Thiolated Polymers in 3D Bioprinting: Control of Gelation

Abstract

ABSTRACT Thiolated polymers represent a versatile class of bioinks for extrusion‐based 3D bioprinting, combining cytocompatibility with tunable crosslinking chemistry and dynamic redox‐responsive behaviour. This review consolidates recent advances in thiomer chemistry, focusing on synthetic strategies that modulate thiol reactivity through pKa adjustment, neighboring‐group interactions, and redox control. Crosslinking mechanisms such as oxidative disulfide formation, thiol–ene, thiol‐yne, and thiol‐polyphenol reactions are compared in terms of their impact on gelation. External triggers, including small‐molecule and polymeric crosslinkers, light activation, oxidants, enzymatic systems, as well as hybrid dual‐stage systems, are discussed for their capacity to achieve controlled gelation and long‐term stability. A comprehensive printability framework links chemical design to performance metrics such as gel point, modulus build‐up rate, collapse angle, filament fusion index, fidelity ratio, and shear thresholds that maintain cell viability. Redox‐driven reversibility provides additional adaptability through self‐healing and stress‐relaxation mechanisms. Applications span soft tissue and cartilage regeneration, vascularized and multicellular constructs, hemostatic adhesives, and extracellular matrix–mimetic scaffolds for stem‐cell culture. These developments collectively establish design principles for balancing gelation kinetics, shape fidelity, and biological functionality in thiomer‐based bioinks.