Double-Network Polysaccharide-Collagen Hybrid Bioink

Over the past decade, three-dimensional bioprinting (3DBP) has evolved into a versatile processing tool for engineering tissues. The key component, the bioink, can be composed of many different hydrogel-forming polymers, which are mostly performant in either mechanical or biological properties but seldom both. Carboxylated agarose (CA) was combined here with collagen type 1 to simultaneously satisfy both properties and combine their attributes, without compromising on either; the result is an innovative, hybrid bioink. It can be printed with high accuracy, good layer-to-layer adhesion, and rapid gelation, enabling overhang printing. Scanning electron microscopy (SEM) and fluorescently labeled collagen demonstrated that the two components mixed well, resulting in uniformly distributed collagen fibrils and a double network. From the biological perspective, a bioink must exhibit cell-adhesion moieties to maintain proliferation and metabolism, which we could ensure through the collagen component. Here, we present an example strategy for combining an inert polysaccharide with bioactive collagen, two polymers with opposing gelation conditions, which yields a bioink that possesses beneficial properties from both without compromising the features of either. The interpenetrating structure of both molecules synergistically balances the mechanical strength of CA and the biological functionality of collagen.