Immobilized Beads Research Articles

3D porous tubular network-structured chitosan-based beads with multifunctional groups: Highly efficient and selective removal of Cu2+

Herein, an effective adsorbent, 3D porous tubular network-structured citric acid-chitosan/Fe/polyethyleneimine beads (CCFPB) with multifunctional active groups and strong selectivity, was prepared for the selective removal of Cu2+ from simulated wastewater. Compared with pure chitosan beads (CB), the adsorption capacity of CCFPB for Cu2+ was increased by 127 mg g−1 (238%), and the adsorption equilibrium time was shortened by 480 min. The CCFPB showed porous surface and a novel 3D porous tubular network structure in interior, which were benefit to the diffusion of Cu2+ from surface to interior of the CCFPB and the shortening of adsorption equilibrium time. The common coexisting ions in the simulated wastewater had almost no effect on the adsorption of Cu2+ by CCFPB, and the adsorption was fast and reached equilibrium within 10 h. The adsorption process followed pseudo-second-order kinetics and the Langmuir isotherm model (qm = 240.9 mg g−1 for Cu2+). The adsorption mechanism of CCFPB for Cu2+ was mainly the synergistic interaction with amino, carboxyl, and hydroxyl groups. This strategy shows great potential for developing a variety of novel, highly active, and reusable immobilized functional beads materials for effective separation of Cu2+ from multi-ion wastewater.

Enhanced biocatalysis of phenanthrene in aqueous phase by novel CA-Ca-SBE-laccase biocatalyst: Performance and mechanism

Enzymes-mediated biocatalysis is believed to be a promising strategy for the degradation of polycyclic aromatic hydrocarbon (e.g., phenanthrene) in aqueous phase, due to its high efficiency and environmental harmfulness. However, the reusability of enzymes-mediated biocatalysis and its requirement for redox mediators limited its application. In this paper, enhanced phenanthrene removal was achieved by using a novel biocatalyst which coencapsulating laccase and natural redox mediator soybean meal extract on calcium modified chitosan-alginate (CA-Ca-SBE-laccase) beads with a network pore structure. High degradation efficiency of 94.4 % was achieved after treating aqueous solutions of 0.5 ppm phenanthrene for 20 min with the CA-Ca-SBE-laccase beads, which was 20–30 % higher than that of free laccase and ordinary immobilized laccase beads. Both the radical pathway of oxygen-containing stable free radicals and the nonradical laccase-SBE combined substrates with higher redox potential generated in CA-Ca-SBE-laccase beads contributed to the degradation of phenanthrene, and achieved the maximum double synergy of mediator and laccase. Benefiting from redox-mediating encapsulated SBE and from Ca modification of chitosan, the biocatalyst maintained fairly stable catalytic activities over a wide range of pH values, and considerable repeatability and storage stability were obtained. This study put forward an efficient laccase, redox mediator and immobilized support cofunctionalization technology, and would provide a new perspective for the increasing application scope of enzymes-mediated biocatalysis.

Surfactant-facilitated alginate-biochar beads embedded with PAH-degrading bacteria and their application in wastewater treatment.

Immobilized Pseudomonas aeruginosa beads with alginate and biochar as composite carriers and a nonionic surfactant (TX100) as degradation promoter were prepared by the gel embedding method. The optimal preparation parameters for the biochar addition amount and the concentrations of the bacterial suspension and TX100 were 1%, OD600 = 1 and 200mg/L, respectively. The addition of TX100 can simultaneously promote biochar sorption of PAHs and PAH degradation by P. aeruginosa. The removal ratio of acenaphthene was 24% higher for the TX100-facilitated immobilized bacterial beads than the beads in the absence of TX100. The surfactant-facilitated immobilized bacterial beads can thoroughly remove PAHs in wastewater under the conditions of 10~50°C, pH2.5~10.5, and less than 0.2mol/L NaCl. The immobilized bacterial beads are suitable for continuous-flow reactors, and 2-mm-diameter beads will achieve better application results than larger beads. The new immobilized material can be widely used in various wastewater treatment reactors and in the in situ remediation of organic polluted water.

Erratum: Preparation of Poly(pentafluorophenyl acrylate) Functionalized SiO2 Beads for Protein Purification.

Erratum: Preparation of Poly(pentafluorophenyl acrylate) Functionalized SiO2 Beads for Protein Purification.

Preparation of Poly(pentafluorophenyl acrylate) Functionalized SiO2 Beads for Protein Purification.

We demonstrate a simple method to prepare poly(pentafluorophenyl acrylate) (poly(PFPA)) grafted silica beads for antibody immobilization and subsequent immunoprecipitation (IP) application. The poly(PFPA) grafted surface is prepared via a simple two-step process. In the first step, 3-aminopropyltriethoxysilane (APTES) is deposited as a linker molecule onto the silica surface. In the second step, poly(PFPA) homopolymer, synthesized via the reversible addition and fragmentation chain transfer (RAFT) polymerization, is grafted to the linker molecule through the exchange reaction between the pentafluorophenyl (PFP) units on the polymer and the amine groups on APTES. The deposition of APTES and poly(PFPA) on the silica particles are confirmed by X-ray photoelectron spectroscopy (XPS), as well as monitored by the particle size change measured via dynamic light scattering (DLS). To improve the surface hydrophilicity of the beads, partial substitution of poly(PFPA) with amine-functionalized poly(ethylene glycol) (amino-PEG) is also performed. The PEG-substituted poly(PFPA) grafted silica beads are then immobilized with antibodies for IP application. For demonstration, an antibody against protein kinase RNA-activated (PKR) is employed, and IP efficiency is determined by Western blotting. The analysis results show that the antibody immobilized beads can indeed be used to enrich PKR while non-specific protein interactions are minimal.

Modeling, Optimization and Kinetic Study for Photocatalytic Treatment of Ornidazole Using Slurry and Fixed-Bed Approach

Ornidazole is a well-known antibiotic which has been widely used for both human and veterinary treatments. The present study investigated the degradation of ornidazole using $$\hbox {TiO}_{2}$$ as a photocatalyst with UV light irradiation. Artificial neural network (ANN) was applied for the modeling of the photocatalytic degradation of ornidazole. In slurry mode, the input parameters were pH, ornidazole concentration, $$\hbox {TiO}_{2}$$ dose, treatment time and % degradation as output. Parametric optimization was performed by Box–Behnken design (BBD). At optimum conditions the % degradation was found to be 84.02, 82.63 and 77.7% as predicted by BBD, simulated by ANN and by experimental run respectively. The results showed that the predictions agreed with the experimental results. The degradation of ornidazole follows the second-order reaction kinetics. For fixed-bed studies, $$\hbox {TiO}_{2}$$ immobilized spherical cement beads were used to carry out the degradation of ornidazole at laboratory scale as well as at pilot scale with volume handling of 5 L. The catalyst immobilized beads were successfully recycled for at-least 40 runs without any significant reduction in the degradation efficiency of ornidazole. The activity as well as stability of immobilized catalyst over the surface of beads was confirmed through SEM/EDS, XRD and DRS analysis. Bioassay test was conducted for the safe disposal of treated wastewater and was found to be non-toxic.

Removal of Radioactivity from Sediment Mud and Soil and Use for Cultivation of Safe Vegetables in Fukushima, and Removal of Toxic Metals Using Photosynthetic Bacteria

The immobilized photosynthetic bacterium, Rhodobacter shpaeroides SSI (SSI), cultured on porous 2 cm ceramic beads, effectively removed and recovered 20 mg/L of non-radioactive Cs (almost 100%) and Sr (≌50%), after 3 - 5 days of aerobic treatment. Toxic and heavy metals such as Hg, Cr, Pb and As were also removed, almost 100%, after 6days of aerobic treatment. A practical method of removal of radioactivity of 10 - 30 μSv/h, caused mainly by radioactive Cs released from the accident at the Daiichi Nuclear Power Plant on 11th March 2011, from sediment mud and soil in Fukushima, Japan, was also carried out. Using immobilized SSI beads, more than 90% and 42% - 73% of radioactive Cs was removed and recovered from sediment mud and soil, respectively, after 3 - 14 days of aerobic treatment in an outdoor 60 L vessel. The weight and mass of the harvested beads could be reduced by more than 97% after desiccation. This technology of removal and recovery had therefore, considerable advantages over other technologies that demanded very large storage facilities in Fukushima. After removal of radioactivity from polluted soil, vegetables like Komatsuna (Turrip leaves) and Chingensai (Green pakchoi) were cultivated on remediated soil. Safe vegetables grown on these treated soils showed a radioactivity content lower than the recommended limit for edible foods in Japan, i.e. less than <100 Bq/kg. Treatment by SSI beads, therefore, appeared to be a compact and suitable technology that could make significant contributions towards agricultural recovery in radioactively polluted areas of Fukushima.

Removal of nickel ions from industrial wastewater using immobilized sericite beads

To efficiently remove nickel ions from actual industrial wastewater which is coexisted with high sodium concentration, powdered sericite was immobilized as a bead form by entrapment method using sodium alginate. The beads with surface area of 7.1m2/g were not untangled to ∼45°C and ∼pH 11.0 in wastewater and have excellent mechanical strength and swelling characteristics. It was also confirmed that natural sericite beads did not appear the characteristic peak for nickel ions, nickel-adsorbed beads clearly shows the peak of nickel ions as about 4.00wt% by means of SEM–EDX analysis. The effect of sodium ions on nickel removal was negligible and the maximum adsorption capacity using Langmuir equation was 10.743mg/g at pH 7.5 of wastewater in batch. The nickel ions can be removed from actual wastewater over 95% up to 90 (1.0mL/min) and 140 bed volumes (0.5mL/min), respectively and 7 bed volumes of 20mM of HNO3 solution was required to get 96% of nickel desorption in continuous process using packed-bed column. Also, breakthrough point of nickel ions could be still maintained as 130 up to the 2nd cycle by reused immobilized sericite beads.

An efficient TiO2 coated immobilized system for the degradation studies of herbicide isoproturon: Durability studies

The investigation presents the observations on the use of cement beads for the immobilization of TiO2 for the degradation of herbicide isoproturon. The immobilized system was effective in degrading and mineralizing the herbicide for continuous thirty cycles without losing its durability. Catalyst was characterized by SEM–EDAX for checking the durability of the catalyst. The degradation rate followed first order kinetics as measured by change in absorption intensity in UV range as well as HPLC analysis. Two rounds of TiO2 coating on inert cement beads with average diameter 1.5cm at UV Intensity 25Wm−2 calcined at 400°C were the optimized conditions for the degradation of herbicide isoproturon. More than 90% TOC and COD reduction along with ammonium ions generation (80%) confirmed the mineralization of isoproturon. Fixed bed baffled reactor studies under solar irradiations using the TiO2 immobilized beads confirmed 85% degradation after 6h. LC–MS studies confirmed the intermediates formation and their subsequent degradation using immobilized system.

Carbon composite beads for immobilization of carbonic anhydrase

Abstract Fixation of anthropogenic CO2 into calcium carbonate using carbonic anhydrase (CA) as a bio-catalyst appears to be a promising option of CO2 sequestration. In the present study, carbonic anhydrase (CA) has been immobilized on chitosan based activated alumina–carbon composite beads. Synthesized adsorbent was thoroughly characterized using XRD, FTIR, SEM and BET-SA. Maximum adsorption capacities were determined using Langmuir model and it was observed to be 172.41 mg/g. Mechanistic and kinetic aspects have been addressed for immobilized as well as free enzyme. The Km and Vmax for immobilized enzyme was 10.35 mM and 0.99 μmol/ml/min, whereas for free enzyme it was 1.89 mM and 0.99 μmol/ml/min respectively. Proof of concept has been established for carbonation reaction. The carbonate has been characterized using various tools such as XRD and SEM which confirms the calcite nature of calcium carbonate. The CO2 sequestration capacity in terms of conversion of CO2 to carbonate was quantified by gas chromatography (GC). The CO2 sequestration capacity of immobilized beads was found to be 19.22 mg of CaCO3/mg of enzyme as compared to 33.06 mg of CaCO3/mg of enzyme for free enzyme.

Selectivity in Enrichment of cAMP-dependent Protein Kinase Regulatory Subunits Type I and Type II and Their Interactors Using Modified cAMP Affinity Resins

cAMP regulates cellular functions primarily by activating PKA. The involvement of PKAs in various signaling pathways occurring simultaneously in different cellular compartments necessitates stringent spatial and temporal regulation. This specificity is largely achieved by binding of PKA to protein scaffolds, whereby a distinct group of proteins called A kinase anchoring proteins (AKAPs) play a dominant role. AKAPs are a diverse family of proteins that all bind via a small PKA binding domain to the regulatory subunits of PKA. The binding affinities between PKA and several AKAPs can be different for different isoforms of the regulatory subunits of PKA. Here we employ a combination of affinity chromatography and mass spectrometry-based quantitative proteomics to investigate specificity in PKA-AKAP interactions. Three different immobilized cAMP analogs were used to enrich for PKA and its interacting proteins from several systems; HEK293 and RCC10 cells and rat lung and testis tissues. Stable isotope labeling was used to confidently identify and differentially quantify target proteins and their preferential binding affinity for the three different cAMP analogs. We were able to enrich all four isoforms of the regulatory subunits of PKA and concomitantly identify more than 10 AKAPs. A selective enrichment of the PKA RI isoforms could be achieved; which allowed us to unravel which AKAPs bind preferentially to the RI or RII regulatory domains of PKA. Of the twelve AKAPs detected, seven preferentially bound to RII, whereas the remaining five displayed at least dual specificity with a potential preference for RI. For some of these AKAPs our data provide the first insights into their specificity.

Efficient biodegradation of cyanide and ferrocyanide by Na-alginate beads immobilized with fungal cells of Trichoderma koningii

Cyanide or metal cyanide contaminations have become serious environmental and food-health problems. A fungal mutant of Trichoderma koningii, TkA8, constructed by restriction enzyme-mediated integration, has been verified to have a high cyanide degradation ability in our previous study. In this study, the mutant cells were entrapped in sodium-alginate (Na-alginate) immobilization beads to degrade cyanide and ferrocyanide in a liquid mineral medium. The results showed that the fungus in immobilization beads consisting of 3% Na-alginate and 3% CaCl2 could degrade cyanide more efficiently than a nonimmobilized fungal culture. For maximum degradation efficiency, the optimal ratio of Na-alginate and wet fungal biomass was 20:1 (m/m) and the initial pH was 6.5. In comparison, cell immobilization took at least 3 and 8 days earlier, respectively, to completely degrade cyanide and ferrocyanide. In addition, we showed that the immobilized beads could be easily recovered from the medium and reused for up to 5 batches without significant losses of fungal remediation abilities. The results of this study provide a promising alternative method for the large-scale remediation of soil or water systems from cyanide contamination.

Antiangiogenic Antithrombin Blocks the Heparan Sulfate-dependent Binding of Proangiogenic Growth Factors to Their Endothelial Cell Receptors

The anticoagulant serpin antithrombin acquires a potent antiangiogenic activity upon undergoing conformational alterations to cleaved or latent forms. Here we show that antithrombin antiangiogenic activity is mediated at least in part through the ability of the conformationally altered serpin to block the proangiogenic growth factors fibroblast growth factor (FGF)-2 and vascular endothelial growth factor (VEGF) from forming signaling competent ternary complexes with their protein receptors and heparan sulfate co-receptors on endothelial cells. Cleaved and latent but not native forms of antithrombin blocked the formation of FGF-2-FGF receptor-1 ectodomain-heparin ternary complexes, and the dimerization of these complexes in solution and similarly inhibited the formation of FGF-2-heparin binary complexes and their dimerization. Only antiangiogenic forms of antithrombin likewise inhibited (125)I-FGF-2 binding to its low affinity heparan sulfate co-receptor and blocked FGF receptor-1 autophosphorylation and p42/44 MAP kinase phosphorylation in cultured human umbilical vein endothelial cells (HUVECs). Moreover, treatment of HUVECs with heparinase III to specifically eliminate the FGF-2 heparan sulfate co-receptor suppressed the ability of antiangiogenic antithrombin to inhibit growth factor-stimulated proliferation. Antiangiogenic antithrombin inhibited full-length VEGF(165) stimulation of HUVEC proliferation but did not affect the stimulation of cells by the heparin-binding domain-deleted VEGF(121). Taken together, these results demonstrate that antiangiogenic forms of antithrombin block the proangiogenic effects of FGF-2 and VEGF on endothelial cells by competing with the growth factors for binding the heparan sulfate co-receptor, which mediates growth factor-receptor interactions. Moreover, the inability of native antithrombin to bind this co-receptor implies that native and conformationally altered forms of antithrombin differentially bind proangiogenic heparan sulfate domains.

Improved immobilized enzyme systems using spherical micro silica sol-gel enzyme beads

Spherical micro silica sol-gel immobilized enzyme beads were prepared in an emulsion system using cyclohexanone and Triton-X 114. The beads were used for thein situ immobilization of transaminase, trypsin, and lipase. Immobilization during the sol to gel phase transition was investigated to determine the effect of the emulsifying solvents, surfactants, and mixing process on the formation of spherical micro sol-gel enzyme beads and their catalytic activity. The different combinations of sol-gel precursors affected both activity and the stability of the enzymes, which suggests that each enzyme has a unique preference for the silica gel matrix dependent upon the characteristics of the precursors. The resulting enzyme-entrapped micronsized beads were characterized and utilized for several enzyme reaction cycles. These results indicated improved stability compared to the conventional crushed form silica sol-gel immobilized enzyme systems.

Biosorption of 2,4-dichlorophenol by immobilized white-rot fungus Phanerochaete chrysosporium from aqueous solutions

The fungus Phanerochaete chrysosporium was immobilized in several polymer matrices: Ca-alginate, Ca-alginate-polyvinyl alcohol (PVA) and pectin, and was then used as a biosorbent for removing 2,4-dichlorophenol (2,4-DCP) in wastewater. Immobilization of P. chrysosporium onto pectin was less efficient than that onto other matrices because of its poor mechanical strength and low adsorption efficiency. Ca-alginate immobilized fungal beads with biocompatibility exhibited good mechanical strength and adsorption efficiency over 60%. Among the different biomass dosages in Ca-alginate immobilized fungal beads, 1.25% (w/v) was the optimum. The adsorption data of 2,4-DCP on the blank Ca-alginate beads, free, and immobilized fungal biomass could be described by the Langmuir and Freundlich isotherms very well. Desorption operation was efficiently completed by using distilled water as eluant, and the desorption efficiency reached 82.16% at an optimum solid/liquid ratio of 14.3. The consecutive adsorption/desorption cycles studies employing the Ca-alginate immobilized fungal beads demonstrated that the immobilized fungal biomass could be reused in five cycles without significant loss of adsorption efficiency and adsorbent weight.

Fine definition of the epitope on the gp41 glycoprotein of human immunodeficiency virus type 1 for the neutralizing monoclonal antibody 2F5.

Matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS), in combination with proteolytic protection assays, has been used to identify the functional epitope on human immunodeficiency virus envelope glycoprotein gp41 for the broadly neutralizing anti-gp41 human monoclonal antibody 2F5. In this protection assay-based procedure, a soluble gp140 protein with a stabilizing intermolecular disulfide bond between the gp120 and gp41 subunits (SOS gp140) was affinity bound to immobilized 2F5 under physiological conditions. A combination of proteolytic enzymatic cleavages was then performed to remove unprotected residues. Residues of SOS gp140 protected by their binding to 2F5 were then identified based on their molecular weights as determined by direct MALDI-MS of the immobilized antibody beads. The epitope, NEQELLELDKWASLWN, determined by this MALDI-MS protection assay approach consists of 16 amino acid residues near the C terminus of gp41. It is significantly longer than the ELDKWA core epitope previously determined for 2F5 by peptide enzyme-linked immunosorbent assay. This new knowledge of the structure of the 2F5 epitope may facilitate the design of vaccine antigens intended to induce antibodies with the breadth and potency of action of the 2F5 monoclonal antibody.

A biotin-avidin labeled enzyme immunoassay for the quantitation of serum TSH using protein-layered solid phase.

A sensitive enzyme immunoassay for serum TSH has been developed utilizing the tight binding between biotin and avidin, and three layered protein polystyrene beads as solid phase. To increase binding capacity of TSH and sensitivity of the assay, the polystyrene beads were coated sequentially with mouse immunoglobulin as first layer, rabbit antimouse immunoglobulin as second layer and monoclonal anti-TSH as third layer. A serum sample was incubated simultaneously with a monoclonal anti-TSH immobilized polystyrene beads and a second monoclonal anti-TSH covalently attached to biotin. After washing, the antibody bound serum TSH-anti-TSH-biotin complex is reacted with horseradish peroxidase (HRP)-labeled avidin. Following a second wash, the bound HRP activity was measured colorimetrically. Reproducible results were obtained within 4 hours for serum TSH in the range between 0 microIU/ml and 50 microIU/ml with detection limit of 0.1 microIU per test.