Bora Garipcan

A Novel Affinity Support Material for the Separation of Immunoglobulin G from Human Plasma

2-Methacrylamidohistidine (MAH) as a pseudospecific ligand was synthesized from methacryl chloride and histidine. Spherical beads with an average size of 50-63 μm were obtained by the radical suspension polymerization of MAH and 2-hydroxyethyl methacrylate (HEMA) conducted in an aqueous dispersion medium. Owing to the reasonably rough character of the bead surface, P(HEMA-co-MAH) beads had a specific surface area of 17.6 m 2 .g -1 . Synthesized MAH was characterized by NMR. P(HEMA-co-MAH) beads were characterized by swelling studies, FT-IR spectroscopy, scanning electron microscopy (SEM) and elemental analysis. P(HEMA-co-MAH) affinity beads with a swelling ratio of 65% were used in the separation of human immunoglobulin G (HIgG) from aqueous solutions and human plasma. The maximum HIgG adsorption on the P(HEMA-co-MAH) adsorbents was observed at pH 7.4 for phosphate and at pH 6.0 for morpholinoethanesulfonic acid buffers. The HIgG adsorption onto the PHEMA adsorbents was negligible. Higher adsorption values (up to 46.5 mg.g -1 ) were obtained when the P(HEMA-co-MAH) adsorbents were used in aqueous solutions. Much higher amounts of HIgG were adsorbed from human plasma (up to 73.8 mg.g -1 ). Adsorption capacities of other blood proteins were obtained as 3.2 mg.g -1 for fibrinogen and 4.6 mg.g -1 for albumin. The total protein adsorption was determined to be 82.2 mg.g -1 . The pseudospecific affinity beads allowed one-step separation of HIgG from human plasma, HIgG molecules could be repeatedly adsorbed and desorbed with these adsorbents without noticeable loss in their HIgG adsorption capacity.

Novel metal-chelate affinity adsorbent for purification of immunoglobulin-G from human plasma

Metal-chelating ligand and/or comonomer 2-methacrylolyamidohistidine (MAH) was synthesized by using methacryloyl chloride and L-histidine methyl ester. MAH was characterized by NMR and FTIR. Spherical beads with an average diameter of 75-125 microm were produced by suspension polymerization of methylmethacrylate (MMA) and MAH carried out in an aqueous dispersion medium. Poly(MMA-MAH) beads had a specific surface area of 37.5 m(2)/g. Poly(MMA-MAH) beads were characterized by water uptake studies, FTIR, SEM and elemental analysis. Elemental analysis of MAH for nitrogen was estimated as 34.7 microM/g of polymer. Then, Cu(2+) ions were chelated on the beads. Cu(2+)-chelated beads with a swelling ratio of 38% were used in the adsorption of human-immunoglobulin G (HIgG) from both aqueous solutions and human plasma. The maximum adsorption capacities of the Cu(2+)-chelated beads were found to be 12.2 mg/g at pH 6.5 in phosphate buffer and 15.7 mg/g at pH 7.0 in MOPS. Higher adsorption value was obtained from human plasma (up to 54.3 mg/g) with a purity of 90.7%. The metal-chelate affinity beads allowed one-step separation of HIgG from human plasma. The adsorption-desorption cycle was repeated 10 times using the same beads without noticeable loss in their HIgG adsorption capacity.

Metal-complexing ligand methacryloylamidocysteine containing polymer beads for Cd(II) removal

Different metal-complexing ligands carrying synthetic and natural adsorbents have been reported in the literature for heavy metal removal. We have developed a novel and new approach to obtain high metal adsorption capacity utilizing 2-methacryloylamidocysteine (MAC) as a metal-complexing ligand and/or comonomer. MAC was synthesized by using methacryloyl chloride and cysteine. Spherical beads with an average size of 150–200 μm were obtained by the radical suspension polymerization of MAC and 2-hydroxyethylmethacrylate (HEMA) conducted in an aqueous dispersion medium. Poly(2-hydroxyethylmethacrylate–methacryloylamidocysteine) p(HEMA–MAC) beads have a specific surface area of 18.9 m2 g−1. p(HEMA–MAC) beads were characterized by swelling studies, FTIR and elemental analysis. The p(HEMA–MAC) beads with a swelling ratio of 72%, and containing 3.9 mmol MAC g−1 were used in the removal of cadmium(II) ions from aqueous solutions. Adsorption equilibrium was achieved in about 15 min. The adsorption of Cd(II) ions onto pHEMA beads was negligible. The MAC incorporation significantly increased the Cd(II) adsorption capacity. Adsorption capacity of MAC incorporated beads increased significantly with pH. Competitive heavy metal adsorption from aqueous solutions containing Cd(II), Cr(III), Pb(II), Hg(II) and As(III) was also investigated. The adsorption capacities are 254 mg g−1 for Cd(II); 90.9 mg g−1 for Cr(III); 150.4 mg g−1 for Hg(II), 91.2 mg g−1 for Pb(II) and 6.7 mg g−1 for As(III) ions. These results are an indication of higher specificity of the p(HEMA–MAC) beads for the Cd(II) ions compared with other ions. Consecutive adsorption and desorption operations showed the feasibility of repeated use for p(HEMA–MAC) chelating beads.

Preparation and Characterization of the Newly Synthesized Metal-Complexing-Ligand N-Methacryloylhistidine Having PHEMA Beads for Heavy Metal Removal from Aqueous Solutions

The aim of this study was to investigate in detail the performance for removal of heavy metal ions of beads composed of poly(2-hydroxyethyl methacrylate) (pHEMA) to which N-methacryloylhistidine (MAH) was copolymerized. The metal-complexing ligand MAH was synthesized by using methacryloyl chloride and histidine. Spherical beads with an average size of 150-200 μm were obtained by the radical suspension polymerization of MAH and HEMA conducted in an aqueous dispersion medium. Owing to the reasonably rough character of the bead surface, p(HEMA-MAH) beads had a specific surface area of 17.6 m 2 /g. The synthesized MAH monomer was characterized by NMR; p(HEMA-MAH) beads were characterized by swelling studies, FTIR and elemental analysis. The p(HEMA-MAH) beads with a swelling ratio of 65%, and containing 1.6 mmol MAH/g, were used in the adsorption/desorption experiments. Adsorption capacity of the beads for the selected metal ions, i.e., Cu(II), Cd(II), Cr(III), Hg(II) and Pb(II), were investigated in aqueous media containing different amounts of these ions (10-750 mg/L) and at different pH values (3.0-7.0). Adsorption equilibria were established in about 20 min. The maximum adsorption capacities of the p(HEMA-MAH) beads were 122.7 mg/g for Cu(II°, 468.8 mg/g for Cr(III), 639.4 mg/g for Cd(II), 714.1 mg/g for Pb(II) and 1234.4 mg/g for Hg(II). pH significantly affected the adsorption capacity of MAH incorporated beads. The chelating beads can be easily regenerated by 0.1 M HNO 3 with high effectiveness. These features make p(HEMA-MAH) beads a potential candidate for heavy metal removal at high capacity.

Preparation of poly(hydroxyethyl methacrylate-co-methacrylamidohistidine) beads and its design as a affinity adsorbent for Cu(II) removal from aqueous solutions

Different metal-complexing ligands carrying synthetic adsorbents have been reported in the literature for heavy metal removal. We have developed a novel and new approach to obtain high metal adsorption capacity utilizing 2-methacrylamidohistidine (MAH) as a metal-complexing ligand. MAH was synthesized by using methacrylochloride and histidine. Spherical beads with an average size of 150–200 μm were obtained by the radical suspension polymerization of MAH and 2-hydroxyethylmethacrylate (HEMA) conducted in an aqueous dispersion medium. Owing to the reasonably rough character of the bead surface, p(HEMA-co-MAH) beads had a specific surface area of 17.6 m2 g−1. Synthesized MAH monomer was characterized by NMR. p(HEMA-co-MAH) beads were characterized by swelling studies, FTIR and elemental analysis. These p(HEMA-co-MAH) affinity beads with a swelling ratio of 65%, and containing 1.6 mmol MAH g−1 were used in the adsorption/desorption of copper(II) ions from metal solutions. Adsorption equilibria was achieved in ∼2 h. The maximum adsorption of Cu(II) ions onto pHEMA was ∼0.36 mg Cu(II) g−1. The MAH incorporation significantly increased the Cu(II) adsorption capacity by chelate formation of Cu(II) ions with MAH molecules (122.7 mg Cu(II) g−1), which was observed at pH 7.0. pH significantly affected the adsorption capacity of MAH incorporated beads. The observed adsorption order under non-competitive conditions was Cu(II)>Cr(III)>Hg(II)>Pb(II)>Cd(II) in molar basis. The chelating beads can be easily regenerated by 0.1 M HNO3 with higher effectiveness. These features make p(HEMA-co-MAH) beads very good candidate for Cu(II) removal at high adsorption capacity.

Nonporous monosize polymeric sorbents: Dye and metal chelate affinity separation of lysozyme

Lysozyme adsorption onto dye-attached nonporous monosize poly(2-hydroxyethyl-methacrylate-methylmethacrylate) [poly(HEMA-MMA)] microspheres was investigated. Poly(HEMA-MMA) microspheres were prepared by dispersion polymerization. The monochloro-triazine dye, Cibacron Blue F3GA, was immobilized covalently as dye-ligand. These dye-affinity microspheres were used in the lysozyme adsorption-desorption studies. The effect of initial concentration of lysozyme and medium pH on the adsorption efficiency of dye-attached and metal-chelated microspheres were studied in a batch reactor. Effect of Cu(II) chelation on lysozyme adsorption was also studied. The nonspecific adsorption of lysozyme on the poly(HEMA-MMA) microspheres was 3.6 mg/g. Cibacron Blue F3GA attachment significantly increased the lysozyme adsorption up to 247.8 mg/g. Lysozyme adsorption capacity of the Cu(II) incorporated microspheres (318.9 mg/g) was greater than that of the Cibacron Blue F3GA-attached microspheres. Significant amount of the adsorbed lysozyme (up to 97%) was desorbed in 1 h in the desorption medium containing 1.0M NaSCN at pH 8.0 and 25 mM EDTA at pH 4.9. In order to examine the effects of separation conditions on possible conformational changes of lysozyme structure, fluorescence spectrophotometry was employed. We conclude that dye- and metal-chelate affinity chromatography with poly(HEMA-MMA) microspheres can be applied for lysozyme separation without causing any significant changes and denaturation. Repeated adsorption/desorption processes showed that these novel dye-attached monosize microspheres are suitable for lysozyme adsorption.

Excitation of Local Field Enhancement on Silicon Nanowires

The interaction between light and reduced-dimensionality silicon attracts significant interest due to the possibilities of designing nanoscaled optical devices, highly cost-efficient solar cells, and ultracompact optoelectronic systems that are integrated with standard microelectronic technology. We demonstrate that Si nanowires (SiNWs) possessing metal-nanocluster coatings support a multiplicatively enhanced near-field light-matter interaction. Raman scattering from chemisorbed probing molecules provides a quantitative measure of the strength of this enhanced coupling. An enhancement factor of 2 orders of magnitude larger than that for the surface plasmon resonance alone (without the SiNWs) along with the attractive properties of SiNWs, including synthetic controllability of shape, indicates that these nanostructures may be an attractive and versatile material platform for the design of nanoscaled optical and optoelectronic circuits.

Synthesis of Poly[(hydroxyethyl methacrylate)-co-(methacrylamidoalanine)] Membranes and Their Utilization as an Affinity Sorbent for Lysozyme Adsorption

Various adsorbent materials have been reported in the literature for protein separation. We have developed a novel and new approach to obtain high protein-adsorption capacity utilizing a 2-methacrylamidoalanine-containing membrane. An amino acid ligand 2-methacrylamidoalanine (MAAL) was synthesized from methacrylochloride and alanine. Then, poly[(2-hydroxyethyl methacrylate)-co-(2-methacrylamidoalanine)] [p(HEMA-co-MAAL)] membranes were prepared by UV-initiated photopolymerization of HEMA and MAAL. The synthesized MAAL monomer was characterized by NMR spectrometry. p(HEMA-co-MAAL) membranes were characterized by swelling studies, porosimeter, scanning electron microscopy, FT-IR spectroscopy and elemental analysis. These membranes have large pores; the micropore dimensions are around 5–10 μm. p(HEMA-co-MAAL) affinity membranes with a swelling ratio of 198.9%, and containing 23.9 (mmol MAAL)·m–2 were used in the adsorption of lysozyme from aqueous media containing different amounts of lysozyme (0.1–3.0 mg·ml–1) and at different pH values (4.0–8.0). The effect of Cu(II) incorporation on lysozyme adsorption was also studied. The non-specific adsorption of lysozyme on the pHEMA membranes was 0.9 μg-cm–2. Incorporation of MAAL molecules into the polymeric structure significantly increased the lysozyme adsorption up to 2.96 mg·cm–2. The lysozyme-adsorption capacity of the membranes incorporated with Cu(II) (9.98 mg·cm–2) was greater than that of the p(HEMA-co-MAAL) membranes. More than 85% of the adsorbed lysozyme was desorbed in 1 h in the desorption medium containing 1.0 M NaCl. The p(HEMA-co-MAAL) membranes are suitable for repeated use for more than 5 cycles without noticeable loss of capacity. These features make p(HEMA-co-MAAL) membrane a very good candidate for bioaffinity adsorption.

Formation and Organization of Amino Terminated Self-assembled Layers on Si(001) Surface.

We have investigated the effects of dipping time, solution concentration and solvent type on the formation of self-assembled monolayers with aminosiloxane molecules (i.e.,N-(3 trimethoxysilylpropyl)diethylenetriamine (TPDA)) on the Si(001) surface. Studies performed with an ellipsometer showed that monolayers with a thickness of about 1.2 nm were formed when the dipping time is about 2 h, while multilayer were observed for longer time periods. The effect of the TPDA concentration on the thickness of the deposited layer was not very profound, however, the contact angle data exhibit importance of concentration on the surface coverage. The type of the solvent used in the formation of the monolayers was found an important parameter. Monolayers were formed with solvent having larger dielectric constants. Relatively thick multilayer was observed when benzene was used as the solvent, due to its quite low dielectric constant (hydrophobicity).

N-methacryloly-(L)-histidinemethylester carrying a pseudospecific affinity sorbent for immunoglobulin-G isolation from human plasma in a column system.

N-methacryloly-(L)-histidinemethylester (MAH) as a pseudospecific ligand was synthesized by using methacryloyl chloride and histidine. Spherical beads with an average size of 63-75 μm were obtained by suspension polymerization of ethylene glycol dimethacrylate (EGDMA), 2-hydroxyethyl methacrylate (HEMA) and MAH conducted in an aqueous dispersion medium. The specific surface area of the beads was found to be 18.3 m2/g. Poly(EGDMA-HEMA-MAH) beads were used in the separation of immunoglobulin-G (HIgG) from aqueous solutions and/or human plasma in a packed-bed column system. HIgG adsorption capacity of the beads decreased with an increase in the flow-rate of plasma. The maximum HIgG adsorption on the poly(EGDMA-HEMA-MAH) sorbents was observed at pH 7.4. HIgG adsorption onto the poly(EGDMA-HEMA) sorbents was negligible. Higher adsorption values (up to 135 mg/g) were obtained when the poly(EGDMA-HEMA-MAH) sorbents were used from aqueous solutions. HIgG adsorption increased with decreasing temperature and the maximum adsorption achieved at 4°C. MAH incorporation significantly affected HIgG adsorption capacity (135 mg/g). Higher amounts of HIgG were adsorbed from human plasma (up to 165 mg/g). Adsorption capacities of other blood proteins were obtained as 8.7 mg/g for fibrinogen and 14.6 mg/g for albumin. The total protein adsorption was determined as 191 mg/g. The pseudospecific affinity beads allowed one-step separation of HIgG from human plasma. HIgG molecules could be repeatedly adsorbed and desorbed with these sorbents without noticeable loss in their HIgG adsorption capacity.