Freeze-printing of pectin/alginate scaffolds with high resolution, overhang structures and interconnected porous network

We report herein the fabrication of a pectin-based scaffold (6 wt% pectin, 3 wt% alginate) with high resolution (small-diameter rods), small pores, and interconnected porosity using a low temperature 3D printing process known as freeze-printing. The ability to successfully print natural polymers has been a long-standing challenge in the field of additive manufacturing of polymeric tissue scaffolds. This is due to the slow evaporation rate of the aqueous solvent, which leads to unstable structures. This problem has been addressed by utilizing the fast solidification rate of the freeze-printing process. Scaffolds with a hgresolution (rod-diameter of 83 ± 14 µm), small pores (<250 µm), overhang structures, and an interconnected porous network (pore height of 319 µm in the z-direction) were obtained. The scaffolds were also found to support the viability of chondrocytes and their synthesis of type II collagen. This report investigates the processing-structure relationship and fundamental science of structurally stable scaffold structures produced by additive manufacturing of natural polymers.