Introduction of broad spectrum antibacterial properties to bacterial cellulose nanofibers via immobilising ε-polylysine nanocoatings

Active packaging plays a role of a barrier to the outside environment to protect food products. The bacterial cellulose (BC) has the potential as active packaging for food due to its high purity of cellulose content and refined nanofibrous network structure mainly. In order to enhance the antibacterial activity of BC, the ε-polylysine (EPL), a natural coming peptide applied as safe food preservative, was introduced to the surfaces of BC nanofibers via crosslinking method by using procyanidins as crosslinker. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier Transformed infrared spectroscopy (FTIR), were employed to characterize the structure of BC/EPL composite nanofibers. SEM and TEM observations revealed that EPL coatings on the surfaces of BC nanofibers were composed of EPL nanoparticles and the thickness of EPL coatings was proportional to the concentration of EPL solution. FTIR results indicated that –NH3+NH3+ groups were preserved after crosslinking process and the introduction of EPL had no influence on the original chemical structure of BC. In addition, BC/EPL composite nanofibers exhibited antibacterial activity against both Escherichia coli (Gram-negative bacteria) and Staphylococcus aureus (Gram-positive bacteria). The antibacterial activity was enhanced with the increase of concentration of EPL solution.

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