Development of an Antibacterial Poly(Lactic Acid)/Poly(ε-Caprolactone)/Tributyl Citrate Film Loaded with Staphylococcus aureus Bacteriophages Using a Sodium Alginate Coating

Biodegradable poly(lactic acid) (PLA)/poly(ε-caprolactone) (PCL) composite films were prepared with a compatibilizer (tributyl citrate, TBC) using a solvent casting method. Incorporation of 5% TBC (w/v, of PCL weight) improved tensile strength and elongation at break (21.93 ± 2.33 MPa and 21.02 ± 1.54%, respectively) and reduced water vapor permeability (from 0.12 ± 0.01 to 0.098 ± 0.01 g·mm·m2·h·kPa), indicating improved compatibility between PLA and PCL. Staphylococcus aureus phage PBSA08 demonstrated rapid and persistent bacteriolytic activity for up to 24 h, suggesting its potential as a promising antibacterial biological agent. To impart antibacterial properties to the developed PLA/PCL/TBC film, PBSA08 was loaded into sodium alginate (SA) and coated on the film surface. The optimal composition was 3% (w/v) SA and 3% (w/v) glycerol, which exhibited suitable dynamic behavior as a coating solution and excellent adhesion to the film surface. The phage-coated antibacterial films demonstrated progressive and significant inhibition against S. aureus starting from 10 to 24 h, with controlled phage-release properties. Overall, the developed active film might exert sustained and remarkable antibacterial effects through controlled release of biological agents (phage) under realistic packaging conditions.