scholarly journals Monovalent Salt and pH-Induced Gelation of Oxidized Cellulose Nanofibrils and Starch Networks: Combining Rheology and Small-Angle X-Ray Scattering

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 951
Author(s):  
Kazi M. Zakir Hossain ◽  
Vincenzo Calabrese ◽  
Marcelo A. da da Silva ◽  
Saffron J. Bryant ◽  
Julien Schmitt ◽  
...  
Keyword(s):  
Rheological Properties ◽  
Small Angle ◽  
Cellulose Nanofibrils ◽  
Salt Content ◽  
Quality Parameters ◽  
X Ray ◽  
X Ray Scattering ◽  
Aggregation Behaviour ◽  
The Stability ◽  
Ray Scattering

Water quality parameters such as salt content and various pH environments can alter the stability of gels as well as their rheological properties. Here, we investigated the effect of various concentrations of NaCl and different pH environments on the rheological properties of TEMPO-oxidised cellulose nanofibril (OCNF) and starch-based hydrogels. Addition of NaCl caused an increased stiffness of the OCNF:starch (1:1 wt%) blend gels, where salt played an important role in reducing the repulsive OCNF fibrillar interactions. The rheological properties of these hydrogels were unchanged at pH 5.0 to 9.0. However, at lower pH (4.0), the stiffness and viscosity of the OCNF and OCNF:starch gels appeared to increase due to proton-induced fibrillar interactions. In contrast, at higher pH (11.5), syneresis was observed due to the formation of denser and aggregated gel networks. Interactions as well as aggregation behaviour of these hydrogels were explored via ζ-potential measurements. Furthermore, the nanostructure of the OCNF gels was probed using small-angle x-ray scattering (SAXS), where the SAXS patterns showed an increase of slope in the low-q region with increasing salt concentration arising from aggregation due to the screening of the surface charge of the fibrils.

scholarly journals TEMPO-oxidised cellulose nanofibrils; probing the mechanisms of gelation via small angle X-ray scattering

2018 ◽  
Vol 20 (23) ◽  
pp. 16012-16020 ◽  
Author(s):  
Julien Schmitt ◽  
Vincenzo Calabrese ◽  
Marcelo A. da Silva ◽  
Saskia Lindhoud ◽  
Viveka Alfredsson ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Small Angle ◽  
Cellulose Nanofibrils ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

The structure of dispersions of TEMPO-oxidised cellulose nanofibrils at various concentrations, in water and in NaCl aqueous solutions, was probed using small angle X-ray scattering and results were compared with rheology.

scholarly journals Structural-stability studies on recombinant human transferrin

2019 ◽  
Author(s):  
A. Kulakova ◽  
S. Indrakumar ◽  
P. Sønderby ◽  
L. Gentiluomo ◽  
W. Streicher ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Blood Brain Barrier ◽  
High Throughput ◽  
Small Angle ◽  
Brain Barrier ◽  
X Ray ◽  
X Ray Scattering ◽  
Blood Brain ◽  
The Stability ◽  
Ray Scattering

AbstractTransferrin is an attractive candidate for drug delivery due to its ability to cross the blood brain barrier. However, in order to be able to use it for therapeutic purposes, it is important to investigate how its stability depends on different formulation conditions. Combining high-throughput thermal and chemical denaturation studies with small angle X-ray scattering (SAXS) and molecular dynamics (MD) simulations, it was possible to connect the stability of transferrin with its conformational changes. The release of iron induces opening of transferrin, which results in a negative effect on its stability. Presence of NaCl, arginine, and histidine leads to opening of the transferrin N-lobe and has a negative impact on the overall protein stability.Statement of significanceProtein-based therapeutics have become an essential part of medical treatment. They are highly specific, have high affinity and fewer off-target effects. However, stabilization of proteins is critical, time-consuming, and expensive, and it is not yet possible to predict the behavior of proteins under different conditions. The current work is focused on a molecular understanding of the stability of human serum transferrin; a protein which is abundant in blood serum, may pass the blood brain barrier and therefore with high potential in drug delivery. Combination of high throughput unfolding techniques and structural studies, using small angle X-ray scattering and molecular dynamic simulation, allows us to understand the behavior of transferrin on a molecular level.

A Revised O2 Reduction Model in Li-O2 Batteries as Revealed by in Situ Small Angle X-Ray Scattering

2019 ◽  
Author(s):  
Christian Prehal ◽  
Aleksej Samojlov ◽  
Manfred Nachtnebel ◽  
Manfred Kriechbaum ◽  
Heinz Amenitsch ◽  
...  
Keyword(s):  
Small Angle ◽  
Wide Angle ◽  
Reduction Mechanism ◽  
Reduction Model ◽  
X Ray ◽  
X Ray Scattering ◽  
O2 Reduction ◽  
Ray Scattering

<b>Here we use in situ small and wide angle X-ray scattering to elucidate unexpected mechanistic insights of the O2 reduction mechanism in Li-O2 batteries.<br></b>

In situ Time-Resolved Small-Angle X-ray Scattering Reveals the Formation Kinetics of Polyelectrolyte Complex Micelles

2019 ◽  
Author(s):  
Hao Wu ◽  
Jeffrey Ting ◽  
Siqi Meng ◽  
Matthew Tirrell
Keyword(s):  
Small Angle ◽  
Self Assembly ◽  
Electrostatic Interactions ◽  
Polyelectrolyte Complex ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Kinetics Of ◽  
Ray Scattering

We have directly observed the <i>in situ</i> self-assembly kinetics of polyelectrolyte complex (PEC) micelles by synchrotron time-resolved small-angle X-ray scattering, equipped with a stopped-flow device that provides millisecond temporal resolution. This work has elucidated one general kinetic pathway for the process of PEC micelle formation, which provides useful physical insights for increasing our fundamental understanding of complexation and self-assembly dynamics driven by electrostatic interactions that occur on ultrafast timescales.

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