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Chemically synthesized PEDOT (poly(3,4-ethylenedioxythiophene)) nanomaterials, with various nanostructured morphologies as well as different intrinsic electrical conductivities and crystallinities, were compared as electrocatalysts for Co(III) reduction in dye-sensitized solar cells (DSSCs). Electrochemical parameters, charge transfer resistance toward the electrode/electrolyte interface, catalytic activity for Co(III)-reduction, and diffusion of cobalt redox species greatly depend on the morphology, crystallinity, and intrinsic electrical conductivity of the chemically synthesized PEDOTs and optimization of the fabrication procedure for counter electrodes. The PEDOT counter electrode, fabricated by spin coating a DMSO-dispersed PEDOT solution with an ordered 1D structure and nanosized fibers averaging 70 nm in diameter and an electrical conductivity of â¼16 S cm-1, exhibits the lowest charge transfer resistance, highest diffusion for a cobalt redox mediator and superior electrocatalytic performance compared to a traditional Pt-counter electrode. The photovoltaic performance of the DSSC using chemically synthesized PEDOT exceeds that of a Pt-electrode device because of the enhanced current density, which is directly related to the superior electrocatalytic ability of PEDOT for Co(III)-reduction. This simple spin-coated counter electrode prepared using cheap and scalable chemically synthesized PEDOT can be a potential alternative to the expensive Pt-counter electrode for cobalt and other redox electrolytes in DSSCs and various flexible electronic devices.
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ConspectusRecent years have witnessed significant interest in two-dimensional metal-organic frameworks (MOFs) due to their unique properties and promising applications across various fields. These materials offer distinct advantages, including high porosity and excellent charge transport properties. Their tunability allows precise control over various factors, including the electronic structure adjustments and local reactivity modulation, facilitating a wide range of properties and applications, such as material sensing and spin dynamics control. Moreover, the precise crystal structure of 2D MOFs supports rational design and mechanism studies, providing insights into their potential applications and enhancing their utility in various scientific and technological endeavors.To fully unveil the latent capabilities of 2D MOFs and advance their applications across diverse fields, thin film synthesis is crucial. Thin films provide a platform for investigating the intrinsic electrical properties of 2D MOFs with anisotropic structures, enabling the exploration of their unique characteristics comprehensively. Additionally, thin films offer the advantage of minimizing interference at contacts and junctions, thereby enhancing the performance of 2D MOFs for various applications. Furthermore, the properties of thin films can vary with thickness, presenting an opportunity to tailor their characteristics based on specific requirements.In this Account, we present an overview of our research focusing on the synthesis of 2D conductive MOF thin films encompassing two primary methods: chemical vapor deposition and solution processing. The chemical vapor deposition method allows for one-step, all-vapor-phase processes resulting in MOFs with edge-on orientation, controllable film thicknesses ranging from 55 to 662.7 nm, and smooth, homogeneous surfaces. On the other hand, solution-processing introduces a novel MOF, Cu3(HHTATP)2, by reducing interlayer interactions through the addition of pendent Brønsted bases on a ligand, enabling spin coating for thin film synthesis. This method yields a concentrated 2D MOF solution, enabling spin coating for thin film synthesis, where reversible electrical conductivity changes occur through doping with an acid and dedoping with a base. Additionally, we discuss various other synthesis methods, such as interfacial synthesis, layer-by-layer assembly, and microfluidic-assisted synthesis, offering versatile approaches for fabricating large-area thin films with tailored properties. Finally, we address ongoing challenges and potential strategies for further advancement in 2D conductive MOF thin film synthesis. We hope that this Account provides insights for selecting synthesis methods tailored to specific purposes, contributes to the development of varied synthesis techniques, and facilitates the exploration of diverse applications, unlocking the full potential of 2D conductive MOFs for next-generation technologies.
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Metal-organic frameworks (MOFs) are crystalline extended structures featuring permanent porosity, assembled from metal ions and organic ligands, often synthesized by the solvothermal method (50-260 °C, 12-72 h). Here, an alternative synthetic approach-solvent-induced structural rearrangement in ultrasound-assisted synthesis is presented. Six representative Zn-based MOFs, each composed of distinct secondary building units, are synthesized within 2-180 min consuming less solvent (>0.03 m) at room temperature. It is observed that ultrasonication induces the construction of a coordination network, and subsequent solvent exchange triggers structural rearrangement to yield MOFs of high crystallinity and porosity. Furthermore, the scalability of this method is demonstrated through the bulk synthesis of MOF-5, MOF-74, ZIF-8, and MFU-4l within 90 min. The initiation of nucleation through ultrasound and the subsequent transformation induced by solvent exchange offer an alternative method for efficiently synthesizing MOFs in bulk, potentially broadening their range of applications.
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The development of conductive metal-organic frameworks (MOFs) presents a unique challenge in materials chemistry because it is unclear how to dope them. Here, we demonstrate that the inclusion of pendant amines on hexahydroxytriphenylene linkages results in two-dimensional (2D) polycrystalline frameworks Cu3(HHTATP)2, isostructural to its Cu3(HHTP)2 parent, and exhibits the highest electrical conductivity of 1.21 S/cm among 2D MOFs featuring CuO4 metal nodes. Moreover, the bulk material can be treated with acid, resulting in a protonation-dependent increase in the conductivity. By spin-coating the acidic solution, we fabricated large-area thin films and collectively demonstrated an intuitive route to solution-processable, dopable, conductive MOFs.
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The electrochemical conversion of small molecules, such as CO2 , O2 , and H2 O, has received significant attention as a potential engine for sustainable life. Metal-organic frameworks (MOFs) are a promising class of electrocatalytic materials for such processes. An attractive aspect of utilizing this class of materials as electrocatalysts is that well-known molecular active sites can be introduced to well-defined crystalline heterogeneous catalytic systems with high tunability. This review offers strategic insights into recent studies on MOF-based electrocatalysts by discussing the notable active sites that have been utilized in both homogeneous and heterogeneous catalysts, while highlighting instances where such active sites have been introduced into MOFs. In addition, material design principles enabling the integration of electrochemically active components with the MOF platform are outlined. Viewpoints on the viability of MOFs as an alternative to currently used electrocatalysts are also discussed. Finally, the future direction of MOF-based electrocatalysis research is established.
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We demonstrated the synthesis of a conductive two-dimensional metal-organic framework (MOF) thin film by single-step all-vapor-phase chemical vapor deposition (CVD). The synthesized large-area thin film of Cu3(C6O6)2 has an edge-on-orientation with high crystallinity. Cu3(C6O6)2 thin film-based microdevices were fabricated by e-beam lithography and had an electrical conductivity of 92.95 S/cm. Synthesis of conductive MOF thin films by the all-vapor-phase CVD will enable fundamental studies of physical properties and may help to accomplish practical applications of conductive MOFs.
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Imprinted genes - critical for growth, metabolism, and neuronal function - are expressed from one parental allele. Parent-of-origin-dependent CpG methylation regulates this expression at imprint control regions (ICRs). Since ICRs are established before tissue specification, these methylation marks are similar across cell types. Thus, they are attractive for investigating the developmental origins of adult diseases using accessible tissues, but remain unknown. We determined genome-wide candidate ICRs in humans by performing whole-genome bisulphite sequencing (WGBS) of DNA derived from the three germ layers and from gametes. We identified 1,488 hemi-methylated candidate ICRs, including 19 of 25 previously characterized ICRs (https://humanicr.org/). Gamete methylation approached 0% or 100% in 332 ICRs (178 paternally and 154 maternally methylated), supporting parent-of-origin-specific methylation, and 65% were in well-described CTCF-binding or DNaseI hypersensitive regions. This draft of the human imprintome will allow for the systematic determination of the role of early-acquired imprinting dysregulation in the pathogenesis of human diseases and developmental and behavioural disorders.
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Metilación de ADN , Impresión Genómica , Adulto , Humanos , Mapeo Cromosómico , Alelos , GenómicaRESUMEN
Although examples of colloidal crystal analogues to metal alloys have been reported, general routes for preparing 3D analogues to random substitutional alloys do not exist. Here, we use the programmability of DNA (length and sequence) to match nanoparticle component sizes, define parent lattice symmetry and substitutional order, and achieve faceted crystal habits. We synthesized substitutional alloy colloidal crystals with either ordered or random arrangements of two components (Au and Fe3O4 nanoparticles) within an otherwise identical parent lattice and crystal habit, confirmed via scanning electron microscopy and small-angle X-ray scattering. Energy dispersive X-ray spectroscopy reveals information regarding composition and local order, while the magnetic properties of Fe3O4 nanoparticles can direct different structural outcomes for different alloys in an applied magnetic field. This work constitutes a platform for independently defining substitution within multicomponent colloidal crystals, a capability that will expand the scope of functional materials that can be realized through programmable assembly.
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Coloides , Nanopartículas , Aleaciones , Coloides/química , Cristalización , ADN/química , Nanopartículas/químicaRESUMEN
In a magnetic field, cubic Fe3 O4 nanoparticles exhibit assembly behavior that is a consequence of a competition between magnetic dipole-dipole and ligand interactions. In most cases, the interactions between short hydrophobic ligands dominate and dictate assembly outcome. To better tune the face-to-face interactions, cubic Fe3 O4 nanoparticles were functionalized with DNA. Their assembly behaviors were investigated both with and without an applied magnetic field. Upon application of a field, the tilted orientation of cubes, enabled by the flexible DNA ligand shell, led to an unexpected crystallographic alignment of the entire superlattice, as opposed to just the individual particles, along the field direction as revealed by small and wide-angle X-ray scattering. This observation is dependent upon DNA length and sequence and cube dimensions. Taken together, these studies show how combining physical and chemical control can expand the possibilities of crystal engineering with DNA.
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BACKGROUND: Although maternal systemic inflammation is hypothesized to link maternal pre-pregnancy obesity to offspring metabolic dysfunction, patient empirical data are limited. OBJECTIVES: In this study, we hypothesized that pre-pregnancy obesity alters systemic chemo/cytokines concentrations in pregnancy, and this alteration contributes to obesity in children. METHODS: In a multi-ethnic cohort of 361 mother-child pairs, we measured prenatal concentrations of plasma TNF-α, IL-6, IL-8, IL-1ß, IL-4, IFN-γ, IL-12 p70 subunit, and IL-17A using a multiplex ELISA and examined associations of pre-pregnancy obesity on maternal chemo/cytokine levels, and associations of these cytokine levels with offspring body mass index z score (BMI-z) at age 2-6 years using linear regression. RESULTS: After adjusting for maternal smoking, ethnicity, age, and education, pre-pregnancy obesity was associated with increased concentrations of TNF-α (P = .026) and IFN-γ (P = .06). While we found no evidence for associations between TNF-α concentrations and offspring BMI-z, increased IFN-γ concentrations were associated with decreased BMI-z (P = .0002), primarily in Whites (P = .0011). In addition, increased maternal IL-17A concentrations were associated with increased BMI-z in offspring (P = .0005) with stronger associations in African Americans (P = .0042) than Whites (P = .24). CONCLUSIONS: Data from this study are consistent with maternal obesity-related inflammation during pregnancy, increasing the risk of childhood obesity in an ethnic-specific manner.
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Citocinas/sangre , Obesidad Materna , Obesidad Infantil , Negro o Afroamericano , Índice de Masa Corporal , Niño , Preescolar , Estudios de Cohortes , Femenino , Humanos , Obesidad Materna/epidemiología , Obesidad Infantil/epidemiología , Embarazo , Población BlancaRESUMEN
Colloidal crystal engineering with nucleic acid-modified nanoparticles is a powerful way for preparing 3D superlattices, which may be useful in many areas, including catalysis, sensing, and photonics. To date, the building blocks studied have been primarily based upon metals, metal oxides, chalcogenide semiconductors, and proteins. Here, we show that metal-organic framework nanoparticles (MOF NPs) densely functionalized with oligonucleotides can be programmed to crystallize into a diverse set of superlattices with well-defined crystal symmetries and compositions. Electron microscopy and small-angle X-ray scattering characterization confirm the formation of single-component MOF superlattices, binary MOF-Au single crystals, and two-dimensional MOF nanorod assemblies. Importantly, DNA-modified porphyrinic MOF nanorods (PCN-222) were assembled into 2D superlattices and found to be catalytically active for the photooxidation of 2-chloroethyl ethyl sulfide (CEES, a chemical warfare simulant of mustard gas). Taken together, these new materials and methods provide access to colloidal crystals that incorporate particles with the well-established designer properties of MOFs and, therefore, increase the scope of possibilities for colloidal crystal engineering with DNA.
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Coloides/química , ADN/química , Estructuras Metalorgánicas/química , Nanopartículas/química , Cristalización , ADN/genética , Ingeniería/métodos , Microscopía Electrónica de Transmisión de Rastreo/métodos , Nanopartículas/ultraestructura , Nanotubos/química , Nanotubos/ultraestructura , Tamaño de la Partícula , Dispersión del Ángulo Pequeño , Plata/química , Difracción de Rayos XRESUMEN
The extension of reticular chemistry concepts to electrically conductive three-dimensional metal-organic frameworks (MOFs) has been challenging, particularly for cases in which strong interactions between electroactive linkers create the charge transport pathways. Here, we report the successful replacement of tetrathiafulvalene (TTF) with a nickel glyoximate core in a family of isostructural conductive MOFs with Mn2+ , Zn2+ , and Cd2+ . Different coordination environments of the framework metals lead to variations in the linker stacking geometries and optical properties. Single-crystal conductivity data are consistent with charge transport along the linker stacking direction, with conductivity values only slightly lower than those reported for the analogous TTF materials. These results serve as a case study demonstrating how reticular chemistry design principles can be extended to conductive frameworks with significant intermolecular contacts.
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Under an applied magnetic field, superparamagnetic Fe3 O4 nanoparticles with complementary DNA strands assemble into crystalline, pseudo-1D elongated superlattice structures. The assembly process is driven through a combination of DNA hybridization and particle dipolar coupling, a property dependent on particle composition, size, and interparticle distance. The DNA controls interparticle distance and crystal symmetry, while the magnetic field leads to anisotropic crystal growth. Increasing the dipole interaction between particles by increasing particle size or external field strength leads to a preference for a particular crystal morphology (e.g., rhombic dodecahedra, stacked clusters, and smooth rods). Molecular dynamics simulations show that an understanding of both DNA hybridization energetic and magnetic interactions is required to predict the resulting crystal morphology. Taken together, the data show that applied magnetic fields with magnetic nanoparticles can be deliberately used to access nanostructures beyond what is possible with DNA hybridization alone.
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Currently, there is considerable interest in developing advanced rechargeable batteries that boast efficient distribution of electricity and economic feasibility for use in large-scale energy storage systems. Rechargeable aqueous zinc batteries are promising alternatives to lithium-ion batteries in terms of rate performance, cost, and safety. In this investigation, we employ Cu3(HHTP)2, a two-dimensional (2D) conductive metal-organic framework (MOF) with large one-dimensional channels, as a zinc battery cathode. Owing to its unique structure, hydrated Zn2+ ions which are inserted directly into the host structure, Cu3(HHTP)2, allow high diffusion rate and low interfacial resistance which enable the Cu3(HHTP)2 cathode to follow the intercalation pseudocapacitance mechanism. Cu3(HHTP)2 exhibits a high reversible capacity of 228 mAh g-1 at 50 mA g-1. At a high current density of 4000 mA g-1 (~18 C), 75.0% of the initial capacity is maintained after 500 cycles. These results provide key insights into high-performance, 2D conductive MOF designs for battery electrodes.
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Cadmium (Cd) is a ubiquitous environmental pollutant associated with a wide range of health outcomes including cancer. However, obscure exposure sources often hinder prevention efforts. Further, although epigenetic mechanisms are suspected to link these associations, gene sequence regions targeted by Cd are unclear. Aberrant methylation of a differentially methylated region (DMR) on the MEG3 gene that regulates the expression of a cluster of genes including MEG3, DLK1, MEG8, MEG9 and DIO3 has been associated with multiple cancers. In 287 infant-mother pairs, we used a combination of linear regression and the Getis-Ord Gi* statistic to determine if maternal blood Cd concentrations were associated with offspring CpG methylation of the sequence region regulating a cluster of imprinted genes including MEG3. Correlations were used to examine potential sources and routes. We observed a significant geographic co-clustering of elevated prenatal Cd levels and MEG3 DMR hypermethylation in cord blood (P = 0.01), and these findings were substantiated in our statistical models (ß = 1.70, se = 0.80, P = 0.03). These associations were strongest in those born to African American women (ß = 3.52, se = 1.32, P = 0.01) compared with those born to White women (ß = 1.24, se = 2.11, P = 0.56) or Hispanic women (ß = 1.18, se = 1.24, P = 0.34). Consistent with Cd bioaccumulation during the life course, blood Cd levels increased with age (ß = 0.015 µg/dl/year, P = 0.003), and Cd concentrations were significantly correlated between blood and urine (ρ > 0.47, P < 0.01), but not hand wipe, soil or house dust concentrations (P > 0.05). Together, these data support that prenatal Cd exposure is associated with aberrant methylation of the imprint regulatory element for the MEG3 gene cluster at birth. However, neither house-dust nor water are likely exposure sources, and ingestion via contaminated hands is also unlikely to be a significant exposure route in this population. Larger studies are required to identify routes and sources of exposure.
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Craniosynostosis is the premature fusion of the sutures of the calvaria and is principally designated as being either syndromic (demonstrating characteristic extracranial malformations) or non-syndromic. While many forms of syndromic craniosynostosis are known to be caused by specific mutations, the genetic etiology of non-syndromic, single-suture craniosynostosis (SSC) is poorly understood. Based on the low recurrence rate (4-7%) and the fact that recurrent mutations have not been identified for most cases of SSC, we propose that some cases of isolated, single suture craniosynostosis may be polygenic. Previous work in our lab identified a disproportionately high number of rare and novel gain-of-function IGF1R variants in patients with SSC as compared to controls. Building upon this result, we used expression array data from calvarial osteoblasts isolated from infants with and without SSC to ascertain correlations between high IGF1 expression and expression of other osteogenic genes of interest. We identified a positive correlation between increased expression of IGF1 and RUNX2, a gene known to cause SSC with increased gene dosage. Subsequent phosphorylation assays revealed that osteoblast cell lines from cases with high IGF1 expression demonstrated inhibition of GSK3ß, a serine/threonine kinase known to inhibit RUNX2, thus activating osteogenesis through the IRS1-mediated Akt pathway. With these findings, we have utilized established mouse strains to examine a novel model of polygenic inheritance (a phenotype influenced by more than one gene) of SSC. Compound heterozygous mice with selective disinhibition of RUNX2 and either overexpression of IGF1 or loss of function of GSK3ß demonstrated an increase in the frequency and severity of synostosis as compared to mice with the RUNX2 disinhibition alone. These polygenic mouse models reinforce, in-vivo, that the combination of activation of the IGF1 pathway and disinhibition of the RUNX2 pathway leads to an increased risk of developing craniosynostosis and serves as a model of human SSC.
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Subunidad alfa 1 del Factor de Unión al Sitio Principal/genética , Craneosinostosis/genética , Glucógeno Sintasa Quinasa 3 beta/genética , Factor I del Crecimiento Similar a la Insulina/genética , Animales , Diferenciación Celular/genética , Craneosinostosis/patología , Modelos Animales de Enfermedad , Mutación con Ganancia de Función/genética , Regulación del Desarrollo de la Expresión Génica/genética , Humanos , Ratones , Osteoblastos/metabolismo , Osteoblastos/patología , Osteogénesis/genética , Receptor IGF Tipo 1/genética , Cráneo/metabolismo , Cráneo/patologíaRESUMEN
Pre-pregnancy obesity is an established risk factor for adverse sex-specific cardiometabolic health in offspring. Epigenetic alterations, such as in DNA methylation (DNAm), are a hypothesized link; however, sex-specific epigenomic targets remain unclear. Leveraging data from the Newborn Epigenetics Study (NEST) cohort, linear regression models were used to identify CpG sites in cord blood leukocytes associated with pre-pregnancy obesity in 187 mother-female and 173 mother-male offsprings. DNAm in cord blood was measured using the Illumina HumanMethylation450k BeadChip. Replication analysis was conducted among the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort. Associations between pre-pregnancy obesity-associated CpG sites and offspring BMI z-score (BMIz) and blood pressure (BP) percentiles at 4-5-years of age were also examined. Maternal pre-pregnacy obesity was associated with 876 CpGs in female and 293 CpGs in male offspring (false discovery rate <5%). Among female offspring, 57 CpG sites, including the top 18, mapped to the TAPBP gene (range of effect estimates: -0.83% decrease to 4.02% increase in methylation). CpG methylation differences in the TAPBP gene were also observed among males (range of effect estimates: -0.30% decrease to 2.59% increase in methylation). While technically validated, none of the TAPBP CpG sites were replicated in ALSPAC. In NEST, methylation differences at CpG sites of the TAPBP gene were associated with BMI z-score (cg23922433 and cg17621507) and systolic BP percentile (cg06230948) in female and systolic (cg06230948) and diastolic (cg03780271) BP percentile in male offspring. Together, these findings suggest sex-specific effects, which, if causal, may explain observed sex-specific effects of maternal obesity.
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Enfermedades Cardiovasculares/genética , Metilación de ADN , Epigénesis Genética , Síndrome Metabólico/genética , Obesidad/genética , Adulto , Presión Sanguínea , Enfermedades Cardiovasculares/epidemiología , Niño , Preescolar , Epigenómica , Femenino , Estudio de Asociación del Genoma Completo , Humanos , Recién Nacido/sangre , Recién Nacido/crecimiento & desarrollo , Masculino , Proteínas de Transporte de Membrana/genética , Síndrome Metabólico/epidemiología , Obesidad/epidemiologíaRESUMEN
A Cu-azolate metal-organic framework (MOF) uptakes stoichiometric loadings of Groups 1 and 2 metal halides, demonstrating efficient reversible release and reincorporation of immobilized anions within the framework. Ion-pairing interactions lead to anion-dependent Li+ and Mg2+ transport in Cu4(ttpm)2·0.6CuCl2, whose high surface area affords a high density of uniformly distributed mobile metal cations and halide binding sites. The ability to systematically tune the ionic conductivity yields a solid electrolyte with a Mg2+ ion conductivity rivaling the best materials reported to date. This MOF is one of the first in a promising class of frameworks that introduces the opportunity to control the identity, geometry, and distribution of the cation hopping sites, offering a versatile template for application-directed design of solid electrolytes.
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A postsynthetic method for stabilizing colloidal crystals programmed from DNA is developed. The method relies on Ag+ ions to stabilize the particle-connecting DNA duplexes within the crystal lattice, essentially transforming them from loosely bound structures to ones with very strong interparticle links. Such crystals do not dissociate as a function of temperature like normal DNA or DNA-interconnected superlattices, and they can be moved from water to organic media or the solid state, and stay intact. The Ag+ -stabilization of the DNA bonds is accompanied by a nondestructive ≈25% contraction of the lattice, and both the stabilization and contraction are reversible with the chemical extraction of the Ag+ ions, by AgCl precipitation with NaCl. This synthetic tool is important, since it allows scientists and engineers to study such crystals in environments that are incompatible with structures made by conventional DNA programmable methods and without the influence of a matrix such as silica.