Preparation and characteristics evaluation of chitosan-coated nanoliposomes containing ferrous sulfate

The nanoliposomes loaded with ferrous sulfate were prepared by thin-layer hydration sonication and coated with nano-chitosan. Chitosan coating (0.2% w/v) and various lecithin: ferrous sulfate ratios (5:1, 10:1, and 20:1 w/w) were characterized based on the antimicrobial activity, particle size, polydispersity index (PDI), zeta potential, and encapsulation efficiency. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of ferrous sulfate against Staphylococcus aureus ATCC 25,923, Bacillus cereus ATCC 11,778, Escherichia coli ATCC 2592, and Pseudomonas aeruginosa ATCC 9027 were 1000 and 1500 mg/mL, respectively. Nanoliposomes containing ferrous sulfate with a higher ratio of lecithin: ferrous sulfate (20:1 w/w) showed more potent antibacterial activity with the MIC and MBC values of 500 and 750 mg/mL against all test microorganisms. The particle size, PDI and zeta potential values of the nanoliposomes loaded with ferrous sulfate increased significantly compared to the free nanoliposomes (84.65 nm, 0.25, - 33.55 mV). Increasing the ratio of lecithin to ferrous sulfate from 5:1 to 20:1 (w/w) decreased the particle size (350.51 nm), PDI (0.22), and zeta potential (- 18.1 mV) and increased the encapsulation efficiency (84.6%) of ferrous sulfate loaded nanoliposomes (p < 0.05). Chitosan coating increased the antimicrobial activity of nanoliposomes toward positive values.