Engineering Spirulina-Based Composites and Postbiotics Using the Electrospinning Process: Physicochemical Characterization, Antioxidant Activity, and Cytotoxicity

Postbiotics, defined as non-viable microorganisms or their structural and metabolic components, have attracted attention for their documented health effects, including modulation of gut homeostasis and inflammatory responses. Tributyrin is among the most promising postbiotics studied, and its safety profile enables it to exert its beneficial effects. However, tributyrin activity must be maintained after its uptake, underscoring the importance of selecting appropriate delivery strategies, such as its incorporation into electrospun composites. Combining postbiotics and natural antioxidants, such as Spirulina and its components, to improve their properties can be a great strategy. Therefore, the present work aimed to produce tributyrin–Spirulina composites via electrospinning. The composites obtained were characterized, and their antioxidant activity and cytotoxicity were determined. All formulations were successfully produced by electrospinning, as the composites retained the bonds of their respective components. In terms of antioxidant activity, the combination of tributyrin and C-phycocyanin was the most promising among the bioactive compounds studied. Overall, the viability and cytotoxicity results indicate that interactions among bioactive composition, redox regulation, and adhesion-dependent survival govern cellular responses to electrospun zein fibers. Tributyrin promotes metabolic adaptation over time, whereas Spirulina-derived fractions are more sensitive to formulation and culture conditions.