ACS Omega. 2022 Jun 27;7(27):23875-23889. doi: 10.1021/acsomega.2c02594. eCollection 2022 Jul 12.
Nanoencapsulation with safe materials improves delivery, stability, and activity of bioactive components. We report a novel safe, and effective method for the development of encapsulated antimicrobial essential oils (EO) for topical creams and gels. The method developed features three aspects that, to our knowledge, had not been previously demonstrated: (1) use of novel liposomes (LPs) to encapsulate EOs, (2) use of the EOs to replace synthetic organic solvents that are potentially toxic and/or leave harmful residues, and (3) an encapsulation process at temperatures below the boiling point of water. The LPs were made from soy lecithin, phytosterol, and α-tocopherol (vitamin E) that were synthesized using the EOs as the solvent. The liposomes were converted to nanoliposomes (NLPs) through a series of sonication, homogenization, and extrusion steps. Transmission electron microscopy indicated that the NLPs alone and nanoliposome encapsulated EOs (NLP-EOs) were spherical in shape with sizes ranging between 50 and 115 nm diameter and with negative zeta potentials ranging from -34 to -43 mV. There was no significant heavy metal contamination [As, Pb, Cd, Hg] based on inductively coupled plasma (ICP) mass spectrometry MS analyses. Nearly complete EO encapsulation (95% encapsulation efficiency) was achieved and confirmed by GC/MS. Three of the NLP-EOs made of various essential oils were used to make topical formulations (cream and gel) which exhibited antimicrobial activities against Escherichia coli (Gram negative) and Bacillus subtilis (Gram positive) bacteria. The creams with NLP-EOs were as active against the two bacteria in the antimicrobial assays as the conventional antibiotic Kanamycin that was used as positive control.