@article{BrandForsterBoecketal.2022,
  author    = {Brand, Jessica S. and Forster, Leonard and B{\"o}ck, Thomas and Stahlhut, Philipp and Teßmar, J{\"o}rg and Groll, J{\"u}rgen and Albrecht, Krystyna},
  title     = {Covalently Cross-Linked Pig Gastric Mucin Hydrogels Prepared by Radical-Based Chain-Growth and Thiol-ene Mechanisms},
  series = {Macromolecular Bioscience},
  volume    = {22},
  journal   = {Macromolecular Bioscience},
  number    = {4},
  doi       = {10.1002/mabi.202100274},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-318453},
  year      = {2022},
  abstract  = {Mucin, a high molecular mass hydrophilic glycoprotein, is the main component of mucus that coats every wet epithelium in animals. It is thus intrinsically biocompatible, and with its protein backbone and the o-glycosidic bound oligosaccharides, it contains a plethora of functional groups which can be used for further chemical modifications. Here, chain-growth and step-growth (thiol-ene) free-radical cross-linked hydrogels prepared from commercially available pig gastric mucin (PGM) are introduced and compared as cost-efficient and easily accessible alternative to the more broadly applied bovine submaxillary gland mucin. For this, PGM is functionalized with photoreactive acrylate groups or allyl ether moieties, respectively. Whereas homopolymerization of acrylate-functionalized polymers is performed, for thiol-ene cross-linking, the allyl-ether-functionalized PGM is cross-linked with thiol-functionalized hyaluronic acid. Morphology, mechanical properties, and cell compatibility of both kinds of PGM hydrogels are characterized and compared. Furthermore, the biocompatibility of these hydrogels can be evaluated in cell culture experiments.},
  language  = {en}
}
@article{ShanBoeckKelleretal.2021,
  author    = {Shan, Junwen and B{\"o}ck, Thomas and Keller, Thorsten and Forster, Leonard and Blunk, Torsten and Groll, J{\"u}rgen and Teßmar, J{\"o}rg},
  title     = {TEMPO/TCC as a Chemo Selective Alternative for the Oxidation of Hyaluronic Acid},
  series = {Molecules},
  volume    = {26},
  journal   = {Molecules},
  number    = {19},
  issn      = {1420-3049},
  doi       = {10.3390/molecules26195963},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-248362},
  year      = {2021},
  abstract  = {Hyaluronic acid (HA)-based hydrogels are very commonly applied as cell carriers for different approaches in regenerative medicine. HA itself is a well-studied biomolecule that originates from the physiological extracellular matrix (ECM) of mammalians and, due to its acidic polysaccharide structure, offers many different possibilities for suitable chemical modifications which are necessary to control, for example, network formation. Most of these chemical modifications are performed using the free acid function of the polymer and, additionally, lead to an undesirable breakdown of the biopolymer's backbone. An alternative modification of the vicinal diol of the glucuronic acid is oxidation with sodium periodate to generate dialdehydes via a ring opening mechanism that can subsequently be further modified or crosslinked via Schiff base chemistry. Since this oxidation causes a structural destruction of the polysaccharide backbone, it was our intention to study a novel synthesis protocol frequently applied to selectively oxidize the C6 hydroxyl group of saccharides. On the basis of this TEMPO/TCC oxidation, we studied an alternative hydrogel platform based on oxidized HA crosslinked using adipic acid dihydrazide as the crosslinker.},
  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}
}