In Situ 4d Printing of Polyelectrolyte/Magnetic Composites for Sutureless Gastric Perforation Sealing.

In situ bioprinting has emerged as one of the most promising techniques for the sutureless tissue sealing of internal organs. However, most existing in situ bioprinting methods are limited by the complex and confined printing space inside the organs, harsh curing conditions for printable bioinks, and poor ability to suturelessly seal injured parts. 4D printing is a technique in which the shape, properties, or functionality of inks or products can be controllably varied over time under external stimuli. The combination of in-situ bioprinting and 4D printing is a promising technique for tissue repair. Herein, we report the in-situ 4D printing of polyelectrolyte/magnetic composites by gastroscopy for sutureless internal tissue sealing. Using gastric perforation as an example, a gelatin/sodium-alginate/magnetic (GSM) bioink was developed, which can be precisely located by a gastroscope with the assistance of an external magnetic field, solidified in gastric fluid, and firmly adhered to tissue surfaces. The solidified gelatin/sodium alginate/magnetic complexes (GSMCs) along the defect can be attracted by an external magnetic field, resulting in sutureless gastric perforation sealing. The working mechanism of the printed GSMC was explained by a numerical simulation method using the COMSOL software. A demonstration using a porcine stomach with an artificial perforation confirmed the feasibility of sutureless perforation using 4D printing. Moreover, an in vivo investigation on gastric perforation in a rat model identified the biocompatibility by H&E and CD68+ staining. This study provides a new orientation and concept for functionality-modified in-situ 4D bioprinting. This article is protected by copyright. All rights reserved.