Exploring the Origins of Association of Poly(acrylic acid) Polyelectrolyte with Lysozyme in Aqueous Environment through Molecular Simulations and Experiments.

This study provides a detailed picture of how a protein (lysozyme) complexes with a poly(acrylic acid) polyelectrolyte (PAA) in water at the atomic level using a combination of all-atom molecular dynamics simulations and experiments. The effect of PAA and temperature on the protein's structure is explored. The simulations reveal that a lysozyme's structure is relatively stable except from local conformational changes induced by the presence of PAA and temperature increase.

Biocompatible Preparation of Beta-Lactoglobulin/Chondroitin Sulfate Carrier Nanoparticles and Modification of Their Colloidal and Hydropathic Properties by Tween 80.

The electrostatic complexation of the protein beta-lactoglobulin (β-LG) with the anionic polysaccharide chondroitin sulfate (CS) and the subsequent stabilization by thermal treatment were studied to achieve the well-defined nanoparticles (NPs). The formation of the well-defined NPs was obtained at pH 4 with a hydrodynamic radius from 60 to 80 nm. NP aggregation was observed at pH 1.

pH-response of protein-polysaccharide multilayers adsorbed on a flat gold surface: A surface plasmon resonance study.

Polysaccharide-protein multilayers (PPMLs) consisting of bovine serum albumin (BSA) and chondroitin sulfate (CS) are assembled in acidic solution (pH 4.2) via layer-by-layer deposition method. The formation of PPMLs on gold surface and their responsiveness to pH change from 4.

A sustainable bioprocess to produce bacterial cellulose (BC) using waste streams from wine distilleries and the biodiesel industry: evaluation of BC for adsorption of phenolic compounds, dyes and metals.

Background: The main challenge for large-scale production of bacterial cellulose (BC) includes high production costs interlinked with raw materials, and low production rates. The valorization of renewable nutrient sources could improve the economic effectiveness of BC fermentation while their direct bioconversion into sustainable biopolymers addresses environmental pollution and/or resource depletion challenges. Herein a green bioprocess was developed to produce BC in high amounts with the rather unexplored bacterial strain Komagataeibacter rhaeticus, using waste streams such as wine distillery effluents (WDE) and biodiesel-derived glycerol.

Advances in Small Angle Neutron Scattering on Polysaccharide Materials.

Polysaccharide materials and biomaterials gain the focus of intense research owing to their great versatility in chemical structures and modification possibilities, as well as their biocompatibility, degradability, and sustainability features. This review focuses on the recent advances in the application of SANS on polysaccharide systems covering a broad range of materials such as nanoparticulate assemblies, hydrogels, nanocomposites, and plant-originating nanostructured systems. It motivates the use of SANS in its full potential by demonstrating the features of contrast variation and contrast matching methods and by reporting the methodologies for data analysis and interpretation.

Hydration effects on thermal transitions and molecular mobility in Xanthan gum polysaccharides.

In this work, the xanthan gum (XG) polysaccharide is studied over a wide range of temperatures and water fractions 0 ≤ ≤ 0.70 (on a wet basis) by employing differential scanning calorimetry (DSC) and broadband dielectric spectroscopy (BDS). The investigation reveals that the critical water fraction for ice formation is about 0.

Thermally stabilized chondroitin sulfate-hemoglobin nanoparticles and their interaction with bioactive compounds.

The preparation of nanoparticles (NPs) based on hemoglobin (Hb) with a fully biocompatible methodology is presented. The spontaneous formation of electrostatic complexes of Hb with chondroitin sulfate (CS) at pH 4 in the polysaccharide/protein mass ratio regime where charge neutrality is met leads to spherical nanostructures with monomodal hydrodynamic radii distribution in the range of 50-100 nm. The integrity of the electrostatic complexes is disturbed at pH 7 as the net electric charge of Hb is very low.

Protein-induced transformation of unilamellar to multilamellar vesicles triggered by a polysaccharide.

We report on the morphological transitions of didodecyldimethylammonium bromide (DDAB) cationic vesicles and hybrid DDAB/hyaluronic acid (HA) vesicles upon addition of BSA at pH 7 where BSA is overall negatively charged. Small angle neutron scattering (SANS) is used to extract the size distributions of the nanovesicles, the thickness of the DDAB bilayers and their lamellarity. Although the HA-decorated DDAB vesicles contain the negatively charged polysaccharide the interaction with BSA appears to be more intense in comparison to bare vesicles.

Physicochemical properties of electrostatically crosslinked carrageenan/chitosan hydrogels and carrageenan/chitosan/Laponite nanocomposite hydrogels.

In this work physical carrageenan/chitosan (Car/Chit) hydrogels are prepared by electrostatic complexation between the two oppositely charged polysaccharides. The hydrogels have storage moduli in the order of 5-10 kPa and swelling ratios in the order of 5000-6000 %. At conditions where both polysaccharides are highly charged (pH 5) the swelling ratios are lower than the ones at conditions of lower dissociation i.

Sustainable Production of Novel Oleogels Valorizing Microbial Oil Rich in Carotenoids Derived from Spent Coffee Grounds.

Sustainable food systems that employ renewable resources without competition with the food chain are drivers for the bioeconomy era. This study reports the valorization of microwave-pretreated spent coffee grounds (SCGs) to produce oleogels rich in bioactive compounds. Microbial oil rich in carotenoids (MOC) was produced under batch fermentation of using SCG enzymatic hydrolysates.

Development of biodegradable films using sunflower protein isolates and bacterial nanocellulose as innovative food packaging materials for fresh fruit preservation.

This study presents the valorization of side streams from the sunflower-based biodiesel industry for the production of bio-based and biodegradable food packaging following circular economy principles. Bacterial cellulose (BC) was produced via fermentation in 6 L static tray bioreactors using nutrient-rich supplements derived from the enzymatic hydrolysis of sunflower meal (SFM) combined with crude glycerol as carbon source. Novel biofilms were produced using either matrices of protein isolates extracted from sunflower meal (SFMPI) alone or SFMPI matrices reinforced with nanocellulose biofillers of commercial or bacterial origin.

Preparation of trypsin-based nanoparticles, colloidal properties and ability to bind bioactive compounds.

Nanoparticles (NPs) based on the proteolytic enzyme trypsin (TRY) were prepared by a biocompatible methodology. TRY co-assembled with the anionic polysaccharide chondroitin sulfate (CS) in complexes with well-defined distributions of radii in the range of 100-200 nm by electrostatic complexation at acidic conditions. At pH 7 the complexes were unstable and lost their monomodal size distribution which is potentially related to TRY's weak positive net surface charge and a large negative charge patch that forms at neutral pH.

Formation and physicochemical properties of glycogen phosphorylase in complex with a cationic polyelectrolyte.

The accumulation of rabbit muscle glycogen phosphorylase b (RMGPb) in electrostatic complexes with the cationic polyelectrolyte poly 2-(dimethylamino) ethyl methacrylate in its quenched form (QPDMAEMA) was studied in two buffer solutions. In the N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid (BES) buffer, large complexes of RMGPb-QPDMAEMA were formed which adopted smaller sizes as QPDMAEMA concentration increased. However, in N-(2-hydroxyethyl)piperazine-N'-(2-ethanesulfonic acid) (HEPES) buffer, the hydrodynamic radius of the formed complexes gradually increased as the polymer concentration increased.

Current Advances of Polysaccharide-Based Nanogels and Microgels in Food and Biomedical Sciences.

Polysaccharides are natural polymers with hydrophilic, biocompatible and biodegradable characteristics and have many opportunities in the food and pharmaceutical sectors. This review focuses on the field of nano and microstructures whose internal structure is based on networked polysaccharide chains in 3D i.e.

Polysaccharide-Protein Multilayers Based on Chitosan-Fibrinogen Assemblies for Cardiac Cell Engineering.

The cell and tissue culture substrates play a pivotal role in the regulation of cell-matrix and cell-cell interactions. The surface properties of the materials control a wide variety of cell functions. Amongst various methods, layer-by-layer (LbL) assembly is a versatile surface coating technique for creating controllable bio-coatings.

Formation of Uni-Lamellar Vesicles in Mixtures of DPPC with PEO-b-PCL Amphiphilic Diblock Copolymers.

The ability of mixtures of 1.2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and the amphiphilic diblock copolymers poly (ethylene oxide)-block-poly(ε-caprolactone) (PEO-b-PCL) to stabilize uni-lamellar nano-vesicles is reported. Small angle neutron scattering (SANS) is used to define their size distribution and bilayer structure and resolve the copresence of aggregates and clusters in solution.

Lamellarity and size distributions in mixed DPPC/amphiphilic poly(2-oxazoline) gradient copolymer vesicles and their temperature response.

Mixed liposomes of dipalmitoylphosphatidylcholine (DPPC) and gradient (pseudodiblock) poly(2-methyl-2-oxazoline)-grad-poly(2-phenyl-2-oxazoline) (MPOx) copolymers are investigated by small angle neutron scattering (SANS). All experimental data, from different phospholipid-copolymer compositions, concentrations and temperatures are fitted with one model. This model allows the determination of the separate contributions from vesicular populations of different lamellarity and size.

Nanoformulation of fibrinogen by thermal stabilization of its electrostatic complexes with hyaluronic acid.

The formulation of well-defined and stable fibrinogen-based nanoparticles (NPs) without the use of any chemical reaction or any toxic organic solvent is reported. Electrostatic interaction between hyaluronic acid (HA) and fibrinogen (Fbg) leads to well-defined complexes at acidic pH which however readily dissolve at neutral pH. On the other hand, when thermal treatment is applied on the pre-formed complexes NPs keep their integrity.

Combining particle tracking microrheology and viscometry for the study of DNA aqueous solutions.

We use video particle tracking microrheology (VPTMR) in order to investigate the viscoelasticity of salmon DNA and correlate it to its steady-flow shear-thinning viscosity. Aqueous solutions of DNA are tested in a wide concentration range from the dilute to the semidilute unentangled concentration regime. The observed mean squared displacement shows power-law scaling with lag-time which is equivalent to power-law behavior of the complex modulus as a function of frequency that is, |G (ω)| = S ∙ ω .

Reorganizations inside thermally stabilized protein/polysaccharide nanocarriers investigated by small angle neutron scattering.

We use small angle neutron scattering (SANS) to characterize the internal morphology of nanoparticles (NPs) formed by the complexation between chondroitin sulfate (CS) and bovine serum albumin (BSA) and subsequent stabilization by thermal treatment. We demonstrate that SANS can quantify the internal rearrangements and protein morphology alterations upon thermal treatment and solution conditions variations. A three-level Guinier/power-law hierarchical model identifies BSA globules, interconnected clusters of globules and higher aggregates.

Temperature-induced aggregation behavior in bovine pancreas trypsin solutions.

In this study, we investigate the effect of temperature treatment on Bovine Pancreas Trypsin (BPT) in aqueous solutions using dynamic, static and electrophoretic light scattering, fluorescence spectroscopy and circular dichroism. Static and dynamic light scattering at various solution conditions i.e.

Association and Internal Morphology of Self-Assembled HPPhOx/BSA Hybrid Nanoparticles in Aqueous Solutions.

We investigate the formation of hybrid polyelectrolyte/protein nanoparticles by associations between aggregates of partially hydrolyzed poly(2-phenyl-2-oxazoline) (HPPhOx) and bovine serum albumin (BSA) in aqueous solutions. Light scattering experiments show that at conditions of low salt, BSA creates interaggregate bridges and increases the size of the HPPhOx nanoparticles. At high salt contents, breaking of aggregates leads to well-defined nanoparticles.

The high-intensity option of the SANS diffractometer KWS-2 at JCNS - characterization and performance of the new multi-megahertz detection system.

A new detection system based on an array of He tubes and innovative fast detection electronics has been installed on the high-intensity small-angle neutron scattering (SANS) diffractometer KWS-2 operated by the Jülich Centre for Neutron Science (JCNS) at the Heinz Meier-Leibnitz Zentrum in Garching, Germany. The new detection system is composed of 18 eight-pack modules of He tubes that work independently of one another (each unit has its own processor and electronics). To improve the read-out characteristics and reduce the noise, the detection electronics are mounted in a closed case on the rear of the He tubes' frame.

Formation of complexes in aqueous solutions of amphiphilic triblock polyelectrolytes of different topologies and an oppositely charged protein.

The complexation of lysozyme with aggregates from two triblock amphiphilic polyelectrolytes of the same blocks but different topologies and block molar masses, namely PS-b-SCPI-b-PEO and SCPI-b-PS-b-PEO, is investigated by scattering and spectroscopy methods. Light scattering reveals that the interaction with lysozyme causes shrinkage of the self-assembled nanoparticles in the case of the hydrophobic-polyelectrolyte-hydrophilic sequence. In the polyelectrolyte-hydrophobic-hydrophilic sequence, the opposite trend is observed.

Modification of xanthan solution properties by the cationic surfactant DTMAB.

The interactions between xanthan gum (XG) and dodecyltrimethylammonium bromide (DTMAB) are studied by static and dynamic light scattering, microrheology and viscometry within the overlapping regime of aqueous xanthan solutions. In the absence of salt mixing with surfactant transforms the complex fluid of interconnected xanthan chains into diffusing aggregates because of the reduction of the polysaccharide's effective charge and the introduction of hydrophobic units. In the presence of salt the effect of complexation is weaker.