Tuning the Thermogelation and Rheology of Poly(2-Oxazoline)/Poly(2-Oxazine)s Based Thermosensitive Hydrogels for 3D Bioprinting

As one kind of “smart” material, thermogelling polymers find applications in biofabrication, drug delivery and regenerative medicine. In this work, we report a thermosensitive poly(2-oxazoline)/poly(2-oxazine) based diblock copolymer comprising thermosensitive/moderately hydrophobic poly(2-N-propyl-2-oxazine) (pPrOzi) hydrophilic poly(2-ethyl-2-oxazoline) (pEtOx). Hydrogels were only formed when block length exceeded certain (?100 repeat units). The tube inversion rheological tests showed that the material has then reversible sol-gel transition above 25 wt.% concentration. Rheological further revealed gel strength around 3 kPa, high shear thinning property rapid recovery after stress, which are highly desirable properties for extrusion three-dimensional (3D) (bio) printing. Attributed to rheology profile, well resolved printability stackability (with added laponite) was also possible. (Cryo) scanning electron microscopy exhibited porous, interconnected, 3D network. sol-state at lower temperatures (in ice bath) facilitated homogeneous distribution (fluorescently labelled) human adipose derived stem cells (hADSCs) hydrogel matrix. Post-printing live/dead assays hADSCs encapsulated within remained viable (?97%). This thermoreversible printable demonstrated promising use tissue engineering applications.