TY - JOUR

T1 - Degradable dendritic nanogels as carriers for antimicrobial peptides

AU - Nordstrom, Randi

AU - Andren, Oliver C. J.

AU - Singh, Shalini

AU - Malkoch, Michael

AU - Davoudi, Mina

AU - Schmidtchen, Artur

AU - Malmsten, Martin

PY - 2019

Y1 - 2019

N2 - In the present study, we investigate degradable anionic dendritic nanogels (DNG) as carriers for antimicrobial peptides (AMPS). In such systems, the dendritic part contains carboxylic acid-based anionic binding sites for cationic AMPs, whereas linear poly(ethylene glycol) (PEG) chains form a shell for promotion of biological stealth. In order to clarify factors influencing membrane interactions of such systems, we here address effects of nanogel charge, cross-linking, and degradation on peptide loading/release, as well as consequences of these factors for lipid membrane interactions and antimicrobial effects. The DNGs were found to bind the AMPs LL-37 (LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES) and DPK-060 (GKHKNKGKKNGKHNGWKWWW). For the smaller DPK-060 peptide, loading was found to increase with increasing nanogel charge density. For the larger LL-37, on the other hand, peptide loading was largely insensitive to nanogel charge density. In line with this, results on the secondary structure, as well as on the absence of stabilization from proteolytic degradation by the nanogels, show that the larger LL-37 is unable to enter into the interior of the nanogels. While 40-60% nanogel degradation occurred over 10 days, promoted at high ionic strength and lower cross-linking density/higher anionic charge content, peptide release at physiological ionic strength was substantially faster, and membrane destabilization not relying on nanogel degradation. Ellipsometry and liposome leakage experiments showed both free peptide and peptide/DNG complexes to cause membrane destabilization, indicated also by antimicrobial activities being comparable for nanogel-bound and free peptide. Finally, the DNGs were demonstrated to display low toxicity towards erythrocytes even at peptide concentrations of 100 mu M. (C) 2019 Elsevier Inc. All rights reserved.

AB - In the present study, we investigate degradable anionic dendritic nanogels (DNG) as carriers for antimicrobial peptides (AMPS). In such systems, the dendritic part contains carboxylic acid-based anionic binding sites for cationic AMPs, whereas linear poly(ethylene glycol) (PEG) chains form a shell for promotion of biological stealth. In order to clarify factors influencing membrane interactions of such systems, we here address effects of nanogel charge, cross-linking, and degradation on peptide loading/release, as well as consequences of these factors for lipid membrane interactions and antimicrobial effects. The DNGs were found to bind the AMPs LL-37 (LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES) and DPK-060 (GKHKNKGKKNGKHNGWKWWW). For the smaller DPK-060 peptide, loading was found to increase with increasing nanogel charge density. For the larger LL-37, on the other hand, peptide loading was largely insensitive to nanogel charge density. In line with this, results on the secondary structure, as well as on the absence of stabilization from proteolytic degradation by the nanogels, show that the larger LL-37 is unable to enter into the interior of the nanogels. While 40-60% nanogel degradation occurred over 10 days, promoted at high ionic strength and lower cross-linking density/higher anionic charge content, peptide release at physiological ionic strength was substantially faster, and membrane destabilization not relying on nanogel degradation. Ellipsometry and liposome leakage experiments showed both free peptide and peptide/DNG complexes to cause membrane destabilization, indicated also by antimicrobial activities being comparable for nanogel-bound and free peptide. Finally, the DNGs were demonstrated to display low toxicity towards erythrocytes even at peptide concentrations of 100 mu M. (C) 2019 Elsevier Inc. All rights reserved.

KW - Antimicrobial peptide

KW - Degradable

KW - Dendritic

KW - Hyperbranched drug delivery

KW - Membrane

KW - Nanogel

U2 - 10.1016/j.jcis.2019.07.028

DO - 10.1016/j.jcis.2019.07.028

M3 - Journal article

C2 - 31330426

VL - 554

SP - 592

EP - 602

JO - Journal of Colloid and Interface Science

JF - Journal of Colloid and Interface Science

SN - 0021-9797

ER -