@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{HaiderAhmadYangetal.2021,
  author    = {Haider, Malik Salman and Ahmad, Taufiq and Yang, Mengshi and Hu, Chen and Hahn, Lukas and Stahlhut, Philipp and Groll, J{\"u}rgen and Luxenhofer, Robert},
  title     = {Tuning the thermogelation and rheology of poly(2-oxazoline)/poly(2-oxazine)s based thermosensitive hydrogels for 3D bioprinting},
  series = {Gels},
  volume    = {7},
  journal   = {Gels},
  number    = {3},
  issn      = {2310-2861},
  doi       = {10.3390/gels7030078},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-241781},
  year      = {2021},
  abstract  = {As one kind of "smart" material, thermogelling polymers find applications in biofabrication, drug delivery and regenerative medicine. In this work, we report a thermosensitive poly(2-oxazoline)/poly(2-oxazine) based diblock copolymer comprising thermosensitive/moderately hydrophobic poly(2-N-propyl-2-oxazine) (pPrOzi) and thermosensitive/moderately hydrophilic poly(2-ethyl-2-oxazoline) (pEtOx). Hydrogels were only formed when block length exceeded certain length (≈100 repeat units). The tube inversion and rheological tests showed that the material has then a reversible sol-gel transition above 25 wt.\% concentration. Rheological tests further revealed a gel strength around 3 kPa, high shear thinning property and rapid shear recovery after stress, which are highly desirable properties for extrusion based three-dimensional (3D) (bio) printing. Attributed to the rheology profile, well resolved printability and high stackability (with added laponite) was also possible. (Cryo) scanning electron microscopy exhibited a highly porous, interconnected, 3D network. The sol-state at lower temperatures (in ice bath) facilitated the homogeneous distribution of (fluorescently labelled) human adipose derived stem cells (hADSCs) in the hydrogel matrix. Post-printing live/dead assays revealed that the hADSCs encapsulated within the hydrogel remained viable (≈97\%). This thermoreversible and (bio) printable hydrogel demonstrated promising properties for use in tissue engineering applications.},
  language  = {en}
}