Complementary Polyelectrolytes Research Articles

Recent Developments in Layer-by-Layer Assembly for Drug Delivery and Tissue Engineering Applications.

Surfaces with biological functionalities are of great interest for biomaterials, tissue engineering, biophysics, and for controlling biological processes. The layer-by-layer (LbL) assembly is a highly versatile methodology introduced 30 years ago, which consists of assembling complementary polyelectrolytes or biomolecules in a stepwise manner to form thin self-assembled films. In view of its simplicity, compatibility with biological molecules, and adaptability to any kind of supporting material carrier, this technology has undergone major developments over the past decades. Specific applications have emerged in different biomedical fields owing to the possibility to load or immobilize biomolecules with preserved bioactivity, to use an extremely broad range of biomolecules and supporting carriers, and to modify the film's mechanical properties via crosslinking. In this review, the focus is on the recent developments regarding LbL films formed as 2D or 3D objects for applications in drug delivery and tissue engineering. Possible applications in the fields of vaccinology, 3D biomimetic tissue models, as well as bone and cardiovascular tissue engineering are highlighted. In addition, the most recent technological developments in the field of film construction, such as high-content liquid handling or machine learning, which are expected to open new perspectives in the future developments of LbL, are presented.

Fast‐Dip Layer‐by‐Layer Self‐Assembly of Polyelectrolytes as a Low‐Cost Biosensing Platform

AbstractPolyelectrolyte multilayer (PEM) films fabricated using Layer‐by‐Layer (LbL) self‐assembly are most versatile for numerous surface tailoring applications. Physicochemical customization of PEM at a nanometer scale is possible by choice of incorporated materials, assembly parameters, and assembly techniques. Conventional dip (CDip) (10–15 min dip time) coating dominates the PEM fabrication due to its simple, geometry‐independent, and economical coating capabilities. Deposition of the PEM in CDip‐LbL happens in two phases, that is, the initial adsorption phase followed by rearrangement of the complementary polyelectrolyte chains. By shortening the prolonged rearrangement phase, thicker stratified PEM films can form with a reduced dipping time (1 min), called Fast Dip (FDip). This reduction in the dipping time is studied in situ using Etched Fiber Bragg Grating‐based sensors. To define the practical utility of the FDip deposited PEM, bio‐molecular loading studies are performed using biotin and Bovine Serum Albumin (BSA). FDip‐LbL is as effective as CDip‐LbL self‐assembly and also better than spin‐LbL. Thus, the FDip deposition prompts a scalable LbL self‐assembly process for quick fabrication of the biosensing platforms.

Ubiquity of complex coacervation of DNA and proteins in aqueous solution.

We report complex coacervation between a primarily hydrophobic protein, elastin, and a strong polyanion DNA (2 kbp) in aqueous and salty solutions at room temperature, 25 °C. The associative interaction at fixed elastin and varying DNA concentration, thereby maintaining a mixing ratio of r = [DNA] : [elastin] = 0.0027 to 0.093, was probed. What distinguishes this study from protein-DNA coacervation reported earlier is that the protein used here was mostly a hydrophobic polyampholyte with low linear charge density, and its complementary polyelectrolyte, DNA, concentration was chosen to be extremely small (1-35 ppm). The interaction profile was found to be strongly hierarchical in the mixing ratio, defined by three distinct regions: (i) Region I (r < 0.02) was defined as the onset of primary binding leading to condensation of DNA; (ii) Region II (0.02 < r < 0.08) indicated secondary binding which led to the formation of fully charge neutralized complexes signaling the onset of coacervation; and (iii) Region III (0.08 < r < 0.12) revealed growth of insoluble complexes of large size facilitating liquid-solid phase separation. The degree of complex coacervation was suppressed in the presence of a monovalent salt implying that screened Coulomb interactions governed the binding. Small angle neutron scattering data attributed an amorphous structure to the coacervates. The elastin-DNA system belongs to a rare class of interacting biopolymers where very weak electrostatic interactions may drive coacervation, thereby implying that coacervation between DNA and proteins may be ubiquitous.

Layer-by-Layer Assembly Modulated by Host–Guest Binding

A strategy has been devised for improving the quality of polyelectrolyte multilayers formed via the layer-by-layer technique. This strategy involves host–guest complexation of the pendant ions of a polyelectrolyte to reduce their affinity toward the pendant ions of a complementary polyelectrolyte. Evidence for the effectiveness of this approach has been obtained on the basis of film thickness, permeability, and surface roughness measurements of polyelectrolyte multilayers derived from poly(sodium 4-styrenesulfonate) and poly(diallyldimethyammonium chloride), using β-cyclodextrin as a host molecule.

Polyelectrolyte-Stabilised Magnetic-Plasmonic Nanocomposites.

In this work, new magnetic-plasmonic nanocomposites have been developed through the use of two complementary polyelectrolytes–polystyrene sulfonate (PSS) and poly(allylamine hydrochloride) (PAH). PSS, a negatively charged polyelectrolyte, was utilized as a stabiliser for magnetite nanoparticles, and PAH, a positively charged polyelectrolyte, was used to stabilize gold nanoparticles. The combination of these two entities resulted in a magnetic-plasmonic nanocomposite that is highly reproducible and scalable. This approach was found to work for a variety of PSS concentrations. The produced magnetic-plasmonic nanomaterials have been characterized by vibrational sample magnetometry (VSM), transmission electron microscopy (TEM) and UV-Vis spectroscopy. These nanocomposite materials have the potential to be used in a variety of biological applications including bioseparation and biosensing.

Calcium Carbonate/Polymers Microparticles Tuned by Complementary Polyelectrolytes as Complex Macromolecular Templates

This study describes the effects of mixed anionic/cationic polyelectrolytes on the crystallization of calcium carbonate in supersaturated solutions in comparison with polyanion-based CaCO3 composite structures. Two simple methods of introducing the polycation in the crystallogenesis of calcium carbonate are proposed: preformed nonstoichiometric polyelectrolyte complexes (NPECs) or in situ mixing of complementary polyelectrolytes, with a very large range of ratios between complementary polyions. For this purpose three polyanions—poly(acrylic acid) sodium salt, poly(sodium 4-styrenesulfonate) and poly(sodium vinylsulfonate)—and poly(diallyl-dimethylammonium chloride) as polycation were used. The molar ratio between complementary polyelectrolytes used in CaCO3 composite synthesis varied between 0 (just polyanions) up to 0.95 (close to the equimolar ratio between ionic charges of complementary polyelectrolytes). The polymer presence into the composite particles, as a function of polyanion structure and the preparation mode, was evidenced by energy dispersive X-ray diffraction and particle charge detection in the supernatant fraction. Scanning electron microscopy was used to provide the particles’ morphology, and Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectroscopy was used to determine the polymorph content ratio. The enhanced CaCO3/polyanion/polycation microparticles stability in ethylenediamine tetraacetic acid has been also shown compared to CaCO3/polyanion microparticles as a function of the molar ratio between complementary polyelectrolytes and the method of introducing the polycation in the crystallogenesis system.

Silica microparticles surface coating by layer-by-layer or polyelectrolyte complex adsorption

This study follows the surface properties modification of some silica particles, by coating with complementary polyelectrolytes by layer-by-layer deposition or by the adsorption of preformed polyelectrolyte complexes. Two polyanions, alginic acid and poly(2-acrylamido-2-methylpropanesulfonic acid - co - acrylic acid), and chitosan as polycation are used. The influence of the polyelectrolytes structure and the molar ratio between ionic charges on the polyelectrolyte complexes characteristics is investigated by turbidimetry, dynamic light scattering and electrophoresis. The properties of the formed inorganic/organic materials are evaluated comparing the size distribution and zeta and streaming potential of the samples prepared by layer-by-layer or preformed polyelectrolyte complexes adsorption. The surface morphology is evidenced by atomic force microscopy, and some specific surface parameters are discussed. A special attention is paid to the responsiveness of the new composite materials to environmental pH changes, as a function of preparation conditions.

Influence of the comonomer structure and of the initial pH on the characteristics of polyelectrolyte complexes based on maleic acid copolymers

The interaction between some hydrophilic and hydrophobic maleic acid copolymers and a strong polycation, poly(diallyldimethylammonium chloride), at low concentration and different pH, with the formation of polyelectrolyte complex (PEC) dispersions, was the object of this study. Poly(maleic acid–alt–vinyl acetate) was used as hydrophilic copolymer and poly(maleic acid–alt–styrene) and poly(maleic acid–alt–2-vinylnaphthalene) were used as more hydrophobic copolymers. A special attention was given to the in-situ investigation by turbidimetry, potentiometry, and conductometry of the formed PECs and to their characterization after 24 h by optical density, dynamic light scattering and atomic force microscopy. Taking into account that the conformation of the copolymers is influenced by their neutralization degree, related to the solution pH, we had investigated the influence of this parameter on the PEC formation at pH = 6, where around half of the carboxylic groups are neutralized, and at pH = 10, at totally dissociated state. This study focused on the influence of the comonomer hydrophilic/hydrophobic nature, polyions mixing order, and starting pH of the solutions on the ratio of the complementary polyelectrolytes at the titration end-point and on the PEC particles size.

Novel Application of Polyelectrolyte Multilayers as Nanoscopic Closures with Hermetic Sealing

Closure systems for personnel protection applications, such as protective clothing or respirator face seals, should provide effective permeation barrier to toxic gases. Currently available mechanical closure systems based on the hook and loop types (example, Velcro) do not provide adequate barrier to gas permeation. To achieve hermetic sealing, we propose a nonmechanical, nanoscopic molecular closure system based on complementary polyelectrolyte multilayers, one with a polycation outermost layer and the other with a polyanion outermost layer. The closure surfaces were prepared by depositing polyelectrolyte multilayers under a variety of deposition conditions, on conformable polymer substrates (thin films of polyethylene teraphthalate, PET or polyimide, PI). The hermetic sealing property of the closures was evaluated by measuring the air flow resistance using the dynamic moisture permeation cell (DMPC) at different humidity conditions. The DMPC measurements show that the polyelectrolyte multilayer closures provide significantly large resistance to air flow, approximately 20-800 times larger than that possible with conventional hook and loop type closure systems, at all humidity levels (from 5 to 95% relative humidity). Hence, from the point of view of providing a hermetic seal against toxic gas permeation, the polyelectrolyte multilayer closures are viable candidates for further engineering development. However, the adhesive strength of the multilayer closures measured by atomic force microscopy suggests that the magnitude of adhesion is much smaller than what is possible with mechanical closures. Therefore, we envisage the development of a composite closure system combining the mechanical closure to provide strong adhesion and the multilayer closure to provide hermetic sealing.

Interpolyelectrolyte complexes of diblock copolymers via interaction of complementary polyelectrolyte–surfactant complexes in chloroform

We have studied the interpolyelectrolyte complexation in chloroform between polystyrene-block-poly(cetyltrimethylammonium acrylate), (PA− CTA+), and poly(2-(methacryloyloxy)ethyldimethylethyl-ammonium dodecyl sulfate) (quaternized poly(2-(dimethylamino)ethyl methacrylate) complexed with sodium dodecyl sulfate), (PDMAEMAQ+ DS−). Turbidimetry, dynamic/static light scattering, and transmission electron microscopy show the formation of large aggregated interpolyelectrolyte complex species, which are colloidally stable in chloroform or even chloroform-soluble if the certain conditions are met. We suggest such co-assemblies to be micellar species with a core assembled from electrostatically coupled fragments of the polymeric components. The corona is built up either from a mixture of polystyrene blocks and excessive fragments of (PDMAEMAQ+ DS−) chains or from a mixture of polystyrene blocks and excessive fragments of (PA− CTA+) blocks, depending on which polymeric component was taken in excess for the interpolyelectrolyte complexation. However, their real structures may deviate from such idealized consideration because of the non-equilibrium character of interpolyelectrolyte complexation in organic media of low polarity.

2P-060 相補的高分子電解質を用いた酵素活性制御(蛋白質-機能(反応機構,生物活性など),第47回日本生物物理学会年会)

2P-060 相補的高分子電解質を用いた酵素活性制御(蛋白質-機能(反応機構,生物活性など),第47回日本生物物理学会年会)

COACERVATES : A NOVEL STATE OF SOFT MATTER — AN OVERVIEW

Coacervation is usually defined as the spontaneous formation of a dense liquid phase from a macromolecular solution of poor solvent affinity. In coacervation, the loss of solvation arises from the interaction of complementary macromolecular species. The formation of such macromolecule-rich fluids is well-known in mixtures of complementary polyelectrolytes; it can also occur from mixtures of polyelectrolytes with colloidal particles, leading to condensed soft matter phases with interesting properties. Though the polymer solution and gel states are adequately studied, characterized and mostly understood, the same for the coacervate phase is not true. Coacervates are macro-ionic hydrated complexes of a pair (self or complementary) of charge-neutralized polymers. Such a condensed phase remains in thermodynamic equilibrium with its supernatant that mostly contains a dilute dispersion of smaller intermolecular aggregates of the constituent polymers. This article intends to elucidate the salient features of this novel soft matter with some specific examples.

Comprehensive study on the formation of polyelectrolyte complexes from (quaternized) poly[2-(dimethylamino)ethyl methacrylate] and poly(2-acrylamido-2-methylpropane sodium sulfonate)

Polyelectrolyte complexes (PECs) have been prepared from well-defined (quaternized) poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) and high molecular weight poly(2-acrylamido-2-methylpropane sodium sulfonate) (PAMPSNa) after a thorough study of their viscometric properties. The effect of pH and quaternization degree of PDMAEMA on PECs stoichiometry has been examined. PEC-based materials have been characterized in terms of thermal stability, equilibrium swelling degree, and free/bound water composition. The stoichiometry and swellability of the physically crosslinked hydrogels obtained from fully quaternized PDMAEMA/PAMPSNa complexes do not depend on pH. In contrast, PECs made of non quaternized PDMAEMA and PAMPSNa are highly affected by pH, and could reversibly disintegrate at pH ≥ 9. Partially quaternized PDMAEMA/PAMPSNa PECs exhibit intermediate properties and form stable loose structures in the whole investigated pH range. Finally, stable dispersions of PECs nanoparticles have been successfully produced from dilute solutions of the complementary polyelectrolytes. The nanoparticle average diameter as determined by dynamic light scattering proved to depend on the molar fraction of DMAEMA-based subunits and on the initial polyelectrolyte concentration. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5468–5479, 2006