Alginate Poly Research Articles

Synthesis, characterization, and adsorption capacity of sodium alginate poly grafted (fumaric acid-co-polyacrylic acid)/graphene oxide hydrogel as adsorbent for Cr (VI) and Pb (II) removal

Synthesis, characterization, and adsorption capacity of sodium alginate poly grafted (fumaric acid-co-polyacrylic acid)/graphene oxide hydrogel as adsorbent for Cr (VI) and Pb (II) removal

Proficiency of some synthetic alginate derivatives for sequestration of Iodine-131 from radioactive liquid waste

ABSTRACT The current effort in environmental remediation is aimed at removing iodine-131 radionuclide from radioactive liquid waste produced by an Egyptian nuclear power plant using some synthesised alginate derivatives. Two different copolymers, namely sodium alginate poly (acrylic acid) (P1) and sodium alginate poly (acrylic acid-methacrylic acid) (P2), are prepared using gamma radiation. The ability of these polymers to remove 131I radionuclide as sorbents has been investigated. The synthesised polymers exhibit excellent adsorption performance for 131I ions, and the adsorption equilibrium requires only 30 min, which reveals that the sorption process is kinetically faster than most of the other materials reported previously. The removal percents for 131I radionuclide at a pH of 3.0 at room temperature on P1 and P2 are 77.7% and 84.2%, respectively. The sorption capacities of the two polymers demonstrate that P2 > P1, with capacities of 67.9 and 58.5 mg/g, respectively. Four linear kinetic models are investigated: pseudo-first order, pseudo-second order, Elovich, and Weber–Morris models. Regarding their calculated parameters, these models indicate that the adsorption process of I-ions on both P1 and P2 is controlled by chemisorption. Four equilibrium isotherm models (Redlich-Peterson, Langmuir, Freundlich, and Harkin-Jura) are investigated, revealing that the adsorption process is a monolayer and multilayer process on a heterogeneous surface.

Alginate poly and oligosaccharide (AOS) from Sargassum sp. as immunostimulant in gnotobiotic artemia challenge tests and antibacterial diffusion disc assay against pathogenic Vibrio parahaemolyticus, V. vulnificus and V. harveyi

Alginate is a polysaccharide derived from Sargassum sp. and is a potent immunostimulant with antibacterial activity, including against Vibrio spp. This genus of bacteria is found in freshwater and marine environments and is a common infectious, pathogenic bacteria both for aquatic cultivans and humans. Here, we determined the ability of sodium alginate polysaccharides and oligosaccharides (AOS) to act as immunostimulants in Artemia challenge tests and antibacterial diffusion disc assays against Vibrio parahaemolyticus, V. vulnificus, and V. harveyi. The AOS was produced by thermal heating. Dry sodium alginates were weighed out from 4.21 to 6.47 grams with a yield varying from 21.05 to 32.35%. Alginate polysaccharides were challenged against V harveyi and showed 8 positive results. The highest inhibitor zone was 12.962±3.623 mm. Based on 18 tests, AOS showed 12 positive results, with the highest inhibitor zone being 10.250±0.09 mm. The encapsulated alginate against Vibrio parahaemolyticus, Vibrio harveyi, Vibrio vulnificus, and the non-challenged tests without any Vibrio spp. addition resulted in the best concentrations of 800 ppm (polysaccharide) and 600 ppm (oligosaccharide), respectively. The lower concentration of oligosaccharides alginate were more effective and has the potential to be superior as an antibacterial agent and immunestimulant, as opposed to alginate polysaccharide.

Sequestration of methylene blue dye using sodium alginate poly(acrylic acid)@ZnO hydrogel nanocomposite: Kinetic, Isotherm, and Thermodynamic Investigations

In this study, a sodium alginate poly(acrylic acid) (SA-poly(AA)) hydrogel and sodium alginate poly(acrylic acid)/zinc oxide (SA-poly(AA)/ZnO) hydrogel nanocomposite (HNC) was synthesized by in situ free-radical polymerization for the sequestration of toxic methylene blue (MB) dye from aqueous solution. The structural properties were analyzed using FTIR, XRD, SEM, TEM, TGA, and DMA The swelling analysis revealed that SA-poly(AA)/ZnO HNC exhibited high water uptake capacity. The kinetics, isotherms, and thermodynamics of adsorption were examined, and results showed that equilibrium data fitted the Langmuir isotherm model, and the adsorption kinetics of MB followed pseudo-second-order model. The maximum adsorption capacity was found to be 1129 mg/g for the SA-poly(AA) hydrogel and 1529.6 mg/g for the SA-poly(AA)/ZnO HNC in 0.25 g/L MB solution at pH 6.0 within 40 min. Thermodynamic parameters for SA-poly(AA) hydrogel and SA-poly(AA)/ZnO HNC substantiated the exothermic and endothermic nature of the adsorption processes, respectively. Moreover, SA-poly(AA)/ZnO HNC presented outstanding reusability with relatively better adsorption efficiencies as compared to SA-poly(AA) hydrogel.

New Alginate/PNIPAAm Matrices for Drug Delivery.

This paper deals with a comparative study on the interpolymeric complexes of alginate poly(N-isopropyl acryl amide (PNIPAAm) and corresponding graft copolymers with various compositions in respect to their toxicity, biocompatibility and in vitro and in vivo release of theophylline (THP). Loading of the various matrices with theophylline and characterization of loaded matrices was studied by near infrared spectroscopy–chemical imaging (NIR–CI) analysis, scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). It was appreciated that THP loading is higher than 40% and the drug is relatively homogeneous distributed within all matrices because of some specific interactions between components of the system. All samples have been found to be non-toxic and biocompatible. It was established that graft copolymers having a good stability show a better drug carrier ability, a higher THP loading, a prolonged release (longer release duration for graft copolymers of 235.4–302.3 min than that for IPC 72/28 of 77.6 min, which means approximately four times slower release from the graft copolymer-based matrices than from the interpolymeric complex) and a good bioavailability. The highest values for THP loading (45%), prolonged release (302.3 min) and bioavailability (175%) were obtained for graft copolymer AgA-g-PNIPAAm 68. The drug release mechanism varies with composition and architecture of the matrix.

Development of stable and active PVA‐PSSA/SA‐PVA catalytic composite membrane for esterification enhancement

ABSTRACTAn active and stable catalytic composite membrane (CCM), poly(vinyl alcohol)–poly(styrene sulfonic acid)/sodium alginate–poly(vinyl alcohol) (PVA‐PSSA/SA‐PVA), was prepared to enhance the esterification of ethanol and propionic acid. The morphologies and crystal structures of the CCMs were investigated by Fourier transform infrared spectroscopy, scanning electron microscopy, and X‐ray diffraction. The effects of catalytic layer thickness, mass ratio of PVA to PSSA, concentration of catalytic layer solution, ratio of reaction volume to membrane area, and molar ratio of propionic acid to ethanol were discussed. The pervaporation results showed that the flux of CCM increased from 118 to 320 g m−2 h−1 compared with the SA‐PVA membrane because of the close affinity and low resistance of PSSA to water. After crosslinking with 3‐aminopropylmethyldiethoxysilane, the CCMs had good catalytic activities. The acid conversion reached 92.8% at 75 °C in 12 h, and the stabilization of the CCM was greatly improved. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46514.

Synthesis, swelling and adsorption studies of a pH-responsive sodium alginate–poly(acrylic acid) superabsorbent hydrogel

Polyacrylic acid grafted sodium alginate (SA-cl-PAA)-based hydrogel was synthesized by an aqueous polymerisation method. An acrylic acid (AA) monomer was grafted onto sodium alginate (SA) using N,N′-methylene-bisacrylamide (MBA) and potassium persulfate (KPS) as a crosslinker–initiator system. The impact of various parameters such as reaction time, the amount of solvent, pH, crosslinker amount, initiator concentration and monomer concentration on the swelling behavior of the synthesized hydrogel was investigated. We obtained a hydrogel with swelling percentage 41,298% which is quite high. Swelling studies were carried out under acidic (pH 2 buffer) and basic (pH 10 buffer) conditions and evaluated kinetically. The results revealed that the swelling process follows second order kinetics, and the water transport inside the hydrogel supports a Fickian mechanism. The swelling results also indicate that the swelling properties of the synthesized hydrogel showed an on- and off-switchable behavior under basic and acidic conditions, respectively. The synthesized hydrogel was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The hydrogel was used in the victoria blue R (VB) and rhodamine 6G (RG6) dye adsorption from wastewater. It was found that hydrogel adsorbed 95.8 and 99% of VB and RG6 (132 ppm), respectively, within 77 min. Adsorption of victoria blue is due to electrostatic interaction only, and removal of rhodamine 6G is explained on the basis of electrostatic interaction and hydrogen bonding.

Synthesis of a three-dimensional network sodium alginate–poly(acrylic acid)/attapulgite hydrogel with good mechanic property and reusability for efficient adsorption of Cu2+ and Pb2+

Water pollution caused by heavy metals has dramatically impacted ecosystems in recent years. For instance, 45.4% of lakes in China are in the category of moderate to high risk of toxic metal pollution, due to excessive mining. There is, therefore, a need for efficient techniques of metal decontamination. Hydrogels are gaining interest as heavy metal adsorbents because of their easy separation, but hydrogel applications are limited due to their poor mechanical property. Here we solve this problem by introducing natural attapulgite into the sodium alginate-poly(acrylic acid) semi-interpenetrating polymer network of the hydrogel. Results show that the compressive stress of the hydrogel with 10% attapulgite, of 1.230 Mpa, was 4.1 times higher than that of pure hydrogel, of 0.299 MPa. The adsorption capacity of hydrogel with 10% attapulgite was high, of 272.8 mg/g for Cu 2+ and 391.7 mg/g for Pb 2+. Even after five cycles of adsorption, the hydrogel with 10% attapulgite still adsorbs 261.7 mg/g Cu 2+ and 368.1 mg/g Pb 2+. Our findings thus reveal that network-structured sodium alginate-poly(acrylic acid)/attapulgite hydrogel holds great potential as an efficient and recyclable adsorbent for heavy metal removal.

Mechanical characterization of microcapsules with membrane permeability by using indentation analysis.

Mechanical modeling of the deformation of a liquid-filled spherical microcapsule indented by a sharp truncated-cone indenter was proposed, in which membrane permeability was taken into account. The change in the internal volume of the microcapsule due to fluid permeation was calculated on the basis of Kedem and Katchalsky equations (1958, "Thermodynamic Analysis of the Permeability of Biological Membranes to Non-electrolytes," Biochim. Biophys. Acta, 27, pp. 229-246). The membrane hydraulic permeability, membrane initial stretch, and effective osmotic pressure difference across the membrane of an alginate-poly(l)lysine-alginate (APA) microcapsule were identified by fitting calculated and measured force-displacement curves. The difference between deformed shapes with and without membrane permeability was shown, suggesting the spatial resolution of image analysis performed to measure the membrane permeability from the volume loss. The influences of changes in permeability, initial stretch, and a parameter β, used for determining the effective osmotic pressure difference, on the force-displacement relationship were examined, and mechanisms causing changes in the force-displacement relationship were discussed.

Removal of methylene blue dye using biodegradable hydrogel and reusing in a secondary adsorption process

Sodium alginate poly itaconic acid (NaAlg/IA) hydrogel was prepared by free radical polymerization using gamma radiation. Characterization of the hydrogel was done by thermogravimetric and Infrared analysis. The hydrogel was used for removal of methylene blue dye (MB) about 85% of dye was removed. The experimental data have been modeled by Langmuir, Freundlich, and Temkin, the adsorption data were well described by the Freundlich model. The adsorption kinetic was studied and the pseudo-second-order reaction was better than pseudo-first-order reaction for low concentrations of MB and vice versa. The calculated dimensionless separation factor RL was 0.1 indicates favorable adsorption process. Thermodynamic parameters suggest that the adsorption is physical process (ΔH° = −17.87 kJ/mol), spontaneous, and exothermic in nature. After adsorption, the NaAlg/IA hydrogel-loaded MB was applied to secondary adsorption of acid fast red dye (AFR) at suitable conditions. Successful results were obtained about 74% of AFR was removed due to the altered surface structures of the used adsorbents.

Enhanced anti-swelling property and dehumidification performance by sodium alginate–poly(vinyl alcohol)/polysulfone composite hollow fiber membranes

Abstract Enhanced membrane dehumidification performance was achieved by physically blending sodium alginate (NaAlg) with poly(vinyl alcohol) (PVA). Both flat-sheet homogenous membranes and hollow-fiber composite membranes were prepared and characterized by Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), positron annihilation lifetime spectroscopy (PALS). When PVA content was 20 wt.% and 30 wt.%, the blend membranes exhibited lower swelling degree and much higher water/propylene selectivity than both NaAlg and PVA control membranes, resulting from the better-controlled free volume cavity size. In particular, the blend membrane containing 20 wt.% PVA showed the best dehumidification performance for propylene-water mixture. Both high water permeance (>10−2 cm3(STP)/cm2 s cmHg) and high selectivity (infinite big) were acquired for 0.13 wt.% water in feed under optimized operating conditions (temperature: 298 K; feed pressure: 250 kPa; feed flowrate: ≥300 ml/min).

Encapsulation of Huh-7 cells within alginate-poly(ethylene glycol) hybrid microspheres

Novel calcium alginate poly(ethylene glycol) hybrid microspheres (Ca-alg-PEG) were developed and evaluated as potentially suitable materials for cell microencapsulation. Grafting 5-13% of the backbone units of sodium alginate (Na-alg) with α-amine-ω-thiol PEG maintained the gelling capacity in presence of calcium ions, while thiol end groups allowed for preparing chemically crosslinked hydrogel via spontaneous disulfide bond formation. The combination of these two gelling mechanisms yielded Ca-alg-PEG. Human hepatocellular carcinoma cells (Huh-7) were encapsulated in Ca-alg-PEG and calcium alginate beads (Ca-alg), and cultured for 2 weeks under agitation conditions. Immediately after completion of the microencapsulation, the cell viability was 60% and similar in Ca-alg-PEG and Ca-alg. The proliferation of Huh-7 encapsulated in Ca-alg-PEG was slightly higher than in Ca-alg. Accelerated proliferation after 2 weeks was observed for the encapsulation in Ca-alg-PEG. The production of albumin confirmed the functionality of the encapsulated Huh-7 cells. The study confirms the suitability of Ca-alg-PEG and the one-step technology for cell microencapsulation.

Preparation of a sodium alginate–poly(vinyl alcohol)–chitosan bipolar membrane and its application in the electrogeneration of ferrate(VI)

AbstractA sodium alginate (SA)–poly(vinyl alcohol) (PVA)–chitosan (CS) bipolar membrane (BPM) was prepared by a paste method with PVA, SA, and CS as starting materials and modified by Fe3+ and GA as a crosslinking agent. The morphology, functional groups, and physical properties of the film were studied by scanning electron microscopy, IR spectroscopy, and tensile testing, respectively. The SA–PVA–CS BPM was used as a separator in the electrolysis cell for electrogenerated ferrate(VI). The results show that the SA–PVA–CS BPM possessed reasonable physical and electrochemical properties. The SA–PVA–CS BPM not only prevented ferrate(VI) from diffusing into the cathode room but also played an important role in the supply of OH− consumed during the electrogenerated ferrate(VI) process. Compared with the traditional method of preparing ferrate(VI), electrodialysis with the BPM (SA–PVA–CS) had the further advantage of lower alkali and energy consumption. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Design a chemically defined/medically approved medium for cell transplantation according to the metabolic characteristics of microencapsulated cells and the process of encapsulation

Cell microencapsulation is a promising therapeutic strategy to many diseases; however, the metabolic characteristics of microencapsulated cells and also the optimum microcapsule additives that meet the criteria for long-term functional immunoisolated transplantation have rarely been taken into consideration hitherto. In this work, the optimized amino acid supplements and several chemically defined compounds were applied to cultivation of the microencapsulated CHO cells. The results show that the optimized medium significantly enhances cell survival and, particularly, endostatin secretion of encapsulated CHO cells over a time period of 8 weeks. Furthermore, long-term in vitro stability of alginate–poly- l-lysine–alginate (APA) microcapsules underwent no changes, which indicated that this optimized medium might be feasible to maintain high viability of microencapsulated cell for short periods of time before implantation.

Alginate–poly(vinyl alcohol) core–shell microspheres for lipase immobilization

AbstractA lipase [triacylglycerol ester hydrolase (EC 3.1.1.3)] was encapsulated in sodium alginate (AlgNa)/poly(vinyl alcohol) (PVA) microspheres. Spherical AlgNa/PVA beads were prepared by the ionotropic gelation of an AlgNa/PVA blend in the presence of calcium tetraborate (CaB4O7). The particles were spherical and had an average diameter of 400 μm. The microspheres were studied with differential scanning calorimetry, Fourier transform infrared (FTIR) spectroscopy, and water transport by the equilibrium degree of swelling. The elevation of the glass‐transition temperature of the microspheres indicated specific crosslinking reactions of the component polymers (AlgNa/PVA). FTIR spectra showed no evidence of a strong chemical interaction changing the nature of the functional groups of both AlgNa and PVA in the AlgNa/PVA blends. The water diffusion coefficients increased with increasing PVA content in the microspheres, indicating a decrease in the resistance to mass transfer through the AlgNa/PVA microsphere wall. The AlgNa/PVA microspheres were characterized by the Michaelis constant (KM) and the maximum reaction velocity (Vmax), which were determined for both free and immobilized lipases. The enzyme affinity for the substrate (KM/Vmax) remained quite good after immobilization. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1553–1560, 2006

Cloning and Sequencing Analysis of Alginate Lyase Genes from the Marine Bacterium Vibrio sp. O2

We isolated a new marine bacteria, which displayed alginate-depolymerizing activity in plate assays, from seawater in Mihonoseki Harbor, Japan. Analysis of the 16S ribosomal RNA gene sequence of one of the isolates proved that this alginate-depolymerizing bacterium belonged to the genus Vibrio and it was named Vibrio sp. O2. The alginate lyase genes of Vibrio sp. O2 were cloned and expressed in Escherichia coli. Two alginate lyase-producing clones, pVOA-A4 and pVOA-B5, were obtained. The alginate lyase gene alyVOA from pVOA-A4 was composed of an 858-bp open reading frame (ORF) encoding 285 amino acid residues, while alyVOB from pVOA-B5 was composed of an 828-bp ORF encoding 275 amino acid residues. The degree of identity between the deduced amino acid sequences of AlyVOA or AlyVOB and Photobacterium sp. ATCC43367 alginate poly(ManA)lyase AlxM was 92.3% or 32.6%, respectively. Alginate lyase consensus regions corresponding to the sequences YFKAGXYXQ and RXELR were observed in all three of these sequences. AlyVOA and AlyVOB both degraded polymannuronate in plate assays and were therefore confirmed to be poly(beta-D-mannuronate)lyases.

Synthesis of an alginate–poly(sodium acrylate‐co‐acrylamide) superabsorbent hydrogel with low salt sensitivity and high pH sensitivity

AbstractThis article describes the synthesis and swelling behavior of a superabsorbing hydrogel based on sodium alginate (NaAlg) and polyacrylonitrile (PAN). The physical mixture of NaAlg and PAN was hydrolyzed with a solution of NaOH to yield an alginate–poly(sodium acrylate‐co‐acrylamide) [Alg–poly(NaAA‐co‐AAm)] superabsorbent hydrogel. A proposed mechanism for hydrogel formation was suggested, and the structure of the product was established with Fourier transform infrared spectroscopy. The effects of reaction variables were systematically optimized to achieve a hydrogel with a swelling capacity as high as possible. Under the optimized conditions concluded, the maximum capacity of swelling in distilled water was 610 g/g. The absorbency of the synthesized hydrogels was also measured in various salt solutions. The swelling ratios decreased with an increase in the ionic strength of the salt solutions. In addition, the swelling capacity was determined in solutions with pHs ranging from 1 to 13. The Alg–poly(NaAA‐co‐AAm) hydrogel exhibited pH responsiveness, so a swelling–deswelling pulsatile behavior was recorded at pHs 2 and 8. This on–off switching behavior made the hydrogel as a good candidate for the controlled delivery of bioactive agents. Finally, the swelling kinetics of the hydrogels with various particle sizes were preliminarily investigated as well. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2927–2937, 2006

Sodium alginate–poly(hydroxyethylmethacrylate) interpenetrating polymeric network membranes for the pervaporation dehydration of ethanol and tetrahydrofuran

AbstractInterpenetrating polymeric network (IPN) membranes of sodium alginate (NaAlg) and various amounts of poly(hydroxyethylmethacrylate) (PHEMA) have been prepared and tested for the pervaporation dehydration of ethanol and tetrahydrofuran (THF). The presence of hydrophilic PHEMA in the IPN matrix was found to be responsible for increase in membrane selectivity to water. NaAlg–PHEMA IPN membrane containing 20 wt % of PHEMA exhibited a selectivity of 571 to water for the water–ethanol mixture and 857 for water–THF mixture. These data are much better than those observed for the pristine NaAlg membrane. However, flux of the IPN membranes was smaller than that of pristine NaAlg membrane. Comparatively higher flux values were observed for water–THF mixture than for water–ethanol mixture. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3324–3329, 2006

Biocompatibility of alginate–poly- l-lysine microcapsules for cell therapy

Cell microencapsulation holds promise for the treatment of many diseases by the continuous delivery of therapeutic products. The biocompatibility of the microcapsules and their biomaterials components is a critical issue for the long-term efficacy of this technology. The objective of this paper is to provide detailed information about the principal factors affecting the biocompatibility of alginates and alginate–poly- l-lysine microcapsules, which are the most frequently employed biomaterials and encapsulation devices for cell immobilization, respectively. Some of these factors include the alginate composition and purification, the selection of the polycation, the interactions between the alginates and the polycation, the microcapsule fabrication process, the uniformity of the devices and the implantation procedure. Improved knowledge will lead to the production of standardized transplantation-grade biomaterials and biocompatible microcapsules.

Synthesis and characterization of a novel alginate–poly(ethylene glycol) graft copolymer

Sodium alginate grafted with low molecular weight polyethylene glycol (PEG) was prepared by reacting a mono-carboxyl terminated PEG with a sodium alginate modified by inserting a given amount of amine functionalities. The coupling between PEG and alginate was carried out using carbodiimide chemistry in aqueous solutions. Significant reduction of the molecular weight of alginate is recorded, as expected from literature reports. The chosen strategy allowed to graft significant amounts of PEG saving the carboxylic functionalities of alginate, necessary for the cross-linking of the polysaccharide. The chemical structure and chemical–physical properties of alginate derivatives were characterized by FTIR, 1H and 13C NMR, DSC, TGA and wide angle X-ray analysis.