CA Beads Research Articles

In vitro kinetic release study of ketoprofen enantiomers from alginate metal complexes

BackgroundTo explore the release behavior of ketoprofen enantiomers from alginate-metal-complexes. Five mathematical models of drug release kinetics were investigated.ResultsBeads of alginate-metal complexes, loaded with racemic ketoprofen, were prepared by the ionotropic method. Divalent (Ca, Ba, Zn) and trivalent (Fe, Al) metals were used in the preparation of single-metal and mixed-metal alginate complexes. In vitro release experiments were carried out in an aqueous phosphate buffer medium at pH = 7.4. The concentrations of ketoprofen released enantiomers were determined using chiral HPLC technique. The obtained data were used to simulate the release kinetic of ketoprofen enantiomers using various mathematical models. The Korsmeyer-Peppas model was the best fit for Ca, Al, and Fe beads. Moreover, alginate-iron beads tend to release the drug faster than all other cases. In contrast, the drug release for alginate-barium complex was the slowest. The presence of barium in alginate mixed-metal complexes reduced ketoprofen release in the case of Fe and Zn, while it increased the release in the case of Al complex.ConclusionIn all the studied cases, ketoprofen showed very slow release for both enantiomers over a period exceeded 5 h (10 days in some cases). The release rate modification is possible using different multivalent metals, and it is also feasible by using two different metals for congealing either consecutively or simultaneously.

Adsorption of Ni2+ and Cd2+ from Water by Calcium Alginate/Spent Coffee Grounds Composite Beads

The use of heavy metals in technological applications has led to detrimental effects on human health and the environment. Activated carbon and ion-exchange resins are commonly used to remove pollutants but they are expensive. Therefore, the research of low-cost alternatives derived from natural resources and organic wastes is being considered. The aim of this study considers the use of Calcium Alginate/Spent Coffee Grounds (CA–SCGs) composite beads to adsorb heavy metals from aqueous solutions, particularly, the removal of Ni2+ or Cd2+ at concentrations from 10 ppm to 100 ppm. CA–SCGs beads were made of equal proportions of alginate and spent coffee grounds and compared with calcium alginate beads (CA beads) and spent coffee grounds (SCGs) in terms of capacity and rate of adsorption. Three cycles of adsorption/desorption were done. The beads were characterized by Scanning Electron Microscopy coupled with an energy-dispersive X-ray spectroscopy (SEM–EDX), Fourier-transform infrared spectroscopy (FT–IR), Raman spectroscopy, and point of zero charge. Langmuir, Freundlich, and Sips models, and a pseudo-second-order kinetic equation were used. Sips model showed the best correlation with the adsorption of CA–SCGs beads with capacities of adsorption of 91.18 mg/g for cadmium and 20.96 mg/g for nickel. CA–SCGs beads had a greater adsorption than the CA beads, achieving adsorption percentages close to 100% than alginate alone, showing their effectiveness in heavy metal removal.

Removal of Copper from Water by Adsorption with Calcium-Alginate/Spent-Coffee-Grounds Composite Beads.

Calcium Alginate/Spent-Coffee-Grounds composite beads (CA-SCGs beads), which were made of two different proportions of alginate and spent-coffee-grounds (3:3 and 3:10), respectively, were used to adsorb Cu2+ in aqueous solution. These beads were compared with calcium alginate beads (CA beads) and spent-coffee-grounds (SCGs) in terms of adsorption capacity and rate of adsorption. The experiments were carried out at an initial pH of 4 at 30 °C with initial concentrations of Cu2+ from 10 ppm to 100 ppm. Equilibrium data was fitted with Langmuir, Freundlich and Sips models, and a pseudo-second-order kinetic equation. The Sips model showed the best correlation with the experimental values. CA-SCGs (3:3) beads showed a faster adsorption rate versus the CA beads. Also, CA-SCGs (3:3) beads showed a larger capacity of adsorption according to the Sips model, but not in the Langmuir model. FT-IR spectra and SEM images were taken for characterization. This study has shown that the CA-SCGs (3:3) beads have a synergistic effect, combining the capacity of adsorption of CA beads with the kinetics of the SCGs. The CA-SCGs beads have proven to be an effective adsorbent of Cu2+. Therefore, they can provide a use for the SCGs; which are considered pollutants in landfills.

Hybridity and Popular Myth on Kitschy TV Ads in Indonesia, A Case Study of Koyo Cabe Ads in Atlas Aladin and Aladin Mummy Versions

Hybridity and Popular Myth on Kitschy TV Ads in Indonesia, A Case Study of Koyo Cabe Ads in Atlas Aladin and Aladin Mummy Versions

Preparation of Ca-alginate coated nZVI core shell beads for uranium (VI) removal from aqueous solution

In this study, the core–shell nanoscale zero-valent iron (nZVI)@Alg–Ca beads were synthesized by coaxial electronic injection method for removal of U (VI) from aqueous solution, and characterized by SEM, EDX and XPS. The results showed that the pseudo-second-order models and the Langmuir isotherm model fitted well with the data obtained. The removal mechanism may include both physical adsorption of U (VI) on the surface or inside of core–shell nZVI@Alg–Ca beads and subsequent reduction of U (VI) to U (IV). Therefore, the core–shell nZVI@Alg–Ca beads would have an application prospect in effective removal of U (VI) contamination from aqueous solution.

Incorporation of no-carrier added 200,203Pb and 200,201,202Tl in calcium alginate and hesperidin incorporated calcium alginate beads

When radioisotopes are injected to human body, instantly free radicals are generated due to the interaction of ionizing radiation with water and fluids present in the body. The vehicle carrying radionuclides into human body should therefore be designed in a way which could also eliminate or reduce such possibilities. For the first time we have used free radical scavenger hesperidin, a polyphenolic compound having a benzo-γ-pyrone with a benzene ring moiety for extraction of no-carrier added (NCA) 200,203Pb and 200,201,202Tl. We have modified CA beads by incorporation of a polyphenol (hesperidin) (CA-Hes). This tailor made beads were characterized and tested for their efficacy towards extraction of no-carrier-added lead and thallium radioisotopes from 40MeV α particle irradiated Hg2Cl2 target.

Calcium and hydrogen effects during sorption of copper onto an alginate-based ion exchanger: Batch and fixed-bed column studies

The characteristics of alginate beads in calcium (Ca2+) and hydrogen (H+) form were studied with respect to the uptake of copper ions (Cu2+) via batch and fixed-bed column experiments. The maximum Cu2+ sorption capacities (Qmax) of calcium and hydrogen alginates (abbreviated as CA and HA, respectively) were found to be 107mg/g and 189mg/g, respectively. At pH 5, more than 95% of Cu2+ was removed, but the amount of Cu2+ sorbed onto CA beads was significantly lowered at pH 2 owing to the pKa value of carboxylic acid. When Ca2+, as a competing ion, was present in solution at a molar ratio of Ca2+ to Cu2+ equal to 8, Qmax was drastically decreased to 20mg/g. A faster equilibrium time (24h) was also observed for HA beads compared to CA beads (48h). In a fixed-bed column packed with CA beads, the breakthrough of Cu2+ occurred immediately with the presence of Ca2+ in the model wastewater. Using HA beads, however, the first breakthrough of Cu2+ appeared after 900 bed volumes. These results suggested that HA beads were more effective than CA beads in reducing the adverse influence of competing cations such as Ca2+ during the initial period of Cu2+ sorption. Moreover, the breakthrough of Cu2+ occurred later than that of Ca2+ due to a higher selectivity of Cu2+ over Ca2+, which was confirmed by a separation factor (αCu/Ca, 10.3) of HA beads. In addition, their reusability was confirmed via ten regeneration cycles.

Inhibition of CXCL10 release by monomeric C3bi and C4b

Cellulose acetate (CA) beads are often used for leucocyte apheresis therapy against inflammatory bowel disease. In order to clarify the mechanism of the anti-inflammatory effects of CA, global analysis of the molecules generated in blood by the interaction with CA beads was performed in this study. An activated medium was collected from whole blood that had been preincubated with CA beads, and the effects of the CA-activated medium on leucocyte function were investigated. Fresh blood was stimulated with lipopolysaccharide (LPS) or interferon (IFN)-β in the presence of the activated medium, and levels of chemokines and cytokines, including CXCL10 (IFN-inducible protein-10), and phosphorylated STAT1 (signal transducer and activator of transcription 1), which is known to be essential for CXCL10 production in leucocytes, were measured. IFN-β- or LPS-induced CXCL10 production, expression of CXCL10 mRNA and phosphorylation of STAT1 were significantly reduced in the presence of the medium pretreated with CA beads compared with the control without the CA bead treatment. The factors inhibiting CXCL10 production were identified as the C3 and C4 fragments by mass spectrometry. The monomeric C3bi and C4b proteins were abundant in the medium pretreated with CA beads. Furthermore, purified C3bi and C4b were found to inhibit IFN-β-induced CXCL10 production and STAT1 phosphorylation. Thus, STAT1-mediated CXCL10 production induced by stimulation with LPS or IFN was potently inhibited by monomeric C3bi and C4b generated by the interaction of blood with CA beads. These mechanisms mediated by monomeric C3bi and C4b may be involved in the anti-inflammatory effects of CA.

Down‐Modulation of Toll‐Like Receptor 2 Expression on Granulocytes and Suppression of Interleukin‐8 Production Due To In Vitro Treatment With Cellulose Acetate Beads

The Adacolumn, which is filled with cellulose acetate beads (CA beads), has been used as a medical device for inflammatory diseases. The CA beads selectively adsorb granulocytes and monocytes and remove them from the peripheral blood. The anti-inflammatory effects of the Adacolumn are possibly caused by removal of these cells but also due to the functional changes in the processed cells. In this study, we investigated the effects of CA beads treatment on modulation of the expression of innate immunity receptors such as the Toll-like receptor (TLR) family and production of an inflammatory cytokine, interleukin-8 (IL-8). Changes in the expressions of TLR1, 2, 4 and 6 in peripheral leukocytes exposed to CA beads were examined by flow cytometry. TLR2 expression on the surface of granulocytes exposed to CA beads was decreased, but the amount of intracellular TLR2 was increased, possibly by internalization. These changes were not observed in monocytes or lymphocytes. Peptidoglycan (PGN) treatment produced similar changes in TLR2 on granulocytes. We also measured the amounts of IL-8 in cultured blood treated with lipopolysaccharide (LPS) and PGN, which are known TLR agonists. PGN-induced IL-8 production was lower in CA beads-treated leukocytes than that in non-treated leukocytes, but LPS did not induce these changes. Based on these findings, we conclude that the down-modulation of TLR2 and suppression of IL-8 production on granulocytes by CA beads, may play an important role in the anti-inflammatory effects of the Adacolumn.

Optimization of Entrapping Conditions of Nitrifying Bacteria and Selection of Entrapping Agent

Sodium alginate and polyvinyl alcohol were selected as entrapping agents to immobilize nitrifying microbia. Through orthogonal tests, optimal conditions of entrapping nitrifying bacteria by the two agents were determined by ammonia nitrogen removal efficiency. The properties of the two immobilized microbial beads produced under their optimum embedding conditions were compared. Results indicate that the optimum embedding conditions of calcium alginate beads (briefly CA beads) were 10ml of nitrifying bacteria, 4% of sodium alginate content, 3mm in bead diameter and 24-hr crosslinking time. The optimum embedding conditions of polyvinyl alcohol beads (briefly PVA beads) were 10ml of nitrifying bacteria, 10% of PVA content, 3mm in bead diameter and 24-hr crosslinking time. Comprehensive comparisons on mechanical strength, stability, mass transfer property and ammonia nitrogen removal efficiency of the two immobilized microbial beads indicate that polyvinyl alcohol is a better embedding agent for nitrifying bacteria in wastewater treatment compared with sodium alginate.

Microbial Removal Using Layered Double Hydroxides and Iron (Hydr)oxides Immobilized on Granular Media

The objective of this study was to investigate microbial removal using layered double hydroxides (LDHs) and iron (hydr)oxides (IHs) immobilized onto granular media. Column experiments were performed using calcium alginate beads (CA beads), LDHs entrapped in CA beads (LDH beads), quartz sand (QS), iron hydroxide-coated sand (IHCS) and hematite-coated sand (HCS). Microbial breakthrough curves were obtained by monitoring the effluent, with the percentage of microbial removal and collector efficiency then quantified from these curves. The results showed that the LDH beads were ineffective for the removal of the negatively-charged microbes (27.7% at 1 mM solution), even though the positively-charged LDHs were contained on the beads. The above could be related to the immobi- lization method, where LDH powders were immobilized inside CA beads with nano-sized pores (about 10 nm); therefore, micro-sized microbes (E. coli = 1.21 µm) could not diffuse through the pores to come into contact with the LDHs in the beads, but adhere only to the exterior surface of the beads via polymeric interaction. IHCS was the most effective in the microbial removal (86.0% at 1 mM solution), which could be attributed to the iron hydroxide coated onto the exterior surface of QS had a positive surface charge and, therefore, effectively attracted the negatively-charged microbes via electrostatic interactions. Meanwhile, HCS was far less effective (35.6% at 1 mM solution) than IHCS because the hematite coated onto the external surface of QS is a crystallized iron oxide with a negative sur- face charge. This study has helped to improve our knowledge on the potential application of functional granular media for microbial removal.

Biodegradation of Chitosan-Tripolyphosphate Beads:In VitroandIn VivoStudies

In this study, chitosan [(1 --> 4) linked 2-amino-2-deoxy-beta-D-glucopyranose] beads were prepared by interacting this polycation (> 90% deacetylated) with the tripolyphosphate (TPP) polyanion. The resulting chitosan-TPP beads (C) were modified either by coating with sodium alginate (CA) or by cross-linking with glutaraldehyde (CGA). The in vitro degradation of C beads was found to be faster than its CA and CGA counterparts. C beads degraded faster at pH 6.5, compared to pH 7.4 conditions. At pH 7.4, about 41%, 37% and 10% of dry mass loss after 12 months was determined for C, CA and CGA, respectively. At pH 6.5, the dry mass loss of CA and CGA after the same period of time was found to be 73% and 37%, respectively. However, C beads completely degraded at pH 6.5 after 8 months of in vitro incubation. The in vivo biodegradation experiments were performed on Wistar rats (n = 24) for a duration of 6 months. No sign of fibrotic capsule formation was observed around any of the implanted beads at 2 and 6 months post-transplantation. At 2 months, the in vivo-degradation was slow-going and the beads in all groups were intact; CGA beads had more tissue reaction than C and CA beads at this time point. While the C beads had almost completely degraded after 6 months, the biodegradation process in CA and CGA beads was progressing. Histomorphometric analysis revealed that the in vivo biodegradation was in the order of C (approximately 85%) > CA (approximately 50%) > CGA (approximately 25%) after 6 months. Neovascularization was observed at the vicinity of the bead implants close to major blood vessels, both at 2 and 6 months time-points.

Elucidation of N-Glycosylation Sites on Human Platelet Proteins

Among known platelet proteins, a prominent and functionally important group is represented by glycoprotein isoforms. They account e.g. for secretory proteins and plasma membrane receptors including integrins and glycoprotein VI as well as intracellular components of cytosol and organelles including storage proteins (multimerin 1 etc.). Although many of those proteins have been studied for some time with regard to their function, little attention has been paid with respect to their glycosylation sites. Here we report the analysis of N-glycosylation sites of human platelet proteins. For the enrichment of glycopeptides, lectin affinity chromatography as well as chemical trapping of protein bound oligosaccharides was used. Therefore, concanavalin A was used for specific interaction with carbohydrate species along with periodic acid oxidation and hydrazide bead trapping of glycosylated proteins. Derivatization by peptide:N-glycosidase F yielded deglycosylated peptides, which provided the basis for the elucidation of proteins and their sites of modification. Using both methods in combination with nano-LC-ESI-MS/MS analysis 70 different glycosylation sites within 41 different proteins were identified. Comparison with the Swiss-Prot database established that the majority of these 70 sites have not been specifically determined by previous research projects. With this approach including hydrazide bead affinity trapping, the immunoglobulin receptor G6f, which is known to couple to the Ras-mitogen-activated protein kinase pathway in the immune system, was shown here for the first time to be present in human platelets.

Fourier transform infrared spectroscopy studies of alginate-PLL capsules with varying compositions.

Microencapsulation of cells is a promising approach to prevention of rejection in the absence of immunosuppression. Clinical application, however, is hampered by insufficient insight into the factors that influence the biocompatibility of the capsules. Capsules prepared of alginates with a high guluronic (G) acid content proved to be more adequate for clinical application since they are more stable, but, unfortunately, they are less biocompatible than capsules prepared of intermediate-G alginate. In order to get some insight into the physicochemical factors that influence the biocompatibility of capsules for the encapsulation of living cells, the chemical compositions of alginate[bond]Ca beads and alginate[bond]PLL capsules were studied by Fourier transform infrared spectroscopy. We found that during the transition of the alginate[bond]Ca beads to alginate[bond]PLL capsules, Ca connecting the alginate molecules, disappeared at the surface of both high-G and intermediate-G alginate[bond]PLL capsules. At the same time, it turned out that high-G alginate[bond]PLL capsules contained more hydrogen bonding than did intermediate[bond]G alginate capsules. Thus the well-known higher stability of high-G alginate[bond]PLL compared to intermediate-G alginate[bond]PLL capsules is not caused by a higher degree of binding to Ca of the alginate molecules but rather by the presence of more hydrogen bonds. Another observation was that after the transition from bead to capsule, high-G alginate[bond]PLL capsules contained 20% more PLL than the intermediate-G alginate[bond]PLL capsules. Finally, we show that in both high-G and intermediate-G alginate[bond]PLL capsules, the PLL exists in the alpha-helix, in the antiparallel beta-sheet, and in the random coil conformation. This study shows that FT-IR allows for successful analyses of the chemical factors essential for understanding differences in the biocompatibility of alginate[bond]PLL capsules.

Arsenate sorption by Fe(III)-doped alginate gels

Although cationic metal contaminants can be effectively removed from wastewaters by treatment with biopolymers, application of biopolymers for the removal of anionic contaminants (such as As, Cr(VI), and Se) has been limited. The objective of this study was to examine the fundamental aspects of a possible remediation strategy for removal of anionic metal species employing the biopolymer alginic acid pretreated with Ca and Fe(III). Spherical gel beads (2 mm in diameter) were formed by dispensing the biopolymer solution dropwise into 0.1 M CaCl 2; Ca beads were then washed and equilibrated with 0.1 M FeCl 3 to achieve partial substitution of Fe(III) for Ca. The resulting Ca–Fe beads were found to be effective at removing As(V) from solution on a time scale of approximately 100 h. As(V) sorption was pH dependent; optimal removal and stability of the Ca–Fe beads was achieved at pH 4. At a given initial As(V) concentration, As(V) removal efficiency increased with increasing Fe content (number of beads); at an initial As(V) concentration of 400 μg/l, up to 94% removal was achieved at pH 4 after 120 h. For a given Fe content, uptake of As(V) increased with increasing initial As(V) concentration until saturation was reached. Sorption data was modeled using a single type of As(V) binding site. Data on As(V) sorption as a function of dissolved As(V) concentration and Fe content were used to obtain and validate the site density and conditional affinity constant for As(V) sorption.