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Nitin W Fadnavis - One of the best experts on this subject based on the ideXlab platform.
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knoevenagel condensation of diethylmalonate with aldehydes catalyzed by immobilized bovine serum albumin bsa
ChemInform, 2014Co-Authors: Perla Ramesh, Basetty Shalini, Nitin W FadnavisAbstract:Bovine serum albumin immobilized covalently on an epoxy-functionalized Polymeric Support is developed and utilized as catalyst for the condensation of aliphatic and aromatic aldehydes with diethyl malonate.
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knoevenagel condensation of diethylmalonate with aldehydes catalyzed by immobilized bovine serum albumin bsa
RSC Advances, 2014Co-Authors: Perla Ramesh, Basetty Shalini, Nitin W FadnavisAbstract:Knoevenagel condensation between aldehydes and diethylmalonate is catalyzed efficiently by bovine serum albumin (BSA) immobilized covalently on an epoxy-functionalized Polymeric Support, Immobead IB-350. The reaction is carried out conveniently at room temperature in DMSO in which aliphatic, heterocyclic and aromatic aldehydes react efficiently. After extraction with heptane and treatment with Candida antarctica lipase CAL B, the products are obtained in >95% purity and 85–89% yield. The solvent DMSO, unreacted diethylmalonate and immobilized BSA were easily recovered. Immobilized BSA and recovered DMSO were recycled 5 times without any appreciable loss in yield.
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adsorption induced enzyme denaturation the role of polymer hydrophobicity in adsorption and denaturation of α chymotrypsin on allyl glycidyl ether age ethylene glycol dimethacrylate egdm copolymers
Langmuir, 2010Co-Authors: Challa Lahari, Nitin W Fadnavis, Lakshmi Swarnalatha Jasti, Kalpana Vishwanathrao Sontakke, Ganesh Ingavle, Sarika Deokar, Surendra PonrathnamAbstract:Effects of changes in hydrophobicity of Polymeric Support on structure and activity of α-chymotrypsin (E.C. 3.4.21.1) have been studied with copolymers of allyl glycidyl ether (AGE) and ethylene glycol dimethacrylate (EGDM) with increasing molar ratio of EGDM to AGE (cross-link density 0.05 to 1.5). The enzyme is readily adsorbed from aqueous buffer at room temperature following Langmuir adsorption isotherms in unexpectedly large amounts (25% w/w). Relative hydrophobicity of the copolymers has been assessed by studying adsorption of naphthalene and Fmoc-methionine by the series of copolymers from aqueous solutions. Polymer hydrophobicity appears to increase linearly on increasing cross-link density from 0.05 to 0.25. Further increase in cross-link density causes a decrease in naphthalene binding but has little effect on binding of Fmoc-Met. Binding of α-chymotrypsin to these copolymers follow the trend for Fmoc-methionine binding, rather than naphthalene binding, indicating involvement of polar interactio...
Robert C Eberhart - One of the best experts on this subject based on the ideXlab platform.
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mechanical properties and in vitro degradation of bioresorbable fibers and expandable fiber based stents
Journal of Biomedical Materials Research Part B, 2005Co-Authors: Meital Zilberman, Kevin D Nelson, Robert C EberhartAbstract:Bioresorbable Polymeric Support devices (stents) are being developed in order to improve the biocompatibility and drug reservoir capacity of metal stents, as well as to offer a temporary alternative to permanent metallic stents. These temporary devices may be utilized for coronary, urethral, tracheal, and other applications. The present study focuses on the mechanical properties of bioresorbable fibers as well as stents developed from these fibers. Fibers made of poly(L-lactide) (PLLA), polydioxanone (PDS), and poly(glycolide-co--capro- lactone) (PGACL) were studied in vitro. These fibers combine a relatively high initial strength and modulus together with sufficient ductility and flexibility, and were therefore chosen for use in stents. The effect of degradation on the tensile mechanical properties and morphology of these fibers was examined. The expandable stents developed from these fibers demonstrated excellent initial radial compression strength. The PLLA stents exhibited excellent in vitro degradation resistance and can therefore Support body conduits such as blood vessels for prolonged periods of time. PDS and PGACL stents can afford good Support for 5 and 2 weeks, respectively, and can therefore be utilized for short-term applications. The degradation resistance of the stents correlates with the profile of mechanical property deterioration of the corresponding bioresorbable fibers. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 74B: 792-799, 2005
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mechanical properties and in vitro degradation of bioresorbable fibers and expandable fiber based stents
Journal of Biomedical Materials Research, 2005Co-Authors: Meital Zilberman, Kevin D Nelson, Robert C EberhartAbstract:Bioresorbable Polymeric Support devices (stents) are being developed in order to improve the biocompatibility and drug reservoir capacity of metal stents, as well as to offer a temporary alternative to permanent metallic stents. These temporary devices may be utilized for coronary, urethral, tracheal, and other applications. The present study focuses on the mechanical properties of bioresorbable fibers as well as stents developed from these fibers. Fibers made of poly(L-lactide) (PLLA), polydioxanone (PDS), and poly(glycolide-co-∈-caprolactone) (PGACL) were studied in vitro. These fibers combine a relatively high initial strength and modulus together with sufficient ductility and flexibility, and were therefore chosen for use in stents. The effect of degradation on the tensile mechanical properties and morphology of these fibers was examined. The expandable stents developed from these fibers demonstrated excellent initial radial compression strength. The PLLA stents exhibited excellent in vitro degradation resistance and can therefore Support body conduits such as blood vessels for prolonged periods of time. PDS and PGACL stents can afford good Support for 5 and 2 weeks, respectively, and can therefore be utilized for short-term applications. The degradation resistance of the stents correlates with the profile of mechanical property deterioration of the corresponding bioresorbable fibers.
Meital Zilberman - One of the best experts on this subject based on the ideXlab platform.
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mechanical properties and in vitro degradation of bioresorbable fibers and expandable fiber based stents
Journal of Biomedical Materials Research Part B, 2005Co-Authors: Meital Zilberman, Kevin D Nelson, Robert C EberhartAbstract:Bioresorbable Polymeric Support devices (stents) are being developed in order to improve the biocompatibility and drug reservoir capacity of metal stents, as well as to offer a temporary alternative to permanent metallic stents. These temporary devices may be utilized for coronary, urethral, tracheal, and other applications. The present study focuses on the mechanical properties of bioresorbable fibers as well as stents developed from these fibers. Fibers made of poly(L-lactide) (PLLA), polydioxanone (PDS), and poly(glycolide-co--capro- lactone) (PGACL) were studied in vitro. These fibers combine a relatively high initial strength and modulus together with sufficient ductility and flexibility, and were therefore chosen for use in stents. The effect of degradation on the tensile mechanical properties and morphology of these fibers was examined. The expandable stents developed from these fibers demonstrated excellent initial radial compression strength. The PLLA stents exhibited excellent in vitro degradation resistance and can therefore Support body conduits such as blood vessels for prolonged periods of time. PDS and PGACL stents can afford good Support for 5 and 2 weeks, respectively, and can therefore be utilized for short-term applications. The degradation resistance of the stents correlates with the profile of mechanical property deterioration of the corresponding bioresorbable fibers. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 74B: 792-799, 2005
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mechanical properties and in vitro degradation of bioresorbable fibers and expandable fiber based stents
Journal of Biomedical Materials Research, 2005Co-Authors: Meital Zilberman, Kevin D Nelson, Robert C EberhartAbstract:Bioresorbable Polymeric Support devices (stents) are being developed in order to improve the biocompatibility and drug reservoir capacity of metal stents, as well as to offer a temporary alternative to permanent metallic stents. These temporary devices may be utilized for coronary, urethral, tracheal, and other applications. The present study focuses on the mechanical properties of bioresorbable fibers as well as stents developed from these fibers. Fibers made of poly(L-lactide) (PLLA), polydioxanone (PDS), and poly(glycolide-co-∈-caprolactone) (PGACL) were studied in vitro. These fibers combine a relatively high initial strength and modulus together with sufficient ductility and flexibility, and were therefore chosen for use in stents. The effect of degradation on the tensile mechanical properties and morphology of these fibers was examined. The expandable stents developed from these fibers demonstrated excellent initial radial compression strength. The PLLA stents exhibited excellent in vitro degradation resistance and can therefore Support body conduits such as blood vessels for prolonged periods of time. PDS and PGACL stents can afford good Support for 5 and 2 weeks, respectively, and can therefore be utilized for short-term applications. The degradation resistance of the stents correlates with the profile of mechanical property deterioration of the corresponding bioresorbable fibers.
Melek Merdivan - One of the best experts on this subject based on the ideXlab platform.
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separation and preconcentration of la3 ce3 and y3 using calix 4 resorcinarene impregnated on Polymeric Support
Mikrochimica Acta, 2007Co-Authors: Cem Gok, Serap Seyhan, Melek Merdivan, Muruvvet YurdakocAbstract:A procedure is proposed for separation and preconcentration of lanthanium, cerium and yttrium using octacarboxymethyl-C-methylcalix [4]resorcinarene impregnated onto a Polymeric matrix, Amberlite XAD-16. The optimization process was carried out using 23 factorial design and three variables (pH, concentration of metal ion, sorption flow rate) were regarded as factors. For Ce3+ extraction, the variance analysis revealed that pH and concentration of Ce3+ was statistically significant. However, for La3+ and Y3+ pH was significant only. The precision of the method (%RSD) was 2.27 for La3+, 1.97 for Ce3+ and 2.01 for Y3+ at 1 µg mL−1 for ten replicate analyses. The preconcentration factors of La3+, Ce3+ and Y3+ were 125, 83 and 100 respectively. The robustness of this procedure is demonstrated by the recovery achieved for determination of La3+, Ce3+ and Y3+ in the presence of several cations. The procedure was satisfactorily applied to the separation of La3+, Ce3+ and Y3+ from each other and also from common actinides such as UO2 2+ and Th4+ by sequential acidic elution system.
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Separation and preconcentration of La^3+, Ce^3+ and Y^3+ using calix[4]resorcinarene impregnated on Polymeric Support
Microchimica Acta, 2007Co-Authors: Cem Gok, Serap Seyhan, Melek Merdivan, Muruvvet YurdakocAbstract:A procedure is proposed for separation and preconcentration of lanthanium, cerium and yttrium using octacarboxymethyl-C-methylcalix [4]resorcinarene impregnated onto a Polymeric matrix, Amberlite XAD-16. The optimization process was carried out using 2^3 factorial design and three variables (pH, concentration of metal ion, sorption flow rate) were regarded as factors. For Ce^3+ extraction, the variance analysis revealed that pH and concentration of Ce^3+ was statistically significant. However, for La^3+ and Y^3+ pH was significant only. The precision of the method (%RSD) was 2.27 for La^3+, 1.97 for Ce^3+ and 2.01 for Y^3+ at 1 µg mL^−1 for ten replicate analyses. The preconcentration factors of La^3+, Ce^3+ and Y^3+ were 125, 83 and 100 respectively. The robustness of this procedure is demonstrated by the recovery achieved for determination of La^3+, Ce^3+ and Y^3+ in the presence of several cations. The procedure was satisfactorily applied to the separation of La^3+, Ce^3+ and Y^3+ from each other and also from common actinides such as UO_2 ^2+ and Th^4+ by sequential acidic elution system.
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chiral separation of amino acids using a chiral crown ether by impregnation on a Polymeric Support and monoamine modified silica gel
Tetrahedron-asymmetry, 2006Co-Authors: Serap Seyhan, Melek Merdivan, Yilmaz Turgut, Halil HosgorenAbstract:Abstract A chiral monoaza-15-crown-5 ether derivative was prepared from l -Leucinol and used as a chiral stationary phase. The new chiral stationary phases CSP- 1 and CSP- 2 were employed in separating the enantiomers of the sodium and potassium salts of amino acids. The sodium and potassium salt of the d -enantiomers of all amino acids (PhyAlaNa, PhyAlaK and PhyGlyNa, PhyGlyK, and TrpNa, TrpK) show higher selectivity than the l -enantiomers for both CSP- 1 and CSP- 2 .
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chiral separation of amino acids by chiral octamide derivatives of calixarenes derived from resorcinol by impregnation on a Polymeric Support
Tetrahedron-asymmetry, 2005Co-Authors: Serap Seyhan, Melek Merdivan, Nadir Demirel, Ozge Ozbayrak, Necmettin PirincciogluAbstract:Abstract Chiral amide derivatives of octaester calixresorcarene were synthesized and employed as chiral stationary phases for chiral discrimination of amino acid derivatives. Enantiomers of phenylglycine and tryptophan were easily discriminated as their sodium and potassium salts. In addition, phenylalanine–trytophan, phenylglycine–trytophan mixtures were separated by column chromatography.
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thorium iv and uranium vi sorption studies on octacarboxymethyl c methylcalix 4 resorcinarene impregnated on a Polymeric Support
Analytica Chimica Acta, 2003Co-Authors: Nadir Demirel, Melek Merdivan, Necmettin Pirinccioglu, Candan HamamciAbstract:Abstract The impregnation of octacarboxymethyl- C -methylcalix[4]resorcinarene into a Polymeric matrix, Amberlite XAD-4, is reported and was characterized by infrared spectroscopy. The sorption capacity of the impregnated resin is 0.34×10 −3 mol g −1 . The resin was used for the sorption of thorium(IV) and uranium(VI) from aqueous solution. The properties of capacity, pH effect, and breakthrough curves of the impregnated resin were investigated. The capacity of the resin for Th(IV) and U(VI) was found to be 0.29 and 0.27×10 −3 mol g −1 , respectively. The metal ions were eluted with 0.4–2 M HCl or HNO 3 . Chromatographic separation of Th(IV) and U(VI) was accomplished by adjustment of pH to 3.0 and 6.0, respectively. The impregnated resin exhibits a high chemical stability, reusability and fast equilibration. Separation of Th(IV) and U(VI) from other metal cations in synthetic solution was achieved.
Jean Martinez - One of the best experts on this subject based on the ideXlab platform.
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synthesis of novel poly ethylene glycol Supported benzazepines the crucial role of peg on the selectivity of an intramolecular heck reaction
Tetrahedron, 2006Co-Authors: Patrice Ribiere, Valerie Declerck, Yannig Nedellec, Neerja Yadavbhatnagar, Jean Martinez, Frederic LamatyAbstract:Poly(ethylene glycol) (PEG 3400) was used as a soluble Polymeric Support for the synthesis of a series of novel benzazepines. The key step for the preparation of these heterocycles was a phosphine-free palladium-catalyzed Heck reaction. Palladium nanoparticles formed during the course of the reaction were characterized. The presence of PEG 3400 influenced the outcome of the reaction in terms of selectivity.
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Imaging combinatorial libraries by mass spectrometry: from peptide to organic-Supported syntheses
Journal of Combinatorial Chemistry, 2003Co-Authors: Christine Enjalbal, Jean Martinez, Delphine Maux, Robert Combarieu, Jean-louis AubagnacAbstract:Supported peptide and drug-like organic molecule libraries were profiled in single nondestructive imaging static secondary ion mass spectrometric experiments. The selective rupture of the bond linking the compound and the insoluble Polymeric Support (resin) produced ions that were characteristic of the anchored molecules, thus allowing unambiguous resin bead assignment. Very high sensitivity and specificity were obtained with such a direct analytical method, which avoids the chemical release of the molecules from the Support. Libraries issued from either mix-and-split or parallel solid-phase organic syntheses were profiled, demonstrating the usefulness of such a technique for characterization and optimization during combinatorial library development. Moreover, the fact that the control was effected at the bead level whatever the structure and quantity of the anchored molecules allows the sole identification of active beads selected from on-bead screening. Under such circumstances, the time-consuming whole-library characterization could thus be suppressed, enhancing the throughput of the analytical process.
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Application of time-of-flight secondary ion mass spectrometry to in situ monitoring of solid-phase peptide synthesis on the Multipin (TM) system
Journal of Mass Spectrometry, 1998Co-Authors: Jean-louis Aubagnac, Christine Enjalbal, Robert Combarieu, Gilles Subra, A.m. Bray, Jean MartinezAbstract:In the rapidly growing field of combinatorial chemistry, the Multipin approach has been used for rapid and efficient multiple parallel syntheses of organic compounds. This strategy is particularly well adapted for the optimization of reaction conditions prior to chemical library syntheses, for the preparation of a wide range of compounds in relation to a lead structure or for the generation of parallel libraries involving complex multistep chemistries. In all cases, direct in situ monitoring of Support-bound products would be highly valuable. In this work, time-of-flight secondary ion mass spectrometry was applied to the analysis of Support-bound intermediates. The analytical method was applied to a range of crowns loaded with various dipeptides. The solid Support was subjected to primary ion bombardment and characteristic ions indicative of both the peptide chain and the Polymeric Support were unambiguously identified. Analysis could be performed at any stage of the synthesis, and as the method is effectively non-destructive, the analyzed crowns could be further used to prepare target compounds
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polyethylene glycol peg as Polymeric Support and phase transfer catalyst in the soluble polymer liquid phase synthesis of α amino esters
Tetrahedron Letters, 1998Co-Authors: Berengere Sauvagnat, Frederic Lamaty, R Lazaro, Jean MartinezAbstract:Abstract α-substituted α-amino esters were synthesized in liquid-phase by polyethylene glycol (ce:simple-paraEG) promoted alkylation of a polyethylene glycol-Supported Schiff base activated glycine ester.