Browsing by Author "Götz, Tobias"

Filter results by typing the first few letters
Now showing 1 - 3 of 3
  • Thumbnail Image
    ItemOpen Access
    Azido-functionalized gelatin via direct conversion of lysine amino groups by diazo transfer as a building block for biofunctional hydrogels
    (2020) Keller, Silke; Bakker, Tomke; Kimmel, Benjamin; Rebers, Lisa; Götz, Tobias; Tovar, Günter E. M.; Kluger, Petra J.; Southan, Alexander
    Gelatin is one of the most prominent biopolymers in biomedical material research and development. It is frequently used in hybrid hydrogels, which combine the advantageous properties of bio-based and synthetic polymers. To prevent the biological component from leaching out of the hydrogel, the biomolecules can be equipped with azides. Those groups can be used to immobilize gelatin covalently in hydrogels by the highly selective and specific azide-alkyne cycloaddition. In this contribution, we functionalized gelatin with azides at its lysine residues by diazo transfer, which offers the great advantage of only minimal side-chain extension. Approximately 84-90% of the amino groups are modified as shown by 1H-NMR spectroscopy, 2,4,6-trinitrobenzenesulfonic acid assay as well as Fourier-transform infrared spectroscopy, rheology, and the determination of the isoelectric point. Furthermore, the azido-functional gelatin is incorporated into hydrogels based on poly(ethylene glycol) diacrylate (PEG-DA) at different concentrations (0.6, 3.0, and 5.5%). All hydrogels were classified as noncyctotoxic with significantly enhanced cell adhesion of human fibroblasts on their surfaces compared to pure PEG-DA hydrogels. Thus, the new gelatin derivative is found to be a very promising building block for tailoring the bioactivity of materials.
  • Thumbnail Image
    ItemOpen Access
    Influence of hard segment content and diisocyanate structure on the transparency and mechanical properties of poly(dimethylsiloxane)-based urea elastomers for biomedical applications
    (2021) Riehle, Natascha; Athanasopulu, Kiriaki; Kutuzova, Larysa; Götz, Tobias; Kandelbauer, Andreas; Tovar, Günter; Lorenz, Günter
  • Thumbnail Image
    ItemOpen Access
    Triazole-based cross-linkers in radical polymerization processes: tuning mechanical properties of poly(acrylamide) and poly(N,N-dimethylacrylamide) hydrogels
    (2018) Götz, Tobias; Schädel, Nicole; Petri, Nadja; Kirchhof, Manuel; Bilitewski, Ursula; Tovar, Günter E. M.; Laschat, Sabine; Southan, Alexander
    Triazole-based cross-linkers with different spacer lengths and different functional end groups (acrylamides, methacrylamides, maleimides and vinylsulfonamides) were synthesized, investigated for cytotoxic and antibacterial activity, and incorporated into poly(acrylamide) (PAAm) and poly(N,N-dimethylacrylamide) (PDMAAm) hydrogels by free radical polymerization. Hydrogels prepared with different cross-linkers and cross-linker contents between 0.2% and 1.0% were compared by gel yields, equilibrium degrees of swelling (S) and storage moduli (G’). Generally with increasing cross-linker content, G’ values of the hydrogels increased, while S values decreased. The different polymerizable cross-linker end groups resulted in a decrease of G’ in the following order for cross-linkers with C4 spacers: acrylamide > maleimide > methacrylamide > vinylsulfonamide. Longer cross-linker alkyl spacer lengths caused an increase in G’ and a decrease in S. Independent of the cross-linker used, a universal correlation between G’ and equilibrium polymer volume fraction phi was found. For PAAm hydrogels, G’ ranged between 4 kPa and 23 kPa and and phi between 0.07 and 0.14. For PDMAAm hydrogels, G’ ranged between 0.1 kPa and 4.9 kPa and and phi between 0.02 and 0.06. The collected data were used to establish an empirical model to predict G’ depending on phi. G’ of PAAm and PDMAAm hydrogels is given by G' = 4034 kPa * phi^2.66 and G' = 4297 kPa * phi^2.46, respectively.