Potential use of niosomes for encapsulation of nisin and EDTA and their antibacterial activity enhancement

Different formulations of niosomes were prepared using Span 80 with sodium stearoyl lactate (SSL) and PEG400 as additives. The corresponding niosomes were used for encapsulation of antibacterial agents including nisin and EDTA. Characterization of unloaded and loaded niosomes was carried out by means of size, zeta-potential, and also encapsulation efficiency and antibacterial activity specifically for loaded niosomes. Unloaded niosomes were stable at least 2 months when temperature challenge was applied at 4 °C, RT, and 45 °C. An addition of 0.5 mM SSL, both with and without PEG was found to enhance stability of loaded niosomes throughout 2-months of storage. Effect of niosome formulation to zeta potential and encapsulation efficiency of nisin and EDTA was discussed in this paper. A 96-well plate assay was used to assess the antibacterial activity between free and encapsulated forms of nisin and EDTA against Staphylococcus aureus and Escherichia coli. A higher and longer-lasting inhibition effect of encapsulated nisin and EDTA against S. aureus as compared to their free forms was observed in an encapsulation using niosome formulations S_0.5s and S_1.0s, both with and without PEG. To our knowledge, this work is the first report on applying niosomes for encapsulation of nisin and EDTA. The results in this study offer an alternative approach to encapsulation of nisin as good as or better than liposomes.