Abstract
D printing is the process by which a 3D-printed object is transformed into a different structure under the influence of a stimulus. The possibility of printing hydrogels in 4D opens up potential applications in the biomedical field. Indeed, the design of medical devices capable of changing shape and function in response to specific physiological or external stimuli can offer personalized and adaptive treatment solutions, thereby improving medical therapies based on the specific therapeutic needs of patients. The systems studied in the literature are often designed from synthetic polymers, which may present certain limitations in terms of biocompatibility and biodegradability. This work proposes the development of hydrogels based on a natural polymer, alginate, obtained through photoreticulation. By modifying parameters such as molecular weight and the degree of methacrylation, it is possible to control the characteristics of the hydrogels and their morphological responses to an ionic stimulus. This flexibility has proven useful for adjusting the morphological and mechanical properties according to a specific application. It was therefore possible to print hydrogels with programmed deformations by controlling the spatial photoreticulation of the gel. To add another stimulus to the alginate-based system, the integration of a thermosensitive polymer based on Pluronic was proposed. To achieve this, an in-depth study was conducted to understand the influence of methacrylation on the thermal properties of Pluronics. This analysis enabled the establishment of phase diagrams for Pluronics P123, P104, and F127, demonstrating how these materials respond to temperature variations. The alginate-based hydrogels reinforced with methacrylated Pluronic F127 showed improved mechanical properties while maintaining programmed deformations. Finally, this work demonstrated proof of concept for devices such as stents and scaffolds for tissue filling, which can adapt to specific implantation sites in the body and respond dynamically to stimuli.