Alginate Hydrogel Beads Research Articles

Dynamic Compression and Aggrecan Modulate Pericellular Matrix Development in Growth Plate Chondrocytes

Cartilage tissue in the long bones is subject to frequent changes in mechanical stress that are transduced through the extracellular matrix to chondrocytes. A specialized matrix called the pericellular matrix (PCM) surrounds chondrocytes and is known to provide biomechanical and biochemical cues to the cells. The PCM is composed of proteoglycans (e.g. aggrecan), glycosaminoglycans, and is the primary localization of type VI collagen (ColVI), which acts as an anchor to hold the chondrocytes to the PCM via β‐integrin transmembrane receptors. Although biomechanical signaling from the matrix to chondrocytes has been extensively studied, detailed studies of effects of mechanotransduction on PCM ultrastructure have not been performed. As a starting point, we developed two culture systems to study matrix formation by single chondrocytes. First, we used a 3D alginate hydrogel bead culture model to assess PCM development in murine hindlimb growth plate chondrocytes in static non‐compressed conditions. Second, we designed and used a microfluidic cell compression device stimulated by pressurized air to examine PCM development under one hour of dynamic compression (1 Hz) per day for four days. The device allows five different magnitudes (3.5–22%) of compressive strain to be tested simultaneously. We compared PCM development in wild type (WT) and Aggrecan (Acan) mutant chondrocytes that lack the proteoglycan component of the PCM. PCM development was assessed using immunofluorescence staining for ColVI, imaged with confocal microscopy, and measured using a MATLAB image processing program. Results show that under non‐compressed conditions, WT chondrocytes form a ring of ColVI at the cell surface within 1 day of culture and this ring expanded radially away from the membrane and increased in area over 21‐days of culturing. By contrast, null Acan chondrocytes did not show detectable ColVI deposition until day 4, and only after 7 days of culture did Acan mutant ColVI deposition equal that of day 1 WT growth plate chondrocyte (distance = 1.12±0.79 vs. 1.17±1.34 μm, respectively). The distance and area of ColVI matrix deposition was directly proportional to the magnitude of dynamic compression in the WT growth plate chondrocytes and similar studies are currently underway with Acan mutant chondrocytes. Our preliminary studies have demonstrated complementary culture systems that can be used to quantitatively analyze effects of compressive strain and mutant phenotypes on chondrocyte matrix development. Our continuing studies will use these tools to determine how chondrocytes build strong matrix and how intracellular and extracellular factors influence matrix structure and integrity. These studies of matrix structure are intended to support tissue engineering of cartilage, which despite decades of research has had little success in recapitulating the biomechanical functions of native cartilage.Support or Funding InformationGrant AR070242 from NIH/NAIMS, Holland Regenerative Medicine Program

Oscillatory Light‐Emitting Biopolymer Based Janus Microswimmers

AbstractJanus particles with a double functionality are synthesized by asymmetric loading of alginate hydrogel beads with Prussian Blue, leading to microswimmers with an original dynamic oscillatory behavior coupled to chemical light emission. This phenomenon results from the combination of two features: 1) Prussian Blue in the gel acts as a catalyst and enables concomitant light emission and oxygen production in the presence of luminol and hydrogen peroxide; 2) the hydrogel particle has a differential porosity distribution, leading to an asymmetric release of oxygen bubbles propelling the particle. The synthesis of these functional materials is achieved using an electric field based symmetry breaking approach with ionically cross‐linked alginate beads and can be applied to a wide range of particle sizes. Such light‐emitting swimmers open up interesting perspectives for the elaboration of autonomous dynamic chemical systems.

Alginate-Derived Porous Carbon Obtained by Nano-ZnO Hard Template-Induced ZnCl2-Activation Method for Enhanced Electrochemical Performance

Biomass-derived hierarchical porous carbons have attracted considerable attention due to their low cost, environmental friendliness and sustainability. However, the preparation of porous carbon with typically hierarchical pores is still challengeable. In this work, a facile and efficient strategy was proposed to obtain alginate-derived porous carbon by a combination of hard-template and chemical-activation technique. During the fabrication process the nano-ZnO particles displayed triple functions: (a) The nano-ZnO particles were behaved as the hard template to generate more pores. (b) ZnCl2 derived from the nano-ZnO particles acted as a cross-linking agent for obtaining zinc alginate (Zn-SA) hydrogel beads. (c) ZnCl2 was also employed as an activating agent to form micropores during the high-temperature carbonization process. As a subsequence, the obtained carbon exhibited well-developed hierarchical porous structure with high specific surface area of up to 2589 m2 g−1. Due to the high specific surface area, good electrical conductivity and synergistic effect among the typically hierarchical pores, the PC-ZnO-ZnCl2-650 exhibited a high specific capacitance of 316 F g−1 at the current density of 0.5 A g−1 and excellent cycling stability with capacitance retention of 94.4% at 5 A g−1 over 5000 cycles. This ingenious synthesis strategy can provide a new way for efficient preparation of hierarchical porous material.

Effect of Rheological Properties of Sodium Alginate-pectin Composite Solution on the Formation and Texture of Core-shell Capsules

Based on the synergistic gel formation mechanism between sodium alginate and pectin in presence of calcium ion,the sodium alginate-pectin hydrogel beads with shell-core structure,i.e. core-shell capsule,were prepared using reverse spherification technique,by adding the calcium-containing core solution into the sodium alginate-pectin complex solution. The rheological properties of both sodium alginate-pectin complex and the core solution were tested with the texture analyzer and rheometer and their effects on the texture properties of the core-shell capsules were studied. Results indicated that the viscosity of the complex solution gradually decreased gradually with the increase of the proportion of pectin in the complex system. The sodium alginate and pectin hydrogel beads prepared with sodium alginate-pectin ratio of 7:3 (w/w)and the concentration was 0.6%,showed the highest value of maximum force((430.1±24.4) g·cm-2)and chewability of the outer shell((1054.9±23.4) g).The optimized spherification(standard rate was 100%)and texture properties(the highest value of maximum force was(376.3±18.2) g·cm-2 the chewability was(1104.0±43.3) g)were obtained with xanthan gum concentration of 0.4% and the calcium lactate concentration of 1.5% in core liquid.

Alginate Hydrogel Beads for Immobilizing Single Photosynthetic Cells

Hydrogel beads of size 25-µm for immobilizing single photosynthetic cells of size approximately 5 µm were prepared by electrospraying and were characterized electrochemically using a microelectrode. A parametric study was then conducted on the size of the hydrogel beads containing the cells. In order to understand the electrochemical properties of the cells in the hydrogel bead, a microelectrode combined with a counter electrode was fabricated and characterized using microfabrication techniques; the electrochemical properties of the cells and beads were subsequently measured by chronoamperometry using this microelectrode system. The electrochemical properties of single cells immobilized in hydrogel were compared with those of single cells without immobilization by examining the oxygen-reduction currents for both cases. Changes in the oxygen-reduction current caused by photosynthesis in the cells show that an appropriate environment for cell survival is formed inside the hydrogel beads. We thus produced hydrogel beads containing photosynthetic cells that could be potentially useful for photosynthesis-based sensor applications.

Amino-carbamate moiety grafted calcium alginate hydrogel beads for effective biosorption of Ag(I) from aqueous solution: Economically-competitive recovery

In present study, pure and amino-carbamate moiety grafted calcium alginate hydrogel beads (CA, PSC-CA) were prepared for their biosorption performance in the recovery of silver ions. The produced sorbents were characterized using FTIR, SEM, EDX and TGA. FTIR and SEM-EDX confirmed the successful modification and loading of silver ions onto hydrogel beads. When compared with CA, PSC-CA showed enhanced sorption but comparable kinetics. Equilibrium sorption studies showed that pH, sorbent dose, contact time and adsorbate concentration influenced the sorption capacity. The uptake kinetic data was well demonstrated by pseudo second order rate equation (PSORE). Elovich equation and the resistance to intra-particle diffusion model (RID) suggested that there were two phases of sorption, first one was rapid followed by relatively slow uptake step. Equilibrium isothermal sorption data was well fitted by Langmuir and Sips models. The separation factor RL was found as 0 < RL < 1 which indicated favourable sorption. The maximum monolayer sorption capacity was computed as 210 mg/g at 298 K. Thermodynamic studies revealed the sorption process to be spontaneous and exothermic. PSC-CA hydrogel beads were found as cost-effective and efficient sorbent for economically-competitive recovery of Ag(I).

Fabrication of efficient alginate composite beads embedded with N-doped carbon dots and their application for enhanced rare earth elements adsorption from aqueous solutions

The increasing demand of rare earth elements in agriculture and industry raises the potential environmental pollution with their inevitable toxicity and biological accumulation. It is necessary to develop an efficient and low-cost technique to effectively remove rare earth elements. N-doped carbon dots (CDs) were green-synthesized using one-pot domestic microwave oven and novel alginate composite (ALG@CDs) beads were fabricated by embedding the N-doped CDs into pure alginate hydrogel beads. The synthetic materials were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, and zeta potential measurement. The ALG@CDs beads could effectively adsorb rare earth elements from aqueous solutions. Taking the adsorption of rare earth element Gd (III) as an example, initial concentration, adsorbent dosage, pH, temperature and contact time were optimized. The adsorption isotherms and kinetics fitted to Langmuir isotherm model (R2 > 0.9991) and pseudo-second-order kinetic model (R2 = 0.9918), respectively. The adsorption capacity of ALG@CDs-3 (201.21 mg/g) for Gd (III) was much higher than that of bare ALG beads (124.38 mg/g) according to the maximum theoretical adsorption capacity of Langmuir model. Competitive adsorption results indicated that ALG@CDs beads had stronger affinity to Gd (III) than to Al (III), Co (II), Ni (II), Zn (II), and Mg (II). The adsorbent could be easily collected and reused for five adsorption-regeneration cycles. The results indicated that the fabricated ALG@CDs beads are the promising materials for adsorption or enrichment of rare earth elements from waste water.

Improvement of fucoxanthin oral efficacy via vehicles based on gum Arabic, gelatin and alginate hydrogel

Abstract The improvement of the stability of fucoxanthin in gastrointestinal tract is an important approach to enhance its edible efficacy. In this study, we designed complex carriers, which were composed by gum Arabic/gelatin microcapsules and alginate hydrogel beads (GA/GE/Alg-Beads), as gastric acid resistant vehicles for oral delivery of fucoxanthin. Various parameters of the obtained fucoxanthin loaded GA/GE/Alg-Beads (FX:GA/GE/Alg-Beads) were characterized. In vitro release rate assay showed that more than 90% of the encapsulated fucoxanthin was released in simulated intestine fluid (SIF), indicated the beads could protect fucoxanthin while incubated in simulated gastric fluid (SGF). In vivo oral efficacy assay exhibited that FX:GA/GE/Alg-Beads could more effectively lower the blood lipid and oxidative stress level of experimental mice than free fucoxanthin. These results demonstrated the beads are favorable oral delivery systems for fucoxanthin and other biologically active substances which are unstable in gastric acid.

EXPRESSION OF THE MICROFOLD CELLS IN THREE-DIMENSIONAL COCULTURE SYSTEM FOR IN VITRO CULTIVATION OF HUMAN NOROVIRUS

Introduction: Human Norovirus (HuNoV), a food-borne virus is the leading cause for acute gastroenteritis. However, its inability to propagate in vitropersists as major challenge in understanding HuNoV biology.Objective: This study aims to determine an effective culture system for HuNoV.Methods: The Caco-2 cells were cocultured with Raji B cells on alginate hydrogel beads. Scanning electron microscopy (SEM) was performed to confirmthe three-dimensional (3D) cells morphology. Western blot (WB) analysis was performed to detect protein markers expressed by Microfold (M) cells.Results: Optimization of Caco-2 cells monoculture in the alginate hydrogel beads showed optimum number of cells of 1 × 106 cells/ml, indicatedby the intact structure of the beads. Result of SEM showed clear structure of monoculture in the alginate hydrogel beads indicated by the presenceof smooth and regular apical surface while the coculture showed reduced apical surface of M cells. The result of WB showed downregulation ofUlex europaeus antibody expression.Conclusion: It is evident that the expression of M cells grown in 3D alginate hydrogel beads was successful, indicated by the structural morphologyseen under SEM as well as expression of protein marker by M cells. This established in vitro system is highly potential for cultivation of HuNoV.

In vitro and in vivo release of diclofenac sodium-loaded sodium alginate/carboxymethyl chitosan-ZnO hydrogel beads

To control release of drugs sensitive to gastrointestinal (GI) environmental effects or irritating to stomach, such as diclofenac sodium (DS), sodium alginate (SA) hydrogel beads are gaining considerable attention gradually. However, due to high swelling ratio, the sustained release performance of SA hydrogel is still far from satisfactory. The objective of this research was to develop new drug delivery device based on SA and ZnO nanoparticles (ZnO NPs). ZnO NPs were prepared by direct precipitation method, and carboxymethyl chitosan (CMCS) acted as stabilizing agent to dominate the preparation of ZnO NPs. The incorporation of CMCS-ZnO NPs resulted in slower and sustained release of DS in vitro. In vivo pharmacokinetics studies showed the bioavailability of DS was better after oral administration of DS-loaded SA/CMCS-ZnO hydrogel beads. These results suggested that SA/CMCS-ZnO hydrogel beads will be a prospective material for loading drugs sensitive to GI environmental effects or irritating to stomach.

Simultaneous redox conversion and sequestration of chromate(VI) and arsenite(III) by iron(III)-alginate based photocatalysis

Multiple heavy-metal ions (e.g. Cr(VI) and As(III)) normally co-exist in acid wastewater, making the wastewater treatment complicated. Herein, the synergistic redox conversion and removal of Cr(VI)/As(III) were effectively achieved by applying iron(III) cross-linking alginate hydrogel beads (Fe-SA) as photocatalyst under simulated sunlight. Results show that not only 100% of the Cr(VI)/As(III) redox conversion was obtained in 150 min at pH 3.0, but also the removal efficiency of the transformed products (Cr(III) and As(V)) was greatly enhanced to above 80% in a wide pH range of 3–7. The CO2− radicals, produced by the ligand to metal charge transfer (LMCT) excitations on Fe-SA, together with the phtocatalysis-generated Fe(II), was responsible for the Cr(VI) reduction. Meanwhile, OH originating from CO2− mainly contributed to the As(III) oxidation, as confirmed by electron paramagnetic resonance and the by-product of CO2. Moreover, Fe-SA composite presented excellent reusability and performance in treatment of Cr(VI)/As(III) in real waters.

Optimization of calcium alginate beads production by electrospray using response surface methodology

Preparing the alginate hydrogel beads with desired size and enough mechanical strength is the main aim in biomedical application. Such beads were produced from the viscid alginate solution using electrospray method. In a recent study, the combined effects of different parameters on calcium alginate beads production were studied using response surface methodology. A 24 full-factorial central composite design was chosen to explain four parameters, viz. concentration of polymer, nozzle diameter, flow rate, and voltage. The small p-value (<0.0001) and large t-value (−16.611) of the coefficient for the linear effect of voltage showed that this independent variable has the greatest effect on calcium alginate beads production. It was found that interactions among the nozzle diameter and other variables were not significant. The optimum values of test variables for production of alginate beads with minimum radius were determined as; 10 g l−1 alginate concentration, 1 mm nozzle diameter, 20 ml h−1 flow rate, and 9000 v voltage. At these conditions, the experimental and predicted values of beads radius are 0.2945 and 0.3 mm, respectively, reveals the accuracy of the developed model.

Multifunctional Nanomaterial-alginate Drug Delivery and Imaging System for Cancer Therapy

Although chemotherapy is mostly performed by direct injection of the chemotherapeutic agents systemically, this approach can cause undesirable side effects in normal tissues and lacks targeting efficiency. In this study, we have developed a micron-sized, bead-type multifunctional anticancer-drug carrier that can be injected in the vicinity of a lesion using a syringe. The multifunctional anticancer-drug carrier bead was fabricated by incorporating functional nanomaterials, such as near-infrared (NIR)-responsive gold nanorod (GNR) and superparamagnetic iron oxide nanoparticles (IONP) that work as a magnetic resonance imaging (MRI) contrast agent, into an alginate hydrogel bead. The carrier bead containing GNR and IONP was spherical, with an average size of 362.2 ± 22.7 µm. These multifunctional anticancer-drug carrier beads could successfully release doxorubicin (Dox) into the external environment upon irradiation with an NIR laser. The laser responsive on-demand release profile demonstrated well-controlled and sustained release of Dox, and the effectiveness of this drug delivery system can be confirmed in vitro by the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay. Additionally, the control experiments evidenced that the thermal effect of GNR was insignificant and the cytotoxic action of Dox was expressed only after irradiation with the NIR laser. The multifunctional anticancer-drug carrier beads can be precisely monitored with the MRI T2 imaging mode.

High extent mass recovery of alginate hydrogel beads network based on immobilized bio-sourced porous carbon@Fe3O4-NPs for organic pollutants uptake

This work goes inside the understanding of organic pollutants adsorption mechanism over network alginate hydrogel beads based on immobilized bio-sourced PC@Fe3O4-NPs (PC@Fe3O4-NPs@Alginate) and highlights its high extent mass recovery in aqueous media. The samples were successfully synthesized, we previously developed porous carbon (PC), which, was used to elaborate PC@Fe3O4-NPs via simple in situ coprecipitation (PC@ Fe3O4-NPs), which was encapsulated by alginate-Ca2+ via the blend crosslinking method. The structural, textural, chemical and morphological proprieties of as prepared materials were studied by XRD, FTIR, Raman spectroscopy, nitrogen adsorption-desorption, XPS, SEM and TEM. The adsorption kinetic and isotherm data were well fitted to the pseudo-second-order and Langmuir models. Magnetic particles exhibited an excellent ability to adsorb methylene blue (MB) from aqueous solutions with maximum MB adsorption capacity of 180.42 mg g−1 (PC@Fe3O4 NPs powder) and 49.66 mg g−1 (beads based PC@Fe3O4-NPs@Alginate). Response surface methodology was used to optimize the removal efficiency of MB from aqueous solution and optimum parameters were determined. Magnetic beads based PC showed good magnetic propriety, long-term stability, regeneration capabilities and high extent mass recovery.

Release mechanism of lipid nanoparticles immobilized within alginate beads influenced by nanoparticle size and alginate concentration

The combination of hydrogels and lipid carriers has been widely used in the encapsulation of oil-soluble active ingredients. The objective of the present work was to understand the release mechanism of lipid nanoparticles (LNP) immobilized within alginate hydrogel beads. To evaluate the amount of LNP released from alginate beads, a simple method derived from dynamic light scattering was established and applied in the dissolution study effectively. The presence of LNP-mediated release was confirmed in the dissolution study. The dissolution study in simulated gastric fluids, involving diffusion-controlled release model, indicated that the LNP-mediated release was susceptible to the size of LNP and alginate concentration. The release study in simulated intestinal fluids, involving swelling-controlled release model, showed that the alginate concentration had a decisive effect on the release. This study will be helpful for the design of a new delivery system, which combines hydrogels and lipid carriers.

Effective biosorption of U(VI) from aqueous solution using calcium alginate hydrogel beads grafted with amino-carbamate moieties

Novel amino-carbamate moiety grafted calcium alginate hydrogel beads (CA-1) were synthesized by reacting sodium alginate with 4-phenylsemicarbazide followed by ionotropic crosslinking with Ca(II) ions. As compared to pure calcium alginate hydrogel beads (CA), CA-1 exhibited fast kinetics and enhanced sorption capacity towards U(VI) ions, from mild acidic conditions. The sorption kinetic could be described by pseudo-second order equation, with the chemisorption as the rate-controlling step. The sorption isotherm were fitted well by Langmuir (qm = 233.2 mg/g at 298 K). CA-1 hydrogel beads exhibited fast kinetic, high sorption capacity and excellent selectivity for U(VI) sorption, thus it could be potentially used for the removal/recovery of U(VI) ions from wastewater.

Adsorptive removal of Cu(II) from aqueous solutions using a novel macroporous bead adsorbent based on poly(vinyl alcohol)/sodium alginate/KMnO4 modified biochar

Abstract In this study, a novel adsorbent was synthesized through the entrapment of KMnO4 modified biochar (MB) in poly(vinyl alcohol)/sodium alginate hydrogel bead (PSMB) and then tested to determine its capacity for removal of Cu(II) from aqueous solutions. The maximum Cu(II) adsorption capacity estimated with Langmuir isotherm modeling was 87.07 mg/g of PSMB, which was higher than that of previously reported adsorbents. PSMB had a good selectivity towards Cu(II) as well as high anti-interference ability. The main species for Cu(II) adsorption likely were the inner-sphere Cu-O complexes, as indicated by the results of spectral analyses. The PSMB was easily collected and exhibited a minimal loss of adsorption capacity after 10 adsorption/regeneration cycles. The effective removal of Cu(II) from environmental water samples with relative low treatment cost indicated a possibility for practical application.

Fabrication of magnetic bentonite/carboxymethyl chitosan/sodium alginate hydrogel beads for Cu (II) adsorption

In this work, composite hydrogel beads based on magnetic bentonite/carboxymethyl chitosan/sodium alginate (Mag-Ben/CCS/Alg) were fabricated and their ability to adsorb copper ions in water was studied. The structure and properties of the composite were characterized via SEM, FTIR, XPS, TGA, VSM, and Zeta potential tests. The effects of the adsorbent dosage, adsorption time, pH, temperature, and initial concentration of Cu(II) on the adsorption results were studied. The results showed that Mag-Ben/CCS/Alg reached equilibrium after 90 min of adsorption, the removal rate of Cu(II) was 92.62 ± 0.39%, and the maximum adsorption capacity was 56.79 mg/g (30 °C). The removal rate of Cu(II) by Mag-Ben/CCS/Alg still remained above 80% after recycling four times. The adsorption process of Cu(II) by Mag-Ben/CCS/Alg occurred in accordance with the quasi-second-order kinetic model and Langmuir adsorption isotherm. The adsorption process was spontaneous and endothermic.

Encapsulation and release behavior of curcumin based on nanoemulsions-filled alginate hydrogel beads

To provide the bilateral advantages of emulsions and hydrogels, a facile approach was used to fabricate nanoemulsions filled hydrogel beads through combining the method of self-emulsification and sodium alginate (SA) ionic gelation. The encapsulation and release behavior of curcumin (Cur) were further investigated. The results indicated that Cur packaged nanoemulsions were with the size of 24.26 ± 0.22 nm. The nanoemulsions filled SA hydrogel beads were spherical shell with the diameter of 0.46 ± 0.02 mm. For Cur, the EE and LC of emulsion filled SA hydrogel beads were 99.15 ± 0.85% and 7.25 ± 3.16 mg/g respectively. The release behavior could be regulated by external pH condition. The release behavior at pH 9.0 displayed a higher release rate than that at pH 7.0. Cur released behavior well followed the Hixcon-Crowell model which indicated that Cur was released in a diffusion-controlled model. Comparatively investigation of microstructure using field emission scanning electron microscope (FE-SEM) further investigates the corrosion behavior of SA gel beads during Cur release. The worth-while endeavor provided a practical combined technique of emulsions and ionic gelation to fabricate hybrid hydrogel beads that have potential in delivery system for hydrophobic composition.

Recovery of gold using graphene oxide/calcium alginate hydrogel beads from a scrap solid state detector

Hydrogel beads was developed for the selective removal of gold from a scrap solid state detector. Beads were synthesized by graphene oxide impregnation in calcium alginate matrix (Gra-Alg) using sol gel method. Scrap solid state detector was dissolved in aqua regia. Copper (Cu) from the solution was recovered using conventional chemical separation where as gold(Au) from the supernatant solution was selectively isolated using Gra-Alg hydrogel beads. The characteristic XRD peak of graphene oxide was observed at 2θ = 11°. The maximum uptake capacity of the hydrogel beads is observed as 81.87 mg g−1. The sorption capacity of the hydrogel beads is highly dependent on the pH of the solution and more than 95% uptake of Au was observed at pH range 2–4. The equilibrium contact time of the sorption of gold on the hydrogel beads was 22 h. Isotherm study suggests that the system is following the Langmuir isotherm model and the maximum sorption capacity (Q0) was observed as 81.87 mg g-1. The experimental data fitted well with the second order pseudo kinetic equation with linear correlation coefficient value as 0.94 and the rate constant is 0.001 g mg-1 min-1.