The development of antimicrobial resistance is a great challenge within the health sector. Antimicrobial peptides (AMPs) are a group of antibiotics that have gained more and more attraction recently. However, these peptides suffer from relatively low stability due to proteolytic and chemical degradation. Carrier systems protecting the peptides are highly needed for achieving efficient treatments. The aim of this work was to investigate the use of lipid-based liquid crystalline phases, and particle dispersions of those i.e. cubosomes and hexosomes, as delivery vehicles for AMPs targeting bacterial membranes. Characterization of the liquid crystalline structures was performed using small angle x-ray scattering, dynamic light scattering, ζ-potential, and cryogenic transmission electron microscopy and peptide loading efficacy by liquid chromatography. Antimicrobial effect of the peptide loaded nanoparticles was studied in vitro using 7 bacterial strains. Proteolytic protection as well as the antimicrobial effect after proteolysis, was also investigated. Interaction between the AMP-loaded particles and supported bacterial mimicking membranes was performed to investigate the delivery mechanism. Results showed that AMPs can induce phase transitions in liquid crystalline systems, and depended on the nature of the introduced AMP. The peptide encapsulation efficacy varied among the different liquid crystalline nanoparticles. The peptide encapsulation did also depend on the peptide loading strategy used. The In vitro bacterial assays displayed a preserved or sometimes a slightly enhanced bacterial killing for cubosomes. Moreover, results showed that the particles can protect the proteolytic sensitive peptide LL-37 from degradation, resulting in a significant better bactericidal effect after proteolysis.

Liquid crystalline particles for delivery of antimicrobial peptides

255th National Meeting (2018)

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