Human Antimicrobial Peptide Triggered Colloidal Transformations in Bacteria Membrane Lipopolysaccharides

Area of Science:

• Biomaterials Science
• Nanotechnology
• Microbiology

Background:

• Rising antibiotic resistance necessitates novel antimicrobial strategies.
• Antimicrobial peptides (AMPs) show promise, but their interaction with bacterial outer membranes, particularly lipopolysaccharides (LPS), requires detailed understanding.
• LL-37, a human cathelicidin AMP, is a candidate for antimicrobial therapies.

Purpose of the Study:

• To elucidate the structural interplay between Escherichia coli LPS and the AMP LL-37.
• To investigate the behavior of LPS-LL-37 complexes within glyceryl monooleate (GMO) lipid nanoparticle formulations.
• To inform the design of LPS-responsive antimicrobial nanocarriers.

Main Methods:

• Synchrotron small-angle X-ray scattering (SAXS)
• Dynamic light scattering (DLS)
• Cryogenic transmission electron microscopy (cryo-TEM)
• Circular dichroism (CD) spectroscopy

Main Results:

• LPS forms elongated micelles, which transform into multilamellar structures upon LL-37 addition.
• LL-37 interaction with LPS alters its secondary structure.
• Encapsulation of LL-37 in GMO cubosomes leads to swelling, while addition of LPS to multilamellar GMO/LL-37 nanocarriers results in unstructured particles.

Conclusions:

• Detailed insights into LPS-LL-37 interactions are provided for both free and encapsulated forms.
• Findings guide the development of advanced LPS-responsive antimicrobial nanocarriers.
• This research aids in formulating nanomaterials for enhanced bacterial membrane penetration and destruction.