A Surface Plasmon Resonance (SPR) aptasensor was developed for the detection of Brucella melitens... more A Surface Plasmon Resonance (SPR) aptasensor was developed for the detection of Brucella melitensis (B. melitensis) in milk samples. Brucellosis is a bacterial zoonotic disease with global distribution caused mostly by contaminated milk or their products. Aptamers recognizing B. melitensis were selected following a whole bacteria-SELEX procedure. Two aptamers were chosen for high affinity and high specificity. The high affinity aptamer (B70 aptamer) was immobilized on the surface of magnetic silica core-shell nanoparticles for initial purification of the target bacteria cells from milk matrix. Another aptamer, highly specific for B. melitensis cells (B46 aptamer), was used to prepare SPR sensor chips for sensitive determination of Brucella in eluted samples from magnetic purification since direct injection of milk samples to SPR sensor chips is known for a high background unspecific signal. Thus, we integrated a quick and efficient magnetic isolation step for subsequent instant detection of B. melitensis contamination in one ml of milk sample by SPR with a LOD value as low as 27 ± 11 cells.
In this study, magnetic nanoparticles (Fe3O4) were modified sequentially with silica (Fe3O4@SiO2)... more In this study, magnetic nanoparticles (Fe3O4) were modified sequentially with silica (Fe3O4@SiO2), glycidyl methacrylate (GMA) by surface initiated atom transfer radical polymerization (SI-ATRP) and hexamethylene diamine (as a spacer arm). The p(GMA) grafted and SA modified form (i.e., Fe3O4@SiO2@pGMA-SA-3) was used for covalent immobilization of invertase (EC 3.2.1.26). The amount of immobilized enzyme on Fe3O4@SiO2@p(GMA) and Fe3O4@SiO2@p(GMA)-SA-3 was 36.1±0.9 and 33.4±1.3mg/g, respectively. The Km and Vmax values of immobilized invertase were found to be 39.4mmol/L and 349.5mmol/L min, and not significantly changed compared with free form (34.3mmol/L and 387.2mmol/Lmin), respectively, revealed that the applied protocol did not have any detrimental effect on the retained activity of immobilized invertase.
Rapid and label-free detection of Brucella melitensis in milk and milk products using an aptasens... more Rapid and label-free detection of Brucella melitensis in milk and milk products using an aptasensor, Talanta,
In this study, an affinity membrane containing L-histidine as an amino acid ligand was used in se... more In this study, an affinity membrane containing L-histidine as an amino acid ligand was used in separation and purification of human immunoglobulin G (HIgG) from solution and human serum. The polarities and the surface free energies of the affinity membranes were determined by contact angle measurements. HIgG adsorption and purification onto the affinity membranes from aqueous solution and human serum were investigated in a batch and a continuous system. Effect of different system parameters such as ligand density, adsorbent dosage, pH, temperature, ionic strength and HIgG initial concentration on HIgG adsorption were investigated. The maximum adsorption capacity of p(HEMA-MAAH-4) membranes for HIgG was 13.06 mgml(-1). The reversible HIgG adsorption on the affinity membrane obeyed both the Langmuir and Freundlich isotherm models. The adsorption data was analysed using the first- and second-order kinetic model and the experimental data was well described by the first-order equations. In the continuous system, the purity of the eluted HIgG, as determined by HPLC, was 93% with recovery 58% for p(HEMA-MAAH-4) membrane. The affinity membranes are stable when subjected to sanitization with sodium hydroxide after repeated adsorption-elution cycles.
Although enzymes are known for their excellent catalytic performance, industrial, medical or biot... more Although enzymes are known for their excellent catalytic performance, industrial, medical or biotechnological applications should overcome some drawbacks like long-term stability under specific conditions of the application. Immobilized enzymes have offered advantages over soluble counterparts in many industrial and laboratory scale applications by increasing operational stability and reusability. When the immobilization matrix has magnetic properties, an additional advantage is obtained as simpler processing. Iron-based superparamagnetic nano-sized particles has large surface area for bio-compatible applications are especially in focus. Adding nanofibrous polymers to magnetic nanoparticles has been an excellent way to increase efficiency of biocatalyst immobilization by further increasing loading capacity. This chapter explains various magnetic enzyme-nanoparticles based preparations with potential for future industrial applications like invertase, lipase and as model studies and focus on the nanofibrous polymer brush grafting as a way to increase catalytic efficiency of magnetic nanoparticles.
Applied Microbiology and Biotechnology, Sep 19, 2013
We report an immuno-magnetic separation system developed by the immobilization of pathogen-specif... more We report an immuno-magnetic separation system developed by the immobilization of pathogen-specific antibodies on the core-shell magnetic beads. The magnetic beads were grafted with glycidylmethacrylate (GMA) using surface-initiated atom transfer radical polymerization (SI-ATRP). For immuno-magnetic separation (IMS) of target bacterial cells from others, antibodies for Escherichia coli and Salmonella enterica serovar Typhimurium cells were immobilized on the magnetic beads via glutaraldehyde coupling reaction. Our IMS system successfully separated Salmonella cells when the concentrations of target (i.e., Salmonella) and interfering (i.e., E. coli) cells were at the same level. Polymerase chain reaction (PCR) assays amplifying the rfb/rfbE region of the E. coli genome and a 647-bp fragment of the invA region of Salmonella were performed as the specific selection to accurately confirm the presence of E. coli and Salmonella, respectively. IMS and multiplex PCR methods can be used for specific and quantitative detection of pathogens from food samples. Thus, this study developed a reliable and direct system for rapid detection of Salmonella and E. coli in food samples. In addition, IMS method could be easily adapted to detect other pathogens by selecting the pertinent antibody.
Highlights Star polymer grafted MP containing amidoxime groups were prepared and used for U(VI)... more Highlights Star polymer grafted MP containing amidoxime groups were prepared and used for U(VI) removal. MP/SiO2/pGMA-AO showed extraordinary adsorption capacity and selectivity to U(VI) ions. High adsorption could resulted from the presence of many amine and hydroxyl groups on the ligand. The maximum equilibrium adsorption capacity of MP/SiO2/pGMA-AO for U(VI) ions was 760.3 mg/g.
General detection methods for S. enterica include PCR analysis, immunologic methods, solid cultur... more General detection methods for S. enterica include PCR analysis, immunologic methods, solid culturing techniques, and various microscopic studies. Milk and other food samples demonstrate an especially difficult challenge for direct detection, resulting from high biological contents. In this report, we aimed fast detection of pathogen cells through an efficient magnetic capture and subsequent quick detection based on aptamer affinity. The Fe 3 O 4 @SiO 2 @pGMA and MCM-41 particles were prepared separately and used for pre-concentration and detection, respectively. Aptamer oligonucleotide sequences against S. enterica was fixed on both amine functionalized MCM-41 and Fe 3 O 4 @SiO 2 @pGMA particles via glutaraldehyde coupling. The captured Salmonella cells were determined by a fluorescent homogenous assay in the samples by aptamer gated MCM-41 silica particles. Our method achieved a sensitive assay to detect Salmonella cells in milk samples as low as 10 3 CFU/ml without any culturing. Hence, the proposed sensing strategy might be an efficient platform for pathogen detection in food matrix.
An aptasensor was designed for sensitive detection of thrombin using in biological fluids by inte... more An aptasensor was designed for sensitive detection of thrombin using in biological fluids by integrating a magnetic aptamer-microbeads. To achieve this goal, the surface of gold plated QCM crystals was coated with L-cysteine and a thrombin binding DNA aptamer was immobilized on the L-cysteine coated QCM crystals surface via glutaraldehyde coupling. The binding interactions of thrombin to QCM crystals were characterized. Magnetic poly(2-hydroxyethyl methacrylate-ethylene glycol dimethacrylate-vinylene carbonate), Mp(HEMA-EGDMA-VC) microbeads were synthesized and thrombin binding aptamer (TBA) was immobilized. The Mp(HEMA-EGDMA-VC)-TBA microbeads were effectively adsorbed thrombin from serum in a relatively short contact time (ca. 5.0 min), and the eluted protein from Mp(HEMA-EGDMA-VC)-TBA was transferred to the QCM aptasensor that showed a specific detection of thrombin from serum. The detection limit of thrombin using aptasensor was 1.00 nmol L. The calculation dissociation constant...
Lentinus concinnus biomass was immobilized to carboxyl derivative of cellulose, carboxymethyl cel... more Lentinus concinnus biomass was immobilized to carboxyl derivative of cellulose, carboxymethyl cellulose (CMC), in the presence of FeCl3 (0.1 mol L−1) via ionic cross-linking. The beads containing immobilized fungal biomass were incubated at 30 °C for three days to permit growth of the fungus. The free and immobilized fungal biomass were tested for adsorption of Disperse Red 60 (DR-60) from aqueous solution using bare CMC beads as a control system. The maximum adsorption of DR-60 on the free and immobilized fungal biomass was observed at pH 6.0. The adsorption of DR-60 by the free, and immobilized fungal biomass increased as the initial concentration of DR-60 in the medium increased up to 100 mg/L. The maximum adsorption capacity of the CMC beads, the free and immobilized fungal biomass (i.e. composite beads) were found to be 43.4, 65.7, and 92.6 mg g−1 dry sorbents, respectively. The equilibrium of the adsorption system was well described by Langmuir and Temkin isotherm models. Adso...
Water science and technology : a journal of the International Association on Water Pollution Research, 2016
Chemical modification of Spirulina platensis biomass was realized by sequential treatment of alga... more Chemical modification of Spirulina platensis biomass was realized by sequential treatment of algal surface with epichlorohydrin and aminopyridine. Adsorptive properties of Cr(VI) ions on native and aminopyridine modified algal biomass were investigated by varying pH, contact time, ionic strength, initial Cr(VI) concentration, and temperature. FTIR and analytical analysis indicated that carboxyl and amino groups were the major functional groups for Cr(VI) ions adsorption. The optimum adsorption was observed at pH 3.0 for native and modified algal biomasses. The adsorption capacity was found to be 79.6 and 158.7 mg g(-1), for native and modified algal biomasses, respectively. For continuous system studies, the experiments were conducted to study the effect of important design parameters such as flow rate and initial concentration of metal ions, and the maximum sorption capacity was observed at a flow rate of 50 mL h(-1), and Cr(VI) ions concentration 200 mg L(-1) with modified biomass...
Magnetic-silica core–shell nanoparticles were proposed as a fast purification strategy for recomb... more Magnetic-silica core–shell nanoparticles were proposed as a fast purification strategy for recombinant enzymes and their subsequent usability in catalysis reactions. A proof-of-concept study with Taq polymerase hybrids was demonstrated.
A novel method was developed for facile immobilization of enzymes on silica surfaces. Herein, we ... more A novel method was developed for facile immobilization of enzymes on silica surfaces. Herein, we describe a single-step strategy for generating of reactive double bonds capable of Michael addition on the surfaces of silica particles. This method was based on reactive thin film generation on the surfaces by heating of impregnated self-curable polymer, alpha-morpholine substituted poly(vinyl methyl ketone) p(VMK). The generated double bonds were demonstrated to be an efficient way for rapid incorporation of enzymes via Michael addition. Catalase was used as model enzyme in order to test the effect of immobilization methodology by the reactive film surface through Michael addition reaction. Finally, a plug flow type immobilized enzyme reactor was employed to estimate decomposition rate of hydrogen peroxide. The highly stable enzyme reactor could operate continuously for 120 h at 30 °C with only a loss of about 36 % of its initial activity.
contact angle blood cell adhesion hemolysis rat mesenchymal stem cells Copolymerization of 2-hydr... more contact angle blood cell adhesion hemolysis rat mesenchymal stem cells Copolymerization of 2-hydroxyethylmethacrylate (HEMA) with glycidylmethacrylate (GMA) in the presence of α-α′-azoisobisbutyronitrile (AIBN) resulted in the formation of hydrogel films carrying reactive epoxy groups. Thirteen kinds of different molecules with pendant \NH 2 group were used for modifications of the p(HEMA-GMA) films. The \NH 2 group served as anchor binding site for immobilization of functional groups on the hydrogel film via direct epoxy ring opening reaction. The modified hydrogel films were characterized by FTIR, and contact angle studies. In addition, mechanical properties of the hydrogel films were studied, and modified hydrogel films showed improved mechanical properties compared with the non-modified film, but they are less elastic than the non-modified film. The biological activities of these films such as platelet adhesion, red blood cells hemolysis, and swelling behavior were studied. The effect of modified hydrogel films, including \NH 2 , (using different aliphatic \CH 2 chain lengths) \CH 3 , \SO 3 H, aromatic groups with substituted \OH and \COOH groups, and amino acids were also investigated on the adhesion, morphology and survival of rat mesenchymal stem cells (MSCs). The MTT colorimetric assay reveals that the p(HEMA-GMA)-GA-AB, p(HEMA-GMA)-GA-Phe, p(HEMA-GMA)-GA-Trp, p(HEMA-GMA)-GA-Glu formulations have an excellent biocompatibility to promote the cell adhesion and growth. We anticipate that the fabricated p(HEMA-GMA) based hydrogel films with controllable surface chemistry and good stable swelling ratio may find extensive applications in future development of tissue engineering scaffold materials, and in various biotechnological areas.
Magnetic beads were prepared via suspension polymerization of glycidyl methacrylate (GMA) and met... more Magnetic beads were prepared via suspension polymerization of glycidyl methacrylate (GMA) and methyl methacrylate (MMA) in the presence of ferric ions. Following polymerization, thermal co-precipitation of the Fe(III) ions in the beads with Fe(II) ions under alkaline condition resulted in encapsulation of Fe 3 O 4 nano-crystals within the polymer matrix. The magnetic beads were activated with glutaraldehyde, and tyrosinase enzyme was covalently immobilized on the support via reaction of amino groups under mild conditions. The immobilized enzyme was used for the synthesis of l-Dopa (1-3,4-dihydroxy phenylalanine) which is a precursor of dopamine. The immobilized enzyme was characterized by temperature, pH, operational and storage stability experiments. Kinetic parameters, maximum velocity of the enzyme (V max) and Michaelis-Menten constant (K m) values were determined as 1.05 U/mg protein and 1.0 mM for 50-75 m and 2.00 U/mg protein and 4.0 mM for 75-150 m beads fractions, respectively. Efficiency factor and catalytic efficiency were found to be 1.39 and 0.91 for 75-150 m beads and 0.73 and 0.75 for 50-75 m beads fractions, respectively. The catalytic efficiency of the soluble tyrosinase was 0.37. The amounts of immobilized protein were on the 50-75 m and 75-150 m fractions were 2.7 and 2.8 mg protein/g magnetic beads, respectively.
The untreated, heat-and alkali-treated Lentinus sajor-caju mycelia were used for the recovery of ... more The untreated, heat-and alkali-treated Lentinus sajor-caju mycelia were used for the recovery of uranium from aqueous solutions. The effect of pH, temperature, initial concentration of UO 2 2+ ions and contact time parameters were investigated in a batch system. The particles sizes of the fungal mycelia were ranging from 100 to 200 m. Biosorption equilibriums were established in about 30 min and the correlation regression coefficients show that the adsorption process can be well defined by the Freundlich equation. The alkali treated form had a high biosorption capacity (378 mg/g) than those of the untreated (268 mg/g) and heat-treated fungal mycelia (342 mg/g). Optimum biosorption was observed at pH 4.5 for all the tested fungal preparations and was independent of temperature (5-35 • C). In addition, the polarity and surface energy of the fungal biomass film preparations were determined by contact angle measurement. The fungal biomass could be regenerated using 10 mM sodium carbonate, with up to 93% recovery. The biosorbents were used in six biosorption-desorption cycles and no considerable loss in the biosorption capacity was observed.
The effective removal of toxic heavy metals from environmental samples still remains a major topi... more The effective removal of toxic heavy metals from environmental samples still remains a major topic of present research. Metal-chelating membranes are very promising materials as adsorbents when compared with conventional beads because they are not compressible, and they eliminate internal diffusion limitations. The purpose of this study was to evaluate the performance of a novel adsorbent, Procion Green H-4G immobilized poly(hydroxyethylmethacrylate (HEMA)/chitosan) composite membranes, for the removal of three toxic heavy metal ions, namely, Cd(II), Pb(II) and Hg(II) from aquatic systems. The Procion Green H-4G immobilized poly(hydroxyethylmethacrylate/chitosan) composite membranes were characterized by elemental analysis, scanning electron microscopy and Fourier transform infrared (FTIR) spectroscopy. The immobilized amount of the Procion Green H-4G was calculated as 0.018+/-0.003 micromol/cm(2) from the nitrogen and sulphur stoichiometry. The adsorption capacity of Procion Green H-4G immobilized poly(hydroxyethylmethacrylate/chitosan) composite membranes for selected heavy metal ions from aqueous media containing different amounts of these ions (30-400mg/l) and at different pH values (2.0-6.0) was investigated. The amount of Cd(II), Pb(II) and Hg(II) adsorbed onto the membranes measured at equilibrium, increased with time during the first 45 min and then remained unchanged toward the equilibrium adsorption. The maximum amounts of heavy metal ions adsorbed were 43.60+/-1.74, 68.81+/-2.75 and 48.22+/-1.92 mg/g for Cd(II), Pb(II) and Hg(II), respectively. The heavy metal ion adsorption on the pHEMA/chitosan membranes (carrying no dye) were relatively low, 6.31+/-0.13 mg/g for Cd(II), 18.73+/-0.37 mg/g for Pb(II) and 18.82+/-0.38 mg/g for Hg(II). Competitive adsorption of the metal ions was also studied. When the metal ions competed with each other, the adsorbed amounts were 12.74+/-0.38 mg Cd(II)/g, 28.80+/-0.86 mg Pb(II)/g and 18.41+/-0.54 mg Hg(II)/g. Procion Green H-4G immobilized poly(hydroxyethylmethacrylate/chitosan) membranes can be regenerated by washing with a solution of nitric acid (0.01 M). The percent desorption achieved was as high as 95%. These novel membranes are suitable for repeated use for more than five adsorption/desorption cycles without any considerable loss in adsorption capacity. Adsorption equilibria were well described by Langmuir equation. It can be concluded that Procion Green H-4G immobilized poly(hydroxyethylmethacrylate/chitosan) membranes may effectively be used for the removal of Cd(II), Pb(II) and Hg(II) ions from aqueous solutions.
A Surface Plasmon Resonance (SPR) aptasensor was developed for the detection of Brucella melitens... more A Surface Plasmon Resonance (SPR) aptasensor was developed for the detection of Brucella melitensis (B. melitensis) in milk samples. Brucellosis is a bacterial zoonotic disease with global distribution caused mostly by contaminated milk or their products. Aptamers recognizing B. melitensis were selected following a whole bacteria-SELEX procedure. Two aptamers were chosen for high affinity and high specificity. The high affinity aptamer (B70 aptamer) was immobilized on the surface of magnetic silica core-shell nanoparticles for initial purification of the target bacteria cells from milk matrix. Another aptamer, highly specific for B. melitensis cells (B46 aptamer), was used to prepare SPR sensor chips for sensitive determination of Brucella in eluted samples from magnetic purification since direct injection of milk samples to SPR sensor chips is known for a high background unspecific signal. Thus, we integrated a quick and efficient magnetic isolation step for subsequent instant detection of B. melitensis contamination in one ml of milk sample by SPR with a LOD value as low as 27 ± 11 cells.
In this study, magnetic nanoparticles (Fe3O4) were modified sequentially with silica (Fe3O4@SiO2)... more In this study, magnetic nanoparticles (Fe3O4) were modified sequentially with silica (Fe3O4@SiO2), glycidyl methacrylate (GMA) by surface initiated atom transfer radical polymerization (SI-ATRP) and hexamethylene diamine (as a spacer arm). The p(GMA) grafted and SA modified form (i.e., Fe3O4@SiO2@pGMA-SA-3) was used for covalent immobilization of invertase (EC 3.2.1.26). The amount of immobilized enzyme on Fe3O4@SiO2@p(GMA) and Fe3O4@SiO2@p(GMA)-SA-3 was 36.1±0.9 and 33.4±1.3mg/g, respectively. The Km and Vmax values of immobilized invertase were found to be 39.4mmol/L and 349.5mmol/L min, and not significantly changed compared with free form (34.3mmol/L and 387.2mmol/Lmin), respectively, revealed that the applied protocol did not have any detrimental effect on the retained activity of immobilized invertase.
Rapid and label-free detection of Brucella melitensis in milk and milk products using an aptasens... more Rapid and label-free detection of Brucella melitensis in milk and milk products using an aptasensor, Talanta,
In this study, an affinity membrane containing L-histidine as an amino acid ligand was used in se... more In this study, an affinity membrane containing L-histidine as an amino acid ligand was used in separation and purification of human immunoglobulin G (HIgG) from solution and human serum. The polarities and the surface free energies of the affinity membranes were determined by contact angle measurements. HIgG adsorption and purification onto the affinity membranes from aqueous solution and human serum were investigated in a batch and a continuous system. Effect of different system parameters such as ligand density, adsorbent dosage, pH, temperature, ionic strength and HIgG initial concentration on HIgG adsorption were investigated. The maximum adsorption capacity of p(HEMA-MAAH-4) membranes for HIgG was 13.06 mgml(-1). The reversible HIgG adsorption on the affinity membrane obeyed both the Langmuir and Freundlich isotherm models. The adsorption data was analysed using the first- and second-order kinetic model and the experimental data was well described by the first-order equations. In the continuous system, the purity of the eluted HIgG, as determined by HPLC, was 93% with recovery 58% for p(HEMA-MAAH-4) membrane. The affinity membranes are stable when subjected to sanitization with sodium hydroxide after repeated adsorption-elution cycles.
Although enzymes are known for their excellent catalytic performance, industrial, medical or biot... more Although enzymes are known for their excellent catalytic performance, industrial, medical or biotechnological applications should overcome some drawbacks like long-term stability under specific conditions of the application. Immobilized enzymes have offered advantages over soluble counterparts in many industrial and laboratory scale applications by increasing operational stability and reusability. When the immobilization matrix has magnetic properties, an additional advantage is obtained as simpler processing. Iron-based superparamagnetic nano-sized particles has large surface area for bio-compatible applications are especially in focus. Adding nanofibrous polymers to magnetic nanoparticles has been an excellent way to increase efficiency of biocatalyst immobilization by further increasing loading capacity. This chapter explains various magnetic enzyme-nanoparticles based preparations with potential for future industrial applications like invertase, lipase and as model studies and focus on the nanofibrous polymer brush grafting as a way to increase catalytic efficiency of magnetic nanoparticles.
Applied Microbiology and Biotechnology, Sep 19, 2013
We report an immuno-magnetic separation system developed by the immobilization of pathogen-specif... more We report an immuno-magnetic separation system developed by the immobilization of pathogen-specific antibodies on the core-shell magnetic beads. The magnetic beads were grafted with glycidylmethacrylate (GMA) using surface-initiated atom transfer radical polymerization (SI-ATRP). For immuno-magnetic separation (IMS) of target bacterial cells from others, antibodies for Escherichia coli and Salmonella enterica serovar Typhimurium cells were immobilized on the magnetic beads via glutaraldehyde coupling reaction. Our IMS system successfully separated Salmonella cells when the concentrations of target (i.e., Salmonella) and interfering (i.e., E. coli) cells were at the same level. Polymerase chain reaction (PCR) assays amplifying the rfb/rfbE region of the E. coli genome and a 647-bp fragment of the invA region of Salmonella were performed as the specific selection to accurately confirm the presence of E. coli and Salmonella, respectively. IMS and multiplex PCR methods can be used for specific and quantitative detection of pathogens from food samples. Thus, this study developed a reliable and direct system for rapid detection of Salmonella and E. coli in food samples. In addition, IMS method could be easily adapted to detect other pathogens by selecting the pertinent antibody.
Highlights Star polymer grafted MP containing amidoxime groups were prepared and used for U(VI)... more Highlights Star polymer grafted MP containing amidoxime groups were prepared and used for U(VI) removal. MP/SiO2/pGMA-AO showed extraordinary adsorption capacity and selectivity to U(VI) ions. High adsorption could resulted from the presence of many amine and hydroxyl groups on the ligand. The maximum equilibrium adsorption capacity of MP/SiO2/pGMA-AO for U(VI) ions was 760.3 mg/g.
General detection methods for S. enterica include PCR analysis, immunologic methods, solid cultur... more General detection methods for S. enterica include PCR analysis, immunologic methods, solid culturing techniques, and various microscopic studies. Milk and other food samples demonstrate an especially difficult challenge for direct detection, resulting from high biological contents. In this report, we aimed fast detection of pathogen cells through an efficient magnetic capture and subsequent quick detection based on aptamer affinity. The Fe 3 O 4 @SiO 2 @pGMA and MCM-41 particles were prepared separately and used for pre-concentration and detection, respectively. Aptamer oligonucleotide sequences against S. enterica was fixed on both amine functionalized MCM-41 and Fe 3 O 4 @SiO 2 @pGMA particles via glutaraldehyde coupling. The captured Salmonella cells were determined by a fluorescent homogenous assay in the samples by aptamer gated MCM-41 silica particles. Our method achieved a sensitive assay to detect Salmonella cells in milk samples as low as 10 3 CFU/ml without any culturing. Hence, the proposed sensing strategy might be an efficient platform for pathogen detection in food matrix.
An aptasensor was designed for sensitive detection of thrombin using in biological fluids by inte... more An aptasensor was designed for sensitive detection of thrombin using in biological fluids by integrating a magnetic aptamer-microbeads. To achieve this goal, the surface of gold plated QCM crystals was coated with L-cysteine and a thrombin binding DNA aptamer was immobilized on the L-cysteine coated QCM crystals surface via glutaraldehyde coupling. The binding interactions of thrombin to QCM crystals were characterized. Magnetic poly(2-hydroxyethyl methacrylate-ethylene glycol dimethacrylate-vinylene carbonate), Mp(HEMA-EGDMA-VC) microbeads were synthesized and thrombin binding aptamer (TBA) was immobilized. The Mp(HEMA-EGDMA-VC)-TBA microbeads were effectively adsorbed thrombin from serum in a relatively short contact time (ca. 5.0 min), and the eluted protein from Mp(HEMA-EGDMA-VC)-TBA was transferred to the QCM aptasensor that showed a specific detection of thrombin from serum. The detection limit of thrombin using aptasensor was 1.00 nmol L. The calculation dissociation constant...
Lentinus concinnus biomass was immobilized to carboxyl derivative of cellulose, carboxymethyl cel... more Lentinus concinnus biomass was immobilized to carboxyl derivative of cellulose, carboxymethyl cellulose (CMC), in the presence of FeCl3 (0.1 mol L−1) via ionic cross-linking. The beads containing immobilized fungal biomass were incubated at 30 °C for three days to permit growth of the fungus. The free and immobilized fungal biomass were tested for adsorption of Disperse Red 60 (DR-60) from aqueous solution using bare CMC beads as a control system. The maximum adsorption of DR-60 on the free and immobilized fungal biomass was observed at pH 6.0. The adsorption of DR-60 by the free, and immobilized fungal biomass increased as the initial concentration of DR-60 in the medium increased up to 100 mg/L. The maximum adsorption capacity of the CMC beads, the free and immobilized fungal biomass (i.e. composite beads) were found to be 43.4, 65.7, and 92.6 mg g−1 dry sorbents, respectively. The equilibrium of the adsorption system was well described by Langmuir and Temkin isotherm models. Adso...
Water science and technology : a journal of the International Association on Water Pollution Research, 2016
Chemical modification of Spirulina platensis biomass was realized by sequential treatment of alga... more Chemical modification of Spirulina platensis biomass was realized by sequential treatment of algal surface with epichlorohydrin and aminopyridine. Adsorptive properties of Cr(VI) ions on native and aminopyridine modified algal biomass were investigated by varying pH, contact time, ionic strength, initial Cr(VI) concentration, and temperature. FTIR and analytical analysis indicated that carboxyl and amino groups were the major functional groups for Cr(VI) ions adsorption. The optimum adsorption was observed at pH 3.0 for native and modified algal biomasses. The adsorption capacity was found to be 79.6 and 158.7 mg g(-1), for native and modified algal biomasses, respectively. For continuous system studies, the experiments were conducted to study the effect of important design parameters such as flow rate and initial concentration of metal ions, and the maximum sorption capacity was observed at a flow rate of 50 mL h(-1), and Cr(VI) ions concentration 200 mg L(-1) with modified biomass...
Magnetic-silica core–shell nanoparticles were proposed as a fast purification strategy for recomb... more Magnetic-silica core–shell nanoparticles were proposed as a fast purification strategy for recombinant enzymes and their subsequent usability in catalysis reactions. A proof-of-concept study with Taq polymerase hybrids was demonstrated.
A novel method was developed for facile immobilization of enzymes on silica surfaces. Herein, we ... more A novel method was developed for facile immobilization of enzymes on silica surfaces. Herein, we describe a single-step strategy for generating of reactive double bonds capable of Michael addition on the surfaces of silica particles. This method was based on reactive thin film generation on the surfaces by heating of impregnated self-curable polymer, alpha-morpholine substituted poly(vinyl methyl ketone) p(VMK). The generated double bonds were demonstrated to be an efficient way for rapid incorporation of enzymes via Michael addition. Catalase was used as model enzyme in order to test the effect of immobilization methodology by the reactive film surface through Michael addition reaction. Finally, a plug flow type immobilized enzyme reactor was employed to estimate decomposition rate of hydrogen peroxide. The highly stable enzyme reactor could operate continuously for 120 h at 30 °C with only a loss of about 36 % of its initial activity.
contact angle blood cell adhesion hemolysis rat mesenchymal stem cells Copolymerization of 2-hydr... more contact angle blood cell adhesion hemolysis rat mesenchymal stem cells Copolymerization of 2-hydroxyethylmethacrylate (HEMA) with glycidylmethacrylate (GMA) in the presence of α-α′-azoisobisbutyronitrile (AIBN) resulted in the formation of hydrogel films carrying reactive epoxy groups. Thirteen kinds of different molecules with pendant \NH 2 group were used for modifications of the p(HEMA-GMA) films. The \NH 2 group served as anchor binding site for immobilization of functional groups on the hydrogel film via direct epoxy ring opening reaction. The modified hydrogel films were characterized by FTIR, and contact angle studies. In addition, mechanical properties of the hydrogel films were studied, and modified hydrogel films showed improved mechanical properties compared with the non-modified film, but they are less elastic than the non-modified film. The biological activities of these films such as platelet adhesion, red blood cells hemolysis, and swelling behavior were studied. The effect of modified hydrogel films, including \NH 2 , (using different aliphatic \CH 2 chain lengths) \CH 3 , \SO 3 H, aromatic groups with substituted \OH and \COOH groups, and amino acids were also investigated on the adhesion, morphology and survival of rat mesenchymal stem cells (MSCs). The MTT colorimetric assay reveals that the p(HEMA-GMA)-GA-AB, p(HEMA-GMA)-GA-Phe, p(HEMA-GMA)-GA-Trp, p(HEMA-GMA)-GA-Glu formulations have an excellent biocompatibility to promote the cell adhesion and growth. We anticipate that the fabricated p(HEMA-GMA) based hydrogel films with controllable surface chemistry and good stable swelling ratio may find extensive applications in future development of tissue engineering scaffold materials, and in various biotechnological areas.
Magnetic beads were prepared via suspension polymerization of glycidyl methacrylate (GMA) and met... more Magnetic beads were prepared via suspension polymerization of glycidyl methacrylate (GMA) and methyl methacrylate (MMA) in the presence of ferric ions. Following polymerization, thermal co-precipitation of the Fe(III) ions in the beads with Fe(II) ions under alkaline condition resulted in encapsulation of Fe 3 O 4 nano-crystals within the polymer matrix. The magnetic beads were activated with glutaraldehyde, and tyrosinase enzyme was covalently immobilized on the support via reaction of amino groups under mild conditions. The immobilized enzyme was used for the synthesis of l-Dopa (1-3,4-dihydroxy phenylalanine) which is a precursor of dopamine. The immobilized enzyme was characterized by temperature, pH, operational and storage stability experiments. Kinetic parameters, maximum velocity of the enzyme (V max) and Michaelis-Menten constant (K m) values were determined as 1.05 U/mg protein and 1.0 mM for 50-75 m and 2.00 U/mg protein and 4.0 mM for 75-150 m beads fractions, respectively. Efficiency factor and catalytic efficiency were found to be 1.39 and 0.91 for 75-150 m beads and 0.73 and 0.75 for 50-75 m beads fractions, respectively. The catalytic efficiency of the soluble tyrosinase was 0.37. The amounts of immobilized protein were on the 50-75 m and 75-150 m fractions were 2.7 and 2.8 mg protein/g magnetic beads, respectively.
The untreated, heat-and alkali-treated Lentinus sajor-caju mycelia were used for the recovery of ... more The untreated, heat-and alkali-treated Lentinus sajor-caju mycelia were used for the recovery of uranium from aqueous solutions. The effect of pH, temperature, initial concentration of UO 2 2+ ions and contact time parameters were investigated in a batch system. The particles sizes of the fungal mycelia were ranging from 100 to 200 m. Biosorption equilibriums were established in about 30 min and the correlation regression coefficients show that the adsorption process can be well defined by the Freundlich equation. The alkali treated form had a high biosorption capacity (378 mg/g) than those of the untreated (268 mg/g) and heat-treated fungal mycelia (342 mg/g). Optimum biosorption was observed at pH 4.5 for all the tested fungal preparations and was independent of temperature (5-35 • C). In addition, the polarity and surface energy of the fungal biomass film preparations were determined by contact angle measurement. The fungal biomass could be regenerated using 10 mM sodium carbonate, with up to 93% recovery. The biosorbents were used in six biosorption-desorption cycles and no considerable loss in the biosorption capacity was observed.
The effective removal of toxic heavy metals from environmental samples still remains a major topi... more The effective removal of toxic heavy metals from environmental samples still remains a major topic of present research. Metal-chelating membranes are very promising materials as adsorbents when compared with conventional beads because they are not compressible, and they eliminate internal diffusion limitations. The purpose of this study was to evaluate the performance of a novel adsorbent, Procion Green H-4G immobilized poly(hydroxyethylmethacrylate (HEMA)/chitosan) composite membranes, for the removal of three toxic heavy metal ions, namely, Cd(II), Pb(II) and Hg(II) from aquatic systems. The Procion Green H-4G immobilized poly(hydroxyethylmethacrylate/chitosan) composite membranes were characterized by elemental analysis, scanning electron microscopy and Fourier transform infrared (FTIR) spectroscopy. The immobilized amount of the Procion Green H-4G was calculated as 0.018+/-0.003 micromol/cm(2) from the nitrogen and sulphur stoichiometry. The adsorption capacity of Procion Green H-4G immobilized poly(hydroxyethylmethacrylate/chitosan) composite membranes for selected heavy metal ions from aqueous media containing different amounts of these ions (30-400mg/l) and at different pH values (2.0-6.0) was investigated. The amount of Cd(II), Pb(II) and Hg(II) adsorbed onto the membranes measured at equilibrium, increased with time during the first 45 min and then remained unchanged toward the equilibrium adsorption. The maximum amounts of heavy metal ions adsorbed were 43.60+/-1.74, 68.81+/-2.75 and 48.22+/-1.92 mg/g for Cd(II), Pb(II) and Hg(II), respectively. The heavy metal ion adsorption on the pHEMA/chitosan membranes (carrying no dye) were relatively low, 6.31+/-0.13 mg/g for Cd(II), 18.73+/-0.37 mg/g for Pb(II) and 18.82+/-0.38 mg/g for Hg(II). Competitive adsorption of the metal ions was also studied. When the metal ions competed with each other, the adsorbed amounts were 12.74+/-0.38 mg Cd(II)/g, 28.80+/-0.86 mg Pb(II)/g and 18.41+/-0.54 mg Hg(II)/g. Procion Green H-4G immobilized poly(hydroxyethylmethacrylate/chitosan) membranes can be regenerated by washing with a solution of nitric acid (0.01 M). The percent desorption achieved was as high as 95%. These novel membranes are suitable for repeated use for more than five adsorption/desorption cycles without any considerable loss in adsorption capacity. Adsorption equilibria were well described by Langmuir equation. It can be concluded that Procion Green H-4G immobilized poly(hydroxyethylmethacrylate/chitosan) membranes may effectively be used for the removal of Cd(II), Pb(II) and Hg(II) ions from aqueous solutions.
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Papers by Yakup Arıca