ε-Polylysine-coated liposomes loaded with a β-CD inclusion complex loaded with carvacrol: Preparation, characterization, and antibacterial activities

Abstract

In this study, carvacrol (Car) is first embedded in β-cyclodextrin (β-CD) by the freeze-drying method to form the β-cyclodextrin-Carvacrol inclusion compound (β-CD-Car), and then β-CD-Car liposomes (β-CD-Car-Lip) and β-CD-Car liposomes coated with ε-polylysine (ε-PL/β-CD-Car-Lip) with different concentrations (0–20 mg/mL) of β-CD-Car were prepared. The liposomes were characterized, and their physicochemical properties, in vitro release characteristics, and antibacterial activities were analyzed. Results showed that the fabricated liposomes β-CD-Car-Lip and ε-PL/β-CD-Car-Lip were nanosized and spherical, and the latter had a larger particle size (152.21 ± 14.48 to 520.45 ± 30.69 nm) and greater encapsulation efficiency (69.23 ± 0.95 to 73.25 ± 0.65%). The in vitro release study results showed that the rate of release from ε-PL-coated liposomes was much lower than that from uncoated liposomes. Inhibition of bacterial growth experiments revealed that the minimum inhibitory concentration of ε-PL/β-CD-Car-Lip against Escherichia coli and Staphylococcus aureus (0.025 and 0.05 mg/mL, respectively) was twice as low as that of β-CD-Car-Lip and nearly 12 times lower than that of Car at the same concentration. The ε-polylysine coating increased the diameter, encapsulation efficiency (EE), release time, and antibacterial activity of β-CD-Car-Lip, and the fabricated complex liposome could be applicable as an additive in the design of antibacterial packaging.