@article{KarakayaBiderFranketal.2022, author = {Karakaya, Emine and Bider, Faina and Frank, Andreas and Teßmar, J{\"o}rg and Sch{\"o}bel, Lisa and Forster, Leonard and Schr{\"u}fer, Stefan and Schmidt, Hans-Werner and Schubert, Dirk Wolfram and Blaeser, Andreas and Boccaccini, Aldo R. and Detsch, Rainer}, title = {Targeted printing of cells: evaluation of ADA-PEG bioinks for drop on demand approaches}, series = {Gels}, volume = {8}, journal = {Gels}, number = {4}, issn = {2310-2861}, doi = {10.3390/gels8040206}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-267317}, year = {2022}, abstract = {A novel approach, in the context of bioprinting, is the targeted printing of a defined number of cells at desired positions in predefined locations, which thereby opens up new perspectives for life science engineering. One major challenge in this application is to realize the targeted printing of cells onto a gel substrate with high cell survival rates in advanced bioinks. For this purpose, different alginate-dialdehyde—polyethylene glycol (ADA-PEG) inks with different PEG modifications and chain lengths (1-8 kDa) were characterized to evaluate their application as bioinks for drop on demand (DoD) printing. The biochemical properties of the inks, printing process, NIH/3T3 fibroblast cell distribution within a droplet and shear forces during printing were analyzed. Finally, different hydrogels were evaluated as a printing substrate. By analysing different PEG chain lengths with covalently crosslinked and non-crosslinked ADA-PEG inks, it was shown that the influence of Schiff's bases on the viscosity of the corresponding materials is very low. Furthermore, it was shown that longer polymer chains resulted in less stable hydrogels, leading to fast degradation rates. Several bioinks highly exhibit biocompatibility, while the calculated nozzle shear stress increased from approx. 1.3 and 2.3 kPa. Moreover, we determined the number of cells for printed droplets depending on the initial cell concentration, which is crucially needed for targeted cell printing approaches.}, language = {en} } @article{HahnBeudertGutmannetal.2021, author = {Hahn, Lukas and Beudert, Matthias and Gutmann, Marcus and Keßler, Larissa and Stahlhut, Philipp and Fischer, Lena and Karakaya, Emine and Lorson, Thomas and Thievessen, Ingo and Detsch, Rainer and L{\"u}hmann, Tessa and Luxenhofer, Robert}, title = {From Thermogelling Hydrogels toward Functional Bioinks: Controlled Modification and Cytocompatible Crosslinking}, series = {Macromolecular Bioscience}, volume = {21}, journal = {Macromolecular Bioscience}, number = {10}, doi = {10.1002/mabi.202100122}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-257542}, year = {2021}, abstract = {Hydrogels are key components in bioink formulations to ensure printability and stability in biofabrication. In this study, a well-known Diels-Alder two-step post-polymerization modification approach is introduced into thermogelling diblock copolymers, comprising poly(2-methyl-2-oxazoline) and thermoresponsive poly(2-n-propyl-2-oxazine). The diblock copolymers are partially hydrolyzed and subsequently modified by acid/amine coupling with furan and maleimide moieties. While the thermogelling and shear-thinning properties allow excellent printability, trigger-less cell-friendly Diels-Alder click-chemistry yields long-term shape-fidelity. The introduced platform enables easy incorporation of cell-binding moieties (RGD-peptide) for cellular interaction. The hydrogel is functionalized with RGD-peptides using thiol-maleimide chemistry and cell proliferation as well as morphology of fibroblasts seeded on top of the hydrogels confirm the cell adhesion facilitated by the peptides. Finally, bioink formulations are tested for biocompatibility by incorporating fibroblasts homogenously inside the polymer solution pre-printing. After the printing and crosslinking process good cytocompatibility is confirmed. The established bioink system combines a two-step approach by physical precursor gelation followed by an additional chemical stabilization, offering a broad versatility for further biomechanical adaptation or bioresponsive peptide modification.}, language = {en} } @article{SunStarlyDalyetal.2020, author = {Sun, Wei and Starly, Binil and Daly, Andrew C and Burdick, Jason A and Groll, J{\"u}rgen and Skeldon, Gregor and Shu, Wenmiao and Sakai, Yasuyuki and Shinohara, Marie and Nishikawa, Masaki and Jang, Jinah and Cho, Dong-Woo and Nie, Minghao and Takeuchi, Shoji and Ostrovidov, Serge and Khademhosseini, Ali and Kamm, Roger D and Mironov, Vladimir and Moroni, Lorenzo and Ozbolat, Ibrahim T}, title = {The bioprinting roadmap}, series = {Biofabrication}, volume = {12}, journal = {Biofabrication}, number = {2}, doi = {10.1088/1758-5090/ab5158}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-254027}, year = {2020}, abstract = {This bioprinting roadmap features salient advances in selected applications of the technique and highlights the status of current developments and challenges, as well as envisioned advances in science and technology, to address the challenges to the young and evolving technique. The topics covered in this roadmap encompass the broad spectrum of bioprinting; from cell expansion and novel bioink development to cell/stem cell printing, from organoid-based tissue organization to bioprinting of human-scale tissue structures, and from building cell/tissue/organ-on-a-chip to biomanufacturing of multicellular engineered living systems. The emerging application of printing-in-space and an overview of bioprinting technologies are also included in this roadmap. Due to the rapid pace of methodological advancements in bioprinting techniques and wide-ranging applications, the direction in which the field should advance is not immediately clear. This bioprinting roadmap addresses this unmet need by providing a comprehensive summary and recommendations useful to experienced researchers and newcomers to the field.}, language = {en} } @article{HazurDetschKarakayaetal.2020, author = {Hazur, Jonas and Detsch, Rainer and Karakaya, Emine and Kaschta, Joachim and Teßmar, J{\"o}rg and Schneidereit, Dominik and Friedrich, Oliver and Schubert, Dirk W and Boccaccini, Aldo R}, title = {Improving alginate printability for biofabrication: establishment of a universal and homogeneous pre-crosslinking technique}, series = {Biofabrication}, volume = {12}, journal = {Biofabrication}, number = {4}, doi = {10.1088/1758-5090/ab98e5}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-254030}, year = {2020}, abstract = {Many different biofabrication approaches as well as a variety of bioinks have been developed by researchers working in the field of tissue engineering. A main challenge for bioinks often remains the difficulty to achieve shape fidelity after printing. In order to overcome this issue, a homogeneous pre-crosslinking technique, which is universally applicable to all alginate-based materials, was developed. In this study, the Young's Modulus after post-crosslinking of selected hydrogels, as well as the chemical characterization of alginate in terms of M/G ratio and molecular weight, were determined. With our technique it was possible to markedly enhance the printability of a 2\% (w/v) alginate solution, without using a higher polymer content, fillers or support structures. 3D porous scaffolds with a height of around 5 mm were printed. Furthermore, the rheological behavior of different pre-crosslinking degrees was studied. Shear forces on cells as well as the flow profile of the bioink inside the printing nozzle during the process were estimated. A high cell viability of printed NIH/3T3 cells embedded in the novel bioink of more than 85\% over a time period of two weeks could be observed.}, language = {en} } @article{PaxtonSmolanBoecketal.2017, author = {Paxton, Naomi and Smolan, Willi and B{\"o}ck, Thomas and Melchels, Ferry and Groll, J{\"u}rgen and Jungst, Tomasz}, title = {Proposal to assess printability of bioinks for extrusion-based bioprinting and evaluation of rheological properties governing bioprintability}, series = {Biofabrication}, volume = {9}, journal = {Biofabrication}, number = {4}, doi = {10.1088/1758-5090/aa8dd8}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-254061}, year = {2017}, abstract = {The development and formulation of printable inks for extrusion-based 3D bioprinting has been a major challenge in the field of biofabrication. Inks, often polymer solutions with the addition of crosslinking to form hydrogels, must not only display adequate mechanical properties for the chosen application but also show high biocompatibility as well as printability. Here we describe a reproducible two-step method for the assessment of the printability of inks for bioprinting, focussing firstly on screening ink formulations to assess fibre formation and the ability to form 3D constructs before presenting a method for the rheological evaluation of inks to characterise the yield point, shear thinning and recovery behaviour. In conjunction, a mathematical model was formulated to provide a theoretical understanding of the pressure-driven, shear thinning extrusion of inks through needles in a bioprinter. The assessment methods were trialled with a commercially available cr{\`e}me, poloxamer 407, alginate-based inks and an alginate-gelatine composite material. Yield stress was investigated by applying a stress ramp to a number of inks, which demonstrated the necessity of high yield for printable materials. The shear thinning behaviour of the inks was then characterised by quantifying the degree of shear thinning and using the mathematical model to predict the window of printer operating parameters in which the materials could be printed. Furthermore, the model predicted high shear conditions and high residence times for cells at the walls of the needle and effects on cytocompatibility at different printing conditions. Finally, the ability of the materials to recover to their original viscosity after extrusion was examined using rotational recovery rheological measurements. Taken together, these assessment techniques revealed significant insights into the requirements for printable inks and shear conditions present during the extrusion process and allow the rapid and reproducible characterisation of a wide variety of inks for bioprinting.}, language = {en} } @article{HorderGuazaLasherasGrummeletal.2021, author = {Horder, Hannes and Guaza Lasheras, Mar and Grummel, Nadine and Nadernezhad, Ali and Herbig, Johannes and Erg{\"u}n, S{\"u}leyman and Teßmar, J{\"o}rg and Groll, J{\"u}rgen and Fabry, Ben and Bauer-Kreisel, Petra and Blunk, Torsten}, title = {Bioprinting and differentiation of adipose-derived stromal cell spheroids for a 3D breast cancer-adipose tissue model}, series = {Cells}, volume = {10}, journal = {Cells}, number = {4}, doi = {10.3390/cells10040803}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-236496}, year = {2021}, abstract = {Biofabrication, including printing technologies, has emerged as a powerful approach to the design of disease models, such as in cancer research. In breast cancer, adipose tissue has been acknowledged as an important part of the tumor microenvironment favoring tumor progression. Therefore, in this study, a 3D-printed breast cancer model for facilitating investigations into cancer cell-adipocyte interaction was developed. First, we focused on the printability of human adipose-derived stromal cell (ASC) spheroids in an extrusion-based bioprinting setup and the adipogenic differentiation within printed spheroids into adipose microtissues. The printing process was optimized in terms of spheroid viability and homogeneous spheroid distribution in a hyaluronic acid-based bioink. Adipogenic differentiation after printing was demonstrated by lipid accumulation, expression of adipogenic marker genes, and an adipogenic ECM profile. Subsequently, a breast cancer cell (MDA-MB-231) compartment was printed onto the adipose tissue constructs. After nine days of co-culture, we observed a cancer cell-induced reduction of the lipid content and a remodeling of the ECM within the adipose tissues, with increased fibronectin, collagen I and collagen VI expression. Together, our data demonstrate that 3D-printed breast cancer-adipose tissue models can recapitulate important aspects of the complex cell-cell and cell-matrix interplay within the tumor-stroma microenvironment}, language = {en} } @article{WeisShanKuhlmannetal.2018, author = {Weis, Matthias and Shan, Junwen and Kuhlmann, Matthias and Jungst, Tomasz and Tessmar, J{\"o}rg and Groll, J{\"u}rgen}, title = {Evaluation of hydrogels based on oxidized hyaluronic acid for bioprinting}, series = {Gels}, volume = {4}, journal = {Gels}, number = {4}, issn = {2310-2861}, doi = {10.3390/gels4040082}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-197600}, pages = {82}, year = {2018}, abstract = {In this study, we evaluate hydrogels based on oxidized hyaluronic acid, cross-linked with adipic acid dihydrazide, for their suitability as bioinks for 3D bioprinting. Aldehyde containing hyaluronic acid (AHA) is synthesized and cross-linked via Schiff Base chemistry with bifunctional adipic acid dihydrazide (ADH) to form a mechanically stable hydrogel with good printability. Mechanical and rheological properties of the printed and casted hydrogels are tunable depending on the concentrations of AHA and ADH cross-linkers.}, language = {en} }