@phdthesis{LiebschergebBloehbaum2020,
  author    = {Liebscher [geb. Bl{\"o}hbaum], Julia},
  title     = {Side chain functional poly(2-oxazoline)s for biomedical applications},
  doi       = {10.25972/OPUS-20396},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-203960},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2020},
  abstract  = {The aim of the thesis was to develop water soluble poly(2-oxazoline) (POx) copolymers with new side group functionalities, which can be used for the formation of hydrogels in biomedical applications and for the development of peptide-polymer conjugates. First, random copolymers of the monomer MeOx or EtOx with ButEnOx and EtOx with DecEnOx were synthesized and characterized. The vinyl functionality brought into the copolymer by the monomers ButEnOx and DecEnOx would later serve for post-polymerization functionalization. The synthesized copolymers were further functionalized with thiols via post-polymerization functionalization using a newly developed synthesis protocol or with a protected catechol molecule for hydrogel formation. For the formation of peptide-polymer conjugates, a cyclic thioester, namely thiolactone acrylamide and an azlactone precursor, whose synthesis was newly developed, were attached to the side chain of P(EtOx-co-ButEnOx) copolymers. The application of the functionalized thiol copolymers as hydrogels using thiol-ene chemistry for cross-linking was demonstrated. The swelling behavior and mechanical properties were characterized. The hydrophilicity of the network as well as the cross-linking density strongly influenced the swelling behavior and the mechanical strength of the hydrogels. All hydrogels showed good cell viability results. The hydrogel networks based on MeOx and EtOx were loaded with two dyes, fluorescein and methylene blue. It was observed that the uptake of the more hydrophilic dye fluorescein depended more on the ability of the hydrogel to swell. In contrast, the uptake of the more hydrophobic dye methylene blue was less dependent on the swelling degree, but much more on the hydrophilicity of the network. For the potential application as cartilage glue, (biohybrid) hydrogels were synthesized based on the catechol-functionalized copolymers, with and without additional fibrinogen, using sodium periodate as the oxidizing agent. The system allowed for degradation due to the incorporated ester linkages at the cross-linking points. The swelling behavior as well as the mechanical properties were characterized. As expected, hydrogels with higher degrees of cross-linking showed less swelling and higher elastic modulus. The addition of fibrinogen however increased the elasticity of the network, which can be favorable for the intended application as a cartilage glue. Biological evaluation clearly demonstrated the advantage of degradable ester links in the hydrogel network, where chondrocytes were able to bridge the artificial gap in contrast to hydrogels without any ester motifs. Lastly, different ways to form peptide-polymer conjugates were presented. Peptides were attached with the thiol of the terminal cysteine group to the vinyl side chain of P(EtOx-co-ButEnOx) copolymers by radical thiol-ene chemistry. Another approach was to use a cyclic thioester, thiolactone, or an azlactone functionality to bind a model peptide via native chemical ligation. The two latter named strategies to bind peptides to POx side chains are especially interesting as one and in the case of thiolactone two free thiols are still present at the binding site after the reaction, which can, for example, be used for further thiol-ene cross-linking to form POx hydrogels. In summary, side functional poly(oxazoline) copolymers show great potential for numerous biomedical applications. The various side chain functionalities can be introduced by an appropriate monomer or by post-polymerization functionalization, as demonstrated. By their multi-functionality, hydrogel characteristics, such as cross-linking degree and mechanical strength, can be fine-tuned and adjusted depending on the application in the human body. In addition, the presented chemoselective and orthogonal reaction strategies can be used in the future to synthesize polymer conjugates, which can, for example, be used in drug delivery or in tissue regeneration.},
  subject      = {Polymere},
  language  = {en}
}
@article{LiebscherTessmarGroll2020,
  author    = {Liebscher, Julia and Teßmar, Joerg Karl and Groll, J{\"u}rgen},
  title     = {In Situ Polymer Analogue Generation of Azlactone Functions at Poly(oxazoline)s for Peptide Conjugation},
  series = {Macromolecular Chemistry and Physics},
  volume    = {221},
  journal   = {Macromolecular Chemistry and Physics},
  number    = {1},
  doi       = {10.1002/macp.201900500},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-208147},
  pages     = {1900500},
  year      = {2020},
  abstract  = {The physical and chemical stability of peptides for biomedical applications can be greatly enhanced through the conjugation of polymers. A well-known but rather underemployed selective coupling functionality is the azlactone group, which readily reacts with a number of different nucleophiles without the need for activation and the formation of any by-products. For example, azlactone functional polymers are used to react with peptides and proteins, rich in amino and thiol groups, to form polymeric beads for affinity-based column chromatography. So far, side chain functional azlactone polymers have been mainly synthesized by radical polymerization using 2-vinyl-4,4-dimethyl azlactone together with different acrylate monomers. Here, a new azlactone precursor equipped with a functional thiol is presented, which can be attached to any vinyl functional polymer by thiol-ene chemistry. Subsequently, the formation of the reactive azlactone ring can be performed in situ at high conversion rate without the need for illumination. This approach is tested on an azlactone side functional poly(2-oxazoline) by coupling amine containing molecules including a model peptide and is proven via \(^1\)H NMR spectroscopy, IR spectroscopy, as well as HPLC measurements.},
  language  = {en}
}
@article{RymaTylekLiebscheretal.2021,
  author    = {Ryma, Matthias and Tylek, Tina and Liebscher, Julia and Blum, Carina and Fernandez, Robin and B{\"o}hm, Christoph and Kastenm{\"u}ller, Wolfgang and Gasteiger, Georg and Groll, J{\"u}rgen},
  title     = {Translation of collagen ultrastructure to biomaterial fabrication for material-independent but highly efficient topographic immunomodulation},
  series = {Advanced materials},
  volume    = {33},
  journal   = {Advanced materials},
  number    = {33},
  doi       = {10.1002/adma.202101228},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256381},
  year      = {2021},
  abstract  = {Supplement-free induction of cellular differentiation and polarization solely through the topography of materials is an auspicious strategy but has so far significantly lagged behind the efficiency and intensity of media-supplementation-based protocols. Consistent with the idea that 3D structural motifs in the extracellular matrix possess immunomodulatory capacity as part of the natural healing process, it is found in this study that human-monocyte-derived macrophages show a strong M2a-like prohealing polarization when cultured on type I rat-tail collagen fibers but not on collagen I films. Therefore, it is hypothesized that highly aligned nanofibrils also of synthetic polymers, if packed into larger bundles in 3D topographical biomimetic similarity to native collagen I, would induce a localized macrophage polarization. For the automated fabrication of such bundles in a 3D printing manner, the strategy of "melt electrofibrillation" is pioneered by the integration of flow-directed polymer phase separation into melt electrowriting and subsequent selective dissolution of the matrix polymer postprocessing. This process yields nanofiber bundles with a remarkable structural similarity to native collagen I fibers, particularly for medical-grade poly(ε-caprolactone). These biomimetic fibrillar structures indeed induce a pronounced elongation of human-monocyte-derived macrophages and unprecedentedly trigger their M2-like polarization similar in efficacy as interleukin-4 treatment.},
  language  = {en}
}