Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, ... more Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.
A Complicated Scaffold, Simply Materials with tailored pore structures can be useful as catalysis... more A Complicated Scaffold, Simply Materials with tailored pore structures can be useful as catalysis supports and for lightweight materials. When preparing medical scaffolds, restrictive preparation conditions have to be met, which can prohibit multistep preparation procedures. Sai et al. (p. 530 ) describe a method for making porous polymers containing both relatively large (several microns) interconnecting pores and a second population of ∼ tens of nanometer pores. The process exploits spinodal decomposition of a block copolymer blended with small-molecule additives and requires a simple washing step with water, methanol, or ethanol.
ABSTRACT Previous results have shown that the nacre specific peptide, n16N, from the Japanese pea... more ABSTRACT Previous results have shown that the nacre specific peptide, n16N, from the Japanese pearl oyster Pinctada fucata has a binding affinity for β-chitin. As a result, the n16N-chitin assembly is able to selectivity nucleate aragonite. Here, we have added silk fibroin hydrogels to the in vitro assay to more fully represent the in vivo matrix. Crystallization, with a silk fibroin hydrogel and n16N on β-chitin, results in metastable vaterite and amorphous calcium carbonate, which form as flat deposits with hemispherical centers. Acidic peptide controls (p-Asp/p-Glu) were also tested in the silk-chitin assay and result in flat calcite that grows into the β-chitin substrate. Fluorescence imaging of that matrix, made with labeled n16N, shows that n16N binds to β-chitin in the presence of silk gel. These results demonstrate that the addition of a silk hydrogel to the n16N−β-chitin assembly changes the microenvironment for mineralization. This work contributes to our understanding of the roles of individual nacre matrix components (and their assemblies) in controlling crystal growth.
ABSTRACT Previous literature by Falini et al. suggests that the cooperation between β-chitin, pro... more ABSTRACT Previous literature by Falini et al. suggests that the cooperation between β-chitin, proteins, and a silk fibroin-like hydrogel determines polymorph selectivity within the nacreous layer of mollusk shells (favoring aragonite over calcite formation). Here we present an in vitro assay in which we combine functionalized organic surfaces with soluble peptides to probe the role of surface−peptide interactions in calcium carbonate polymorph selectivity. Specifically, we combined n16N (a 30 amino acid peptide from the Japanese pearl oyster Pinctada fucata) and its sequence variants, n16Ns (randomly scrambled) and n16NN (global Asp → Asn, Glu → Gln substitution), with different forms of chitin (α and β). We found that the combination of n16N adsorbed onto β-chitin leads to the formation of aragonite in vitro as well as demonstrated chitin binding ability. Negative controls, including sequence modified versions of n16N (n16Ns and n16NN), exhibit variation in β-chitin binding and the ability to nucleate aragonite. The peptide + α-chitin combination exhibits very little chitin binding and nucleates exclusively calcite with minor morphological effects. The n16N and n16Ns peptides used in this study are considered intrinsically disordered and have previously been shown to interact with calcium carbonate. We propose that the intrinsically disordered structure of n16N also allows the peptide to interact with the substrate creating a new organic matrix interface. The cooperation between the peptide and substrate may explain the polymorph specificity among these samples.
Recent developments in quantum materials hold promise for revolutionizing energy and information ... more Recent developments in quantum materials hold promise for revolutionizing energy and information technologies. The use of soft matter self-assembly, for example, by employing block copolymers (BCPs) as structure directing or templating agents, offers facile pathways toward quantum metamaterials with highly tunable mesostructures via scalable solution processing. Here, we report the preparation of patternable mesoporous niobium carbonitride-type thin film superconductors through spin-coating of a hybrid solution containing an amphiphilic BCP swollen by niobia sol precursors and subsequent thermal processing in combination with photolithography. Spin-coated as-made BCP-niobia hybrid thin films on silicon substrates after optional photolithographic definition are heated in air to produce a porous oxide, and subsequently converted in a multistep process to carbonitrides via treatment with high temperatures in reactive gases including ammonia. Grazing incidence small-angle X-ray scattering suggests the presence of ordered mesostructures in as-made BCP-niobia films without further annealing, consistent with a distorted alternating gyroid morphology that is retained upon thermal treatments. Wide-angle X-ray scattering confirms the synthesis of phase-pure niobium carbonitride nanocrystals with rock-salt lattices within the mesoscale networks. Electrical transport measurements of unpatterned thin films show initial exponential rise in resistivity characteristic of thermal activation in granular systems down to 12.8 K, at which point resistivity drops to zero into a superconducting state. Magnetoresistance measurements determine the superconducting upper critical field to be over 16 T, demonstrating material quality on par with niobium carbonitrides obtained from traditional solid-state synthesis methods. We discuss how such cost-effective and scalable solution-based quantum materials fabrication approaches may be integrated into existing microelectronics processing, promising the emergence of a technology with tremendous academic and industrial potential by combining the capabilities of soft matter self-assembly with quantum materials.
Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, ... more Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.
A Complicated Scaffold, Simply Materials with tailored pore structures can be useful as catalysis... more A Complicated Scaffold, Simply Materials with tailored pore structures can be useful as catalysis supports and for lightweight materials. When preparing medical scaffolds, restrictive preparation conditions have to be met, which can prohibit multistep preparation procedures. Sai et al. (p. 530 ) describe a method for making porous polymers containing both relatively large (several microns) interconnecting pores and a second population of ∼ tens of nanometer pores. The process exploits spinodal decomposition of a block copolymer blended with small-molecule additives and requires a simple washing step with water, methanol, or ethanol.
ABSTRACT Previous results have shown that the nacre specific peptide, n16N, from the Japanese pea... more ABSTRACT Previous results have shown that the nacre specific peptide, n16N, from the Japanese pearl oyster Pinctada fucata has a binding affinity for β-chitin. As a result, the n16N-chitin assembly is able to selectivity nucleate aragonite. Here, we have added silk fibroin hydrogels to the in vitro assay to more fully represent the in vivo matrix. Crystallization, with a silk fibroin hydrogel and n16N on β-chitin, results in metastable vaterite and amorphous calcium carbonate, which form as flat deposits with hemispherical centers. Acidic peptide controls (p-Asp/p-Glu) were also tested in the silk-chitin assay and result in flat calcite that grows into the β-chitin substrate. Fluorescence imaging of that matrix, made with labeled n16N, shows that n16N binds to β-chitin in the presence of silk gel. These results demonstrate that the addition of a silk hydrogel to the n16N−β-chitin assembly changes the microenvironment for mineralization. This work contributes to our understanding of the roles of individual nacre matrix components (and their assemblies) in controlling crystal growth.
ABSTRACT Previous literature by Falini et al. suggests that the cooperation between β-chitin, pro... more ABSTRACT Previous literature by Falini et al. suggests that the cooperation between β-chitin, proteins, and a silk fibroin-like hydrogel determines polymorph selectivity within the nacreous layer of mollusk shells (favoring aragonite over calcite formation). Here we present an in vitro assay in which we combine functionalized organic surfaces with soluble peptides to probe the role of surface−peptide interactions in calcium carbonate polymorph selectivity. Specifically, we combined n16N (a 30 amino acid peptide from the Japanese pearl oyster Pinctada fucata) and its sequence variants, n16Ns (randomly scrambled) and n16NN (global Asp → Asn, Glu → Gln substitution), with different forms of chitin (α and β). We found that the combination of n16N adsorbed onto β-chitin leads to the formation of aragonite in vitro as well as demonstrated chitin binding ability. Negative controls, including sequence modified versions of n16N (n16Ns and n16NN), exhibit variation in β-chitin binding and the ability to nucleate aragonite. The peptide + α-chitin combination exhibits very little chitin binding and nucleates exclusively calcite with minor morphological effects. The n16N and n16Ns peptides used in this study are considered intrinsically disordered and have previously been shown to interact with calcium carbonate. We propose that the intrinsically disordered structure of n16N also allows the peptide to interact with the substrate creating a new organic matrix interface. The cooperation between the peptide and substrate may explain the polymorph specificity among these samples.
Recent developments in quantum materials hold promise for revolutionizing energy and information ... more Recent developments in quantum materials hold promise for revolutionizing energy and information technologies. The use of soft matter self-assembly, for example, by employing block copolymers (BCPs) as structure directing or templating agents, offers facile pathways toward quantum metamaterials with highly tunable mesostructures via scalable solution processing. Here, we report the preparation of patternable mesoporous niobium carbonitride-type thin film superconductors through spin-coating of a hybrid solution containing an amphiphilic BCP swollen by niobia sol precursors and subsequent thermal processing in combination with photolithography. Spin-coated as-made BCP-niobia hybrid thin films on silicon substrates after optional photolithographic definition are heated in air to produce a porous oxide, and subsequently converted in a multistep process to carbonitrides via treatment with high temperatures in reactive gases including ammonia. Grazing incidence small-angle X-ray scattering suggests the presence of ordered mesostructures in as-made BCP-niobia films without further annealing, consistent with a distorted alternating gyroid morphology that is retained upon thermal treatments. Wide-angle X-ray scattering confirms the synthesis of phase-pure niobium carbonitride nanocrystals with rock-salt lattices within the mesoscale networks. Electrical transport measurements of unpatterned thin films show initial exponential rise in resistivity characteristic of thermal activation in granular systems down to 12.8 K, at which point resistivity drops to zero into a superconducting state. Magnetoresistance measurements determine the superconducting upper critical field to be over 16 T, demonstrating material quality on par with niobium carbonitrides obtained from traditional solid-state synthesis methods. We discuss how such cost-effective and scalable solution-based quantum materials fabrication approaches may be integrated into existing microelectronics processing, promising the emergence of a technology with tremendous academic and industrial potential by combining the capabilities of soft matter self-assembly with quantum materials.
Uploads
Papers by Lara Estroff