Phage therapy has significant potential in specifically targeting bacterial pathogens in food and medicine. There is a significant interest to combine phages with materials to enhance and broaden potential applications of phages. This study compares non-specific adsorption, protein–ligand binding, and electrostatic interactions on cellulose microfibers without any chemical or genetic modification of phages. Success in immobilization of phages on biomaterials without genetic and chemical modification can enable effective translation of naturally occurring phages and their cocktails for antimicrobial applications. The immobilization approaches were characterized by phage loading efficiency, phage distribution, and phage release from fibers. The results indicated that non-specific adsorption and protein–ligand binding had insignificant phage loading while electrostatic interactions yielded approximately 15–25% phage loading normalized to the initial titer of the phage loading solution. Confocal imaging of the electrostatically immobilized phage fibers revealed a random phage distribution on the fiber surface. Phage release from the electrostatically immobilized phage fibers indicated a slow release over a period of 24 h. Overall, the electrostatic immobilization approach bound more active phages than non-specific adsorption and protein–ligand binding and thus may be considered the optimal approach to immobilizing phages onto biomaterial surfaces
