Self-standing 3D constructs derived from natural polymers

초록

Self-standing bioprint constructs have been achieved by controlling the cross-linking chemistry or rheological properties. Unlike synthetic polymers that change their fluidal properties under high pressure and temperature, natural polymers can handle their physical gelation in relatively mild environments. It allowed natural polymers to contain mammalian cells within the bioink and be extruded through 3D printers. Nevertheless, as the number of layers increased, the irregular layer accumulation happened due to its insufficient material’s self-standing ability. In this study, two natural polymers derived from terrestrial silk and marine polysaccharide were utilized to promote self-standing ability. Silk is one of the well-known examples of fibrous proteins which are producible with a bulk scale and have high durability. However, silk’s tightly packed molecular structure prefers solubilizing acidic conditions and interferes with cell harboring within silk-based bioink. Here, the silk was randomly cleavaged into the low molecular weight, leading to high solubility in an aqueous buffer, and the addition of carrageenan is in compensation of viscosity. The carrageenan is the natural linear sulfated polysaccharide that behaves as a solution over 60°C and gels after cooling down the 60°C solutions lower than 25°C. This temperature responsiveness holds silk/carrageenan 3D ink not to be spread out and provides sufficient time to be photo-crosslinked. The combination of natural polymers and those physical/chemical gelation mechanisms enable 3D constructs to be self-standing with long-time durability.