Antibacterial bionanocomposite films based on CaSO4-crosslinked alginate and zinc oxide nanoparticles

Abstract Antibacterial bionanocomposite films (BNCFs) were successfully developed using CaSO4-crosslinked alginate and zinc oxide (ZnO) nanoparticles. The alginate film crosslinked with 1% (w/w) CaSO4 resulted in an increase in thickness (96.64 ± 6.15 μm) and tensile strength (35.15 ± 1.65 MPa), but decreased elongation at break (4.72 ± 0.69%) and water solubility (55.73 ± 1.51%) compared to the pure alginate film (89.00 μm; 24.7 MPa; 8.33%; 78.14%). Incorporation of ZnO into the BNCFs resulted in enhanced mechanical and UV barrier properties. The tensile strength of the BNCF-2.0 (containing 2% ZnO nanoparticles; w/w based on alginate) was 42.23 ± 4.65 MPa, whereas its elongation at break decreased to 2.75 ± 0.53%. BNCF-2.0 also exhibited strong UV-light barrier properties with a slight decrease in transparency. In addition, the BNCFs were effective against both Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria, demonstrating potential as antibacterial bio-based nanocomposite films for food packaging applications.