Using a novel layer-by-layer approach we have deposited metal−organic open frameworks (MOFs) based on benzenetricarboxylic acid ligands and Cu(II)-ions on a COOH-terminated organic surface. The deposited layers were characterized using a number of surface analysis techniques. XRD measurements show that the MOFs deposited using this method have the same bulk structure of HKUST-1.
We report the synthesis of layered [Zn(2)(bdc)(2)(H(2)O)(2)] and [Cu(2)(bdc)(2)(H(2)O)(2)] (bdc = benzdicarboxylate) metal-organic frameworks (MOF) carried out using the liquid-phase epitaxy approach employing self-assembled monolayer (SAM) modified Au-substrates. We obtain Cu and Zn MOF-2 structures, which have not yet been obtained using conventional, solvothermal synthesis methods. The 2D Cu(2+) dimer paddle wheel planes characteristic for the MOF are found to be strictly planar, with the planes oriented perpendicular to the substrate. Intercalation of an organic dye, DXP, leads to a reversible tilting of the planes, demonstrating the huge potential of these surface-anchored MOFs for the intercalation of large, planar molecules.
The influence of pressure on the structure and protein-protein interaction potential of dense protein solutions was studied and analyzed using small-angle x-ray scattering in combination with a liquid state theoretical approach. The structural as well as the interaction parameters of dense lysozyme solutions are affected by pressure in a nonlinear way. The structural properties of water lead to a modification of the protein-protein interactions below 4 kbar, which might have significant consequences for the stability of proteins in extreme natural environments.
Organosilane self-assembled monolayers (SAMs) are commonly used for modifying a wide range of substrates. Depending on the end group, highly hydrophobic or hydrophilic surfaces can be achieved. Silanization bases on the adsorption, self-assembly and covalent binding of silane molecules onto surfaces and results in a densely packed, SAM. Following wet chemical routines, the quality of the monolayer is often variable and, therefore, unsatisfactory. The process of self-assembly is not only affected by the chemicals involved and their purity but is also extremely sensitive to ambient parameters such as humidity or temperature and to contaminants. Here, a reliable and efficient wet-chemical recipe is presented for the preparation of ultra-smooth, highly ordered alkyl-terminated silane SAMs on Si wafers. The resulting surfaces are characterized by means of atomic force microscopy, X-ray reflectometry and contact angle measurements.
The islet amyloid polypeptide (IAPP) or amylin is a pancreatic hormone and crucially involved in the pathogenesis of type-II diabetes mellitus (T2DM). Aggregation and amyloid formation of IAPP is considered as the primary culprit for pancreatic beta-cell loss in T2DM patients. In this study, first X-ray reflectivity (XRR) measurements on IAPP at lipid interfaces have been carried out, providing a molecular level characterization of the first steps of the lipid-induced fibrillation process of IAPP, which is initiated by lipid-induced nucleation, oligomerization, followed by detachment of larger IAPP aggregate structures from the lipid membrane, and terminated by the formation of mature fibrils in the bulk solution. The adsorption process of IAPP at lipid interfaces in the absence and presence of negatively charged lipid has also been studied by complementary ATR-FTIR spectroscopic measurements. The morphological properties were followed by atomic force microscopy (AFM). Moreover, we show that the polyphenolic red wine compound resveratrol is able to inhibit IAPP aggregation also in the presence of aggregation-fostering negatively charged lipid interfaces, revealing its potential as a drug candidate for T2DM.
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