Issue 28, 2025

X-ray fluorescence standing wave study of the interaction of the antimicrobial peptide indolicidin with a supported model membrane

Abstract

Indolicidin, a cationic antimicrobial peptide, interacts with lipid bilayers through electrostatic and hydrophobic interactions, disrupting microbial membranes. We investigated the depth-dependent localization of gold-nanoparticle-labeled indolicidin in a supported model membrane using X-ray fluorescence standing wave (SWXF) analysis. Liposomes composed of DMPC and DMPG were incubated with indolicidin labeled at its C-terminus with a 1.8 nm gold nanoparticle, then deposited onto a Si/Mo multilayer substrate via vesicle bursting. SWXF measurements revealed that at low peptide incubation concentrations (2–5 μM), gold-nanoparticle-labeled indolicidin remains primarily associated with the bilayer's outer leaflet. At higher concentrations (10 μM), the peptide penetrates deeper into the bilayer, with the labeled C-terminal region either localizing near the membrane's hydrophobic core or inducing membrane breakup. These findings suggest a concentration-dependent insertion mechanism.

Graphical abstract: X-ray fluorescence standing wave study of the interaction of the antimicrobial peptide indolicidin with a supported model membrane

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Article information

Article type
Paper
Submitted
11 Mar 2025
Accepted
16 Jun 2025
First published
17 Jun 2025

Soft Matter, 2025,21, 5785-5792

X-ray fluorescence standing wave study of the interaction of the antimicrobial peptide indolicidin with a supported model membrane

G. Basnet, J. Maloney, J. Lal, E. Gaillard, D. T. Keane, E. A. Karapetrova, R. Conley and L. Lurio, Soft Matter, 2025, 21, 5785 DOI: 10.1039/D5SM00257E

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