| 1. |
- Armanious, Antonius, 1981, et al.
(författare)
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Probing the Separation Distance between Biological Nanoparticles and Cell Membrane Mimics Using Neutron Reflectometry with Sub-Nanometer Accuracy
- 2022
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 144:45, s. 20726-20738
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Tidskriftsartikel (refereegranskat)abstract
- Nanoparticle interactions with cellular membranes are controlled by molecular recognition reactions and regulate a multitude of biological processes, including virus infections, biological nanoparticle-mediated cellular communication, and drug delivery applications. Aided by the design of various supported cell membrane mimics, multiple methods have been employed to investigate these types of interactions, revealing information on nanoparticle coverage, interaction kinetics, as well as binding strength; however, precise quantification of the separation distance across which these delicate interactions occur remains elusive. Here, we demonstrate that carefully designed neutron reflectometry (NR) experiments followed by an attentive selection and application of suitable theoretical models offer a means to quantify the distance separating biological nanoparticles from a supported lipid bilayer (SLB) with sub-nanometer precision. The distance between the nanoparticles and SLBs was tuned by exploiting either direct adsorption or specific binding using DNA tethers with different conformations, revealing separation distances of around 1, 3, and 7 nm with nanometric accuracy. We also show that NR provides precise information on nanoparticle coverage, size distribution, material composition, and potential structural changes in the underlying planar SLB induced upon nanoparticle binding. The precision with which these parameters could be quantified should pave an attractive path for investigations of the interactions between nanoparticles and interfaces at length scales and resolutions that were previously inaccessible. This thus makes it possible to, for example, gain an in-depth understanding of the molecular recognition reactions of inorganic and biological nanoparticles with cellular membranes.
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| 2. |
- Badell, Maria Valldeperas, et al.
(författare)
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Lipid Sponge-Phase Nanoparticles as Carriers for Enzymes
- 2018
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Ingår i: Biophysical Journal. - : Cell Press. - 0006-3495 .- 1542-0086. ; 114:3, suppl 1, s. 15A-15A
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Immobilization of enzymes into different support materials has been widely studied as means to control their activity and stability. Here we will consider lipid liquid crystalline phases as enzyme carriers, as they have been demonstrated to have a high potential in a range of applications such as drug delivery, protein encapsulation or crystallization thanks to the wide range of self-assembly structures they can form, which have cavities of nano-scale dimensions. Furthermore, such structures have also been observed in a range of living organisms. Although, reverse cubic or hexagonal lipid aqueous phase can be used to entrap smaller biomolecules, it is still challenging to encapsulate bioactive macromolecules, such as proteins. Here, we will present a novel lipid system able to form highly swollen sponge phases (L3), with aqueous pores up to 13 nm of diameter. We will show that this structure is preserved even in excess aqueous solution, where they form sponge-like nanoparticles (L3 NPs) in which two enzymes of different sizes, Aspartic protease and beta-galactosidase (34 KDa and 460 KDa, respectively), could be included. To reveal the nature of the interaction between the enzymes and the lipid matrix, we studied the adsorption of both proteins on the lipid layers formed by the L3 NPs. The results will be discussed in terms of the ability of these nanoparticles to encapsulate and release of the proteins in the lipid matrix.
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| 3. |
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| 4. |
- Boyd, Hannah, 1994-, et al.
(författare)
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A comparison between the structures of reconstituted salivary pellicles and oral mucin (MUC5B) films.
- 2021
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier. - 0021-9797 .- 1095-7103. ; 584, s. 660-668
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Tidskriftsartikel (refereegranskat)abstract
- HYPOTHESIS: Salivary pellicles i.e., thin films formed upon selective adsorption of saliva, protect oral surfaces against chemical and mechanical insults. Pellicles are also excellent aqueous lubricants. It is generally accepted that reconstituted pellicles have a two-layer structure, where the outer layer is mainly composed of MUC5B mucins. We hypothesized that by comparing the effect of ionic strength on reconstituted pellicles and MUC5B films we could gain further insight into the pellicle structure.EXPERIMENTS: Salivary pellicles and MUC5B films reconstituted on solid surfaces were investigated at different ionic strengths by Force Spectroscopy, Quartz Crystal Microbalance with Dissipation, Null Ellipsometry and Neutron Reflectometry.FINDINGS: Our results support the two-layer structure for reconstituted salivary pellicles. The outer layer swelled when ionic strength decreased, indicating a weak polyelectrolyte behavior. While initially the MUC5B films exhibited a similar tendency, this was followed by a drastic collapse indicating an interaction between exposed hydrophobic domains. This suggests that mucins in the pellicle outer layer form complexes with other salivary components that prevent this interaction. Lowering ionic strength below physiological values also led to a partial removal of the pellicle inner layer. Overall, our results highlight the importance that the interactions of mucins with other pellicle components play on their structure.
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| 5. |
- Boyd, Hannah, 1994-, et al.
(författare)
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Effect of nonionic and amphoteric surfactants on salivary pellicles reconstituted in vitro
- 2021
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Surfactants are important components of oral care products. Sodium dodecyl sulfate (SDS) is the most common because of its foaming properties, taste and low cost. However, the use of ionic surfactants, especially SDS, is related to several oral mucosa conditions. Thus, there is a high interest in using non-ionic and amphoteric surfactants as they are less irritant. To better understand the performance of these surfactants in oral care products, we investigated their interaction with salivary pellicles i.e., the proteinaceous films that cover surfaces exposed to saliva. Specifically, we focused on pentaethylene glycol monododecyl ether (C12E5) and cocamidopropyl betaine (CAPB) as model nonionic and amphoteric surfactants respectively, and investigated their interaction with reconstituted salivary pellicles with various surface techniques: Quartz Crystal Microbalance with Dissipation, Ellipsometry, Force Spectroscopy and Neutron Reflectometry. Both C12E5 and CAPB were gentler on pellicles than SDS, removing a lower amount. However, their interaction with pellicles differed. Our work indicates that CAPB would mainly interact with the mucin components of pellicles, leading to collapse and dehydration. In contrast, exposure to C12E5 had a minimal effect on the pellicles, mainly resulting in the replacement/solubilisation of some of the components anchoring pellicles to their substrate.
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| 6. |
- Gerelli, Yuri, et al.
(författare)
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Spontaneous Formation of Cushioned Model Membranes Promoted by an Intrinsically Disordered Protein
- 2020
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 36:15, s. 3997-4004
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Tidskriftsartikel (refereegranskat)abstract
- In this article, it is shown that by exposing commonly used lipids for biomembrane mimicking studies, to a solution containing the histidine-rich intrinsically disordered protein histatin 5, a protein cushion spontaneously forms underneath the bilayer. The underlying mechanism is attributed to have an electrostatic origin, and it is hypothesized that the observed behavior is due to proton charge fluctuations promoting attractive electrostatic interactions between the positively charged proteins and the anionic surfaces, with concomitant counterion release. Hence, we anticipate that this novel "green" approach of forming cushioned bilayers can be an important tool to mimic the cell membrane without the disturbance of the solid substrate, thereby achieving a further understanding of protein-cell interactions.
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| 7. |
- Gonzalez-Martinez, Juan F, et al.
(författare)
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MUC5B mucin films under mechanical confinement : A combined neutron reflectometry and atomic force microscopy study.
- 2022
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier. - 0021-9797 .- 1095-7103. ; 614, s. 120-129
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Tidskriftsartikel (refereegranskat)abstract
- HYPOTHESIS: Among other functions, mucins hydrate and protect biological interfaces from mechanical challenges. Mucins also attract interest as biocompatible coatings with excellent lubrication performance. Therefore, it is of high interest to understand the structural response of mucin films to mechanical challenges. We hypothesized that this could be done with Neutron Reflectometry using a novel sample environment where mechanical confinement is achieved by inflating a membrane against the films.EXPERIMENTS: Oral MUC5B mucin films were investigated by Force Microscopy/Spectroscopy and Neutron Reflectometry both at solid-liquid interfaces and under mechanical confinement.FINDINGS: NR indicated that MUC5B films were almost completely compressed and dehydrated when confined at 1 bar. This was supported by Force Microscopy/Spectroscopy investigations. Force Spectroscopy also indicated that MUC5B films could withstand mechanical confinement by means of steric interactions for pressures lower than ∼ 0.5 bar i.e., mucins could protect interfaces from mechanical challenges of this magnitude while keeping them hydrated. To investigate mucin films under these pressures by means of the employed sample environment for NR, further technological developments are needed. The most critical would be identifying or developing more flexible membranes that would still meet certain requirements like chemical homogeneity and very low roughness.
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| 8. |
- Gustafsson, Emil, et al.
(författare)
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Understanding interactions of plasticisers with a phospholipid monolayer
- 2024
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Ingår i: Soft Matter. - : Royal Society of Chemistry. - 1744-683X .- 1744-6848. ; 20:13, s. 2892-2899
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Tidskriftsartikel (refereegranskat)abstract
- The use of DEHP (diethylhexyl phthalate) is now banned for most applications in Europe; the exception is for blood bags, where its toxicity is overshadowed by its ability to extend the storage life of red blood cells. Another plasticiser, BTHC (butanoyl trihexyl citrate), is used in paediatric blood bags but does not stabilise blood cells as effectively. Interactions between plasticisers and lipids are investigated with a phospholipid, DMPC, to understand the increased stability of blood cells in the presence of DEHP as well as bioaccumulation and identify differences with BTHC. Mixed monolayers of DMPC and DEHP or BTHC were studied on Langmuir troughs where surface pressure/area isotherms can be measured. Neutron reflection measurements were made to determine the composition and structure of these mixed layers. A large amount of plasticiser can be incorporated into a DMPC monolayer but once an upper limit is reached, plasticiser is selectively removed from the interface at high surface pressures. The upper limit is found to occur between 40–60 mol% for DEHP and 20–40 mol% for BTHC. The areas per molecule are also different with DEHP being in the range of 50–100 Å2 and BTHC being 65–120 Å2. Results indicate that BTHC does not fit as well as DEHP in DMPC monolayers which could help explain the differences observed with regards to the stability of blood cells.
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| 9. |
- Gustafsson, Emil, et al.
(författare)
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Understanding interactions of plasticisers with a phospholipid monolayer
- 2024
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Ingår i: Soft Matter. - : Royal Society of Chemistry. - 1744-683X .- 1744-6848. ; 20:13, s. 2892-2899
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Tidskriftsartikel (refereegranskat)abstract
- The use of DEHP (diethylhexyl phthalate) is now banned for most applications in Europe; the exception is for blood bags, where its toxicity is overshadowed by its ability to extend the storage life of red blood cells. Another plasticiser, BTHC (butanoyl trihexyl citrate), is used in paediatric blood bags but does not stabilise blood cells as effectively. Interactions between plasticisers and lipids are investigated with a phospholipid, DMPC, to understand the increased stability of blood cells in the presence of DEHP as well as bioaccumulation and identify differences with BTHC. Mixed monolayers of DMPC and DEHP or BTHC were studied on Langmuir troughs where surface pressure/area isotherms can be measured. Neutron reflection measurements were made to determine the composition and structure of these mixed layers. A large amount of plasticiser can be incorporated into a DMPC monolayer but once an upper limit is reached, plasticiser is selectively removed from the interface at high surface pressures. The upper limit is found to occur between 40-60 mol% for DEHP and 20-40 mol% for BTHC. The areas per molecule are also different with DEHP being in the range of 50-100 Å2 and BTHC being 65-120 Å2. Results indicate that BTHC does not fit as well as DEHP in DMPC monolayers which could help explain the differences observed with regards to the stability of blood cells.
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| 10. |
- Nguyen, Ky V., et al.
(författare)
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The Effect of Direct Electron Beam Patterning on the Water Uptake and Ionic Conductivity of Nafion Thin Films
- 2023
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Ingår i: Advanced Electronic Materials. - 2199-160X. ; 9:8
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Tidskriftsartikel (refereegranskat)abstract
- The effect of electron-beam patterning on the water uptake and ionic conductivity of Nafion films using a combination of X-ray photoelectron spectroscopy, quartz crystal microbalance studies, neutron reflectometry, and impedance spectroscopy is reported. The aim is to further characterize the nanoscale patterned Nafion structures recently used as a key element in novel ion-to-electron transducers by Gluschke et al. To enable this, the electron beam patterning process is developed for large areas, achieving patterning speeds approaching 1 cm2 h−1, and patterned areas as large as 7 cm2 for the neutron reflectometry studies. It is ultimately shown that electron-beam patterning affects both the water uptake and the ionic conductivity, depending on film thickness. Type-II adsorption isotherm behavior is seen for all films. For thick films (≈230 nm), a strong reduction in water uptake with electron-beam patterning is found. In contrast, for thin films (≈30 nm), electron-beam patterning enhances water uptake. Notably, for either thickness, the reduction in ionic conductivity arising from electron-beam patterning is kept to less than an order of magnitude. Mechanisms are proposed for the observed behavior based on the known complex morphology of Nafion films to motivate future studies of electron-beam processed Nafion.
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