Dataset Information

PH-Responsive Host?Guest Complexation in Pillar[6]arene-Containing Polyelectrolyte Multilayer Films.

ABSTRACT: A water-soluble, anionic pillar[6]arene derivative (WP6) is applied as monomeric building block for the layer-by-layer self-assembly of thin polyelectrolyte multilayer films, and its pH-dependent host?guest properties are employed for the reversible binding and release of a methylviologen guest molecule. The alternating assembly of anionic WP6 and cationic diazo resin (DAR) is monitored in-situ by a dissipative quartz crystal microbalance (QCM-D). In solution, the formation of a stoichiometric inclusion complex of WP6 and cationic methylviologen (MV) as guest molecule is investigated by isothermal titration calorimetry and UV-vis spectroscopy, respectively, and attributed to electrostatic interactions as primary driving force of the host?guest complexation. Exposure of WP6-containing multilayers to MV solution reveals a significant decrease of the resonance frequency, confirming MV binding. Subsequent release is achieved by pH lowering, decreasing the host?guest interactions. The dissociation of the host?guest complex, release of the guest from the film, as well as full reversibility of the binding event are identified by QCM-D. In addition, UV-vis data quantify the surface coverage of the guest molecule in the film after loading and release, respectively. These findings establish the pH-responsiveness of WP6 as a novel external stimulus for the reversible guest molecule recognition in thin films.

SUBMITTER: Nicolas H

PROVIDER: S-EPMC6418545 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature

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pH-Responsive Host⁻Guest Complexation in Pillar[6]arene-Containing Polyelectrolyte Multilayer Films.

Nicolas Henning H Yuan Bin B Xu Jiangfei J Zhang Xi X Schönhoff Monika M

Polymers 20171216 12

A water-soluble, anionic pillar[6]arene derivative (WP6) is applied as monomeric building block for the layer-by-layer self-assembly of thin polyelectrolyte multilayer films, and its pH-dependent host⁻guest properties are employed for the reversible binding and release of a methylviologen guest molecule. The alternating assembly of anionic WP6 and cationic diazo resin (DAR) is monitored in-situ by a dissipative quartz crystal microbalance (QCM-D). In solution, the formation of a stoichiometric i ...[more]

PMID: 30966019

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Project description:The field of membranes saw huge developments in the last decades with the introduction of both polyelectrolyte multilayer (PEM)-based membranes and biomimetic membranes. In this work, we combine these two promising systems and demonstrate that proteopolymersomes (PP+) with the incorporated aquaporin protein can be distributed in a controlled fashion using PEMs, even on the inner surface of a hollow fiber membrane. In this way, various proteopolymersome multilayers (PPMs) are fabricated using PP+ as the positively charged species in combination with the polyanions poly(styrene 4-sulfonate) (PSS) and poly(acrylic acid) (PAA). It is shown by reflectometry through alternately adsorbing the polyanions and PP+ that, for both PAA and PSS, a good layer growth is possible. However, when the multilayers are imaged by SEM, the PAA-based PPMs show dewetting, whereas vesicular structures can only be clearly observed in and on the PSS-based PPMs. In addition, membrane permeability decreases upon coating the PPMs to 2.6 L?m-2?h-1?bar-1 for PAA/PP+ and 7.7 L?m-2?h-1?bar-1 for PSS/PP+. Salt retentions show that PAA/PP+ layers are defective (salt retentions <10% and high molecular weight cut-off (MWCO)), in line with the observed dewetting behavior, while PPMs based on PSS show 80% MgSO4 retention in combination with a low MWCO. The PSS/PP+ membranes show a Donnan-exclusion behavior with moderate MgCl2 retention (50%-55%) and high Na2SO4 retention (85%-90%) indicating a high amount of negative charge present within the PPMs. The corresponding PEMs, on the other hand, are predominately positively charged with MgCl2 retention of 97%-98% and Na2SO4 retention of 57%-80%. This means that the charge inside the multilayer and, thus, its separation behavior can be changed when PP+ is used instead of a polycation. When comparing the PPM membranes to the literature, similar performances are observed with other biomimetic membranes that are not based on interfacial polymerization, but these are the only ones prepared using a desired hollow fiber geometry. Combining PEMs and biomimetic approaches can, thus, lead to relevant membranes, especially adding to the versatility of both systems.

Dataset Information

PH-Responsive Host?Guest Complexation in Pillar[6]arene-Containing Polyelectrolyte Multilayer Films.

Publications

pH-Responsive Host⁻Guest Complexation in Pillar[6]arene-Containing Polyelectrolyte Multilayer Films.

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