Biomedical subjects

Ridvan Say

Publications and source records attributed to Ridvan Say.

13 recordsLinked to original sources

PubMed2006

Synthesis of cholesterol imprinted polymeric particles.

The aim of this study is to prepare cholesterol-imprinted polymeric particles. N-Methacryloyl-(L)-tyrosinemethylester (MAT) was chosen as the complexing monomer. In the first step, functional monomer MAT was synthesized by the reaction of L-tyrosine methylester and methacryloyl chloride and characterized by FTIR and NMR. Then, cholesterol was complexed with MAT in different mol ratios and the cholesterol-imprinted poly(2-hydroxyethyl methacrylate-N-methacryloyl-(L)-tyrosine methylester) [MIP] particles were synthesized by bulk polymerization. After that, the template molecules (i.e., cholesterol) were removed using chloroform. MIP particles were characterized by elemental analysis, FTIR, SEM, swelling tests and surface area measurements. Cholesterol adsorption experiments were performed in a batch experimental set-up. Adsorption medium was methanol or intestinal mimicking solution. Stigmasterol and estradiol were used as competing molecules in selectivity tests. Obtained results were as follows: swelling ratio of MIP and non-imprinted (NIP) particles were 60.8% and 44.1% in water. With the increase in the amount of MAT in the polymerization medium, incorporation of MAT was increased (16.6-78.0 micromol/g). SEM photographs showed the surface roughness and porosity. Specific surface area of NIP and MIP particles were found as 19.2 and 31.5 m(2)/g, respectively. Template molecules (i.e., cholesterol) were removed from the polymer structure in the ratio of 76-84% of the initial concentration. Cholesterol adsorption increased with the increase in cholesterol concentration up to 1.5 mg/mL. MIP particles prepared using higher amounts of cholesterol exhibit significantly higher capacity to the NIP particles (i.e., control polymer). MIP particles were 3.09 and 3.60 times selective with respect to the stigmasterol and estradiol, respectively. Reusability of MIP particles was also investigated. MIP particles showed negligible loss in the cholesterol adsorption capacity after five adsorption-desorption cycles with the same adsorbent.

Adsorption↗

PubMed2006

L-histidine imprinted synthetic receptor for biochromatography applications.

We have proposed novel surface-imprinted beads for selective separation of cytochrome c (cyt c) by N-methacryloyl-(L)-histidine-copper(II) [MAH-Cu(II)] as a new metal-chelating monomer via metal coordination interactions and histidine template. We have combined molecular imprinting with the ability of histidine to chelate metal ions to create ligand exchange beads suitable for the binding of cyt c (surface histidine exposed protein). The histidine imprinted beads were produced by suspension polymerization of MAH-Cu(II)-L-histidine and ethylene glycol dimethacrylate. After polymerization, the template (L-histidine) was removed from the beads using methanolic KOH, thus getting histidine imprinted metal-chelate beads. L-Histidine imprinted metal-chelate beads can be used several times without considerable loss of cyt c adsorption capacity. The association constant (Ka) for the specific interaction between the template imprinted polymer and the template (L-histidine) itself were determined by Scatchard plots using L-histidine imprinted beads and found as 58,300 M(-1). Finally, we have used these histidine imprinted beads for cyt c and ribonuclease A (surface histidine exposed proteins) and enantiometric separation of D- and L-histidine by FPLC.

Adsorption↗

PubMed2006

Cr(III)-imprinted polymeric beads: Sorption and preconcentration studies.

The purpose of this study is to prepare a novel molecular imprinted adsorbent to Cr(III) analysis with high selectivity. Initially, chromium (III)-methacryloylhistidine (MAH/Cr(III)) complex monomer was synthesized and then Cr(III) ion imprinted ethyleneglycoldimethacrylate-methacryloylhistidine (poly(EDMA-MAH/Cr(III))) was polymerized. Cr(III) ions were removed from the Cr(III)-imprinting polymer. Selective cavity for the chromium (III) ions was obtained in the (poly(EDMA-MAH/Cr(III))) beads. These Cr(III)-imprinted beads were used in the sorption-desorption process. The effect of initial concentration of metal, the sorption rate and the pH of the medium on sorption capacity of Cr(III)-imprinting sorbents were studied. Sorption equilibrium time was achieved in about 30min. The maximum sorption of Cr(III) ions onto imprinted beads was about 69.28mg/g. Sorption studies of Co(II), Ni(II), Cr(III) and Cr(VI) ions were also investigated using Cr(III)-imprinting polymers. The obtained results show that selectively adsorbed amount of Cr(III) ion on Cr(III)-imprinting polymers is higher than all other studied ions. When the beads were used repeatedly, their adsorption capacity was showed feasibility.

Adsorption↗

PubMed2006

Immunoglobulin G depletion from human serum with metal-chelated beads under magnetic field.

Magnetic poly(ethylene glycol dimethacrylate-N-methacryloyl-(L)-histidine methyl ester) [mag-poly(EGDMA-MAH) beads, 50-100 microm in diameter, were produced by suspension polymerization for affinity depletion of immunoglobulin G (IgG) from human serum. Cu2+ ions were complexed directly via MAH groups (Cu2+ loading: 4.1 micromol/g). IgG depletion studies were performed by magnetically stabilized fluidized bed column. Acetate, Tris-HCl, MES and phosphate buffers all allow adsorption of similar quantities of IgG (27.3-45.6 mg/g). MOPS and HEPES allow higher adsorption quantities (79.6 mg/g and 74.1mg/g, respectively). Maximum adsorption capacities in MOPS buffer were 46.8 mg/g for mag-poly(EGDMA-MAH) and 102.1mg/g for Cu2+ chelated mag-poly(EGDMA-MAH) beads. The adsorption capacity decreased drastically from 102.1mg/g to 30.7 mg/g with the increase of the flow rate from 0.2 ml/min to 3.5 ml/min. The elution studies were performed by 1.0M NaCl. The elution results demonstrated that the adsorption of IgG to the adsorbent was reversible. To test the efficiency of IgG depletion from human serum, proteins in the serum and eluted portion were analyzed by two-dimensional gel electrophoresis. The depletion efficiency for IgG was above 99.4%. Eluted proteins include mainly IgG, and a small number of non-albumin proteins such as apo-lipoprotein A1, sero-transferrin, haptoglobulin and alpha1-antitrypsin. When anti-HSA-sepharose adsorbent is used together with our metal-chelated mag-beads, IgG and HSA can be depleted in a single step.

Chelating Agents↗

PubMed2006

Ion-imprinted beads for molecular recognition based mercury removal from human serum.

The aim of this study is to prepare ion-imprinted polymers which can be used for the selective removal of mercury ions [Hg(2+)] from human serum. N-Methacryloyl-(L)-cysteine (MAC) was chosen as the complexing monomer. In the first step, Hg(2+) was complexed with MAC and the Hg(2+)-imprinted poly(hydroxyethyl methacrylate-N-methacryloyl-(l)-cysteine) (MIP) beads were synthesized by suspension polymerization. After that, the template ions (i.e., Hg(2+)) were removed using thiourea (0.5%, v/v) in 0.05 M HCl. The specific surface area of the MIP beads was found to be 59.04 m(2)/g with a size range of 63-140 micro m in diameter and the swelling ratio was 91.5%. According to the elemental analysis results, the MIP beads contained 87.0 micro mol MAC/g polymer. The maximum adsorption capacity was 0.45 mg Hg(2+)/g beads. The applicability of two kinetic models including pseudo-first order and pseudo-second order model was estimated on the basis of comparative analysis of the corresponding rate parameters, equilibrium capacity and correlation coefficients. Results suggest that chemisorption processes could be the rate-limiting step in the adsorption process. The relative selectivity coefficients of MIP beads for Hg(2+)/Cd(2+), Hg(2+)/Zn(2+) were 14.7 and 21.5 times greater than the non-imprinted (NIP) matrix, respectively. The MIP beads could be used many times without decreasing in their adsorption capacities significantly.

Cations, Divalent↗

PubMed2006

Synthesis and characterization of pseudo-affinity ligand for penicillin acylase purification.

The aim of this work was to test a chromatographic affinity support containing methacryloyl antipyrine (MAAP) for penicillin acylase (PA) purification by using pure penicillin acylase and crude extract. First, MAAP as a pseudo-specific ligand was synthesized by using methacryloyl chloride and 4-aminoantipyrine. Polymer beads (average size diameter: 40-120 micro m) were prepared by suspension polymerization of ethylene glycol dimethacrylate (EGDMA) and MAAP. This approach for the preparation of adsorbent has several advantages over conventional preparation protocols. An expensive and time consuming step in the preparation of adsorbent is immobilization of a ligand to the adsorption matrix. In this procedure, affinity ligand MAAP acts as comonomer without further modification steps. Poly(EGDMA-MAAP) beads were characterized by FTIR, NMR and screen analysis. Elemental analysis of MAAP for nitrogen was estimated as 89.3 micro mol/g. The prepared adsorbent was then used for the capture of penicillin acylase in batch system. The maximum penicillin acylase adsorption capacity of the poly(EGDMA-MAAP) beads was found to be 82.2 mg/g at pH 5.0. Chromatography with crude feedstock resulted in 23.2-fold purification and 93% recovery with 1.0 M NaOH.

Adsorption↗

PubMed2006

Affinity separation of immunoglobulin G subclasses on dye attached poly(hydroxypropyl methacrylate) beads.

Poly(hydroxypropyl methacrylate) [poly(HPMA)] gel beads with an average size of 150-200 micro m were prepared by suspension polymerization of hydroxypropyl methacrylate (HPMA). The poly(HPMA) gel beads were characterized by swelling studies, surface area measurements, scanning electron microscopy (SEM) and elemental analysis. Poly(HPMA) gel beads had a specific surface area of 88.6 m(2)/g. The dye Reactive Green HE 4BD was chemically attached to yield dye-poly(HPMA) gel beads at an average concentration of 44.3 micro mol dye/g bead with a swelling ratio of 75%. These dye attached gel beads were used in the separation of immunoglobulin-G (IgG) through adsorption-elution studies. The non-specific adsorption of IgG on the poly(HPMA) gel beads was 0.5 mg/g. The attachment of Reactive Green HE 4BD significantly increased the adsorption of IgG up to 71 mg/g. The Langmuir adsorption model was found to be applicable in interpretation of data pertaining to the adsorption studies of IgG with Reactive Green HE 4BD attached to the poly(HPMA) gel beads. The adsorption of IgG was found to be optimal at pH 7.0. The adsorption of IgG was observed to decrease by about 76% as the NaCl concentration was increased from 0.001 to 0.1 M. The IgG adsorption capacity of the dye attached poly(HPMA) gel beads was determined for a commercially available IgG solution to be 4.2 mg/g for IgG(1), 64.5 mg/g for IgG(2), 7.1 mg/g for IgG(3) and 10.8 mg/g for IgG(4). The Reactive Green HE 4BD attached poly(HPMA) gel beads have a significant adsorption capacity for IgG(2). The quantity of adsorbed IgG(2) is three times higher than the quantity of the other subclasses, IgG(1), IgG(3) and IgG(4). A similar adsorption behaviour was observed when the albumin free human plasma was used. The quantity of adsorbed IgG(2) is higher than the quantity of the other subclasses, IgG(1), IgG(3) and IgG(4). Adsorption capacities for albumin free human plasma were obtained as 6.4 mg/g for IgG(1), 67.8 mg/g for IgG(2), 5.2 mg/g for IgG(3) and 8.6 mg/g for IgG(4). Significant amount of the adsorbed IgG (up to 95%) was eluted in 1h in the elution medium containing 2.0 M NaCl. Repeated adsorption/elution processes showed that these dye attached gel beads are suitable for IgG adsorption.

Adsorption↗

PubMed2006

Methacryloylamidoglutamic acid having porous magnetic beads as a stationary phase in metal chelate affinity chromatography.

We have prepared a novel magnetic metal-chelate adsorbent utilizing methacryloylamidoglutamic acid (MAGA) as a metal-chelating ligand. MAGA was synthesized by using methacryloyl chloride and L-glutamic acid dihydrochloride. Magnetic beads with an average diameter of 50-100 microm were produced by suspension polymerization of 2-hydroxyethyl methacrylate (HEMA) and MAGA in the presence of Fe3O4 particles carried out in an aqueous dispersion medium. Magnetic beads were charged with the Cu2+ ions directly via MAGA for the adsorption of cytochrome c (cyt c) from aqueous solutions. The maximum cyt c adsorption capacity of the Cu2+-chelated beads (0.86 mmol/g Cu2+ loading) was found to be 37 mg/g at pH 8.0 in phosphate buffer. Cyt c adsorption on the poly(HEMA-MAGA) beads was 15.4 mg/g. Cu2+ charging increased the cyt c adsorption significantly (37 mg/g). Cyt c adsorption decreased with increasing temperature. Cyt c molecules could be adsorbed and desorbed five times with these adsorbents without noticeable loss in their cyt c adsorption capacity. The resulting magnetic chelator beads posses excellent long term storage stability.

Animals↗

PubMed2005

Molecularly imprinted ligand-exchange recognition assay of glucose by quartz crystal microbalance.

Molecular imprinted polymers (MIP) as a recognition element for sensors are increasingly of interest and MIP-quartz crystal microbalance (QCM) have started to appear in the literature. In this study, we have combined quartz crystal microbalance with MIP to prepare a sensor using the ability of glucose to chelate of copper (II) ion of methacrylamidohistidine (MAH) monomer to create ligand exchange (LE) assembled monolayer which is suitable for glucose determination. The study includes the measurement of binding interaction of molecularly imprinted QCM sensor via ligand interaction, investigation of the pH effect on frequency shift and recognition selectivity studies of glucose-imprinted polymer with respect to methyl-alpha-d-glucopyranoside and sucrose. Bmax (number of binding sites) and K(D) (dissociation constant of the metal-chelate copolymer) were also calculated using Scathard plot and the detection limit was found as 0.07 mM. MIP showed higher glucose-binding affinity than a well-known glucose binding protein, conconavalin A.

Copper↗

PubMed2004

Molecular recognition based cadmium removal from human plasma.

Molecularly imprinted polymers (MIPs) are easy to prepare, stable, inexpensive and capable of molecular recognition. MIPs can be considered as affinity separation media. Cadmium is a carcinogenic and mutagenic element. There is no specific treatment available for acute or chronic metal poisoning. Besides supportive therapy and hemodialysis, metal poisoning is often treated with commercially available chelating agents including EDTA and dimercaprol. However, there is histopathological evidence for increased toxicity in animals when these agents are utilized. The aim of this study is to prepare ion-imprinted polymers, which can be used for the selective removal of Cd2+ ions from Cd2+-overdosed human plasma. N-Methacryloly-(L)-cysteinemethylester (MAC) was chosen as the complexing monomer. In the first step, Cd2+ was complexed with MAC and the Cd2+ -imprinted p(HEMA-MAC) beads were synthesized by suspension polymerization. After that, the template (i.e., Cd2+ ions) were removed using 0.1 M thiourea solution. The specific surface area of the Cd2+ -imprinted poly(HEMA-MAC) beads was found to be 19.4 m2/g with a size range of 63-140 microm in diameter and the swelling ratio was 78%. According to the elemental analysis results, the beads contained 42.1 micromol MAC/g polymer. The maximum adsorption capacity was 32.5 micromol Cd2+/g beads. The relative selectivity coefficients of imprinted beads for Cd2+/Pb2+ and Cd2+/Zn2+ were 7.8 and 1683 times greater than non-imprinted matrix, respectively. The Cd2+-imprinted poly(HEMA-MAC) beads could be used many times without decreasing their adsorption capacities significantly.

Adsorption↗

PubMed2004

Performance of dye-affinity beads for aluminium removal in magnetically stabilized fluidized bed.

BACKGROUND: Aluminum has recently been recognized as a causative agent in dialysis encephalopathy, osteodystrophy, and microcytic anemia occurring in patients with chronic renal failure who undergo long-term hemodialysis. Only a small amount of Al(III) in dialysis solutions may give rise to these disorders. METHODS: Magnetic poly(2-hydroxyethyl methacrylate) (mPHEMA) beads in the size range of 80-120 microm were produced by free radical co-polymerization of HEMA and ethylene dimethacrylate (EDMA) in the presence of magnetite particles (Fe3O4). Then, metal complexing ligand alizarin yellow was covalently attached onto mPHEMA beads. Alizarin yellow loading was 208 micromol/g. These beads were used for the removal of Al(III) ions from tap and dialysis water in a magnetically stabilized fluidized bed. RESULTS: Al(III) adsorption capacity of the beads decreased with an increase in the flow-rate. The maximum Al(III) adsorption was observed at pH 5.0. Comparison of batch and magnetically stabilized fluidized bed (MSFB) maximum capacities determined using Langmuir isotherms showed that dynamic capacity (17.5 mg/g) was somewhat higher than the batch capacity (11.8 mg/g). The dissociation constants for Al(III) were determined using the Langmuir isotherm equation to be 27.3 mM (MSFB) and 6.7 mM (batch system), indicating medium affinity, which was typical for pseudospecific affinity ligands. Al(III) ions could be repeatedly adsorbed and desorbed with these beads without noticeable loss in their Al(III) adsorption capacity. CONCLUSIONS: Adsorption of Al(III) demonstrate the affinity of magnetic dye-affinity beads. The MSFB experiments allowed us to conclude that this inexpensive sorbent system may be an important alternative to the existing adsorbents in the removal of aluminium.

Journal Article↗

PubMed2002

Poly(hydroxyethyl methacrylate-co-methacrylamidoalanine) membranes and their utilization as metal-chelate affinity adsorbents for lysozyme adsorption.

Different adsorbents have been reported in the literature for protein purification. The authors have developed a novel and new approach to obtain high protein adsorption capacity utilizing a 2-methacrylamidoalanine-containing membrane. Amino acid ligand 2-methacrylamidoalanine (MAAL) monomer was synthesized using methacryloyl chloride and alanine. Poly(2-hydroxyethylmethacrylate-co-2-methacrylamidoalanine) [p(HEMA-co-MAAL)] membranes were then prepared by UV-initiated photopolymerization of HEMA and MAAL in the presence of an initiator (azobisisobutyronitrile, AIBN). The synthesized MAAL monomer was characterized by NMR. p(HEMA-co-MAAL) membranes were characterized by swelling studies, porosimeter, SEM, FTIR, and elemental analysis. These membranes have macropores in the size range of 5-10 microm. Cu(II) ions (25.9 mmol/m2) were chelated on these membranes. p(HEMA-co-MAAL) membranes were used to study the adsorption of lysozyme from aqueous media containing different amounts of lysozyme (0.1-3.0 mg/l) and at different pH values (4.0-8.0). The non-specific adsorption of lysozyme on the pHEMA membranes was negligible (0.9 microg/cm2). Incorporation of MAAL increased the lysozyme adsorption significantly up to 2.96 mg/cm2. The lysozyme adsorption capacity of the Cu(II) incorporated membranes (9.98 mg/cm2) was greater than that of the p(HEMA-co-MAAL) membranes. More than 90% of the adsorbed lysozyme was desorbed in 1 h in the desorption medium containing 1.0 M NaCl and 0.025 M EDTA. The metal-chelate affinity membranes are suitable for repeated use for more than ten cycles without a noticeable loss of capacity.

Adsorption↗

PubMedDate not supplied

A new metal chelate affinity adsorbent for cytochrome C.

We have prepared a novel metal-chelate adsorbent utilizing N-methacryloyl-L-histidine methyl ester (MAH) as a metal-chelating ligand. MAH was synthesized by using methacryloyl chloride and l-histidine methyl ester dihydrochloride. Spherical beads with an average diameter of 75-125 microm were produced by suspension polymerization of 2-hydroxyethyl methacrylate (HEMA) and MAH carried out in an aqueous dispersion medium. Then, Cu(2+) ions were chelated directly on the chelating beads. Cu(2+)-chelated beads were used in the adsorption of cytochrome c (cyt c) from aqueous solutions. The maximum cyt c adsorption capacity of the Cu(2+)-chelated beads (658.2 micromol/g Cu(2+) loading) was found to be 31.7 mg/g at pH 10 in phosphate buffer. The nonspecific cyt c adsorption on the naked PHEMA beads was 0.2 mg/g. Cyt c adsorption increased with increasing Cu(2+) loading. Cyt c adsorption capacity was demonstrated for the buffer types with the effects in the order phosphate > HEPES > MOPS > MES > Tris-HCl. Cyt c molecules could be adsorbed and desorbed five times with these adsorbents without noticeable loss in their cyt c adsorption capacity.

Adsorption↗