| 1. |
- Dicko, Cedric, et al.
(författare)
-
NUrF-Optimization of in situ UV-vis and fluorescence and autonomous characterization techniques with small-angle neutron scattering instrumentation
- 2020
-
Ingår i: Review of Scientific Instruments. - : AMER INST PHYSICS. - 0034-6748 .- 1089-7623. ; 91:7
-
Tidskriftsartikel (refereegranskat)abstract
- We have designed, built, and validated a (quasi)-simultaneous measurement platform called NUrF, which consists of neutron small-angle scattering, UV-visible, fluorescence, and densitometry techniques. In this contribution, we illustrate the concept and benefits of the NUrF setup combined with high-performance liquid chromatography pumps to automate the preparation and measurement of a mixture series of Brij35 nonionic surfactants with perfluorononanoic acid in the presence of a reporter fluorophore (pyrene).
|
|
| 2. |
- Hazra, Nabanita, et al.
(författare)
-
Structure of Responsive Microgels down to Ultralow Cross-Linkings
- 2023
-
Ingår i: Macromolecules. - 0024-9297.
-
Tidskriftsartikel (refereegranskat)abstract
- Although microgels have been widely used as model systems for soft colloids, their properties are still far from being completely understood. This stems from their heterogeneous structure strongly differing from that of an idealized polymeric network. Indeed, microgels synthesized by conventional precipitation polymerization exhibit not only a fuzzy structure with respect to the difference of reactivity between monomers and cross-linker molecules but also static heterogeneities related to the distribution in the length of the chains constituting their network. These features can be reproduced in computer simulations using the so-called in silico synthesis. Hereby, a designing force acting on the cross-linkers during the in silico synthesis allows us to finely adjust the radial density distribution and, thus, to reproduce both the fuzziness and local heterogeneities present in real microgel systems. In this study, poly(N-isopropylacrylamide) (PNIPAM) microgels were synthesized with different degrees of cross-linking ccross down to cross-linker free conditions corresponding to so-called ultralow cross-linked microgels (ULC microgels). The experimental characterization was accompanied by numerical simulations at different ccross with the same designing force, which is found to be independent of the cross-linker concentration, as well as the size of the microgels. For the ULC microgels, it was found that no designing force is needed, but the number density of the network is much smaller. The number of effective cross-linkers in this case is found to be ∼0.1%. The form factors of all microgels were measured at different temperatures across their volume phase transition with both static light scattering and small-angle X-ray scattering, favorably comparing them to the simulated ones. Furthermore, the swelling behavior was experimentally determined by dynamic light scattering and viscosimetry and also compared to the simulated results. Finally, experimental and simulated results indicate that the cross-linking dependence of the swelling is well-described by theoretical predictions for the isotropic swelling of an ideal network despite the highly heterogeneous character of real microgels.
|
|
| 3. |
- Lee, Wai Tung, et al.
(författare)
-
Polarisation Development at the European Spallation Source
- 2023
-
Ingår i: EPJ Web of Conferences. - 2100-014X. ; 286, s. 03004-03004
-
Tidskriftsartikel (refereegranskat)abstract
- To meet the ever-increasing user demand, eleven of the fifteen European Spallation Source (ESS) instruments under construction aim to offer polarised neutrons for user experiments. They include an imaging instrument, a SANS instruments, two reflectometers, three diffractometers, and four spectrometers. In conjunction with in-kind contributions and instrumentation grants, the ESS Polarisation Project will support the incorporation of polarisation analysis on eight of the eleven instruments. The project aims to deliver polarised neutrons for first-science experiments as instruments enter operation. Different polariser and polarisation analyser techniques will be available to accommodate the specifics of experiments on a given instrument. Polarised 3He neutron spin filter using either Metastable Optical Pumping (MEOP) or Spin-Exchange Optical Pumping (SEOP) techniques will provide shared-use equipment among many instruments, with SEOP’s main application being in situ beam-polarisation. Several instruments will also use polarising-supermirror devices. To provide wide-bandwidth spin-flipping capability to the time-of-flight instruments, Adiabatic Fast Passage (AFP) neutron spin flippers, also known as gradient-field radiofrequency spin flippers will be the main method of choice. Devices based on the same AFP principle will also be used to flip 3He nuclear spins. We are constructing our first 3He polariser setup, including field coils to produce highly uniform magnetic field. Monte Carlo simulations are being done for the supermirror polarisers. To ensure science-focused development, we are working with university partners in doing scientific experiments with polarised neutrons. These are some of the activities developing polarisation analysis for ESS instruments in our project.
|
|
| 4. |
- Lessard, Christopher J., et al.
(författare)
-
Variants at multiple loci implicated in both innate and adaptive immune responses are associated with Sjogren's syndrome
- 2013
-
Ingår i: Nature Genetics. - : NATURE PUBLISHING GROUP, 75 VARICK ST, 9TH FLR, NEW YORK, NY 10013-1917 USA. - 1061-4036 .- 1546-1718. ; 45:11, s. 1284-
-
Tidskriftsartikel (refereegranskat)abstract
- Sjogrens syndrome is a common autoimmune disease (affecting similar to 0.7% of European Americans) that typically presents as keratoconjunctivitis sicca and xerostomia. Here we report results of a large-scale association study of Sjogrens syndrome. In addition to strong association within the human leukocyte antigen (HLA) region at 6p21 (P-meta = 7.65 x 10(-114)), we establish associations with IRF5-TNPO3 (P-meta = 2.73 x 10(-19)), STAT4 (Pmeta = 6.80 x 10-15), IL12A (P-meta = 1.17 x 10(-10)), FAM167ABLK (P-meta = 4.97 x 10(-10)), DDX6-CXCR5 (P-meta = 1.10 x 10(-8)) and TNIP1 (P-meta = 3.30 x 10(-8)). We also observed suggestive associations (P-meta andlt; 5 x 10(-5)) with variants in 29 other regions, including TNFAIP3, PTTG1, PRDM1, DGKQ, FCGR2A, IRAK1BP1, ITSN2 and PHIP, among others. These results highlight the importance of genes that are involved in both innate and adaptive immunity in Sjogrens syndrome.
|
|
| 5. |
- Li, He, et al.
(författare)
-
Identification of a Sjögren's syndrome susceptibility locus at OAS1 that influences isoform switching, protein expression, and responsiveness to type I interferons
- 2017
-
Ingår i: PLOS Genetics. - : PUBLIC LIBRARY SCIENCE. - 1553-7390 .- 1553-7404. ; 13:6
-
Tidskriftsartikel (refereegranskat)abstract
- Sjogren's syndrome (SS) is a common, autoimmune exocrinopathy distinguished by keratoconjunctivitis sicca and xerostomia. Patients frequently develop serious complications including lymphoma, pulmonary dysfunction, neuropathy, vasculitis, and debilitating fatigue. Dysregulation of type I interferon (IFN) pathway is a prominent feature of SS and is correlated with increased autoantibody titers and disease severity. To identify genetic determinants of IFN pathway dysregulation in SS, we performed cis-expression quantitative trait locus (eQTL) analyses focusing on differentially expressed type I IFN-inducible transcripts identified through a transcriptome profiling study. Multiple cis-eQTLs were associated with transcript levels of 2'-5'-oligoadenylate synthetase 1 (OAS1) peaking at rs10774671 (PeQTL = 6.05 x 10(-14)). Association of rs10774671 with SS susceptibility was identified and confirmed through meta-analysis of two independent cohorts (P-meta = 2.59 x 10(-9); odds ratio = 0.75; 95% confidence interval = 0.66-0.86). The risk allele of rs10774671 shifts splicing of OAS1 from production of the p46 isoform to multiple alternative transcripts, including p42, p48, and p44. We found that the isoforms were differentially expressed within each genotype in controls and patients with and without autoantibodies. Furthermore, our results showed that the three alternatively spliced isoforms lacked translational response to type I IFN stimulation. The p48 and p44 isoforms also had impaired protein expression governed by the 3' end of the transcripts. The SS risk allele of rs10774671 has been shown by others to be associated with reduced OAS1 enzymatic activity and ability to clear viral infections, as well as reduced responsiveness to IFN treatment. Our results establish OAS1 as a risk locus for SS and support a potential role for defective viral clearance due to altered IFN response as a genetic pathophysiological basis of this complex autoimmune disease.
|
|
| 6. |
- Nickel, Anne C., et al.
(författare)
-
Anisotropic Hollow Microgels That Can Adapt Their Size, Shape, and Softness
- 2019
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992.
-
Tidskriftsartikel (refereegranskat)abstract
- The development of soft anisotropic building blocks is of great interest for various applications in soft matter. Furthermore, such systems would be important model systems for ordering phenomena in fundamental soft matter science. In this work, we address the challenge of creating hollow and anisotropically shaped thermoresponsive microgels, polymeric networks with a solvent filled cavity in their center that are swollen in a good solvent. Sacrificial elliptical hematite silica particles were utilized as a template for the synthesis of a cross-linked N-isopropylacrylamide (NIPAm) shell. By varying the amount of NIPAm, two anisotropic microgels were synthesized with either a thin or thick microgel shell. We characterized these precursor core-shell and the resulting hollow microgels using a combination of light, X-ray, and neutron scattering. New form factor models, accounting for the cavity, the polymer distribution and the anisotropy, have been developed for fitting the scattering data. With such models, we demonstrated the existence of the cavity and simultaneously the anisotropic character of the microgels. Furthermore, we show that the thickness of the shell has a major influence on the shape and the cavity dimension of the microgel after etching of the sacrificial core. Finally, the effect of temperature is investigated, showing that changes in size, softness, and aspect ratio are triggered by temperature.
|
|
| 7. |
- Nickel, Anne C., et al.
(författare)
-
Beyond simple self-healing : How anisotropic nanogels adapt their shape to their environment
- 2022
-
Ingår i: The Journal of chemical physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 157:19, s. 194901-194901
-
Tidskriftsartikel (refereegranskat)abstract
- The response of soft colloids to crowding depends sensitively on the particles' compressibility. Nanogel suspensions provide model systems that are often studied to better understand the properties of soft materials and complex fluids from the formation of colloidal crystals to the flow of viruses, blood, or platelet cells in the body. Large spherical nanogels, when embedded in a matrix of smaller nanogels, have the unique ability to spontaneously deswell to match their size to that of the nanogel composing the matrix. In contrast to hard colloids, this self-healing mechanism allows for crystal formation without giving rise to point defects or dislocations. Here, we show that anisotropic ellipsoidal nanogels adapt both their size and their shape depending on the nature of the particles composing the matrix in which they are embedded. Using small-angle neutron scattering with contrast variation, we show that ellipsoidal nanogels become spherical when embedded in a matrix of spherical nanogels. In contrast, the anisotropy of the ellipsoid is enhanced when they are embedded in a matrix of anisotropic nanogels. Our experimental data are supported by Monte Carlo simulations that reproduce the trend of decreasing aspect ratio of ellipsoidal nanogels with increasing crowding by a matrix of spherical nanogels.
|
|
| 8. |
- Sanchez-Fernandez, Adrian, et al.
(författare)
-
An integrative toolbox to unlock the structure and dynamics of protein-surfactant complexes
- 2020
-
Ingår i: Nanoscale Advances. - : Royal Society of Chemistry (RSC). - 2516-0230. ; 2:9, s. 4011-4023
-
Tidskriftsartikel (refereegranskat)abstract
- The interactions between protein and surfactants play an important role in the stability and performance of formulated products. Due to the high complexity of such interactions, multi-technique approaches are required to study these systems. Here, an integrative approach is used to investigate the various interactions in a model system composed of human growth hormone and sodium dodecyl sulfate. Contrast variation small-angle neutron scattering was used to obtain information on the structure of the protein, surfactant aggregates and surfactant-protein complexes. 1H and 1H-13C HSQC nuclear magnetic resonance spectroscopy was employed to probe the local structure and dynamics of specific amino acids upon surfactant addition. Through the combination of these advanced methods with fluorescence spectroscopy, circular dichroism and isothermal titration calorimetry, it was possible to identify the interaction mechanisms between the surfactant and the protein in the pre- and post-micellar regimes, and interconnect the results from different techniques. As such, the protein was revealed to evolve from a partially unfolded conformation at low SDS concentration to a molten globule at intermediate concentrations, where the protein conformation and local dynamics of hydrophobic amino acids are partially affected compared to the native state. At higher surfactant concentrations the local structure of the protein appears disrupted, and a decorated micelle structure is observed, where the protein is wrapped around a surfactant assembly. Importantly, this integrative approach allows for the identification of the characteristic fingerprints of complex transitions as seen by each technique, and establishes a methodology for an in-detail study of surfactant-protein systems. This journal is
|
|
