Biodesign of microalgae-laden engineered living materials via 3D bioprinting: a roadmap

Abstract Microalgae-based engineered living materials (ELMs) are increasingly explored in biodesign, yet initiating experimental work remains technically complex and parameter-sensitive. This pictorial presents a structured, experimentally grounded roadmap for extrusion-based bioprinting of microalgae-laden hydrogels, framing fabrication not as a matter of achieving geometric fidelity, but as a process of designing conditions for living systems to persist and perform. Using alginate–Pluronic F-127 formulations as a reference system, we document key stages from microalgae preparation and hydrogel characterization through printing optimization and viability assessment. Systematic evaluation across formulation composition, extrusion pressure, and printing speed shows how biological integration shifts the printable window and why geometry-based metrics alone are insufficient – print outcomes emerge from negotiating intertwined material, process, and organism constraints. Post-printing analyses confirm sustained photosynthetic activity and cell viability within the printed constructs. Translating microalgae-based ELMs from concept to practice requires coordinated decisions spanning biology, hydrogel design, rheology, and printing parameters, while most studies report only optimized end points. The presented framework supports more reproducible and design-oriented development of microalgae-based ELMs within the biodesign community.