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Immobilization Strategies (immobilization + strategy)
Selected AbstractsCover Picture: Divide et Impera , Multiphase, Green Solvent and Immobilization Strategies for Molecular Catalysis (Adv. Synth.ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 12-13 2006Catal. No abstract is available for this article. [source] Nucleosome Immobilization Strategies for Single-Pair FRET Microscopy,CHEMPHYSCHEM, Issue 14 2008Wiepke J. A. Koopmans Abstract All genomic transactions in eukaryotes take place in the context of the nucleosome, the basic unit of chromatin, which is responsible for DNA compaction. Overcoming the steric hindrance that nucleosomes present for DNA-processing enzymes requires significant conformational changes. The dynamics of these have been hard to resolve. Single-pair Fluorescence Resonance Energy Transfer (spFRET) microscopy is a powerful technique for observing conformational dynamics of the nucleosome. Nucleosome immobilization allows the extension of observation times to a limit set only by photobleaching, and thus opens the possibility of studying processes occurring on timescales ranging from milliseconds to minutes. It is crucial however, that immobilization itself does not introduce artifacts in the dynamics. Here we report on various nucleosome immobilization strategies, such as single-point attachment to polyethylene glycol (PEG) or surfaces coated with bovine serum albumin (BSA), and confinement in porous agarose or polyacrylamide gels. We compare the immobilization specificity and structural integrity of immobilized nucleosomes. A crosslinked star polyethylene glycol coating performs best with respect to tethering specificity and nucleosome integrity, and enables us to reproduce for the first time bulk nucleosome unwrapping kinetics in single nucleosomes without immobilization artifacts. [source] Protease Immobilization on ,-Fe2O3/Fe3O4 Magnetic Nanoparticles for the Synthesis of Oligopeptides in Organic SolventsCHEMISTRY - AN ASIAN JOURNAL, Issue 6 2010Bao-juan Xin Abstract The use of nanobiocatalysts, with the combination of nanotechnology and biotechnology, is considered as an exciting and rapidly emerging area. The use of iron oxide magnetic nanoparticles, as enzyme immobilization carriers, has drawn great attention because of their unique properties, such as controllable particle size, large surface area, modifiable surface, and easy recovery. In this study, various ,-Fe2O3/Fe3O4 magnetic nanoparticles with immobilized proteases were successfully prepared by three different immobilization strategies including A),direct binding, B),with thiophene as a linker, and C),with triazole as a linker. The oligopeptides syntheses catalyzed by these magnetic nanoparticles (MNPs) with immobilized proteases were systematically studied. Our results show that i),for magnetic nanoparticles immobilized ,-chymotrypsin, both immobilization strategies A and B furnished good reusability for the Z-Tyr-Gly-Gly-OEt synthesis, the MNPs enzymes can be readily used at least five times without significant loss of its catalytic performance: ii),In the case of Z-Asp-Phe-OMe synthesis catalyzed by magnetic nanoparticles immobilized thermolysin, immobilization Strategy,B provided the best recyclability: iii),For the immobilized papain, although Strategy,A or B afforded an immobilized enzyme for the first cycle of Z-Ala-Leu-NHNHPh synthesis in good yield, their subsequent catalytic activity decreased rapidly. In general, the ,-Fe2O3 MNPs were better for use as an immobilization matrix, rather than the Fe3O4 MNPs, owing to their smaller particle size and higher surface area. [source] Comparison of Different Strategies on DNA Chip Fabrication and DNA-Sensing: Optical and Electrochemical ApproachesELECTROANALYSIS, Issue 22 2005Sabine Szunerits Abstract New strategies for the construction of DNA chips and the detection of DNA hybridization will be discussed in this review. The focus will be on the use of polypyrrole as a linker between a substrate and oligonucleotide probes. The modification step is based on the electrochemical copolymerization of pyrrole and oligonucleotides bearing a pyrrole group on its 5, end. This strategy was employed for the immobilization of oligonucleotides on millimeter-sized electrodes, microelectrode arrays, as well as for the local structuring of homogeneous gold surfaces. Our approaches for the localized patterning of gold surfaces will be also discussed. Localized immobilization was achieved by using an electrospotting technique, where a micropipette served as an electrochemical cell where spot sizes with 800,,m diameters were fabricated. The use of a microcell using a Teflon covered metal needle with a cavity of 100,,m resulted in immobilized probe spots of 300,,m. Scanning electrochemical microscopy (SECM) was also used, and surface modifications of 100,,m were obtained depending on the experimental conditions. Different detection methods were employed for the reading of the hybridization event: fluorescence imaging, surface plasmon resonance imaging (SPRI), photocurrent measurements, and voltamperometric measurements using intercalators. Their advantages concerning the various immobilization strategies will also be discussed. [source] Versatile protein microarray based on carbohydrate-binding modulesPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 7 2005Keren Ofir Abstract Non-DNA microarrays, such as protein, peptide and small molecule microarrays, can potentially revolutionize the high-throughput screening tools currently used in basic and pharmaceutical research. However, fundamental obstacles remain that limit their rapid and widespread implementation as an alternative bioanalytical approach. These include the prerequisite for numerous proteins in active and purified form, ineffectual immobilization strategies and inadequate means for quality control of the considerable numbers of multiple reagents. This study describes a simple yet efficient strategy for the production of non-DNA microarrays, based on the tenacious affinity of a carbohydrate-binding module (CBM) for its three-dimensional substrate, i.e., cellulose. Various microarray formats are described, e.g., conventional and single-chain antibody microarrays and peptide microarrays for serodiagnosis of human immunodeficiency virus patients. CBM-based microarray technology overcomes many of the previous obstacles that have hindered fabrication of non-DNA microarrays and provides a technically simple but effective alternative to conventional microarray technology. [source] Protease Immobilization on ,-Fe2O3/Fe3O4 Magnetic Nanoparticles for the Synthesis of Oligopeptides in Organic SolventsCHEMISTRY - AN ASIAN JOURNAL, Issue 6 2010Bao-juan Xin Abstract The use of nanobiocatalysts, with the combination of nanotechnology and biotechnology, is considered as an exciting and rapidly emerging area. The use of iron oxide magnetic nanoparticles, as enzyme immobilization carriers, has drawn great attention because of their unique properties, such as controllable particle size, large surface area, modifiable surface, and easy recovery. In this study, various ,-Fe2O3/Fe3O4 magnetic nanoparticles with immobilized proteases were successfully prepared by three different immobilization strategies including A),direct binding, B),with thiophene as a linker, and C),with triazole as a linker. The oligopeptides syntheses catalyzed by these magnetic nanoparticles (MNPs) with immobilized proteases were systematically studied. Our results show that i),for magnetic nanoparticles immobilized ,-chymotrypsin, both immobilization strategies A and B furnished good reusability for the Z-Tyr-Gly-Gly-OEt synthesis, the MNPs enzymes can be readily used at least five times without significant loss of its catalytic performance: ii),In the case of Z-Asp-Phe-OMe synthesis catalyzed by magnetic nanoparticles immobilized thermolysin, immobilization Strategy,B provided the best recyclability: iii),For the immobilized papain, although Strategy,A or B afforded an immobilized enzyme for the first cycle of Z-Ala-Leu-NHNHPh synthesis in good yield, their subsequent catalytic activity decreased rapidly. In general, the ,-Fe2O3 MNPs were better for use as an immobilization matrix, rather than the Fe3O4 MNPs, owing to their smaller particle size and higher surface area. [source] Nucleosome Immobilization Strategies for Single-Pair FRET Microscopy,CHEMPHYSCHEM, Issue 14 2008Wiepke J. A. Koopmans Abstract All genomic transactions in eukaryotes take place in the context of the nucleosome, the basic unit of chromatin, which is responsible for DNA compaction. Overcoming the steric hindrance that nucleosomes present for DNA-processing enzymes requires significant conformational changes. The dynamics of these have been hard to resolve. Single-pair Fluorescence Resonance Energy Transfer (spFRET) microscopy is a powerful technique for observing conformational dynamics of the nucleosome. Nucleosome immobilization allows the extension of observation times to a limit set only by photobleaching, and thus opens the possibility of studying processes occurring on timescales ranging from milliseconds to minutes. It is crucial however, that immobilization itself does not introduce artifacts in the dynamics. Here we report on various nucleosome immobilization strategies, such as single-point attachment to polyethylene glycol (PEG) or surfaces coated with bovine serum albumin (BSA), and confinement in porous agarose or polyacrylamide gels. We compare the immobilization specificity and structural integrity of immobilized nucleosomes. A crosslinked star polyethylene glycol coating performs best with respect to tethering specificity and nucleosome integrity, and enables us to reproduce for the first time bulk nucleosome unwrapping kinetics in single nucleosomes without immobilization artifacts. [source] Rapid Microfluidic Generation of Patterned Aldehydes from Hydroxy-Terminated Self-Assembled Monolayers for Ligand and Cell Immobilization on Optically Transparent Indium Tin Oxide SurfacesADVANCED MATERIALS, Issue 30 2009Abigail Pulsipher Selective immobilization of a wide range of ligands on an indium tin oxide (ITO) surface is demonstrated. A chemoselective immobilization strategy to tailor ITO surfaces is developed by selectively oxidizing hydroxyl-terminated phosphonate self-assembled monolayers (SAMs) to aldehyde-presenting SAMs using microfluidic channels and then reacting with oxyamine-containing ligands , all on a chip. [source] Direct atomic force microscopy observations of monovalent ion induced binding of DNA to micaJOURNAL OF MICROSCOPY, Issue 3 2004J. S. ELLIS Summary Multivalent ions in solution are known to mediate attraction between two like-charged molecules. Such attraction has proved useful in atomic force microscopy (AFM) where DNA may be immobilized to a mica surface facilitating direct imaging in liquid. Theories of DNA immobilization suggest that either ,salt bridging' or fluctuation in the positions of counter ions about both the mica surface and DNA backbone secure DNA to the mica substrate. Whilst both theoretical and experimental evidence suggest that immobilization is possible in the presence of divalent ions, very few studies identify that such immobilization is possible with monovalent ions. Here we present direct AFM evidence of DNA immobilized to mica in the presence of only monovalent ions. Our data depict E. coli plasmid pBR322 adsorbed onto the negatively charged mica both after short (10 min) and long (24 h) incubation periods. These data suggest the need to re-explore current theories of like-charge attraction to include the possibility of monovalent interactions. We suggest that this DNA immobilization strategy may offer the potential to image natural processes with limited immobilization forces and hence enable maximum conformational freedom of the immobilized biomolecule. [source] Mesoporous Silica Nanosphere-Supported Chiral Ruthenium Catalysts: Synthesis, Characterization, and Asymmetric Hydrogenation StudiesCHEMCATCHEM, Issue 3 2009David Abstract Chiral RuCl2,diphosphine,diamine complexes with a pendant siloxy group were synthesized and characterized by NMR spectroscopy and mass spectrometry. The Ru complexes were grafted onto three different types of mesoporous silica nanospheres (MSNs) through the siloxane linkage, and the resulting MSN-supported Ru catalysts were highly active for the asymmetric hydrogenation of aromatic ketones, to afford chiral secondary alcohols, and racemic arylaldehydes, to give chiral primary alcohols. Excellent activities and enantioselectivities were observed for these MSN-supported Ru catalysts owing to readily accessible and uniform catalytic sites within the large channels of MSNs (diameters of >2,nm) and short diffusion lengths for the organic compounds as a result of small nanoparticle sizes of less than 1,,m. This catalyst immobilization strategy with MSN supports should be amenable to the design of many highly active and enantioselective heterogeneous asymmetric catalysts. [source] | ||||||||||