The Experts below are selected from a list of 9 Experts worldwide ranked by ideXlab platform
Olli Ikkala - One of the best experts on this subject based on the ideXlab platform.
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Deoxyguanosine Phosphate mediated sacrificial bonds promote synergistic mechanical properties in nacre-mimetic nanocomposites.
Biomacromolecules, 2013Co-Authors: Lahja Martikainen, Andreas Walther, Jani Seitsonen, Lars Berglund, Olli IkkalaAbstract:We show that functionalizing polymer-coated colloidal nanoplatelets with guanosine groups allows synergistic increase of mechanical properties in nacre-mimetic lamellar self-assemblies. Anionic montmorillonite (MTM) was first coated using cationic poly(diallyldimethylammonium chloride) (PDADMAC) to prepare core-shell colloidal platelets, and subsequently the remaining chloride counterions allowed exchange to functional anionic 2'-Deoxyguanosine 5'-monoPhosphate (dGMP) counterions, containing hydrogen bonding donors and acceptors. The compositions were studied using elemental analysis, scanning and transmission electron microscopy, wide-angle X-ray scattering, and tensile testing. The lamellar spacing between the clays increases from 1.85 to 2.14 nm upon addition of the dGMP. Adding dGMP increases the elastic modulus, tensile strength, and strain 33.0%, 40.9%, and 5.6%, respectively, to 13.5 GPa, 67 MPa, and 1.24%, at 50% relative humidity. This leads to an improved toughness seen as a ca. 50% increase of the work-to-failure. This is noteworthy, as previously it has been observed that connecting the core-shell nanoclay platelets covalently or ionically leads to increase of the stiffness but to reduced strain. We suggest that the dynamic supramolecular bonds allow slippage and sacrificial bonds between the self-assembling nanoplatelets, thus promoting toughness, still providing dynamic interactions between the platelets.
Barbara Ramsay Shaw - One of the best experts on this subject based on the ideXlab platform.
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Boron-containing oligodeoxyribonucleotide 14mer duplexes: enzymatic synthesis and melting studies
Nucleic acids research, 1995Co-Authors: Kenneth W. Porter, Faqing Huang, Barbara Ramsay ShawAbstract:Abstract A set of three 14mer oligodeoxyribonucleotides of sequence d(5'-CTATGGCCTCAG*CT-3'/3'-GATACCGGAGTCGA-5') containing G* variants either as 2'-Deoxyguanosine Phosphate (unmodified), N7-cyanoborane 2'-Deoxyguanosine Phosphate (base-modified) or 2'-Deoxyguanosine boranoPhosphate (backbone-modified) were synthesized by template-directed primer extension. Both the N7-cyanoborane 2'-Deoxyguanosine triPhosphate and 2'-Deoxyguanosine alpha-boranotriPhosphate nucleotides are good substrates for Sequenase. We infer that a single Sp boranoPhosphate linkage (which has a stereochemistry equivalent to the corresponding Rp thioPhosphate analog) is formed in the backbone-modified 14mer. Thermally induced helix-coil transitions were monitored for the hybridized duplexes using UV and circular dichroism (CD) spectroscopy. The CD spectra of the two types of boron-modified hybrids closely resemble the unmodified parent duplex, forming B-type helices in 150 mM NaCl, 1 mM EDTA, 10 mM Phosphate, pH 7.4, buffer. UV melting results indicate that both hybrids have stabilities comparable with the parent duplex as measured by Tm or delta G degree 25. These studies indicate that singly modified base- or backbone-boronated DNA are good analogs of normal DNA.
Lahja Martikainen - One of the best experts on this subject based on the ideXlab platform.
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Deoxyguanosine Phosphate mediated sacrificial bonds promote synergistic mechanical properties in nacre-mimetic nanocomposites.
Biomacromolecules, 2013Co-Authors: Lahja Martikainen, Andreas Walther, Jani Seitsonen, Lars Berglund, Olli IkkalaAbstract:We show that functionalizing polymer-coated colloidal nanoplatelets with guanosine groups allows synergistic increase of mechanical properties in nacre-mimetic lamellar self-assemblies. Anionic montmorillonite (MTM) was first coated using cationic poly(diallyldimethylammonium chloride) (PDADMAC) to prepare core-shell colloidal platelets, and subsequently the remaining chloride counterions allowed exchange to functional anionic 2'-Deoxyguanosine 5'-monoPhosphate (dGMP) counterions, containing hydrogen bonding donors and acceptors. The compositions were studied using elemental analysis, scanning and transmission electron microscopy, wide-angle X-ray scattering, and tensile testing. The lamellar spacing between the clays increases from 1.85 to 2.14 nm upon addition of the dGMP. Adding dGMP increases the elastic modulus, tensile strength, and strain 33.0%, 40.9%, and 5.6%, respectively, to 13.5 GPa, 67 MPa, and 1.24%, at 50% relative humidity. This leads to an improved toughness seen as a ca. 50% increase of the work-to-failure. This is noteworthy, as previously it has been observed that connecting the core-shell nanoclay platelets covalently or ionically leads to increase of the stiffness but to reduced strain. We suggest that the dynamic supramolecular bonds allow slippage and sacrificial bonds between the self-assembling nanoplatelets, thus promoting toughness, still providing dynamic interactions between the platelets.
Kenneth W. Porter - One of the best experts on this subject based on the ideXlab platform.
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Boron-containing oligodeoxyribonucleotide 14mer duplexes: enzymatic synthesis and melting studies
Nucleic acids research, 1995Co-Authors: Kenneth W. Porter, Faqing Huang, Barbara Ramsay ShawAbstract:Abstract A set of three 14mer oligodeoxyribonucleotides of sequence d(5'-CTATGGCCTCAG*CT-3'/3'-GATACCGGAGTCGA-5') containing G* variants either as 2'-Deoxyguanosine Phosphate (unmodified), N7-cyanoborane 2'-Deoxyguanosine Phosphate (base-modified) or 2'-Deoxyguanosine boranoPhosphate (backbone-modified) were synthesized by template-directed primer extension. Both the N7-cyanoborane 2'-Deoxyguanosine triPhosphate and 2'-Deoxyguanosine alpha-boranotriPhosphate nucleotides are good substrates for Sequenase. We infer that a single Sp boranoPhosphate linkage (which has a stereochemistry equivalent to the corresponding Rp thioPhosphate analog) is formed in the backbone-modified 14mer. Thermally induced helix-coil transitions were monitored for the hybridized duplexes using UV and circular dichroism (CD) spectroscopy. The CD spectra of the two types of boron-modified hybrids closely resemble the unmodified parent duplex, forming B-type helices in 150 mM NaCl, 1 mM EDTA, 10 mM Phosphate, pH 7.4, buffer. UV melting results indicate that both hybrids have stabilities comparable with the parent duplex as measured by Tm or delta G degree 25. These studies indicate that singly modified base- or backbone-boronated DNA are good analogs of normal DNA.
Andreas Walther - One of the best experts on this subject based on the ideXlab platform.
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Deoxyguanosine Phosphate mediated sacrificial bonds promote synergistic mechanical properties in nacre-mimetic nanocomposites.
Biomacromolecules, 2013Co-Authors: Lahja Martikainen, Andreas Walther, Jani Seitsonen, Lars Berglund, Olli IkkalaAbstract:We show that functionalizing polymer-coated colloidal nanoplatelets with guanosine groups allows synergistic increase of mechanical properties in nacre-mimetic lamellar self-assemblies. Anionic montmorillonite (MTM) was first coated using cationic poly(diallyldimethylammonium chloride) (PDADMAC) to prepare core-shell colloidal platelets, and subsequently the remaining chloride counterions allowed exchange to functional anionic 2'-Deoxyguanosine 5'-monoPhosphate (dGMP) counterions, containing hydrogen bonding donors and acceptors. The compositions were studied using elemental analysis, scanning and transmission electron microscopy, wide-angle X-ray scattering, and tensile testing. The lamellar spacing between the clays increases from 1.85 to 2.14 nm upon addition of the dGMP. Adding dGMP increases the elastic modulus, tensile strength, and strain 33.0%, 40.9%, and 5.6%, respectively, to 13.5 GPa, 67 MPa, and 1.24%, at 50% relative humidity. This leads to an improved toughness seen as a ca. 50% increase of the work-to-failure. This is noteworthy, as previously it has been observed that connecting the core-shell nanoclay platelets covalently or ionically leads to increase of the stiffness but to reduced strain. We suggest that the dynamic supramolecular bonds allow slippage and sacrificial bonds between the self-assembling nanoplatelets, thus promoting toughness, still providing dynamic interactions between the platelets.