A careful examination of the adsorption step in the alternate layer-by-layer assembly of linear polyanion and polycation

Lvov, Yuri; Ariga, Katsuhiko; Onda, Mitsuhiko; Ichinose, Izumi; Kunitake, Toyoki

doi:10.1016/s0927-7757(98)00789-4

Cited by 238 publications

(209 citation statements)

References 27 publications

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“…[40][41][42][43] In all these studies the authors also included strong short-ranged attraction between all the monomers. This is thought to be an important prerequisite for the occurrence of charge 105 reversal and formation of multi-layers. 42 The simulations provide valuable information on the dynamic of adsorption but remain rather time consuming.…”

Section: Introductionmentioning

confidence: 99%

Mixed protein–polysaccharide interfacial layers: effect of polysaccharide charge distribution

2012

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The influence of the polysaccharide charge distribution on the structure, thickness, and charge reversal of the interfacial layers, formed by adsorbed positively charged protein and oppositely charged polysaccharide, has been investigated using lattice-based self-consistent field (SCF) approach. We compare the adsorption behaviour of a uniformly charged polysaccharide model with that consisting of a short and a long block carrying different charge densities. For homogeneously charged 10 polysaccharide we observe a resulting interfacial layer that is closer to a mixed protein + polysaccharide film, rather than a multi-layer. We also find that the maximum adsorption of polysaccharide occurs at an optimal value of its charge, above and below which the adsorbed amount decreases. In contrast, for heterogeneously charged chains, as their charge is increasingly located on the shorter block, a much thicker interfacial layer results. In such cases the weakly charged longer blocks extend well away from 15 the surface into the solution. The interfacial film begins to resemble a multilayer with a primary protein and a distinct secondary polysaccharide layer. When the weakly charged long blocks still have a sufficient amount of negative charge, we also observe a reversal of the sign of surface potential from positive to a negative value. Our SCF calculated values for the reversed surface potential are of the order of −25 mV, in good agreement with several experimental results involving -potential measurements on 20 particles covered with such protein + polysaccharide films.

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Section: Introductionmentioning

confidence: 99%

Mixed protein–polysaccharide interfacial layers: effect of polysaccharide charge distribution

2012

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“…9 The adsorption properties are dependent on many factors, such as pH and ionic strength of supporting electrolyte, 10 charge density of polyelectrolytes used, 11 solvent quality 12 and temperature. 13 The characterization methods are very versatile, from ex-situ detection such as ellipsometry, 14 atomic force microscopy, 14 quartz crystal microbalance 15 and X-ray reflectivity, 16 to in-situ measurements such as streaming potential method, 17 attenuated total reflection, 18 neutron reflectivity 16 and scanning angle reflectometry. 19 Recently, liquid-liquid interfaces coated with polyelectrolyte multilayers were studied utilizing conventional electrochemical methods such as AC voltammetry and cyclic voltammetry, and the multilayers exhibited a kinetic ion transfer hindrance.…”

mentioning

confidence: 99%

Kinetic Modulation of Pulsed Chronopotentiometric Polymeric Membrane Ion Sensors by Polyelectrolyte Multilayers

Shvarev

et al. 2007

Anal. Chem.

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Polymeric membrane ion selective electrodes are normally interrogated by zero current potentiometry, and their selectivity is understood to be primarily dependent on an extraction/ionexchange equilibrium between the aqueous sample and polymeric membrane. If concentration gradients in the contacting diffusion layers are insubstantial, the membrane response is thought to be rather independent of kinetic processes such as surface blocking effects. In this work, the surface of calcium-selective polymeric ion-selective electrodes is coated with polyelectrolyte multilayers as evidenced by zeta potential measurements, atomic force microscopy and electrochemical impedance spectroscopy. Indeed, such multilayers have no effect on their potentiometric response if the membranes are formulated in a traditional manner, containing a lipophilic ion-exchanger and a calcium-selective ionophore. However, drastic changes in the potential response are observed if the membranes are operated in a recently introduced kinetic mode using pulsed chronopotentiometry. The results suggest that the assembled nanostructured multilayers drastically alter the kinetics of ion transport to the sensing membrane, making use of the effect that polyelectrolyte multilayers have different permeabilities toward ions with different valences. The results have implications to the design of chemically selective ion sensors since surface localized kinetic limitations can now be used as an additional dimension to tune the operational ion selectivity.Polymer membrane ion-selective electrodes are widely established for the reliable assessment of ion activities in complex samples and are indispensable tools in clinical analysis. Their ionselectivity is dictated by the thermodynamic ion-exchange selectivity of the polymer membrane. Recently, ion-selective membrane electrodes have started to be interrogated by pulsed chronopotentiometry. In this new technique, a discrete current pulse is imposed across an ion-selective membrane void of added ion-exchanger sites. The potential change associated with the resulting ion flux from the sample into the sensing phase can be monitored during or, at open circuit, immediately after the pulse before the membrane is regenerated under controlled potential conditions. At high sample concentrations the observed sensitivity (electrode slope) and selectivity normally agrees with that of the corresponding ion-selective electrodes interrogated at zero current. 1, 2 The imposed ion flux, however, depletes the analyte ions in the Nernst diffusion layer at a critical concentration, and very large (ca. 10-fold Nernstian) electrode slopes are observed in this concentration range. 3 The operational ion Ultra-thin films assembled from alternate adsorption of polycations and polyanions onto a charged substrate has attracted much attention in recent years due to their facile fabrication, high versatility and multi-functionality. The application of this technique has expanded into a number of areas, including biosensor surface modificat...

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“…LbL was selected as it provided nm to μm thicknesses [15][16][17], and coating complex microstructured surfaces in a conformable way [18]. The used primer layer allowed protection of the Mg alloy substrate from in-process degradation during the LbL dip coating phase.…”

Section: Methodsmentioning

confidence: 99%

Laser surface structuring affects polymer deposition, coating homogeneity, and degradation rate of Mg alloys

et al. 2015

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A careful examination of the adsorption step in the alternate layer-by-layer assembly of linear polyanion and polycation

Cited by 238 publications

References 27 publications

Mixed protein–polysaccharide interfacial layers: effect of polysaccharide charge distribution

Mixed protein–polysaccharide interfacial layers: effect of polysaccharide charge distribution

Kinetic Modulation of Pulsed Chronopotentiometric Polymeric Membrane Ion Sensors by Polyelectrolyte Multilayers

Laser surface structuring affects polymer deposition, coating homogeneity, and degradation rate of Mg alloys

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