Preparation, characterization and releasing property of antibacterial nano-capsules composed of ε-PL-EGCG and sodium alginate-chitosan

Aquatic products with high moisture and protein content are susceptible to bacterial growth and spoilage. Searching for efficient and safe natural antibacterial agents to preserve aquatic products has been concerned widely. In this study, ε-poly-lysine-epigallocatechin gallate/sodium alginate-chitosan nanoparticles (ε-PL-EGCG/SA-CS NPs) were prepared using sodium alginate and chitosan as wall materials and ε-PL-EGCG as core material. The size of nanoparticles was about 200 nm and the encapsulation efficiency was 78.2%. Transmission electron microscopy (TEM) images confirmed the prepared spherical nanoparticles. Fourier transform infrared spectroscopy (FTIR) and multifunctional polycrystalline X-ray diffraction (XRD) spectra indicated that ε-PL-EGCG was encapsulated in the nanoparticles. Thermo-gravimetric analysis (TGA) illustrated that the thermal stability of encapsulated ε-PL-EGCG was improved more than that of bare ε-PL-EGCG. In addition, in vitro release assays showed that the ε-PL-EGCG was released continuously over 36 h. Bacteria inhibition results showed that the ε-PL-EGCG/SA-CS NPs significantly inhibited specific spoilage bacteria E3 that screened out of aquatic products, Escherichia coli and Staphylococcus aureus. In conclusion, ε-PL-EGCG/SA-CS NPs are an effective antibacterial means with wide application prospects in the field of aquatic products preservation.