摘要：SummaryIn microextrusion-based 3D bioprinting, shaping gel fibers online, i.e., in narrow tubes, benefits the structural maintenance after extrusion, but it is challenging for materials possessing slow sol-gel transition dynamics. Gelatin, for example, transforms into thermostable fibers via transglutaminase (TG) reaction in as much as 10 min. It causes dramatic flow resistance accumulation and shear stress increase in fluids moving along narrow tubes, resulting in channel clogging and cell detriments. In this study, we overcome the limitations by adopting cascade pumping and performing in a single peristaltic pump that comprises multi-channel pumping units. The pressure and shear stress reduction by over 1-fold are verified by finite element simulation; continuous gelatin fiber production and patterning in a substrate-free manner are achieved via slow online enzymatic cross-linking. The online fiber shaping can be scaled up by numbering up the pumping units and provides another paradigm for biomanufacturing.Graphical AbstractDisplay OmittedHighlights•Cascade pumping overcomes hydraulic resistance and reduces shear stress significantly•Cascade pumping suits online gelatin fiber shaping via slow enzymatic cross-linking•Online fiber shaping enables substrate-free 3D printing•Gelatin fibers are stronger when gelled via thermal and enzymatic dual cross-linkingMaterials in Biotechnology; Materials Processing; Biomaterials
