posted on 2020-03-06, 15:56authored byLukas Hahn, Matthias Maier, Philipp Stahlhut, Matthias Beudert, Vanessa Flegler, Stefan Forster, Alexander Altmann, Fabian Töppke, Karl Fischer, Sebastian Seiffert, Bettina Böttcher, Tessa Lühmann, Robert Luxenhofer
Amphiphilic
block copolymers that undergo (reversible) physical gelation in aqueous
media are of great interest in different areas including drug delivery,
tissue engineering, regenerative medicine, and biofabrication. We
investigated a small library of ABA-type triblock copolymers comprising
poly(2-methyl-2-oxazoline) as the hydrophilic shell A and different
aromatic poly(2-oxazoline)s and poly(2-oxazine)s cores B in an aqueous
solution at different concentrations and temperatures. Interestingly,
aqueous solutions of poly(2-methyl-2-oxazoline)-block-poly(2-phenyl-2-oxazine)-block-poly(2-methyl-2-oxazoline)
(PMeOx-b-PPheOzi-b-PMeOx) undergo
inverse thermogelation below a critical temperature by forming a reversible
nanoscale wormlike network. The viscoelastic properties of the resulting
gel can be conveniently tailored by the concentration and the polymer
composition. Storage moduli of up to 110 kPa could be obtained while
the material retains shear-thinning
and rapid self-healing properties. We demonstrate three-dimensional
(3D) printing of excellently defined and shape-persistent 24-layered
scaffolds at different aqueous concentrations to highlight its application
potential, e.g., in the research area of biofabrication. A macroporous
microstructure, which is stable throughout the printing process, could
be confirmed via cryo-scanning electron microscopy (SEM) analysis.
The absence of cytotoxicity even at very high concentrations opens
a wide range of different applications for this first-in-class material
in the field of biomaterials.