@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{HahnLuxenhoferHeltenetal.2021,
  author    = {Hahn, Lukas and Luxenhofer, Robert and Helten, Holger and Forster, Stefan and Fritze, Lars and Polzin, Lando and Keßler, Larissa},
  title     = {ABA Type Amphiphiles with Poly(2-benzhydryl-2-oxazine) Moieties: Synthesis, Characterization and Inverse Thermogelation},
  series = {Macromolecular Chemistry and Physics},
  volume    = {222},
  journal   = {Macromolecular Chemistry and Physics},
  number    = {17},
  doi       = {10.1002/macp.202100114},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-265124},
  year      = {2021},
  abstract  = {Thermoresponsive polymers are frequently involved in the development of materials for various applications. Here, polymers containing poly(2- benzhydryl-2-oxazine) (pBhOzi) repeating units are described for the first time. The homopolymer pBhOzi and an ABA type amphiphile comprising two flanking hydrophilic A blocks of poly(2-methyl-2-oxazoline) (pMeOx) and the hydrophobic aromatic pBhOzi central B block (pMeOx-b-pBhOzi-b-pMeOx) are synthesized and the latter is shown to exhibit inverse thermogelling properties at concentrations of 20 wt.\% in water. This behavior stands in contrast to a homologue ABA amphiphile consisting of a central poly(2-benzhydryl-2-oxazoline) block (pMeOx-b-pBhOx-b-pMeOx). No inverse thermogelling is observed with this polymer even at 25 wt.\%. For 25 wt.\% pMeOx-b-pBhOzi-b-pMeOx, a surprisingly high storage modulus of ≈22 kPa and high values for the yield and flow points of 480 Pa and 1.3 kPa are obtained. Exceeding the yield point, pronounced shear thinning is observed. Interestingly, only little difference between self-assemblies of pMeOx-b-pBhOzi-b-pMeOx and pMeOx-b-pBhOx-b-pMeOx is observed by dynamic light scattering while transmission electron microscopy images suggest that the micelles of pMeOx-b-pBhOzi-b-pMeOx interact through their hydrophilic coronas, which is probably decisive for the gel formation. Overall, this study introduces new building blocks for poly(2-oxazoline) and poly(2-oxazine)-based self-assemblies, but additional studies will be needed to unravel the exact mechanism.},
  language  = {en}
}