, T.V. Chirila, P.D. Dalton. 3D printing strategies for peripheral nerve regeneration. Biofabrication, 2018. 10(3):03200.

M. de Ruijter, A. Hrynevich, J.N. Haigh, G. Hochleitner, M. Castilho, J. Groll, J. Malda, P.D. Dalton. Out-of-plane 3D-Printed Microfibers Improve the Shear Properties of Hydrogel Composites. Small, 2018. 14, 1702773.

P.D. Dalton. Melt Electrowriting with Additive Manufacturing Principles. Curr Opin Biomed Eng, 2017. 2, 49–57.

A. Youssef, S. Hollister, P.D. Dalton. Additive manufacturing of polymer melts for implantable devices and scaffolds. Biofabrication, 2017, 9, 012002.

N. Paxton, W. Smolan, T. Böck, F. Melchels, J. Groll, T. Jungst. Proposal to assess printability of bioinks for extrusion-based bioprinting and evaluation of rheological properties governing bioprintability, Biofabrication. 2017 Nov 14;9(4):044107

S. Bertlein, G. Brown, K.S. Lim, T. Jungst, T. Boeck, T. Blunk, J. Tessmar, G.J. Hooper, T.B.F. Woodfield, J. Groll. Thiol–ene clickable gelatin: a platform bioink for multiple 3D biofabrication technologies, Advanced Materials 2017 Nov;29(44).29

S. Stichler, T. Jungst, M. Schamel, I. Zilkowski, M. Kuhlmann, T. Böck, T. Blunk, J. Tessmar, J. Groll. Thiol-ene clickable poly (glycidol) hydrogels for biofabrication, Annals of biomedical engineering 2017 Jan;45(1):273-285

F. Chen, G. Hochleitner, T. Woodfield, J. Groll, P.D. Dalton, B.G. Amsden. Additive Manufacturing of a Photo-Cross-Linkable Polymer via Direct Melt Electrospinning Writing for Producing High Strength Structures. Biomacromolecules 2016, Jan 11;17(1):208-14.

G. Hochleitner, T. Jüngst, T.D. Brown, K. Hahn, C. Moseke, F. Jakob, P.D. Dalton, J. Groll. Additive manufacturing of scaffolds with sub-micron filaments via melt electrospinning writing. Biofabrication 2015; 7, Jun 12;7(3):035002

T.D. Brown, P.D. Dalton, D.W. Hutmacher. Melt Electrospinning Today: An Opportune Time for an Emerging Polymer Process. Progress in Polymer Science 2016; 56, May:116-166

G. Hochleitner, A. Youssef, A. Hrynevich, J.N. Haigh, T. Jüngst, J. Groll, P.D. Dalton. Fibre pulsing during melt electrospinning writing. BioNanoMaterials 2016 17(3-4), pp. 159-171.

F. Chen, G. Hochleitner, T. Woodfield, J. Groll, P.D. Dalton, B.G. Amsden. Additive Manufacturing of a Photo-Cross-Linkable Polymer via Direct Melt Electrospinning Writing for Producing High Strength Structures. Biomacromolecules 2016, 17 (1), pp 208–214

G. Hochleitner, T. Jüngst, T.D. Brown, K. Hahn, C. Moseke, F. Jakob, P.D. Dalton, J. Groll. Additive manufacturing of scaffolds with sub-micron filaments via melt electrospinning writing. Biofabrication 2015; 7, Jun 12;7(3):035002.

German Research Foundation SFB/TRR 225; project # 326998133

A02 | Hyaluronic acid based hydrogel platform with multi-functional cross-linkers for the controlled differentiation of mesenchymal stem cells

A04 | Expansion of the biofabrication window using 2.5D scaffolds made from (AB)n-segmented copolymers

A06 | Cell-loaded microgels as mechanical protection and controlled microenvironment for cells in bioinks

B01 | Ultra-soft matrix composites for the 3D neuroglia in vitro research

B02 | Pre-endothelialized perfusable microvascular networks for biofabrication of standardized in vitro tissue models.

B04 | 3D printing of vascular structures from vascular wall-resident stem cells

German Research Foundation Melt Electrospinning Writing of PLGA for Tissue Engineering Applications. project # 322483321.

German Research Foundation Crosslinking of Melt Electrospun scaffolds for Hydrogel Fabrication. project # 310771104.

EU Research Project DESIGN2HEAL Rational design of scaffold architecture and functionalization to induce healing and tissue regeneration # 617989

EU Research Project EFRE Bio3D-Druck project # 20-3400-2-10.

Volkswagen Foundation Coaxial 3D Printing of Actuating Electroactive Scaffolds for Muscle Regeneration. Project # 93 417.

Bundesministerium für Bildung und Forschung (BMBF)

PhotonControl Project # 13N14205

SOP_Bioprint. Project # 13XP5071A