Search

Superparamagnetic iron oxide nanoparticles (SPIONs) are a promising tool for biomedical applications, including drug delivery, imaging, and magnetic hyperthermia. However, their tendency to agglomerate limits their performance efficiency. To overcome this limitation, a coating can be applied during or after synthesis. This work investigates the effect of three biocompatible coatings, namely sodium citrate, (3-aminopropyl)triethoxysilane (APTES), and dextran, on controlling the agglomeration of iron oxide nanoparticles. Various experimental techniques were used to characterize the structural and magnetic properties of the coated nanoparticles, including cryogenic transmission electron microscopy (cryo-TEM), magnetometry, Mössbauer spectroscopy, and small-angle X-ray and neutron scattering. The results indicate that the coatings effectively stabilize the nanoparticles, leading to clusters of different sizes that modify their magnetic behaviour due to magnetic inter-particle interactions. The oxidation kinetics of the nanoparticles prepared with the various coating materials were investigated to characterize their oxidation behaviour and stability over time. This research provides valuable insights into the design of an optimized nanoparticle functionalization strategy for biomedical applications. [ABSTRACT FROM AUTHOR]

KWS-2 is a classical small angle neutron diffractometer where, following recent upgrades, the pinhole mode with different neutron-wavelengths and detector distances can be combined with focusing mode with MgF2 lenses to reach a wide Q-range between 2x10−4 and 1.0 Å−1. Further upgrades of the detection system and sample positioning system are currently in progress. A wide-angle detection prototype is currently being tested and optimized aiming at measurement conditions over an extended Q-range up to 2.0 Å−1, which will be beneficial for semi-crystalline materials and small biological morphologies. The high neutron flux provided by the FRMII reactor and transported by the optimized neutron guidance system requires an adjustment of the measurement routine for a more rational use of the beam time. A new versatile in-beam sample positioning system, which includes a multi-position carousel with temperature control, robotic elements, and a storage pool for sample cuvettes, has just been installed at the instrument’s sample position. This allows the instrument to be continuously supplied with samples and provides the ability to combine experiments on similar samples or topics into a common long experimental session. Here we report in detail on the expanded Q-range option of the KWS-2 from the perspective of current performance and planned upgrades, as well as the new sample positioning system with robotic elements.

Plant-based emulsions with increasing dry matter content show a large range of structural features from atomic to macroscopic length scales, which may be examined with scattering techniques in reciprocal space and microscopic techniques in real space. In this contribution, we focus on plan-based emulsions in terms of mesoscopic structure, and report on the impact of temperature and humidity on the structure measured via environmental scanning electron microscopy (ESEM) in real space. Small angle x-ray scattering in reciprocal space extends the knowledge on structural properties on smaller length scales at different temperature. Decreasing the humidity for the ESEM experiments revealed structural properties of different products. Temperature decrease from room temperature to 5 °C showed emerging crystalline peaks during SAXS measurements.

The functional efficacy of colocalized, linked protein domains is dependent on linker flexibility and system compaction. However, the detailed characterization of these properties in aqueous solution presents an enduring challenge. Here, we employ a novel, to our knowledge, combination of complementary techniques, including small-angle neutron scattering, neutron spin-echo spectroscopy, and all-atom molecular dynamics and coarse-grained simulation, to identify and characterize in detail the structure and dynamics of a compact form of mercuric ion reductase (MerA), an enzyme central to bacterial mercury resistance. MerA possesses metallochaperone-like N-terminal domains (NmerA) tethered to its catalytic core domain by linkers. The NmerA domains are found to interact principally through electrostatic interactions with the core, leashed by the linkers so as to subdiffuse on the surface over an area close to the core C-terminal Hg(II)-binding cysteines. How this compact, dynamical arrangement may facilitate delivery of Hg(II) from NmerA to the core domain is discussed.

We have measured the dynamics of water confined in a porous magnesium carbonate material, Upsalite®, using the high-resolution neutron backscattering spectrometer SPHERES. We found quasielastic scattering that does not flatten out up to 360 K, which means that the dynamics of water are much slower than in other matrix materials. Specifically, a single Lorentzian line could be fitted to the quasielastic part of the acquired spectra between 220 and 360 K. This, accompanied by an elastic line from dynamically frozen water present at all experimental temperatures, even above the melting point, signaled a significant amount of bound or slow water. [ABSTRACT FROM AUTHOR]