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

Abstract 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.