| 1. |
- BUCCIARELLI, SASKIA, et al.
(författare)
-
Extended Law of Corresponding States Applied to Solvent Isotope Effect on a Globular Protein
- 2016
-
Ingår i: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 7:9, s. 1610-1615
-
Tidskriftsartikel (refereegranskat)abstract
- Investigating proteins with techniques such as NMR or neutron scattering frequently requires the partial or complete substitution of D2O for H2O as a solvent, often tacitly assuming that such a solvent substitution does not significantly alter the properties of the protein. Here, we report a systematic investigation of the solvent isotope effect on the phase diagram of the lens protein gamma B-crystallin in aqueous solution as a model system exhibiting liquid-liquid phase separation. We demonstrate that the observed strong variation of the critical temperature T-c can be described by the extended law of corresponding states for all H2O/D2O ratios, where scaling of the temperature by T-c or the reduced second virial coefficient accurately reproduces the binodal, spinodal, and osmotic compressibility. These findings highlight the impact of H2O/D2O substitution on gamma B-crystallin properties and warrant further investigations into the universality of this phenomenon and its underlying mechanisms.
|
|
| 2. |
- Gibaud, Thomas, et al.
(författare)
-
New routes to food gels and glasses
- 2012
-
Ingår i: Faraday Discussions. - : Royal Society of Chemistry (RSC). - 1364-5498 .- 1359-6640. ; 158, s. 267-284
-
Tidskriftsartikel (refereegranskat)abstract
- We describe the possibility to create solid-like protein samples whose structural and mechanical properties can be varied and tailored over an extremely large range in a very controlled way through an arrested spinodal decomposition process. We use aqueous lysozyme solutions as a model globular protein system. A combination of video microscopy, small-angle neutron and X-ray scattering and reverse Monte Carlo modeling is used to characterize the structure of the bicontinuous network with two coexisting phases of a dilute protein solution and a glassy or arrested dense protein backbone at all relevant length scales. Rheological measurements are then used to determine the complex mechanical response of these protein gels as a function of protein concentration and quench temperature. While in particular the origin of the dependence of the mechanical properties on quench depth and concentration is not well understood currently, it seems ultimately connected to the particular bicontinuous structure of the arrested spinodal network created by the interplay between the early stage of a spinodal decomposition and the position of the glass line. We then generalize this behavior and discuss how this could open up new routes to prepare gel-like food systems with adjustable structural and mechanical properties. We present results from a first feasibility study where we use a depletion interaction caused by the addition of small non-adsorbing polymers to suspensions of casein micelles in order to create food gels with tunable structural and mechanical properties through an arrested spinodal decomposition process.
|
|
| 3. |
- Gilbert, Jennifer, et al.
(författare)
-
Evolution of the structure of lipid nanoparticles for nucleic acid delivery : From in situ studies of formulation to colloidal stability
- 2024
-
Ingår i: Journal of Colloid and Interface Science. - 0021-9797. ; 660, s. 66-76
-
Tidskriftsartikel (refereegranskat)abstract
- The development of lipid nanoparticle (LNP) based therapeutics for delivery of RNA has triggered the advance of new strategies for formulation, such as high throughput microfluidics for precise mixing of components into well-defined particles. In this study, we have characterised the structure of LNPs throughout the formulation process using in situ small angle x-ray scattering in the microfluidic chip, then by sampling in the subsequent dialysis process. The final formulation was investigated with small angle x-ray (SAXS) and neutron (SANS) scattering, dynamic light scattering (DLS) and cryo-TEM. The effect on structure was investigated for LNPs with a benchmark lipid composition and containing different cargos: calf thymus DNA (DNA) and two model mRNAs, polyadenylic acid (polyA) and polyuridylic acid (polyU). The LNP structure evolved during mixing in the microfluidic channel, however was only fully developed during the dialysis. The colloidal stability of the final formulation was affected by the type of incorporated nucleic acids (NAs) and decreased with the degree of base-pairing, as polyU induced extensive particle aggregation. The main NA LNP peak in the SAXS data for the final formulation were similar, with the repeat distance increasing from polyU
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Larsson, Johan, et al.
(författare)
-
The effect of the anomeric configuration on the micellization of hexadecylmaltoside surfactants
- 2019
-
Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 35:43, s. 13904-13914
-
Tidskriftsartikel (refereegranskat)abstract
- The self-assembly of the two anomeric forms of n-hexadecyl-D-maltopyranoside (denoted α-C16G2 and β-C16G2) has been studied in dilute aqueous solution by means of surface tension measurements, scattering methods (dynamic light scattering, static light scattering, and small-angle X-ray and neutron scattering) and cryo-transmission electron microscopy at different surfactant concentrations and temperatures. Surface tension measurements demonstrate differences in the surfactant adsorption at the air-water interface, where α-C16G2 shows a lower CMC than β-C16G2. Similarly, micelle morphology was found to profoundly depend on anomerism. β-C16G2 preferentially forms very elongated micelles with large persistence lengths, whereas α-C16G2 assembles into smaller micelles for which the structure varies with concentration and temperature. The differences between the two surfactant anomers in terms of self-assembly can be attributed to the interaction between neighboring headgroups. Specifically, β-C16G2 allows for a closer packing in the palisade layer, hence reducing the micelle curvature and promoting the formation of more elongated micelles. Strong intermolecular headgroup interactions may also account for the observed rigidity of the micelles.
|
|
| 7. |
- Mahmoudi, Najet, et al.
(författare)
-
Making Food Protein Gels via an Arrested Spinodal Decomposition
- 2015
-
Ingår i: The Journal of Physical Chemistry Part B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106. ; 119:50, s. 15522-15529
-
Tidskriftsartikel (refereegranskat)abstract
- We report an investigation of the structural and dynamic properties of mixtures of food colloid casein micelles and low molecular weight poly(ethylene oxide). A combination of visual observations, confocal laser scanning microscopy, diffusing wave spectroscopy, and oscillatory shear rheometry is used to characterize the state diagram of the mixtures and describe the structural and dynamic properties of the resulting fluid and solid-like structures. We demonstrate the formation of gel-like structures through an arrested spinodal decomposition mechanism. We discuss our observations in view of previous experimental and theoretical studies with synthetic and food colloids, and comment on the potential of such a route toward gels for food processing.
|
|
| 8. |
- Oliver, Ryan C, et al.
(författare)
-
Assembly of Capsids from Hepatitis B Virus Core Protein Progresses through Highly Populated Intermediates in the Presence and Absence of RNA
- 2020
-
Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 14:8, s. 10226-10238
-
Tidskriftsartikel (refereegranskat)abstract
- The genetic material of viruses is protected by protein shells that are assembled from a large number of subunits in a process that is efficient and robust. Many of the mechanistic details underpinning efficient assembly of virus capsids are still unknown. The assembly mechanism of hepatitis B capsids has been intensively researched using a truncated core protein lacking the C-terminal domain responsible for binding genomic RNA. To resolve the assembly intermediates of hepatitis B virus (HBV), we studied the formation of nucleocapsids and empty capsids from full-length hepatitis B core proteins, using time-resolved small-angle X-ray scattering. We developed a detailed structural model of the HBV capsid assembly process using a combination of analysis with multivariate curve resolution, structural modeling, and Bayesian ensemble inference. The detailed structural analysis supports an assembly pathway that proceeds through the formation of two highly populated intermediates, a trimer of dimers and a partially closed shell consisting of around 40 dimers. These intermediates are on-path, transient and efficiently convert into fully formed capsids. In the presence of an RNA oligo that binds specifically to the C-terminal domain the assembly proceeds via a similar mechanism to that in the absence of nucleic acids. Comparisons between truncated and full-length HBV capsid proteins reveal that the unstructured C-terminal domain has a significant impact on the assembly process and is required to obtain a more complete mechanistic understanding of HBV capsid formation. These results also illustrate how combining scattering information from different time-points during time-resolved experiments can be utilized to derive a structural model of protein self-assembly pathways.
|
|
| 9. |
- Urimi, Dileep, et al.
(författare)
-
Structural Characterization Study of a Lipid Nanocapsule Formulation Intended for Drug Delivery Applications Using Small-Angle Scattering Techniques
- 2022
-
Ingår i: Molecular Pharmaceutics. - : American Chemical Society (ACS). - 1543-8384 .- 1543-8392. ; 19:4, s. 1068-1077
-
Tidskriftsartikel (refereegranskat)abstract
- Lipid nanocapsules (LNCs) are increasingly being used for various drug delivery applications due to their versatile nature and ability to carry a wide variety of therapeutic drug molecules. In the present investigation, small-angle X-ray (SAXS) and neutron scattering (SANS) techniques were used to elucidate the structure of LNCs. Overall, size measurements obtained from SAXS and SANS techniques were complemented with dynamic light scattering, zeta potential, and cryogenic transmission electron microscopy measurements. The structural aspects of LNCs can be affected by drug loading and the properties of the drug. Here, the impact of drug loading on the overall structure was evaluated using DF003 as a model drug molecule. LNCs with varying compositions were prepared using a phase inversion method. Combined analysis of SAXS and SANS measurements indicated the presence of a core-shell structure in the LNCs. Further, the drug loading did not alter the overall core-shell structure of the LNCs. SANS data revealed that the core size remained unchanged with a radius of 20.0 +/- 0.9 nm for unloaded LNCs and 20.2 +/- 0.6 nm for drug-loaded LNCs. Furthermore, interestingly, the shell becomes thicker in an order of similar to 1 nm in presence of the drug compared to the shell thickness of unloaded LNCs as demonstrated by SAXS data. This can be correlated with the strong association of hydrophilic DF003 with Kolliphor HS 15, a polyethylene glycol-based surfactant that predominantly makes up the shell, resulting in a drug-rich hydrated shell.
|
|
| 10. |
- Valldeperas, Maria, et al.
(författare)
-
Interfacial properties of lipid sponge-like nanoparticles and the role of stabilizer on particle structure and surface interactions
- 2019
-
Ingår i: Soft Matter. - : ROYAL SOC CHEMISTRY. - 1744-683X .- 1744-6848. ; 15:10, s. 2178-2189
-
Tidskriftsartikel (refereegranskat)abstract
- The advantage of using nonlamellar lipid liquid crystalline phases has been demonstrated in many applications, such as drug delivery, protein encapsulation and crystallisation. We have recently reported that a mixture of mono-and diglycerides is able to form sponge-like nanoparticles (L-3-NPs) with large enough aqueous pores to encapsulate macromolecules such as proteins. Here we use small angle neutron scattering (SANS) to reveal morphology, structural and chemical composition of these polysorbate 80 (P80) stabilized sponge phase nanoparticles, not previously known. Our results suggest that L-3-NPs have a core-shell sphere structure, with a shell rich in P80. It was also found that even if P80 is mostly located on the surface, it also contributes to the formation of the inner sponge phase structure. An important aspect for the application and colloidal stability of these particles is their interfacial properties. Therefore, the interfacial behaviour of the nanoparticles on hydrophilic silica was revealed by Quartz crystal microbalance with dissipation (QCM-D) and neutron reflectivity (NR). Adsorption experiments reveal the formation of a thin lipid layer, with the dimension corresponding to a lipid bilayer after L-3-NPs are in contact with hydrophilic silica. This suggests that the diglycerol monoleate/ Capmul GMO-50/P80 particles reorganize themselves on this surface, probably due to interactions between P80 head group and SiO2.
|
|
