A predictive rheological framework to define printability of thermo-sensitive bioinks using non-temperature-controlled bioprinters

3D-bioprinting requires bioinks with a set of mechanical and chemical characteristics, including biocompatibility, suitable flow, the preservation of cell viability during extrusion, and shape retention upon printing to construct structures in 3D. Biopolymer-based hydrogels including mixtures of gelatin and alginate are ideal, although their printability is challenging due to important thermoresponsive behavior, requiring expensive temperature-controlled printers. Here, we present a methodological framework that predicts the printability of gelatin–alginate bioinks directly from rheological parameters. By quantitatively linking viscosity and storage/loss ratio to extrusion fidelity, and by identifying gelation temperature and gelation speed as key windows for adjusting the printing process, we establish actionable design rules that enable printing with non-temperature-controlled devices, resulting in shape fidelity, spreading ratios, and printability scores close to 1, while permitting a high cell viability after printing (92.4±2.2%) that can be maintained for up to 8 days (96.5 ± 0.9%). This predictive approach provides a practical pathway to design thermosensitive bioinks without relying on trial-and-error or specialized equipment, broadening the accessibility of 3D bioprinting technologies for tissue engineering. • Temperature-aware rheology provides actionable design rules for gelatin-alginate bioinks. • Printability window quantified: viscosity 2,123–13,616 mPa·s; G′/G″ = 1.0–2.1. • Framework enables scheduled printing without active thermal control (room-temperature time window). • Printability window aligns with 92–96% MDA-MB-231 viability over 9 days post-print. • Multilayer and composite constructs (12–17 layers) are printable and remain stable.