4D Printed Self-Deploying Bio-Based Scaffolds for the Regeneration of Endoluminal Tissue

Self-deploying bio-based scaffolds able to lay out in programmable way according to a defined external stimulus are extremely useful for the treatment and regeneration of endoluminal tissues, since they combine biocompatibility with the ability to be brought into place in a minimally invasive way through, for instance, endoscopic or laparoscopic instruments. Here, four-dimensional (4D) printing is exploited to design and fabricate, via extrusion-based additive manufacturing on a rotating spindle, a self-deploying scaffold for the minimally invasive treatment of gastrointestinal tissue. Starting from a tubular configuration, upon hydration, the scaffold automatically unfolds, forming a flat sheet able to cover a wider surface of the damaged tissue. The desired shape morphing is achieved thanks to a specific spatial arrangement of silk/gelatin-based solution, featuring differential swelling behavior. The geometry of the scaffold is guided by finite element modeling. The silk/gelatin-based solution is tested via Raman and Fourier-transform infrared spectroscopy (FTIR) measurements, rheological tests and biological assays. The latter is performed on two colorectal cell lines, HT-29 and Caco-2, and proves the ability of the materials to support the growth of the seeded cells.