Boron Trifluoride Gas Adsorption in Metal-Organic Frameworks.

Coordinatively unsaturated metal-organic frameworks (MOFs) were studied for boron trifluoride (BF3) sorption. MOF-74-Mg, MOF-74-Mn, and MOF-74-Co show high initial uptake (below 6.7 × 10-3 bar) with negligible deliverable capacity. The BF3 isotherm of MOF-74-Cu exhibits gradual uptake up to 0.9 bar and has a deliverable gravimetric capacity that is more than 100% higher than activated carbon. Two other Cu2+ MOFs, MOF-505 and HKUST-1, have slightly lower deliverable capacities compared to MOF-74-Cu.

Phosphine Gas Adsorption in a Series of Metal-Organic Frameworks.

For the first time, phosphine adsorption has been evaluated in a series of metal-organic frameworks (MOFs). Open-metal coordination sites were found to significantly enhance the ability of MOFs to adsorb highly toxic phosphine gas, with the identity of the open-metal site also modulating the amount of gas adsorbed. The MOFs studied outperform activated carbon, a commonly used material to capture phosphine.

High-throughput differentiation of heparin from other glycosaminoglycans by pyrolysis mass spectrometry.

Sensors with high chemical specificity and enhanced sample throughput are vital to screening food products and medical devices for chemical or biochemical contaminants that may pose a threat to public health. For example, the rapid detection of oversulfated chondroitin sulfate (OSCS) in heparin could prevent reoccurrence of heparin adulteration that caused hundreds of severe adverse events including deaths worldwide in 2007-2008. Here, rapid pyrolysis is integrated with direct analysis in real time (DART) mass spectrometry to rapidly screen major glycosaminoglycans, including heparin, chondroitin sulfate A, dermatan sulfate, and OSCS. The results demonstrate that, compared to traditional liquid chromatography-based analyses, pyrolysis mass spectrometry achieved at least 250-fold higher sample throughput and was compatible with samples volume-limited to about 300 nL. Pyrolysis yielded an abundance of fragment ions (e.g., 150 different m/z species), many of which were specific to the parent compound. Using multivariate and statistical data analysis models, these data enabled facile differentiation of the glycosaminoglycans with high throughput. After method development was completed, authentically contaminated samples obtained during the heparin crisis by the FDA were analyzed in a blinded manner for OSCS contamination. The lower limit of differentiation and detection were 0.1% (w/w) OSCS in heparin and 100 ng/µL (20 ng) OSCS in water, respectively. For quantitative purposes the linear dynamic range spanned approximately 3 orders of magnitude. Moreover, this chemical readout was successfully employed to find clues in the manufacturing history of the heparin samples that can be used for surveillance purposes. The presented technology and data analysis protocols are anticipated to be readily adaptable to other chemical and biochemical agents and volume-limited samples.

Beyond fat grafting: what adipose tissue can teach us about the molecular mechanisms of human aging.

BACKGROUND: The concept of aging and the mechanisms responsible for soft tissue aging have become progressively more important as the world's population ages and demands a higher quality of life. Although molecular mechanisms of aging have been evaluated in model organisms, specific genomic, genetic, and epigenetic modifications that can be translated to normal human tissue aging have yet to be identified. We propose that adipose tissue is an excellent model with which to investigate molecular aging pathways. The goal of this study is to demonstrate that primary human adipose tissue can serve as a model of human aging, and further, can be used to detect differences in genomic transcriptional profiling between cell types in adipose tissue as well as between youthful and older age groups. METHODS: Subcutaneous adipose tissue was excised during cosmetic procedures from healthy patients. Adipocytes and stromal vascular fractions from the anterior abdomen were isolated from 3 young (26-39 years) and 3 old (52-64 years) patients and analyzed for genome-wide transcriptional differences between varying ages and cell types using the Affymetrix GeneChip Human Gene Chip 1.0ST. RESULTS: Genes specific to adipocytes were more highly expressed in adipocytes than in stromal vascular fractions, validating that adipose tissue should be examined in a cell-specific manner. An increase in overall gene expression was observed among patients in the older age group, consistent with senescence-related chromatin dysregulation. Principal components analysis revealed no clear delineation between age groups and a clear separation by cell type. Analysis of variance revealed cell type as the most significant variable in transcriptional differences, whereas age-related differences were a distant second. Gene Ontology categories of the most significantly modified genes included RNA splicing and mRNA metabolism, plasma membrane, and mitochondrial metabolism. CONCLUSIONS: Primary adipose tissue is an effective model for the study of the molecular mechanisms of human aging. Our findings are consistent with the hypothesis that epigenetic modifications play a more important role than transcriptional modifications in early human adipose tissue aging. Our future studies will examine the contribution of specific epigenetic markers to human adipose tissue aging and promise to advance approaches in regenerative medicine, and the prevention and treatment of aging.

Surviving Under Pressure: The Role of Solvent, Crystal Size, and Morphology During Pelletization of Metal-Organic Frameworks.

As metal-organic frameworks (MOFs) gain traction for applications, such as hydrogen storage, it is essential to form the as-synthesized powder materials into shaped bodies with high packing densities to maximize their volumetric performance. Mechanical compaction, which involves compressing the materials at high pressure, has been reported to yield high monolith density but often results in a significant loss in accessible porosity. Herein, we sought to systematically control (1) crystal size, (2) solvation, and (3) compacting pressure in the pelletization process to achieve high packing density without compromising the porosity that makes MOFs functional. It was determined that solvation is the most critical factor among the three factors examined. Solvation that exceeds the pore volume prevents the framework from collapsing, allowing for porosity to be maintained through pelletization. Higher pelletization pressure results in higher packing density, with extensive loss of porosity being observed at a higher pressure if the solvation is below the pore volume. Lastly, we observed that the morphology and size of the MOF particles result in variation in the highest achievable packing efficiency, but these numbers (75%) are still greater than many existing techniques used to form MOFs. We concluded that the application of pressure through pelletization is a suitable and widely applicable technique for forming high-density MOF-monoliths.