3D-printable emulsion gels structured via depletion attraction from Chlamydomonas reinhardtii biomass

Depletion attraction, driven by interactions between colloidal particles and non-adsorbing macromolecules, offers a simple and effective route for fabricating emulsion gels with desirable viscoelasticity and shear-thinning behavior essential for extrusion-based three-dimensional (3D) food printing. In this study, we propose a facile, additive-free strategy to construct emulsion gels by leveraging the intrinsic depletion effects derived from the biomolecular components of Chlamydomonas reinhardtii (C. reinhardtii) biomass. By adjusting the oil-to-water phase ratio, self-supporting Pickering-type C. reinhardtii emulsion (CRE) gels were successfully developed. Autofluorescence spectroscopy, microscopy, and SDS-PAGE analyses revealed that chlorophyll-containing pigment-protein complexes served as interfacial stabilizers, while endogenous polysaccharides acted as natural depletants. Lower water-to-oil ratios with enhanced depletion interactions, promoting droplet shrinkage and cohesive gel formation with plastic-like mechanical behavior. The CRE inks exhibited excellent printing precision, and standardized dysphagia tests showed that they met the criteria for grade four, highlighting their potential as microalgae-derived materials for sustainable 3D food printing, particularly for personalized nutrition and for individuals with chewing and swallowing problems.