TY - JOUR

T1 - Membrane interactions of antimicrobial peptide-loaded microgels

AU - Nordström, Randi

AU - Browning, Kathryn L

AU - Parra-Ortiz, Elisa

AU - Damgaard, Liv Sofia Elinor

AU - Häffner, Sara Malekkhaiat

AU - Maestro, Armando

AU - Campbell, Richard A

AU - Cooper, Joshaniel F K

AU - Malmsten, Martin

N1 - Copyright © 2019 Elsevier Inc. All rights reserved.

PY - 2020

Y1 - 2020

N2 - In the present study, lipid membrane interactions of anionic poly(ethyl acrylate-co-methacrylic acid) (MAA) microgels as carriers for the cationic antimicrobial peptide LL-37 (LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES) were investigated. In doing so, neutron reflectometry (NR), Fourier-transform infrared spectroscopy with attenuated total reflection (FTIR-ATR), zeta potential, ellipsometry, and circular dichroism spectroscopy (CD) experiments were employed to investigate the relative importance of membrane interactions of peptide-loaded microgel particles and of released peptide. For the free peptide, NR results showed membrane binding occurring preferentially in the tail region in a concentration-dependent manner. At low peptide concentration (0.3 μM) only peptide insertion in the outer leaflet was seen, however, pronounced membrane defects and peptide present in both leaflets was observed at higher peptide concentration (5.0 μM). LL-37 loaded into MAA microgels qualitatively mirrored these effects regarding both peptide localization within the membrane and concentration-dependent defect formation. In addition, very limited membrane binding of microgel particles was observed, in agreement with FTIR-ATR and liposome leakage results. FTIR-ATR showed LL-37 to undergo α-helix formation on membrane insertion, also supported by CD results, the kinetics of which was substantially reduced for microgel-loaded LL-37 due to sustained peptide release. Together, these findings demonstrate that membrane interactions for microgel-loaded LL-37 are dominated by released peptide, but also that slow release of microgel-loaded LL-37 translates into kinetic effects on peptide-membrane interactions, relating to both peptide localization within the bilayer, and to bilayer structure.

AB - In the present study, lipid membrane interactions of anionic poly(ethyl acrylate-co-methacrylic acid) (MAA) microgels as carriers for the cationic antimicrobial peptide LL-37 (LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES) were investigated. In doing so, neutron reflectometry (NR), Fourier-transform infrared spectroscopy with attenuated total reflection (FTIR-ATR), zeta potential, ellipsometry, and circular dichroism spectroscopy (CD) experiments were employed to investigate the relative importance of membrane interactions of peptide-loaded microgel particles and of released peptide. For the free peptide, NR results showed membrane binding occurring preferentially in the tail region in a concentration-dependent manner. At low peptide concentration (0.3 μM) only peptide insertion in the outer leaflet was seen, however, pronounced membrane defects and peptide present in both leaflets was observed at higher peptide concentration (5.0 μM). LL-37 loaded into MAA microgels qualitatively mirrored these effects regarding both peptide localization within the membrane and concentration-dependent defect formation. In addition, very limited membrane binding of microgel particles was observed, in agreement with FTIR-ATR and liposome leakage results. FTIR-ATR showed LL-37 to undergo α-helix formation on membrane insertion, also supported by CD results, the kinetics of which was substantially reduced for microgel-loaded LL-37 due to sustained peptide release. Together, these findings demonstrate that membrane interactions for microgel-loaded LL-37 are dominated by released peptide, but also that slow release of microgel-loaded LL-37 translates into kinetic effects on peptide-membrane interactions, relating to both peptide localization within the bilayer, and to bilayer structure.

U2 - 10.1016/j.jcis.2019.12.022

DO - 10.1016/j.jcis.2019.12.022

M3 - Journal article

C2 - 31855795

VL - 562

SP - 322

EP - 332

JO - Journal of Colloid and Interface Science

JF - Journal of Colloid and Interface Science

SN - 0021-9797

ER -