Development of foam-based support material for coaxial bioprinting of ionically crosslinking bioinks

In this study, a foam-based method is developed for three-dimensional coaxial bioprinting of ionically crosslinking bioinks. This method introduces the crosslinker to the bioink in calcium chloride-albumin foam which eliminates the need for multiple crosslinking steps and offers an excellent control over the crosslinking rate and the diameter of the hollow fibers. The effects of the foam and alginate flow rates were investigated on the outer diameter and the wall thickness of the hollow fibers. Various structures were 3D printed and characterized by printability number and the method showed an excellent layer adhesion among printed layers. The effects of foam composition and the alginate concentration on the mechanical properties were assessed through breaking strain and filament collapse tests to determine the optimum composition for hollow fiber fabrication. The hollow fiber composed of 2% (w/v) sodium alginate that is crosslinked with a foam made of 1.07% (w/v) albumin and 1.07% (w/v) calcium chloride showed superior mechanical properties. Furthermore, the viability of co-incubation with Neuro-2a cells over seven days was investigated and no significant negative effect of the used concentrations of albumin and calcium chloride was observed on the viability of the cells.