scholarly journals On the Formation and Stability of Chitosan/Hyaluronan-Based Complex Coacervates

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1071
Author(s):  
Franco Furlani ◽  
Pietro Parisse ◽  
Pasquale Sacco
Keyword(s):  
Electrostatic Interactions ◽  
Colloidal Stability ◽  
Molar Mass ◽  
Osmotic Swelling ◽  
Average Molar Mass ◽  
X Ray ◽  
X Ray Scattering ◽  
Chitosan Hydrochloride ◽  
The Stability ◽  
Phosphate Buffered Saline

This contribution is aimed at extending our previous findings on the formation and stability of chitosan/hyaluronan-based complex coacervates. Colloids are herewith formed by harnessing electrostatic interactions between the two polyelectrolytes. The presence of tiny amounts of the multivalent anion tripolyphosphate (TPP) in the protocol synthesis serves as an adjuvant “point-like” cross-linker for chitosan. Hydrochloride chitosans at different viscosity average molar mass, M v ¯ , in the range 10,000–400,000 g/mol, and fraction of acetylated units, FA, (0.16, 0.46 and 0.63) were selected to fabricate a large library of formulations. Concepts such as coacervate size, surface charge and homogeneity in relation to chitosan variables are herein disclosed. The stability of coacervates in Phosphate Buffered Saline (PBS) was verified by means of scattering techniques, i.e., Dynamic Light Scattering (DLS) and Small-Angle X-ray Scattering (SAXS). The conclusions from this set of experiments are the following: (i) a subtle equilibrium between chitosan FA and M v ¯ does exist in ensuring colloidal stability; (ii) once diluted in PBS, osmotic swelling-driven forces trigger the enlargement of the polymeric mesh with an ensuing increase of coacervate size and porosity.

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.

scholarly journals On the Stability of 3C-SiC Single Crystals at High Temperatures

2012 ◽  
Vol 717-720 ◽  
pp. 493-496
Author(s):  
Deborah Dompoint ◽  
Irina G. Galben-Sandulache ◽  
Alexandre Boulle ◽  
Didier Chaussende ◽  
Dominique Eyidi ◽  
...  
Keyword(s):  
Single Crystals ◽  
Volume Fraction ◽  
Diffuse Intensity ◽  
X Ray ◽  
Partial Dislocations ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
The Stability ◽  
Kinetics Of ◽  
Evolution With Time

The 3C-6H polytypic transition in 3C-SiC single crystals is studied by means of diffuse X-ray scattering (DXS) coupled with transmission electron microscopy (TEM). TEM reveals that the partially transformed SiC crystals contain regions of significantly transformed SiC (characterized by a high density of stacking faults) co-existing with regions of pure 3C-SiC. The simulation of the diffuse intensity allows to determine both the volume fraction of transformed material and the transformation level within these regions. It is further shown that the evolution with time and temperature of the transition implies the multiplication and glide of partial dislocations, the kinetics of which are quantified by means of DXS.

Time-Resolved Imaging of Correlation-Driven Charge Migration in Light-Induced Molecular Magnets by X-ray Scattering

2020 ◽  
Author(s):  
Jean-Christophe Tremblay ◽  
Gunter Hermann ◽  
Vincent Pohl ◽  
Gopal Dixit
Keyword(s):  
Molecular Magnets ◽  
Time Dependent ◽  
Electron Dynamics ◽  
Charge Migration ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Induced Charge ◽  
Time Resolved Imaging ◽  
The Stability

In this contribution, we investigate the effect of correlation-induced charge migration on the stability of light-induced molecular magnets. Laser-driven electron dynamics is simulated using density-matrix based time-dependent configuration interaction. The...

scholarly journals Improved Electronic Transport in Ion Complexes of Crown Ether Based Columnar Liquid Crystals

Crystals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 74 ◽  
Author(s):  
Peter Staffeld ◽  
Martin Kaller ◽  
Philipp Ehni ◽  
Max Ebert ◽  
Sabine Laschat ◽  
...  
Keyword(s):  
Ionic Conductivity ◽  
Crown Ether ◽  
Electronic Transport ◽  
Columnar Structure ◽  
Strong Increase ◽  
Temperature Dependent ◽  
X Ray ◽  
X Ray Scattering ◽  
Structural And Electronic Properties ◽  
The Stability

The Li+- and K+-complexes of new discotic mesogens, where two n-alkoxy-substituted triphenylene cores are connected by a central crown ether (12-crown-4 and 18-crown-6), provide interesting structural and electronic properties. The inter- and intra-columnar structure was investigated by small and wide angle X-ray scattering. The electronic and ionic transports were studied by temperature dependent photoconductivity and impedance spectroscopy, respectively. Besides a strong increase of the stability and the width of the columnar phases the presence of soft anions (iodide, thiocyanate, tetrafluoroborate) leads to an improved intra-columnar order. The hereby shortened stacking-distance of the triphenylene cores leads to a significant increase of the photoconductivity in the columnar mesophase. Furthermore, the ionic conductivity of the new materials was investigated on macroscopically aligned thin films. The existence of channels for fast cation transport formed by the stacked crown ether moieties in the centre of each column can be excluded. The cations are coordinated strongly and therefore contributing only little to the conductivity. The ionic conductivity is dominated by the anisotropic migration of the non-coordinated anions through the liquid, like side chains favouring the propagation parallel to the columns. Iodide migrates about 20 times faster than thiocyanate and 100 times faster than tetrafluoroborate.

Cartilage: Multiscale Structure and Biomechanical Properties

MRS Advances ◽  
2016 ◽  
Vol 1 (8) ◽  
pp. 509-519
Author(s):  
Ferenc Horkay ◽  
Peter J. Basser ◽  
Anne-Marie Hecht ◽  
Erik Geissler
Keyword(s):  
Hyaluronic Acid ◽  
Small Angle ◽  
Swelling Pressure ◽  
Biomechanical Properties ◽  
Tissue Level ◽  
Biological Functions ◽  
Osmotic Swelling ◽  
X Ray ◽  
X Ray Scattering ◽  
Compressive Resistance

ABSTRACTCartilage is a load bearing tissue that has multiple biological functions. The major proteoglycan in cartilage is the bottlebrush shaped aggrecan whose complexes with hyaluronic acid provide the compressive resistance of cartilage. The negatively charged aggrecan-hyaluronic acid complexes generate an osmotic swelling pressure within the tissue, which is balanced by the collagen network. To better understand the function of cartilage at the tissue level, we study aggrecan assemblies using an array of microscopic and macroscopic techniques. The organization of aggrecan assemblies at the supramolecular level is probed by light scattering, small-angle neutron scattering and small-angle X-ray scattering. Osmotic and rheological measurements are used to investigate the macroscopic physical properties.

Study of the Stability of 3C-SiC Single Crystals Using High-Resolution Diffuse X-Ray Scattering

2010 ◽  
Author(s):  
D. Dompoint ◽  
A. Boulle ◽  
I. G. Galben-Sandulache ◽  
D. Chaussende ◽  
Gabriel Ferro ◽  
...  
Keyword(s):  
High Resolution ◽  
Single Crystals ◽  
X Ray ◽  
X Ray Scattering ◽  
The Stability ◽  
Ray Scattering

Hydrolytic stability of water-soluble spruce O-acetyl galactoglucomannans

Holzforschung ◽  
2009 ◽  
Vol 63 (1) ◽  
Author(s):  
Chunlin Xu ◽  
Andrey Pranovich ◽  
Jarl Hemming ◽  
Bjarne Holmbom ◽  
Simone Albrecht ◽  
...  
Keyword(s):  
Food Processing ◽  
Molar Mass ◽  
Hydrolytic Stability ◽  
Water Soluble ◽  
Average Molar Mass ◽  
Acidic Conditions ◽  
The Stability ◽  
Stability Of Water ◽  
Hydrolysis Of

Abstract Water-soluble native O-acetyl galactoglucomannan (GGM) from spruce is a polysaccharide that can be produced in an industrial scale. To develop GGM applications, information is needed on its stability, particularly under acidic conditions. Therefore, acid hydrolysis of spruce GGM was investigated at various pH levels and temperatures. The results allow an estimation of the stability of GGM under food processing conditions and in biological systems. Determination of the average molar mass demonstrated that spruce GGM was stable at pH 1 and 37°C, as well as at pH 3 and 70°C. GGM was hydrolysed at pH 1 and 90°C. GGM oligomers and monomers were detected after degradation. Some of the oligomers contained O-acetyl groups. Monosaccharides were the predominant products in the hydrolysates after treatment at pH 1 and 90°C for 48 h. Pentoses, present in GGM samples as impurities, were released more easily than GGM hexoses. Glucose was more difficult to release than mannose. Traces of 6-deoxy-mannose and levoglucosan were found in the hydrolysates, indicating further degradation of hydrolysed monosaccharides.

scholarly journals Using crystallography tools to improve vaccine formulations

IUCrJ ◽  
2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Márcia Carvalho de Abreu Fantini ◽  
Cristiano Luis Pinto Oliveira ◽  
José Luiz de Souza Lopes ◽  
Tereza da Silva Martins ◽  
Milena Apetito Akamatsu ◽  
...  
Keyword(s):  
Oral Vaccine ◽  
Porous Silica ◽  
Protein Antigens ◽  
X Ray ◽  
X Ray Crystallography ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
X Ray Imaging ◽  
The Stability ◽  
Phase Contrast Tomography

This article summarizes developments attained in oral vaccine formulations based on the encapsulation of antigen proteins inside porous silica matrices. These vaccine vehicles show great efficacy in protecting the proteins from the harsh acidic stomach medium, allowing the Peyer's patches in the small intestine to be reached and consequently enhancing immunity. Focusing on the pioneering research conducted at the Butantan Institute in Brazil, the optimization of the antigen encapsulation yield is reported, as well as their distribution inside the meso- and macroporous network of the porous silica. As the development of vaccines requires proper inclusion of antigens in the antibody cells, X-ray crystallography is one of the most commonly used techniques to unveil the structure of antibody-combining sites with protein antigens. Thus structural characterization and modelling of pure antigen structures, showing different dimensions, as well as their complexes, such as silica with encapsulated hepatitis B virus-like particles and diphtheria anatoxin, were performed using small-angle X-ray scattering, X-ray absorption spectroscopy, X-ray phase contrast tomography, and neutron and X-ray imaging. By combining crystallography with dynamic light scattering and transmission electron microscopy, a clearer picture of the proposed vaccine complexes is shown. Additionally, the stability of the immunogenic complex at different pH values and temperatures was checked and the efficacy of the proposed oral immunogenic complex was demonstrated. The latter was obtained by comparing the antibodies in mice with variable high and low antibody responses.

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