Influence of Zwitterionic CAPB on Flocculation of the Aqueous Cationic Guar Gum/Glauconite Suspensions at Various pH

The influence of the pseudoamphoteric zwitterionic surfactant cocamidopropylbetaine (CAPB) on the stabilizing flocculating properties of the aqueous suspensions of glauconite (GT) with cationic guar gum (CGG) at various pH values was investigated. The following techniques were used: turbidimetry, UV-VIS spectrophotometry, tensiometry, electrophoretic mobility measurements, SEM, CHN, XRD, and FT-IR. It was established that CGG is an effective glauconite flocculant. Moreover, the most probable mechanism that is responsible for flocculation is bridge flocculation resulting from polymer adsorption on the glauconite surface. The adsorption process is caused by electrostatic interactions between the negatively charged glauconite surface and the positively charged polymer. The amount of CGG adsorption increases with the increase of the pH, which was confirmed by the adsorption and zeta potential measurements. The addition of CAPB increases the amount of the polymer adsorption due to the formation of intermolecular polymer–surfactant complexes; however, it reduces flocculation effectiveness.

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Surfactant-Like Behavior for the Adsorption of Mixtures of a Polycation and Two Different Zwitterionic Surfactants at the Water/Vapor Interface

Molecules ◽

10.3390/molecules24193442 ◽

2019 ◽

Vol 24 (19) ◽

pp. 3442 ◽

Cited By ~ 9

Author(s):

Andrew Akanno ◽

Eduardo Guzmán ◽

Laura Fernández-Peña ◽

Francisco Ortega ◽

Ramón G. Rubio

Keyword(s):

Interfacial Properties ◽

Zwitterionic Surfactant ◽

Fluid Interface ◽

Surfactant Mixtures ◽

Zwitterionic Surfactants ◽

Dimethylammonium Chloride ◽

Polymer Surfactant ◽

Charged Group ◽

Positively Charged ◽

Dilational Rheology

The bulk and interfacial properties of solutions formed by a polycation (i.e., poly(diallyl-dimethylammonium chloride), PDADMAC) and two different zwitterionic surfactants (i.e., coco-betaine (CB) and cocoamidopropyl-betaine (CAPB)) have been studied. The bulk aggregation of the polyelectrolyte and the two surfactants was analyzed by turbidity and electrophoretic mobility measurements, and the adsorption of the solutions at the fluid interface was studied by surface tension and interfacial dilational rheology measurements. Evidence of polymer–surfactant complex formation in bulk was only found when the number of surfactant molecules was closer to the number of charged monomers in solutions, which suggests that the electrostatic repulsion associated with the presence of a positively charged group in the surfactant hinders the association between PDADMAC and the zwitterionic surfactant for concentrations in which there are no micelles in solution. This lack of interaction in bulk is reflected in the absence of an influence of the polyelectrolyte in the interfacial properties of the mixtures, with the behavior being controlled by the presence of surfactant. This work has evidenced the significant importance of the different interactions involved in the system for controlling the interaction and complexation mechanisms of in polyelectrolyte–surfactant mixtures.

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Characteristics of the Interaction between Thrombin Exosite1 and the Sequence 269-297 of Platelet Glycoprotein Ibα

Thrombosis and Haemostasis ◽

10.1055/s-0037-1615193 ◽

1998 ◽

Vol 80 (08) ◽

pp. 310-315 ◽

Cited By ~ 8

Author(s):

Marie-Christine Bouton ◽

Christophe Thurieau ◽

Marie-Claude Guillin ◽

Martine Jandrot-Perrus

Keyword(s):

Platelet Activation ◽

Electrostatic Interactions ◽

Platelet Glycoprotein ◽

Thrombin Receptor ◽

Central Position ◽

Amidolytic Activity ◽

N Terminus ◽

Hydrolysis Of ◽

Chemical Cross Linking ◽

Positively Charged

SummaryThe interaction between GPIb and thrombin promotes platelet activation elicited via the hydrolysis of the thrombin receptor and involves structures located on the segment 238-290 within the N-terminal domain of GPIbα and the positively charged exosite 1 on thrombin. We have investigated the ability of peptides derived from the 269-287 sequence of GPIbα to interact with thrombin. Three peptides were synthesized, including Ibα 269-287 and two scrambled peptides R1 and R2 which are comparable to Ibα 269-287 with regards to their content and distribution of anionic residues. However, R2 differs from both Ibα 269-287 and R1 by the shifting of one proline from a central position to the N-terminus. By chemical cross-linking, we observed the formation of a complex between 125I-Ibα 269-287 and α-thrombin that was inhibited by hirudin, the C-terminal peptide of hirudin, sodium pyrophosphate but not by heparin. The complex did not form when γ-thrombin was substituted for α-thrombin. Ibα 269-287 produced only slight changes in thrombin amidolytic activity and inhibited thrombin binding to fibrin. R1 and R2 also formed complexes with α-thrombin, modified slightly its catalytic activity and inhibited its binding to fibrin. Peptides Ibα 269-287 and R1 inhibited platelet aggregation and secretion induced by low thrombin concentrations whereas R2 was without effect. Our results indicate that Ibα 269-287 interacts with thrombin exosite 1 via mainly electrostatic interactions, which explains why the scrambled peptides also interact with exosite 1. Nevertheless, the lack of effect of R2 on thrombin-induced platelet activation suggests that proline 280 is important for thrombin interaction with GPIb.

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Mercury Removal from Wastewater by Steamed Hoof Powder

Water Science & Technology ◽

10.2166/wst.1999.0340 ◽

1999 ◽

Vol 40 (7) ◽

pp. 109-116 ◽

Cited By ~ 4

Author(s):

M. H. Ansari ◽

A. M. Deshkar ◽

P. S. Kelkar ◽

D. M. Dharmadhikari ◽

M. Z. Hasan ◽

...

Keyword(s):

Heavy Metals ◽

Adsorption Capacity ◽

Adsorption Process ◽

Adsorption Equilibrium ◽

Light Metal ◽

Mercury Removal ◽

High Adsorption ◽

Surface Sites ◽

Ph Values ◽

High Adsorption Capacity

Steamed Hoof Powder (SHP), size < 53μ, was observed to have high adsorption capacity for Hg(II) with >95% removal from a solution containing 100 mg/L of Hg(II) with only 0.1% (W/V) concentration of SHP. The SHP has good settling properties and gives clear and odour free effluent. Studies indicate that pH values between 2 and 10 have no effect on the adsorption of Hg(II) on SHP. Light metal ions like Na+, K+, Ca2+ and Mg2+ up to concentrations of 500 mg/L and heavy metals like Cu2+, Zn2+, Cd2+, Co2+, Pb2+, Ni2+, Mn2+, Cr3+, Cr6+, Fe2+ and Fe3+ up to concentrations of 100 mg/L do not interfere with the adsorption process. Anions like sulphate, acetate and phosphate up to concentrations of 200 mg/L do not interfere. Chloride interferes in the adsorption process when Hg(II) concentration is above 9.7 mg/L. The adsorption equilibrium was established within two hours. Studies indicate that adsorption occurs on the surface sites of the adsorbent.

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Hybrid Acrylated Chitosan and Thiolated Pectin Cross-Linked Hydrogels with Tunable Properties

Polymers ◽

10.3390/polym13020266 ◽

2021 ◽

Vol 13 (2) ◽

pp. 266

Author(s):

Shaked Eliyahu ◽

Alexandra Galitsky ◽

Esther Ritov ◽

Havazelet Bianco-Peled

Keyword(s):

Electrostatic Interactions ◽

Profile Analysis ◽

Hybrid Hydrogel ◽

Texture Profile ◽

Ph Values ◽

X Ray Scattering ◽

Wide Range ◽

Michael Type Addition ◽

Physical And Chemical ◽

Hydrogel System

We developed and characterized a new hydrogel system based on the physical and chemical interactions of pectin partially modified with thiol groups and chitosan modified with acrylate end groups. Gelation occurred at high pectin thiol ratios, indicating that a low acrylated chitosan concentration in the hydrogel had a profound effect on the cross-linking. Turbidity, Fourier transform infrared spectroscopy, and free thiol determination analyses were performed to determine the relationships of the different bonds inside the gel. At low pH values below the pKa of chitosan, more electrostatic interactions were formed between opposite charges, but at high pH values, the Michael-type addition reaction between acrylate and thiol took place, creating harder hydrogels. Swelling experiments and Young’s modulus measurements were performed to study the structure and properties of the resultant hydrogels. The nanostructure was examined using small-angle X-ray scattering. The texture profile analysis showed a unique property of hydrogel adhesiveness. By implementing changes in the preparation procedure, we controlled the hydrogel properties. This hybrid hydrogel system can be a good candidate for a wide range of biomedical applications, such as a mucosal biomimetic surface for mucoadhesive testing.

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Subunit assembly of hemoglobin: an important determinant of hematologic phenotype

Blood ◽

10.1182/blood.v69.1.1.bloodjournal6911 ◽

1987 ◽

Vol 69 (1) ◽

pp. 1-6 ◽

Cited By ~ 4

Author(s):

HF Bunn

Keyword(s):

Electrostatic Interactions ◽

Hemoglobin Concentration ◽

Cytoskeletal Proteins ◽

Membrane Receptors ◽

Target Cells ◽

Red Cell Membrane ◽

Alpha Beta ◽

The Difference ◽

Polypeptide Chains ◽

Positively Charged

Hemoglobin's physiologic properties depend on the orderly assembly of its subunits in erythropoietic cells. The biosynthesis of alpha- and beta-globin polypeptide chains is normally balanced. Heme rapidly binds to the globin subunit, either during translation or shortly thereafter. The formation of the alpha beta-dimer is facilitated by electrostatic attraction of a positively charged alpha-subunit to a negatively charged beta-subunit. The alpha beta-dimer dissociates extremely slowly. The difference between the rate of dissociation of alpha beta- and alpha gamma-dimers with increasing pH explains the well-known alkaline resistance of Hb F. Two dimers combine to form the functioning alpha 2 beta 2-tetramer. This model of hemoglobin assembly explains the different levels of positively charged and negatively charged mutant hemoglobins that are encountered in heterozygotes and the effect of alpha-thalassemia and heme deficiency states in modifying the level of the variant hemoglobin as well as Hb A2. Electrostatic interactions also affect the binding of hemoglobin to the cytoplasmic surface of the red cell membrane and may underlie the formation of target cells. Enhanced binding of positively charged variants such as S and C trigger a normally dormant pathway for potassium and water loss. Thus, the positive charge on beta c is responsible for the two major contributors to the pathogenesis of Hb SC disease: increased proportion of Hb S and increased intracellular hemoglobin concentration. It is likely that electrostatic interactions play an important role in the assembly of a number of other multisubunit macromolecules, including membrane receptors, cytoskeletal proteins, and DNA binding proteins.

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A Comparative Study on The Adsorption Behavior of Congo Red on to ZnAl and ZnCr Layered Double Hydroxides

The Journal of Pure and Applied Chemistry Research ◽

10.21776/ub.jpacr.2020.009.02.519 ◽

2020 ◽

Vol 9 (2) ◽

pp. 108-116

Author(s):

Tarmizi Taher ◽

◽

Nyanyu Ummu Hani ◽

Neza Rahayu Palapa ◽

Risfidian Mohadi ◽

...

Keyword(s):

Experimental Data ◽

Surface Area ◽

Adsorption Kinetics ◽

Layered Double Hydroxides ◽

Congo Red ◽

Adsorption Process ◽

Bet Surface Area ◽

Pseudo Second Order ◽

Ft Ir ◽

Double Hydroxides

In this work, two synthetic layered double hydroxides (LDH) consists of Zn2+ as M2+ cation with different M3+ cation, i.e., Al3+ and Cr3+ were used as an adsorbent for Congo Red removal aqueous solution. Both Zn-Al and Zn-Cr LDH were characterized by X-ray diffraction, FT-IR, and BET surface area analyzer. The effect of contact time, initial dye concentration, and temperature were evaluated in a batch technique in order to investigate the characteristic of Congo Red adsorption onto both adsorbents. The experimental data were assessed according to the parameter of adsorption kinetics, isotherm, and thermodynamics. The results of LDH characterization showed that Zn-Al LDH has a higher interlayer distance than Zn-Cr LDH, although Zn-Cr LDH has a higher surface area. The FT-IR analysis indicated the interlayer space of both Zn-Cr and Zn-Al LDH was dominated by CO32- as the interlayer anion species. The adsorption kinetics study of Congo Red on both LDH revealed that the adsorption process followed the pseudo-second-order model. For the adsorption isotherm, the experimental data fit well with the Freundlich model rather than the Langmuir model. The thermodynamic study indicated that the adsorption process that occurred on both adsorbents was spontaneous with exothermic nature.

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The C-terminal peptide of CCL21 drastically augments CCL21 activity through the dendritic cell lymph node homing receptor CCR7 by interaction with the receptor N-terminus

Cellular and Molecular Life Sciences ◽

10.1007/s00018-021-03930-7 ◽

2021 ◽

Author(s):

Astrid Sissel Jørgensen ◽

Emma Probst Brandum ◽

Jeppe Malthe Mikkelsen ◽

Klaudia A. Orfin ◽

Ditte Rahbæk Boilesen ◽

...

Keyword(s):

Lymph Node ◽

Electrostatic Interactions ◽

Immune Cell ◽

Direct Interaction ◽

Receptor Interaction ◽

Binding Model ◽

Lymph Node Homing ◽

Gating Mechanism ◽

N Terminus ◽

Positively Charged

AbstractThe endogenous chemokines CCL19 and CCL21 signal via their common receptor CCR7. CCL21 is the main lymph node homing chemokine, but a weak chemo-attractant compared to CCL19. Here we show that the 41-amino acid positively charged peptide, released through C-terminal cleavage of CCL21, C21TP, boosts the immune cell recruiting activity of CCL21 by up to 25-fold and the signaling activity via CCR7 by ~ 100-fold. Such boosting is unprecedented. Despite the presence of multiple basic glycosaminoglycan (GAG) binding motifs, C21TP boosting of CCL21 signaling does not involve interference with GAG mediated cell-surface retention. Instead, boosting is directly dependent on O-glycosylations in the CCR7 N-terminus. As dictated by the two-step binding model, the initial chemokine binding involves interaction of the chemokine fold with the receptor N-terminus, followed by insertion of the chemokine N-terminus deep into the receptor binding pocket. Our data suggest that apart from a role in initial chemokine binding, the receptor N-terminus also partakes in a gating mechanism, which could give rise to a reduced ligand activity, presumably through affecting the ligand positioning. Based on experiments that support a direct interaction of C21TP with the glycosylated CCR7 N-terminus, we propose that electrostatic interactions between the positively charged peptide and sialylated O-glycans in CCR7 N-terminus may create a more accessible version of the receptor and thus guide chemokine docking to generate a more favorable chemokine-receptor interaction, giving rise to the peptide boosting effect.

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Effect of hydrocolloids on physicochemical properties, stability, and digestibility of Pickering emulsions stabilized by nanofibrillated cellulose

Food & Function ◽

10.1039/d1fo02933a ◽

2022 ◽

Author(s):

Nuttinee Tangsrianugul ◽

Thunnalin Winuprasith ◽

Manop Suphantharika ◽

Jirarut Wongkongkatep

Keyword(s):

Physicochemical Properties ◽

Xanthan Gum ◽

Guar Gum ◽

Nanofibrillated Cellulose ◽

Pickering Emulsions ◽

Positively Charged

In this study, effect of hydrocolloids with different electrostatic characteristics, i.e. negatively charged xanthan gum (XG), positively charged chitosan (CH), and non-ionic guar gum (GG) on physicochemical properties, stability, and...

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Oxaliplatin–Biomimetic Magnetic Nanoparticle Assemblies for Colon Cancer-Targeted Chemotherapy: An In Vitro Study

Pharmaceutics ◽

10.3390/pharmaceutics11080395 ◽

2019 ◽

Vol 11 (8) ◽

pp. 395 ◽

Cited By ~ 6

Author(s):

Ylenia Jabalera ◽

Beatriz Garcia-Pinel ◽

Raul Ortiz ◽

Guillermo Iglesias ◽

Laura Cabeza ◽

...

Keyword(s):

Colon Cancer ◽

Electrostatic Interactions ◽

Magnetic Nanoparticle ◽

In Vitro Study ◽

Targeted Chemotherapy ◽

Proof Of Concept ◽

Therapeutic Approaches ◽

Ph Values ◽

Common Cancer

Conventional chemotherapy against colorectal cancer (CRC), the third most common cancer in the world, includes oxaliplatin (Oxa) which induces serious unwanted side effects that limit the efficiency of treatment. Therefore, alternative therapeutic approaches are urgently required. In this work, biomimetic magnetic nanoparticles (BMNPs) mediated by MamC were coupled to Oxa to evaluate the potential of the Oxa–BMNP nanoassembly for directed local delivery of the drug as a proof of concept for the future development of targeted chemotherapy against CRC. Electrostatic interactions between Oxa and BMNPs trigger the formation of the nanoassembly and keep it stable at physiological pH. When the BMNPs become neutral at acidic pH values, the Oxa is released, and such a release is greatly potentiated by hyperthermia. The coupling of the drug with the BMNPs improves its toxicity to even higher levels than the soluble drug, probably because of the fast internalization of the nanoassembly by tumor cells through endocytosis. In addition, the BMNPs are cytocompatible and non-hemolytic, providing positive feedback as a proof of concept for the nanoassembly. Our study clearly demonstrates the applicability of Oxa–BMNP in colon cancer and offers a promising nanoassembly for targeted chemotherapy against this type of tumor.

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Inhibition of Pipeline Steel Corrosion in 0.5 M H2SO4 Using Cotyledon of Chrysophyllum Albidum

Journal of Applied Sciences and Environmental Management ◽

10.4314/jasem.v24i4.22 ◽

2020 ◽

Vol 24 (4) ◽

pp. 691-697

Author(s):

E.P. Othaki ◽

N.C. Ngobiri

Keyword(s):

Corrosion Inhibitors ◽

Inhibition Efficiency ◽

Adsorption Process ◽

Pipeline Steel ◽

Steel Corrosion ◽

Langmuir Adsorption ◽

Extract Concentration ◽

Ir Studies ◽

Ft Ir ◽

As Adsorption

The corrosion inhibition characteristics of Chrysophyllum albidum cotyledon extract was studied as a green and sustainable corrosion inhibitors for pipeline steel in acidic environment attemperatures, 303,313 and 323K using gravimetric technique.The results obtained showed that the inhibition efficiency increased with increase in extract concentration but decrease with increase in temperature. The extract attained an inhibition efficiency of 94 % with 5 g/L at 303 K and 52.2 % with 1 g/L at 333K. Also increase in concentration of the extract lead to increase in activation energydepicting an exothermic process.Fourier transform infrared spectroscopy (FT-IR) studies showed the mode of inhibition as adsorption of phytochemicals from the extract on pipeline steel surface. Langmuir adsorption isotherm best fitted into the adsorption process which is spontaneous and physical. Keywords: Chrysophyllum albidum, Pipeline steel, Inhibition, Adsorption.

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