Modification of MOF-5 Hydrostability for Peptide Absorption Studies

Metal-organic frameworks (MOFs) are an intriguing class of hybrid materials that consist of infinite crystalline lattices formed by metal ions bridged by organic linkers. Their porous interiors have highly variable properties, depending on the metal ions and linkers used. To date, MOFs have primarily been examined for uses such as gas separation and storage and catalysis, but recently researchers have described the adsorption of proteins and peptides, such as cytochrome C and a trypsin digest of bovine serum albumin, in MOF pores. The MOF pore provides a stable, ordered environment in which to isolate and characterize peptides. Our research thus far has suggested that MOF-5 readily adsorbs proteins and peptides, however most preparations of MOF-5 suffer from water sensitivity. This is problematic because water or water-based solutions are the most relevant solvent for disease-relevant peptides. We therefore have explored reported methods to improve the hydrostability of MOF-5 through several doping techniques as well as annealing processes. We then studied the adsorption behavior of MOF-5 derivatives toward a number of peptides, the results of which are presented here. Through these studies we strive to understand which differences brought about by structural changes may better facilitate peptide adsorption.https://digitalcommons.morris.umn.edu/urs_2015/1006/thumbnail.jp

Triammonium hexa­hydroxidoocta­deca­oxidohexa­molybdogallate(III) hepta­hydrate

The title compound, (NH4)3[GaMo6(OH)6O18]·7H2O, contains two centrosymmetric GaMo6 B-type Anderson cluster units consisting of central GaO6 octa­hedra surrounded by a hexa­gonal assembly of MoO6 edge-sharing octa­hedra. Like other B-type Anderson clusters, where the central Mo atom is substituted with a di- or trivalent metal ion, the central six μ3-oxido bridges are protonated. The average Ga—O bond length is 1.97 (1) Å, whereas the average Mo—O distances are 2.29 (2), 1.94 (1) and 1.709 (5) Å, respectively, for Mo—(μ3-OH), Mo—(μ2-O) and Mo=O bonds. In the crystal structure, the Ga(μ3-OH)6Mo6O18 3− polyanionic clusters are surrounded by NH4 + cations and solvent water mol­ecules, forming an extended network of hydrogen bonds

Purified and synthetic Alzheimer's amyloid beta (Aβ) prions.

The aggregation and deposition of amyloid-β (Aβ) peptides are believed to be central events in the pathogenesis of Alzheimer's disease (AD). Inoculation of brain homogenates containing Aβ aggregates into susceptible transgenic mice accelerated Aβ deposition, suggesting that Aβ aggregates are capable of self-propagation and hence might be prions. Recently, we demonstrated that Aβ deposition can be monitored in live mice using bioluminescence imaging (BLI). Here, we use BLI to probe the ability of Aβ aggregates to self-propagate following inoculation into bigenic mice. We report compelling evidence that Aβ aggregates are prions by demonstrating widespread cerebral β-amyloidosis induced by inoculation of either purified Aβ aggregates derived from brain or aggregates composed of synthetic Aβ. Although synthetic Aβ aggregates were sufficient to induce Aβ deposition in vivo, they exhibited lower specific biological activity compared with brain-derived Aβ aggregates. Our results create an experimental paradigm that should lead to identification of self-propagating Aβ conformations, which could represent novel targets for interrupting the spread of Aβ deposition in AD patients

Transmetalation of Aqueous Inorganic Clusters: A Useful Route to the Synthesis of Heterometallic Aluminum and Indium HydroxoAquo Clusters

[Al_<i>x</i>In_<i>y</i>(μ₃-OH)₆(μ-OH)₁₈(H₂O)₂₄]­(NO₃)₁₅ hydroxy–aquo clusters (<b>Al_<i>x</i>In_{13–<i>x</i>}</b>) are synthesized through the evaporation of stoichiometrically varied solutions of <b>Al₁₃</b> and In­(NO₃)₃ using a transmetalation reaction. Several spectroscopic techniques (¹H NMR, ¹H-diffusion ordered spectroscopy, dynamic light scattering, and Raman) are used to compare <b>Al_<i>x</i>In_{13–<i>x</i>}</b> to its <b>Al₁₃</b> counterpart. A thin film of aluminum indium oxide was prepared from an <b>Al₇In₆</b> cluster ink, showing its utility as a precursor for materials

Synthesis and Solid-State Structural Characterization of a Series of Aqueous Heterometallic Tridecameric Group 13 Clusters

The synthesis and solid-state characterization of a complete series of new heterometallic aqueous nanoscale Ga/In tridecameric clusters is presented. These hydroxo–aquo species significantly expand the library of discrete, aqueous group 13 clusters. This report details the synthetic and structural characterization of these compounds, which are of interest as precursors (inks) for thin-film oxides with materials applications. Single-crystal X-ray diffraction (XRD) data show that the hexagonal unit cell lengths of these clusters fall within the range <i>a</i>, <i>b</i> = 20.134–20.694 Å and <i>c</i> = 18.266–18.490 Å. The unit cell volumes become larger (<i>V</i> = 6494–6774 A³) with increasing indium occupancy. The compositions of several Ga/In clusters determined by electron probe microanalysis and elemental analysis are in agreement with single-crystal XRD results. The transformation of the Ga/In clusters to metal oxides at high temperature was studied using variable-temperature powder XRD. With heating, the Ga/In clusters with lower indium occupancies convert to the β-Ga₂O₃ structure. For clusters with higher indium occupancies, phase separation occurs, and an In₂O₃ bixbyite-type structure forms. The stoichiometric control at the molecular level demonstrated herein is important in designing functional thin films of metal oxides due to the tunable nature of these heterometallic solution precursors. In addition, information about the solid-state structure of these compounds leads to a fundamental understanding of the materials properties of these clusters for future thin-film and precursor development