Alkali Metals Ion Exchange on Muscovite Mica

Osman, Maged A.; Moor, C. G.; Caseri, Walter; Suter, Ulrich W.

doi:10.1006/jcis.1998.5878

Cited by 48 publications

(50 citation statements)

References 22 publications

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“…The surface Li cations were exchanged against K + , which is a quite fast reaction. Although the platelets of the high surface area Li-mica collapse during this reaction and most of the surface area gained by delamination is lost, the CEC remains relatively high compared to that of natural mica and the surface of the resulting mica is also homoionic (30,33).…”

Section: Resultsmentioning

confidence: 96%

“…To ensure this result, the CEC of the high surface area Li-mica was measured by different methods, including the Cu(trien)SO 4 , and compared. The CEC of the high surface area Li-mica was measured by exchange with Na + , K + , Rb + , or Cs + , and gave a mean value of 435 µmol/g (33). The same sample gave a CEC value of 408 µmol/g on exchanging with NDP + (31), while the exchange with Cu(trien) 2+ showed a CEC of 210 µmol/g.…”

Section: Resultsmentioning

confidence: 99%

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Determination of the Cation-Exchange Capacity of Muscovite Mica

Osman¹,

Suter²

2000

Journal of Colloid and Interface Science

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Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

Determination of the Cation-Exchange Capacity of Muscovite Mica

Osman¹,

Suter²

2000

Journal of Colloid and Interface Science

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“…For example, the double-layered structures are predominant in 100-mM KCl, MgCl 2 , and MgSO 4 solutions, whereas a mixture of single-and double-layered structures is observed in 100 mM NaCl. This can be explained by differences in their ion-exchange capacity on mica, where Mg 2+ can adsorb onto mica with higher strength and lower mobility than K + and H 3 O + (36, 37), whereas Na + has lower binding affinity than K + on mica (38). Specifically, there is a cation order of Mg 2+ > K + > Na + in its enhancement for the multilayered formation with the increase of the salt concentration, following an exact reverse order of the Hofmeister series for cations.…”

Section: Resultsmentioning

confidence: 99%

Salts drive controllable multilayered upright assembly of amyloid-like peptides at mica/water interface

Dai

Kang

Huynh

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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Surface-assisted self-assembly of amyloid-like peptides has received considerable interest in both amyloidosis research and nanotechnology in recent years. Despite extensive studies, some controlling factors, such as salts, are still not well understood, even though it is known that some salts can promote peptide selfassemblies through the so-called "salting-out" effect. However, they are usually noncontrollable, disordered, amorphous aggregates. Here, we show via a combined experimental and theoretical approach that a conserved consensus peptide NH 2 -VGGAVVAGV-CONH 2 (GAV-9) (from representative amyloidogenic proteins) can self-assemble into highly ordered, multilayered nanofilaments, with surprising all-upright conformations, under high-salt concentrations. Our atomic force microscopy images also demonstrate that the vertical stacking of multiple layers is highly controllable by tuning the ionic strength, such as from 0 mM (monolayer) to 100 mM (mainly double layer), and to 250 mM MgCl 2 (double, triple, quadruple, and quintuple layers). Our atomistic molecular dynamics simulations then reveal that these individual layers have very different internal nanostructures, with parallel β-sheets in the first monolayer but antiparallel β-sheets in the subsequent upper layers due to their different microenvironment. Further studies show that the growth of multilayered, all-upright nanostructures is a common phenomenon for GAV-9 at the mica/water interface, under a variety of salt types and a wide range of salt concentrations.amyloid peptide | atomic force microscopy | salt effect | self-assembly on mica A better understanding of the self-assembly of highly ordered peptide nanostructures is critical because it not only helps to uncover the pathogenesis of various neurodegenerative diseases (1) but provides an attractive "bottom-up" nanotechnology for de novo nanodevice design (2) and fabrication (3). In addition to a series of factors (4-6) previously discovered to modulate peptide self-assembly, solid substrates have been found to drive this process directly acting as templates (7,8), controlling both assembly kinetics and morphology of amyloid peptide aggregates (8-11). These findings emphasize the importance of the substrate surface, whether it be a cellular membrane or an inorganic solid surface, on the assembly of various peptides, which is critical in many biological processes. It has been shown recently that fibrous nanostructures form a fundamental framework ubiquitous in normal cellular metabolism, including cell division and signaling, as well as in over 27 different human amyloid diseases and 9 in animals (12).Due to the complexity of cellular membranes and associated physiological conditions (13,14), hydrophilic mica and hydrophobic highly oriented pyrolytic graphite (HOPG) are the two commonly used model substrates for the investigation of surface effects (10,11,15). For example, it was found that amyloid-β (Aβ) peptide formed oligomeric protofibrillar aggregates on mica but only 1D nanofilaments on HOPG (...

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“…These observations may lead to the conclusion that poly͑acrylic acid͒ is not strongly cross-linked on the mica surface under the processing conditions used here 31 and dissolves away in the water solution, for which the cation exchange on the cleaved mica surface might also be responsible. 32,33 Nonetheless, it has been shown that the glass coverslips can be effectively coated with the polymer. This enabled us to proceed with the functionalization of the silica colloid probes with fibrinogen considering, at the same time, any compressibility effects of the swelled polymer layer.…”

Section: A Probe Modificationmentioning

confidence: 99%

Measurement of interaction forces between fibrinogen coated probes and mica surface with the atomic force microscope: The pH and ionic strength effect

Tsapikouni¹,

Allen²,

Missirlis³

2008

Biointerphases

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The study of protein-surface interactions is of great significance in the design of biomaterials and the evaluation of molecular processes in tissue engineering. The authors have used atomic force microscopy (AFM) to directly measure the force of attraction/adhesion of fibrinogen coated tips to mica surfaces and reveal the effect of the surrounding solution pH and ionic strength on this interaction. Silica colloid spheres were attached to the AFM cantilevers and, after plasma deposition of poly(acrylic acid), fibrinogen molecules were covalently bound on them with the help of the cross-linker 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) in the presence of N-hydroxysulfosuccinimide (sulfo-NHS(. The measurements suggest that fibrinogen adsorption is controlled by the screening of electrostatic repulsion as the salt concentration increases from 15 to 150 mM, whereas at higher ionic strength (500 mM) the hydration forces and the compact molecular conformation become crucial, restricting adsorption. The protein attraction to the surface increases at the isoelectric point of fibrinogen (pH 5.8), compared with the physiological pH. At pH 3.5, apart from fibrinogen attraction to the surface, evidence of fibrinogen conformational changes is observed, as the pH and the ionic strength are set back and forth, and these changes may account for fibrinogen aggregation in the protein solution at this pH.

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Alkali Metals Ion Exchange on Muscovite Mica

Cited by 48 publications

References 22 publications

Determination of the Cation-Exchange Capacity of Muscovite Mica

Determination of the Cation-Exchange Capacity of Muscovite Mica

Salts drive controllable multilayered upright assembly of amyloid-like peptides at mica/water interface

Measurement of interaction forces between fibrinogen coated probes and mica surface with the atomic force microscope: The pH and ionic strength effect

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