A novel platform of synthetic polyurea bioinks with tailorable properties

Bioprinting enables the fabrication of living tissue constructs through the deposition of bioinks containing live cells within a three-dimensional architecture that mimics the native tissue microenvironment. A major challenge in bioprinting is the lack of an ideal bioink that simultaneously offers suitable biocompatibility, rheological behavior, mechanical strength and elasticity, particularly for load bearing and dynamically active tissues such as skeletal muscle. Currently the bioinks available are mainly based on animal or plant derived natural polymers, such as gelatin, collagen, hyaluronic acid, fibrin, silk fibroin, chitosan, alginates and their derivatives. These materials are often chemically modified with acrylates to enable photo-crosslinking. Polyethylene glycol di (meth)acrylate is one of the few synthetic bioinks available. Unfortunately, both natural and synthetic bioinks exhibit limitations in terms of mechanical stability, printability, and support for cellular function. In this study, we present a novel class of light-curable synthetic polymers based on polyurea chemistry (PUMA), as a platform for bioink development. These materials offer tunable structural and biological properties suitable for skeletal muscle tissue engineering. Comprehensive structural and mechanical characterization of the polyurea bioinks developed was performed, including their rheological properties, printability, and post-crosslinking dimensional stability. Furthermore, cytocompatibility was assessed by in vitro assays, and successful 3D bioprinting was demonstrated under visible light (lambda = 405 nm) with C2C12 mouse myoblasts, indicating the potential of PUMA materials as a robust and customizable synthetic bioink platform for skeletal muscle tissue regeneration.