| 1. |
- Gerelli, Yuri, et al.
(författare)
-
Softness matters : effects of compression on the behavior of adsorbed microgels at interfaces.
- 2024
-
Ingår i: Soft Matter. - : Royal Society of Chemistry. - 1744-683X .- 1744-6848. ; 20:17, s. 3653-3665
-
Tidskriftsartikel (refereegranskat)abstract
- Deformable colloids and macromolecules adsorb at interfaces as they decrease the interfacial energy between the two media. The deformability, or softness, of these particles plays a pivotal role in the properties of the interface. In this study, we employ a comprehensive in situ approach, combining neutron reflectometry with molecular dynamics simulations, to thoroughly examine the profound influence of softness on the structure of microgel Langmuir monolayers under compression. Lateral compression of both hard and soft microgel particle monolayers induces substantial structural alterations, leading to an amplified protrusion of the microgels into the aqueous phase. However, a critical distinction emerges: hard microgels are pushed away from the interface, in stark contrast to the soft ones, which remain firmly anchored to it. Concurrently, on the air-exposed side of the monolayer, lateral compression induces a flattening of the surface of the hard monolayer. This phenomenon is not observed for the soft particles as the monolayer is already extremely flat even in the absence of compression. These findings significantly advance our understanding of the key role of softness on both the equilibrium phase behavior of the monolayer and its effect when soft colloids are used as stabilizers of responsive interfaces and emulsions.
|
|
| 2. |
- Nielsen, Josefine Eilsø, et al.
(författare)
-
Lipid membrane interactions of self-assembling antimicrobial nanofibers : effect of PEGylation
- 2020
-
Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 10, s. 35329-35340
-
Tidskriftsartikel (refereegranskat)abstract
- Supramolecular assembly and PEGylation (attachment of a polyethylene glycol polymer chain) of peptides can be an effective strategy to develop antimicrobial peptides with increased stability, antimicrobial efficacy and hemocompatibility. However, how the self-assembly properties and PEGylation affect their lipid membrane interaction is still an unanswered question. In this work, we use state-of-the-art small angle X-ray and neutron scattering (SAXS/SANS) together with neutron reflectometry (NR) to study the membrane interaction of a series of multidomain peptides, with and without PEGylation, known to self-assemble into nanofibers. Our approach allows us to study both how the structure of the peptide and the membrane are affected by the peptide–lipid interactions. When comparing self-assembled peptides with monomeric peptides that are not able to undergo assembly due to shorter chain length, we found that the nanofibers interact more strongly with the membrane. They were found to insert into the core of the membrane as well as to absorb as intact fibres on the surface. Based on the presented results, PEGylation of the multidomain peptides leads to a slight net decrease in the membrane interaction, while the distribution of the peptide at the interface is similar to the non-PEGylated peptides. Based on the structural information, we showed that nanofibers were partially disrupted upon interaction with phospholipid membranes. This is in contrast with the considerable physical stability of the peptide in solution, which is desirable for an extended in vivo circulation time.
|
|
| 3. |
- Nordström, Randi, et al.
(författare)
-
Membrane Interactions of Antimicrobial Peptide-Loaded Microgels
- 2020
-
Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797 .- 1095-7103. ; 562, s. 322-332
-
Tidskriftsartikel (refereegranskat)abstract
- 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 mu M) 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 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 alpha-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.
|
|
| 4. |
- Waldie, Sarah, et al.
(författare)
-
Lipoprotein ability to exchange and remove lipids from model membranes as a function of fatty acid saturation and presence of cholesterol.
- 2020
-
Ingår i: Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids. - : Elsevier. - 1388-1981 .- 1879-2618. ; 1865:10
-
Tidskriftsartikel (refereegranskat)abstract
- Lipoproteins play a central role in the development of atherosclerosis. High and low-density lipoproteins (HDL and LDL), known as 'good' and 'bad' cholesterol, respectively, remove and/or deposit lipids into the artery wall. Hence, insight into lipid exchange processes between lipoproteins and cell membranes is of particular importance in understanding the onset and development of cardiovascular disease. In order to elucidate the impact of phospholipid tail saturation and the presence of cholesterol in cell membranes on these processes, neutron reflection was employed in the present investigation to follow lipid exchange with both HDL and LDL against model membranes. Mirroring clinical risk factors for the development of atherosclerosis, lower exchange was observed in the presence of cholesterol, as well as for an unsaturated phospholipid, compared to faster exchange when using a fully saturated phospholipid. These results highlight the importance of membrane composition on the interaction with lipoproteins, chiefly the saturation level of the lipids and presence of cholesterol, and provide novel insight into factors of importance for build-up and reversibility of atherosclerotic plaque. In addition, the correlation between the results and well-established clinical risk factors suggests that the approach taken can be employed also for understanding a broader set of risk factors including, e.g., effects of triglycerides and oxidative stress, as well as local effects of drugs on atherosclerotic plaque formation.
|
|
