A dual-gelling poly(N-isopropylacrylamide)-based ink and thermoreversible poloxamer support bath for high-resolution bioprinting

Extrusion bioprinting is a popular method for fabricating tissue engineering scaffolds because of its potential to rapidly produce complex,bioactive or cell-laden scaffolds.However,due to the relatively high viscosity required to maintain shape fidelity during printing,many extrusion-based inks lack the ability to achieve precise structures at scales lower than hundreds of micrometers.In this work,we present a novel poly(N-isopropylacrylamide)(PNIPAAm)-based ink and poloxamer support bath system that produces precise,multi-layered structures on the tens of micrometers scale.The support bath maintains the structure of the ink in a hydrated,heated environment ideal for cell culture,while the ink undergoes rapid thermogelation followed by a spontaneous covalent crosslinking reaction.Through the combination of the PNIPAAm-based ink and poloxamer bath,this system was able to produce hydrogel scaffolds with uniform fibers possessing diameters tunable from 80 to 200μm.A framework of relationships between several important printing factors involved in maintaining support and thermogelation was also elucidated.As a whole,this work demonstrates the ability to produce precise,acellular and cell-laden PNIPAAm-based scaffolds at high-resolution and contributes to the growing body of research surrounding the printability of extrusion-based bioinks with support baths.