An Inverse Thermogelling Bioink Based on an ABA-Type Poly(2-oxazoline) Amphiphile

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Tissue Engineering

Background:

• Hydrogels are crucial in biomedical applications like drug delivery and tissue engineering.
• Novel polymer architectures are needed to create advanced hydrogel materials with tailored properties.

Purpose of the Study:

• To introduce a novel ABA-type triblock copolymer for hydrogel formation.
• To investigate the self-assembly, gelation, and printability of the new hydrogel.
• To evaluate the potential of the hydrogel in biofabrication and as a sacrificial bioink.

Main Methods:

• Synthesis of an ABA-type triblock copolymer with hydrophilic poly(2-methyl-2-oxazoline) and hydrophobic poly(2-phenethyl-2-oxazoline) blocks.
• Characterization of polymer self-assembly into micelles.
• Investigation of thermoresponsive inverse gelation and hydrogel properties (viscoelasticity, shear-thinning, printability).
• Preliminary bioprinting experiments to assess cell viability.

Main Results:

• The polymer self-assembles into spherical micelles (8-8.5 nm hydrodynamic radius).
• Rapid thermoresponsive inverse gelation occurs above 20 wt % polymer concentration, forming a macroporous hydrogel.
• The hydrogel exhibits solid-like viscoelasticity, shear-thinning, rapid recovery, and good strain resistance.
• Excellent 3D-printability was achieved at lower temperatures.
• Over 95% cell viability was observed in preliminary bioprinting experiments.
• The hydrogel demonstrated potential as a printing support and sacrificial bioink due to dissolution at physiological conditions.

Conclusions:

• A novel ABA triblock copolymer forms a thermoresponsive hydrogel with desirable viscoelastic and printability properties.
• The hydrogel is suitable for biofabrication applications, including use as a sacrificial bioink.
• High cell viability confirms its biocompatibility for tissue engineering scaffolds.