Ionic Strength Of Medium Research Articles

Zika Virus NS1 Protein Detection Using Gold Nanoparticle-Assisted Dynamic Light Scattering.

The Zika virus (ZIKV) is a global health threat due to its rapid spread and severe health implications, including congenital abnormalities and neurological complications. Differentiating ZIKV from other arboviruses such as dengue virus (DENV) is crucial for effective diagnosis and treatment. This study presents the development of a biosensor for detecting the ZIKV non-structural protein 1 (NS1) using gold nanoparticles (AuNPs) functionalized with monoclonal antibodies employing dynamic light scattering (DLS). The biosensor named ZINS1-mAb-AuNP exhibited specific binding to the ZIKV NS1 protein, demonstrating high colloidal stability indicated by a hydrodynamic diameter (DH) of 140 nm, detectable via DLS. In the absence of the protein, the high ionic strength medium caused particle aggregation. This detection method showed good sensitivity and specificity, with a limit of detection (LOD) of 0.96 μg mL-1, and avoided cross-reactivity with DENV2 NS1 and SARS-CoV-2 spike proteins. The ZINS1-mAb-AuNP biosensor represents a promising tool for the early and accurate detection of ZIKV, facilitating diagnostic and treatment capabilities for arboviral infections.

A microfluidic in vitro method predicting the fate of peptide drugs after subcutaneous administration

For many biopharmaceuticals, subcutaneous (sc) administration is the only viable route. However, there is no in vitro method available accurately predicting the absorption profiles of subcutaneously injected pharmaceuticals. In this work, we show that a recently developed microfluidics method for interaction studies (MIS) has the potential to be useful in this respect. The method utilises the responsiveness of polyelectrolyte microgel networks to oppositely charged molecules as a means to monitor the interaction between peptides and hyaluronic acid (HA), a major constituent of the subcutaneous extracellular matrix. We use the method to determine parameters describing the strength of interaction between peptide and HA as well as the peptide’s aggregation tendency and transport properties in HA networks. The results from MIS studies of the peptide drugs exenatide, pramlintide, vancomycin, polymyxin B, lanreotide, MEDI7219 and AZD2820 are compared with results from measurements with the commercially available SCISSOR system and in vivo absorption and bioavailability data from the literature. We show that both MIS and SCISSOR reveal differences in the peptides’ diffusivity and tendency to aggregate in the presence of HA. We show that MIS is particularly good at discriminating between peptides forming aggregates stabilised by non-electrostatic forces in the presence of HA, and peptides forming complexes stabilised by electrostatic interactions with HA. The method provides two parameters that can be used to quantify the peptides’ aggregation tendency, the one describing the peptide packing density in complexes with HA and the other the apparent diffusivity upon release in a medium of physiological ionic strength and pH. The order of the peptides when ranked by increasing binding strength at pH 7.4 determined with MIS is shown to be in agreement with the order when ranked by the apparent 1st order absorption rate constant (ka) after sc administration in humans: lanreotide (Autogel) < exenatide (IRF) < AZD2820 < pramlintide < lanreotide (IRF) (IRF: Immediate release formulation). A correlation is found between the 1st order release rate constant determined with SCISSOR and ka for lanreotide (Autogel), exenatide and AZD2820. A mechanism relating the magnitude of ka to the peptides’ charge is proposed.

Evaluation of extraction and storage conditions for quantification and characterization of silver nanoparticles in complex samples by single particle-ICP-MS

The extraction of nanoparticles (NPs) from complex matrices and subsequent storage can potentially alter the NPs physicochemical properties and hinder cross-study comparisons. Most NPs extraction methods are designed and tested at high NPs concentrations, although (eco)toxicological and regulatory monitoring programs require methods capable of analyzing NPs at environmentally relevant concentrations (lower ppb range). In this study, we investigated how extraction methods affect the characteristics of PVP coated and citrate-stabilized silver NPs (AgNPs) spiked into soil, sewage sludge, and biological samples at environmentally relevant concentrations using Single Particle Inductively Coupled Plasma Mass Spectrometry spICP-MS). Further we investigated the impact of storage temperature (-80 °C – 21 °C) and storage duration (1–28 days) on the particle characteristics such as particle size.We found that aqueous AgNPs samples with low ionic strength media retained their original characteristics (like particle size, particle concentration and particle-based Ag mass) when preserved at 4 °C for up to 28 days. AgNPs dispersed in high ionic strength media were however better preserved at −80 °C. Among the extraction agents, tetrasodium pyrophosphate was efficient in extracting AgNPs from soil and sewage sludge matrices, while Proteinase K was most suitable for biological samples from organisms (earthworms or fish).Although our study focused only on AgNPs, it provides crucial information to aid interlaboratory comparisons and data interpretation for (eco)toxicological studies.

Application of Novel Ruthenium (II) Polypyridyl Complexes as Robust DNA Probes, Optical Material and Antimicrobials-An Experimental and DFT Approach.

The nature of the interaction of DNA with heteroleptic Ruthenium (II) Polypyridyl complexes of the type [Ru (A)2TPIP]2+, where TPIP = 2-(1-p-tolyl-1H pyrazol-4 -yl)-1H-imidazo [4, 5-f[1. 10] phenanthroline and A = 1,10 phenanthroline (1),4,4'-dimethyl-1,10-ortho Phenanthroline (2),2,2' - bipyridine(3) and 4, 4' dimethyl 2, 2'- bipyridine (4), has been investigated by experimentaland molecular docking approaches. The order of the DNA binding affinities of the synthesised complexes is 1 > 2 > 3 > 4. The findings imply that the unsubstitutedcomplex has a better affinity to bind with DNA than the substituted (dmp and dmb) emphasizing the significance of the auxiliary ligand. Additionally, as the medium's ionic strength drops, the DNA/Ru ratio rises, or when water is displaced by glycerol, the intercalation of complexes into DNA increases. DFT calculations at the B3LYP/LANL2MBlevel was used for molecular geometry (Ground State) and electronic characteristic calculations. The HOMO-LUMO gap of the Ru [II]complex is less than the intercalator and hence kinetically labile. Among the complexes, the bpy complex has shown utmost non-linear optical properties (α = -153.9099 10-24esuand β = 3.8498 10-30esu). The docking study shows the significance of the Metal-intercalator's shorter length may increase DNA binding affinity. This study divulges that the Ruthenium (II) polypyridyl complexes bind to DNA preponderantly by intercalation supporting Viscosity studies. All the complexes have a considerable attraction for guanine. The standarddiskdiffusion method reveals that complexes (1,2,3 and 4) have good antibacterial activity.

A Careful Insight into DDI-Type Receptor Layers on the Way to Improvement of Click-Biology-Based Immunosensors.

Protein-based microarrays are important tools for high-throughput medical diagnostics, offering versatile platforms for multiplex immunodetection. However, challenges arise in protein microarrays due to the heterogeneous nature of proteins and, thus, differences in their immobilization conditions. This article advocates DNA-directed immobilization (DDI) as a solution, emphasizing its rapid and cost-effective fabrication of biosensing platforms. Thiolated single-stranded DNA and its analogues, such as ZNA® and PNA probes, were used to immobilize model proteins (anti-CRP antibodies and SARS-CoV nucleoprotein). The study explores factors influencing DDI-based immunosensor performance, including the purity of protein-DNA conjugates and the stability of their duplexes with DNA and analogues. It also provides insight into backfilling agent type and probe surface density. The research reveals that single-component monolayers lack protection against protein adsorption, while mixing the probes with long-chain ligands may hinder DNA-protein conjugate anchoring. Conventional DNA probes offer slightly higher surface density, while ZNA® probes exhibit better binding efficiency. Despite no enhanced stability in different ionic strength media, the cost-effectiveness of DNA probes led to their preference. The findings contribute to advancing microarray technology, paving the way for new generations of DDI-based multiplex platforms for rapid and robust diagnostics.

Switchable Coacervate Formation via Amino Acid Functionalization of Poly(dehydroalanine).

Our group recently developed a family of side-chain amino acid-functionalized poly(S-alkyl-l-homocysteines), Xaa-CH (Xaa = generic amino acid), which possess the ability to form environmentally responsive coacervates in water. In an effort to further study how the molecular structure affects polypeptide coacervate formation, we prepared side-chain amino acid-functionalized poly(S-alkyl-rac-cysteines), Xaa-rac-C, via post-polymerization modification of poly(dehydroalanine), ADH. The use of the ADH platform allowed straightforward synthesis of a diverse range of side-chain amino acid-functionalized polypeptides via direct reaction of unprotected l-amino acid 2-mercaptoethylamides with ADH. Despite their differences in the main-chain structure, we found that Xaa-rac-C can form coacervates with properties similar to those seen with Xaa-CH. These results suggest that the incorporation of side-chain amino acids onto polypeptides may be a way to generally favor coacervation. The incorporation of l-methionine in Met-rac-C allowed the preparation of coacervates with improved stability against high ionic strength media. Further, the presence of additional thioether groups in Met-rac-C resulted in an increased solubility change upon oxidation allowing facile reversible redox switching of coacervate formation in aqueous media.

Effect of Lipid Corona on Phenylalanine-Functionalized Gold Nanoparticles to Develop Stable and Corona-Free Systems.

Conventional gold nanoparticles (Au NPs) have many limitations, such as aggregation and subsequent precipitation in the medium of high ionic strength and protein molecules. Furthermore, when exposed to biological fluids, nanoparticles form a protein corona, which controls different biological processes such as the circulation lifetime, drug release profile, biodistribution, and in vivo cellular distribution. These limitations reduce the functionality of Au NPs in targeted delivery, bioimaging, gene delivery, drug delivery, and other biomedical applications. To circumvent these problems, there are numerous attempts to design corona-free and stable nanoparticles. Here, we report for the first time that lipid corona (coating of lipid) formation on phenylalanine-functionalized Au NPs (AuPhe NPs) imparts excellent stability against the high ionic strength of bivalent metal ions, amino acids, and proteins of different charges as compared to bare nanoparticles. Moreover, this work is focused on the ability of lipid corona formation on AuPhe NPs to prevent protein adsorption in the presence of cell culture medium (CCM), oppositely charged protein (e.g., histone 3), and human serum albumin (HSA). The results demonstrate that the lipid corona successfully protects the AuPhe NPs from protein adsorption, leading to the development of corona-free character. This unique achievement has profound implications for enhancing the biomedical utility and safety of these nanoparticles.

Assessing the Structure and Equilibrium Conditions of Complex Coacervate Core Micelles by Varying Their Shell Composition and Medium Ionic Strength.

Complex coacervates result from an associative phase separation commonly involving oppositely charged polyelectrolytes. When this associative interaction occurs between charged-neutral diblock copolymers and oppositely charged homopolymers, a nanometric aggregate called a complex coacervate core micelle, C3M, is formed. Recent studies have addressed the issue of their thermodynamic or kinetic stability but without a clear consensus. To further investigate this issue, we have studied C3Ms formed by the combination of poly(diallyldimethylammonium) and copolymer poly(acrylamide)-b-poly(acrylate) using different preparation protocols. Dynamic light scattering and small-angle X-ray scattering measurements suggest that these structures are in an equilibrium condition because the aggregates do not vary with different preparation protocols or upon aging. In addition, their stability and structures are critically dependent on several parameters such as the density of neutral blocks in their shell and the ionic strength of the medium. Decreasing the amount of copolymer in the system and, hence, the density of neutral blocks in the shell results in an increase in the aggregate size because of the core growth, although their globular shape is retained. On the other hand, larger clusters of micelles were formed at higher ionic strengths. Partially replacing 77% of the copolymer with a homopolymer of the same charge or increasing the ionic strength of the system (above 100 mmol L-1 NaCl) leads to a metastable state, after which phase separation is eventually observed. SAXS analyses reveal that this phase separation above a certain salt concentration occurs due to the coagulation of individual micelles that seem to retain their individual globular structures. Overall, these results confirm earlier claims that equilibrium C3Ms are achieved close to 1:1 charge stoichiometry but also reveal that these conditions may vary at different shell densities or higher ionic strengths, which constitute vital information for envisioning future applications of C3Ms.

Removal of polymethyl methacrylate nanoplastics and silver nanoparticles by a novel ferrofluid-COF-aminated natural cotton-based hydrogel nanosorbent

In this work, an innovative nanosorbent is assembled based on the combination of Fe2VO6 ferrofluid, silane covalent organic frameworks (COFs) and gelatin/aminated natural cotton/chitosan hydrogel (FF-SiCOF@Gel-ANC@Ch.Hgel). The developed nanomaterial was fully identified using several characterization techniques such as FTIR, electron microscopy, XRD and XPS; and was then studied as an effective nanosorbent for removal of organic nanopollutants such as polymethyl methacrylate nanoplastics (PMMA) and inorganic nanopollutants such as silver nanoparticles from water. Optimization of experimental parameters such as reaction duration, nanosorbent mass, nanopollutant concentration, solution pH, temperature and medium ionic strength revealed promising removal efficiencies towards both nanopollutants with 98.3% and 99.2% recovery for Ag and PMMA nanopollutants, respectively. Kinetic studies confirmed that the adsorptive removal of both nanosorbent followed via a pseudo-second order chemisorption process. Thermodynamic investigations highlighted that spontaneity of the chemisorption process in terms of negative ΔG° values. Industrial scale applicability was confirmed with interestingly high removal efficiencies toward both nanopollutants (99.45% and 96.80% for Ag and PMMA, respectively) in industrial wastewater. Furthermore, proposed nanosorbent showed appreciable recyclability with little decrease in removal efficiencies (from 95.30% to 91.00% and from 97.20% to 93.00% for Ag and PMMA respectively) after 5 adsorption/regeneration cycles. Considering nanosorbent comparatively high adsorption capacities, together with its industrial applicability and reusability, it was proposed as a promising candidate for wastewater treatment applications. The green aspects in this study were investigated in terms of reusing the recovered Ag@FF-SiCOF@Gel-ANC@Ch.Hgel as a potential nanocatalyst in reductive degradation of sulfasalazine drug, a potentially hazardous pollutant. High degradation rates were deduced at optimal conditions providing 2.3 min−1pseudo-first order rate constant with only 3.18% drop in the catalytic activity after 5 successive reduction/regeneration cycles. This accounts for the promising potential of recycled Ag@FF-SiCOF@Gel-ANC@Ch.Hgel as reductive degradation catalyst for targeted water treatment applications.

Molecular mechanism of casein-chitosan fouling during microfiltration

In this study, the casein-chitosan complexes were subjected to microfiltration. The filtration property was analyzed, and the molecular mechanism of fouling was explained under different medium pH, casein-chitosan ratios and ionic strength. Results suggest that a higher pH and more polysaccharide can slow down the fouling growth rate, but a higher pH is unfavorable for long-term processing. Especially the effect of pH on the process was far more significant than the others. At pH 2.8, most of amino acid residues combined with chitosan to form the denser particles and to generate the gel consistency and yield stress. Thus, the severe fouling resistance was caused by the tight gel layer stacked on membrane surface. At pH 6.8–7.8, the electrostatic binding energy between casein and chitosan decreased. The complexes gel consistency and yield stress disappeared, and the incompact network was formed. Thereby, the cake layer density and the fouling growth rate were reduced. At pH 4.8, the amino acid residues of αS1- and β-casein bound to chitosan decreased. Although the complex exhibited the gel consistency and yield stress, the microfiltration efficiency was improved due to the decrease of binding sites. This work provides new evidences into understanding the membrane fouling mechanism.

QCM‐D Viscoelastic and Adhesion Monitoring Facilitate Label‐Free and Strain‐Selective Bacterial Discrimination

Discriminating bacterial adhesion profiles at strain‐specific level is crucial for simulating and predicting infections and persistence, as well as developing more efficient antibacterial therapies. Herein, it is proposed that label‐ and receptor‐free bacterial discrimination can be achieved by dynamic viscoelastic and adhesion monitoring over specified timescales using the quartz crystal microbalance with dissipation monitoring (QCM‐D). Using two closely related E. coli strains, ATCC 8739 and JM109(DE3), it is shown that their viscoelastic and adhesion properties evolve in time through strain‐specific profiles that are clearly distinguishable over a period of 3–4 h. In addition, the viscoelasticity of both E. coli strains shows a strong strain‐specific dependence on the medium ionic strength, allowing to further amplify the differences in the bacterial adhesion signatures. Furthermore, the viscoelastic and adhesion behaviors of the two E. coli strains with two additional bacteria, Citrobacter freundii and Serratia marcescens, are compared. For all four bacteria, distinct viscoelastic profiles and adhesion fingerprints emerge over similar timescales that allow to reliably discriminate the various bacteria. These results and similar studies on other bacteria might have pharmacological benefits, for instance, by highlighting the role of bacterial–substrate adhesion and viscoelastic properties on disease pathogenesis and persistence, toward developing more effective therapies.

Prevention of alloimmunization in patients with sickle cell disease in Chad

The objective of this study was to contribute to the prevention of anti-erythrocyte alloimmunization in patients with sickle cell disease (DS) in Chad. This was a descriptive and analytical cross-sectional study from December 2021 to June 2022 in sickle cell patients regularly followed in two University Hospital Centers (CHU) in N'Djamena. The search for irregular antibodies was carried out by a combination of three techniques: indirect anti-globulin test (Coombs), enzymatic test (Papain) and the test in a low ionic strength medium, in a partner laboratory of the National Blood Transfusion Center in France. The study included 57 sickle cell patients, 45 of whom (78.9%) were actually transfused. Sickle cell patients accounted for 84.2% of cases. The sex ratio Male/Female (M/F) was 1.03. The average age of the transfused was 9.3 ± 5.4 years. Four of the transfused patients (8.8%) had produced 7 antibodies including 85.7% anti-rhesus and 14.3% anti-Kell. Age, sex and number of blood units were associated with antibody production with probabilities of 0.046, 0.041 and 0.035, respectively. In view of the results obtained from this study, we recommend the application of the blood transfusion rules and procedures in force in Chad.

Characterization and Behaviour of Silica Engineered Nanocontainers in Low and High Ionic Strength Media.

Mesoporous silica engineered nanomaterials are of interest to the industry due to their drug-carrier ability. Advances in coating technology include using mesoporous silica nanocontainers (SiNC) loaded with organic molecules as additives in protective coatings. The SiNC loaded with the biocide 4,5-dichloro-2-octyl-4-isothiazolin-3-one (DCOIT), i.e., SiNC-DCOIT, is proposed as an additive for antifouling marine paints. As the instability of nanomaterials in ionic-rich media has been reported and related to shifting key properties and its environmental fate, this study aims at understanding the behaviour of SiNC and SiNC-DCOIT in aqueous media with distinct ionic strengths. Both nanomaterials were dispersed in (i) low- (ultrapure water-UP) and (ii) high- ionic strength media-artificial seawater (ASW) and f/2 medium enriched in ASW (f/2 medium). The morphology, size and zeta potential (ζP) of both engineering nanomaterials were evaluated at different timepoints and concentrations. Results showed that both nanomaterials were unstable in aqueous suspensions, with the initial ζP values in UP below -30 mV and the particle size varying from 148 to 235 nm and 153 to 173 nm for SiNC and SiNC-DCOIT, respectively. In UP, aggregation occurs over time, regardless of the concentration. Additionally, the formation of larger complexes was associated with modifications in the ζP values towards the threshold of stable nanoparticles. In ASW, SiNC and SiNC-DCOIT formed aggregates (<300 nm) independently of the time or concentration, while larger and heterogeneous nanostructures (>300 nm) were detected in the f/2 medium. The pattern of aggregation detected may increase engineering nanomaterial sedimentation rates and enhance the risks towards dwelling organisms.

Macroporous Hyaluronic Acid/Chitosan Polyelectrolyte Complex-Based Hydrogels Loaded with Hydroxyapatite Nanoparticles: Preparation, Characterization and In Vitro Evaluation

The aim of the study was to fabricate and characterize composite macroporous hydrogels based on a hyaluronic acid/chitosan (Hyal/Ch) polyelectrolyte complex (PEC) loaded with homogeneously distributed hydroxyapatite nanoparticles (nHAp), and to evaluate them in vitro using mouse fibroblasts (L929), osteoblast-like cells (HOS) and human mesenchymal stromal cells (hMSC). Hydrogel morphology as a function of the hydroxyapatite nanoparticle content was studied using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The mean pore size in the Hyal/Ch hydrogel was 204 ± 25 μm. The entrapment of nHAp (1 and 5 wt. %) into the Hyal/Ch hydrogel led to a mean pore size decrease (94 ± 2 and 77 ± 9 μm, relatively). Swelling ratio and weight loss of the hydrogels in various aqueous media were found to increase with an enhancement of a medium ionic strength. Cell morphology and localization within the hydrogels was studied by CLSM. Cell viability depended upon the nHAp content and was evaluated by MTT-assay after 7 days of cultivation in the hydrogels. An increase of the hydroxyapatite nanoparticles loading in a range of 1–10 wt. % resulted in an enhancement of cell growth and proliferation for all hydrogels. Maximum cell viability was obtained in case of the Hyal/Ch/nHAp-10 sample (10 wt. % nHAp), while a minimal cell number was found for the Hyal/Ch/nHAp-1 hydrogel (1 wt. % nHAp). Thus, the proposed simple original technique and the design of PEC hydrogels could be promising for tissue engineering, in particular for bone tissue repair.

Early α-synuclein aggregation is overall delayed and it can occur by a stepwise mechanism

It is well-known that α-synuclein (Syn) protein aggregation is implicated in the pathogenesis of Parkinson's disease. There is an increased evidence that large protein aggregates populate very early the subsaturated solutions of several aggregate-prone proteins, including Syn. The role of these early large protein aggregates and the reaction processes that they involve remain elusive.Amyloid protein's fluorophores (aromatic residues) can retrieve information regarding the amyloid protein's aggregation, by monitoring their fluorescence intensity. By excitation of Syn tyrosine residues in a low ionic strength medium (0.01 M tris-HCl) and collecting the time resolved fluorescence (stopped-flow analysis) it was possible to discriminate a time window of the first ca. 2 s, corresponding to the prevalent dissociation of early large Syn aggregates formed. Lowering even further the media ionic strength, such as Syn in water and Syn in solution containing 1,4-dioxane (pH ≈ 6.5), the above referred time window of the first ca. 2 s was abolished. It should be expected that Syn aggregation mainly occurred. In fact, Syn aggregation is initially delayed by the addition of a structure-induced agent (1,4-dioxane) in a stepwise mechanism. This study retrieves that very early the large Syn aggregates formed are unstructured and, in low ionic strength media (>0.01 M), they restructure in the dissociation process and intertwined the occurrence of its aggregation. In lower ionic strength media (<0.01 M), the large Syn aggregates dissociation is abolished and its aggregation is initially delayed, conferring to these protein aggregates restructuring in a stepwise mechanism.

Influence of Ethanol on the Acid-Induced Flocculation of Casein Micelles

The influence of ethanol (0–10%, v/v) on the acid-induced flocculation of casein micelles was examined using diffusing wave spectroscopy. For this purpose, samples containing 10% (w/w) reconstituted skim milk powder and 0–10% (v/v) ethanol were acidified with glucono-delta-lactone and acid-induced coagulation was monitored by diffusing wave spectroscopy. The pH at which acid-induced flocculation of the casein micelles commenced (pHf) increased near-linearly with increasing ethanol content, whereas the rate of flocculation was not affected by ethanol. The results are discussed in terms of the steric stabilisation of casein micelles by a polyelectrolyte brush in a medium of high ionic strength. Ethanol-induced increases in pHf are probably primarily due to an ethanol-induced reduction in solvent quality; an ethanol-induced reduction in dissociation of carboxylic acid groups in the brush is likely to contribute.

The structural rearrangement and depolymerisation induced by high‐pressure homogenisation inhibit the thermal aggregation of myofibrillar protein

SummaryThe effects of heating on the dissolution and aggregation of high‐pressure homogenisation (HPH)‐treated myofibrillar protein (MP) in low ionic strength medium were investigated in this study. Upon heating, HPH‐treated MP (HTMP) had a greater solubility and lower turbidity than control MP (P &lt; 0.05). The rheological measurement exhibited that the thermal aggregation ability of HTMP was hampered due to lower storage modulus (G′) and loss modulus (G″), except near 50 °C. The increased G′ and G″ of HTMP at near 50 °C could be attributed to structural rearrangement induced by HPH. The analysis of proteomics indicated that HPH destroyed the cytoskeletal proteins in myofibrillar structure, made MP structure more swollen and flexible, promoted MP rearrangement and formation of oligomers with higher negative charge, which produced stronger steric hindrance and electrostatic repulsion between molecules, thus inhibiting thermally induced MP aggregation. The depolymerisation effect induced by HPH destroyed myosin head and tail portion, hampered the assembly of myosin into filaments and therefore suppressed the formation of strand‐type aggregates under heating. The in vitro digestion suggested that the depolymerisation and rearrangement effect significantly improved MP digestibility (P &lt; 0.05) regardless of whether the protein was heat treated or not.

Improved water solubility of myofibrillar proteins by ultrasound combined with glycation: A study of myosin molecular behavior

The poor water solubility of myofibrillar proteins (MPs) limits their application in food industry, and is directly related to the molecular behavior associated with myosin assembly into filaments. This study aims to explore the effect of high-intensity ultrasound (HIU) combined with nonenzymatic glycation on the solubility, structural characteristics, and filament-forming behavior of MPs in low ionic strength media. The results showed that the HIU (200–400 W) application could promote the subsequent glycation reaction between MPs and dextran (DX) and interfere with the electrostatic balance between myosin rods, suppressing the formation of filamentous myosin polymers. Glycated MPs pretreated by 400 W HIU had the highest solubility, which corresponded to the smallest particle size, highest zeta potential, and optimum storage stability (P < 0.05). Structure analysis and microscopic morphology observations suggested that the loss of the MP superhelix and the depolymerization of filamentous polymers were the main mechanisms for MP solubilization. In conclusion, HIU combined with glycation can effectively improve the water solubility of MPs by destroying or suppressing the assembly of myosin molecules.

Thalassiosira pseudonana and Skeletonema costatum biomass optimization: Cultivation, harvesting, extraction of oils and biodiesel and pelletization of the residue

Microalgae are one of the most promising feedstocks for biofuel production that can solve the energy crisis, climate change, and the depletion of fossil fuels. Biorefineries have production capacity bottlenecks that prevent them from being economically profitable, without leaving aside the environmental safety of by-products. This research aims to analyze critical stages such as harvesting or lipid extraction from two microalgae species currently unknown, such as Thalassiosira pseudonana and Skeletonema costatum. Inorganic flocculation with a low concentration of iron or aluminum salts (FeCl3 and Al2(SO4)3) was achieved to recover >60% biomass in just 20 min in both cases. Lipids extractions through chloroform: methanol (solvent ratio 2:1) obtained low performance due to the ionic strength medium. The fatty acid composition of the algae extracts showed that stearic acid (C18:0) and palmitoleic acid (C16:1) were predominant in both species. In addition, residues from the lipid extraction process were used for the manufacture of pellets. The data collected showed that these solid biofuels should be combined with other biomass typologies if the end-use are biomass boilers. The development of these studies provides new information on different microalgae species and their potential to use their biomass through an integrated utilization.

Improving the solubility of myofibrillar proteins in water by destroying and suppressing myosin molecular assembly via glycation

Filamentous myosin is a self-assembling polymer that prevents myofibrillar proteins (MPs) from functioning in low ionic strength media. This study was aimed at investigating if glycation has the potential to improve the solubility of MPs in water. MPs were conjugated with monosaccharides, oligosaccharides, and polysaccharides under wet reaction conditions at 37 °C. The conjugation was verified by SDS-PAGE, FT-IR and amino acid analyses. MPs conjugated with dextran (DX) exhibited a higher solubility and dispersion stability in water, which corresponded to smaller particle size and more uniform distribution (P < 0.05). According to secondary and tertiary structure analyses, the loss of α-helix structures and unfolding of the MPs appear to be the main reasons for MP solubilization. Additionally, according to the zeta-potential, confocal laser scanning microscopy, and atomic force microscopy observation results, glycation can provide electrostatic repulsion or steric hindrance to disintegrate existing filamentous myosin aggregates and inhibit further self-assembly behavior.