Adsorption of Amyloid Beta Peptide by Metal-Organic Frameworks.

Metal-organic frameworks (MOFs) are capable of adsorbing a wide range of molecules. In addition to the more commonly investigated small molecules, researchers have demonstrated that MOFs adsorb much larger molecules, such as proteins and peptides. We have investigated whether MOFs are capable of adsorbing amyloid beta peptide. Amyloid beta plays a pivotal role in the progression of Alzheimer's disease because individual copies of the peptides can aggregate, forming neurotoxic oligomers and the amyloid plaques found in brains of Alzheimer's patients. After synthesizing a number of commonly studied MOFs, their adsorption capabilities were tested. We found that the MOFs tested readily adsorbed small amounts of amyloid beta (as determined by gel electrophoresis). It was determined that in most cases, adsorption occurs rapidly, with complete adsorption within minutes of incubation. Overall adsorption capacity was found to vary between different MOFs as well. Once adsorbed, amyloid beta peptide can subsequently be eluted from some MOFs by treatment with acetonitrile/water solutions, though retention strength varied between different MOFs. In some cases, MOFs that showed complete adsorption also saw high levels of peptide elution, but others showed little to no elution of the peptide. Together these data can help us begin to understand the interactions between amyloid beta and MOFs.

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 a, b = 20.134-20.694 Å and c = 18.266-18.490 Å. The unit cell volumes become larger (V = 6494-6774 A(3)) 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 ß-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.

Transmetalation of aqueous inorganic clusters: a useful route to the synthesis of heterometallic aluminum and indium hydroxo-aquo clusters.

[AlxIny(µ3-OH)6(µ-OH)18(H2O)24](NO3)15 hydroxy-aquo clusters (AlxIn13-x) are synthesized through the evaporation of stoichiometrically varied solutions of Al13 and In(NO3)3 using a transmetalation reaction. Several spectroscopic techniques ((1)H NMR, (1)H-diffusion ordered spectroscopy, dynamic light scattering, and Raman) are used to compare AlxIn13-x to its Al13 counterpart. A thin film of aluminum indium oxide was prepared from an Al7In6 cluster ink, showing its utility as a precursor for materials.

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

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

Oligomeric Group 13 hydroxide compounds--a rare but varied class of molecules.

This tutorial review surveys the wide variety of oligomeric hydroxide structures formed from aluminum, gallium, and indium. Both inorganic and ligand-supported structures are reviewed, providing a leading introduction to this research area. In addition to homometallic clusters comprising only one metal type, a series of heterometallic structures are described. This review highlights the synthesis and characterization of these nanoscale cluster compounds that have implications in a variety of fields, including catalysis, mineral mimicry, environmental chemistry, geochemistry, materials science, and semiconductors.

Synthesis and crystallization of infinite indium and gallium acetate 1D chain structures and concomitant ethyl acetate hydrolysis.

Two unusual complexes of formula [M(mu-OH)(mu-O(2)CCH(3))(2)](n) [M = In (1) or Ga (2)] were crystallized by diffusion of ethyl acetate into methanolic solutions of the M(NO(3))(3) salts and N-nitrosopyrrolidine. They represent the first examples of such simple group 13 containing structures comprising 1D chains, and their formation results from the surprising hydrolysis of ethyl acetate to provide the bridging acetate ligands.

Facile synthesis of the tridecameric Al13 nanocluster Al13(mu3-OH)6(mu2-OH)18(H2O)24(NO3)15.

Treatment of aluminum nitrate with an organic nitroso-containing compound yields the "flat", tridecameric nanocluster Al 13(mu 3-OH) 6(mu 2-OH) 18(H 2O) 24(NO 3) 15 ( Al 13 ) in good yield on a preparative scale under ambient conditions. Synthetic procedures yielding two different single-crystal forms of the Al 13 cation with two varying counterion compositions are described.

Triammonium hexa-hydroxidoocta-deca-oxidohexa-molybdogallate(III) hepta-hydrate.

The title compound, (NH(4))(3)[GaMo(6)(OH)(6)O(18)]·7H(2)O, contains two centrosymmetric GaMo(6) B-type Anderson cluster units consisting of central GaO(6) octa-hedra surrounded by a hexa-gonal assembly of MoO(6) edge-sharing octa-hedra. Like other B-type Anderson clusters, where the central Mo atom is substituted with a di- or trivalent metal ion, the central six µ(3)-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-(µ(3)-OH), Mo-(µ(2)-O) and Mo=O bonds. In the crystal structure, the Ga(µ(3)-OH)(6)Mo(6)O(18) (3-) polyanionic clusters are surrounded by NH(4) (+) cations and solvent water mol-ecules, forming an extended network of hydrogen bonds.