Preparation and Properties of Lysozyme Self-assembled Nanofibrils Films

Abstract

This study exploited the use of lysozyme (LYZ) as a material to generate amyloid fibrosis process tuned by acid-heat induction under pH2.0 and 90 ℃. The structural characteristics of the lysozyme amyloid fibrils (A-LYZ) were characterized by nanoparticle size analyzer, atomic force microscopy (AFM), circular dichroism (CD), and fluorescence spectrophotometer. The four performance indicators on original lysozyme film and lysozyme amyloid fibrils film prepared by the flow-casting method, which were tensile strength (TS), elongation at break (E), water vapor permeability (WVP) and water solubility (WS), were inspected. Furthermore, the vanillin was added to lysozyme solution to obtain an antibacterial film, and its inhibitory effects on E. coli and B. subtilis were investigated. The results showed that the average particle size of lysozyme after amyloid fibrosis increased significantly, the structures of proteins changing from spherical to linear were confirmed by atomic force microscopy (AFM). Circular dichroism (CD) showed that the protein secondary structure was changed from α-helix to β-sheet. After acid and heat treatment, the surface structure of A-LYZ films was uniform and smooth. The mechanical properties of the films were increased and the WVP and WS of the films were decreased significantly (P<0.05). Additionally, the A-LYZ-vanillin seemed to further promote better antibacterial performance compared to original lysozyme (O-LYZ), the inhibition zone against E. coli and B. subtilis was expanded to 453.75 mm2 and 293.78 mm2, respectively. A biodegradable and environmentally friendly biological packaging material was prepared in this study, which provides a great idea to be applied in food packaging fields.

Keywords

• lysozyme
• amyloid fibrosis
• film
• bacteriostatic effect
• structure characterization
• performance analysis