Polyelectrolyte complex layers: a promising concept for anti-fouling coatings verified by in-situ ATR-FTIR spectroscopy (original) (raw)
Related papers
Protein Adsorption onto Auto-Assembled Polyelectrolyte Films
Langmuir, 2001
Surface modification by deposition of ordered protein systems constitutes one of the major objectives of bio-related chemistry and biotechnology. In this respect a concept has recently been reported aimed at fabricating multilayers by the consecutive adsorption of positively and negatively charged polyelectrolytes. We investigate the adsorption processes between polyelectrolyte multilayers and a series of positively and negatively charged proteins. The film buildup and adsorption experiments were followed by Scanning Angle Reflectometry (SAR). We find that proteins strongly interact with the polyelectrolyte film whatever the sign of the charge of both the multilayer and the protein. When charges of the multilayer and the protein are similar, one usually observes the formation of protein monolayers, which can become dense. We also show that when the protein and the multilayer become oppositely charged, the adsorbed amounts are usually larger and the formation of thick protein layers extending up to several times the largest dimension of the protein can be observed. Our results confirm that electrostatic interactions dominate protein/polyelectrolyte multilayer interactions.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2004
We have investigated the polyelectrolyte multilayer build-up of positively charged poly(allylamine hydrochloride) (PAH) and negatively charged poly(sodium 4-styrenesulfate) (PSS), adsorbed to oxidised silicon wafers and colloidal silica substrates. Properties of multilayers with a first layer of polyethylenimine (PEI), were compared with the pure PAH/PSS multilayers. Ellipsometric thickness measurements show that the initial five layers, "precursor regime", have lower layer thickness than the layers adsorbed later in the adsorption cycle. Heterogeneity in the pure PAH/PSS multilayers in the precursor regime is seen in AFM images. This heterogeneity is further expressed as qualitative differences in adhesion in different positions on the film. Once a sufficient number of layers are adsorbed, i.e. when the true multilayer regime is reached, no effects of heterogeneity are seen anymore and the layer thickness increase becomes constant. With a PEI first layer, the heterogeneity effects in the precursor regime are eliminated, without any change of the thickness. Furthermore, the PEI layer dramatically decreases the roughness of the film in the precursor regime.
Langmuir, 2004
Adsorption of proteins onto film surfaces built up layer by layer from oppositely charged polyelectrolytes is a complex phenomenon, governed by electrostatic forces, hydrogen bonds, and hydrophobic interactions. The amounts of the interacting charges, however, both in polyelectrolytes and in proteins adsorbed on such films are a function of the pH of the solution. In addition, the number and the accessibility of free charges in proteins depend on the secondary structure of the protein. The subtle interplay of all these factors determines the adsorption of the proteins onto the polyelectrolyte film surfaces. We investigated the effect of these parameters for polyelectrolyte films built up from weak "protein-like" polyelectrolytes (i.e., polypeptides), poly(L-lysine) (PLL), and poly(glutamic acid) (PGA) and for the adsorption of human serum albumin (HSA) onto these films in the pH range 3.0-10.5. It was found that the buildup of the polyelectrolyte films is not a simple function of the pure charges of the individual polyelectrolytes, as estimated from their respective pKa values. The adsorption of HSA onto (PLL/PGA)n films depended strongly on the polyelectrolyte terminating the film. For PLL-terminated polyelectrolyte films, at low pH, repulsion, as expected, is limiting the adsorption of HSA (having net positive charge below pH 4.6) since PLL is also positively charged here. At high pH values, an unexpected HSA uptake was found on the PGA-ending films, even when both PGA and HSA were negatively charged. It is suggested that the higher surface rugosity and the decrease of the R-helix content at basic pH values (making accessible certain charged groups of the protein for interactions with the polyelectrolyte film) could explain this behavior.
Advanced Materials, 2003
In this communication, anti-streptavidin M13 viruses were used to self-assemble various nanosized materials. We believe the anti-streptavidin M13 viruses provide a convenient method to organize a variety of nanosized materials into self-assembled ordered structures. Because the modification of the DNA insert allows controlled modification of the virus length, the spacing in the smectic layer can be genetically controlled. [12] By conjugating other nanosized materials (magnetic nanoparticles, II±VI semiconductor nanoparticles, functional chemicals, etc.) with streptavidin, we believe that this anti-streptavidin method can be used to align various nanosized materials at the desired length scale, which is defined by the smectic layers.
Dynamical Behavior of Human Serum Albumin Adsorbed on or Embedded in Polyelectrolyte Multilayers
The Journal of Physical Chemistry B, 2002
We investigate the lateral diffusion of Human Serum Albumin-Fluorescein Isothiocyanate (HSA) adsorbed "on" or embedded "in" poly(sodium 4-styrenesulfonate)/poly(allylamine hydrochloride) (PSS/PAH) multilayers. Special attention is brought to the evolution of the diffusion coefficient with the surface HSA concentration. We find that while on PSS terminating films the diffusion coefficient of adsorbed HSA is independent of the protein surface concentration in the explored range, it decreases strongly with the surface concentration when HSA is adsorbed on PAH ending films. On both films, the mobile fraction of adsorbed protein molecules decreases when the surface concentration increases. At low surface coverage, up to 90% of the adsorbed protein molecules are mobile both on PSS and PAH terminating films. The decrease of the mobile fraction with the HSA surface concentration is more pronounced on PSS than on PAH reaching, respectively, 50% and 70% of mobile HSA molecules at high surface coverage. This behavior is typical for protein aggregation. Infrared spectroscopy in the ATR mode confirms the presence of protein interactions but also rules out that this constitutes the unique reason for the evolution of the mobile fraction with the surface coverage. We also find that the diffusion coefficient, at small surface concentration, is more than 1 order of magnitude smaller on PSS than on PAH ending films, the diffusion coefficients being, respectively, equal to 6.2 × 10 -11 cm 2 /s and 2 × 10 -9 cm 2 /s. A tentative model based on the wrapping of HSA molecules by PAH chains and bridging between the chains by both polyelectrolytes is proposed to explain the observed features. Finally, we also determine the diffusion coefficient of HSA embedded in PSS/PAH multilayers. We find that the diffusion coefficient of HSA embedded in -PAH-HSA-PAH-type multilayers is close to that determined when HSA is adsorbed on PAH terminating films. When HSA is embedded in -PSS-HSA-PSS-type films the diffusion coefficient is independent of the HSA surface concentration and is surprisingly slightly larger than when HSA is adsorbed on PSS terminating films, 1.1 × 10 -10 cm 2 /s compared to 6.2 × 10 -11 cm 2 /s.
POLYELECTROLYTE MULTILAYERS AND THEIR INTERACTIONS
Journal of Adhesion, 2004
An overview is given of our recent IR spectroscopic, optical, electrokinetic, and microscopic studies on polyelectrolyte multilayers (PEMs), built up using the consecutive layer-by-layer technique, their interactions, and application possibilities. The influence of pH on the deposition of PEMs consisting of commercial polyelectrolytes (PELs) like poly(ethyleneimine) and poly(acrylic acid) and the adopted surface morphology of isotropic PEMs consisting of flexible PELs are reported. PEMs of azo dye/PEL are included. Those are compared with anisotropic PEMs containing stiff PELs like charged α-helical polypeptides. Furhermore, examples concerning the swelling behavior of PEMs in the presence of solutions of different low molecular salt types and the hydration of dried PEMs by the relative humidity, respectively, are given. As potent application fields, their interaction with proteins regarding both prevention of bioadhesion and protein immobilization by electrostatic interaction forces are illustrated. Those studies led to principles for membrane surface modification in order to prevent biofouling and optimize their flux and separation performance.
On the Way to Functional Coatings: Polyelectrolyte Multilayers
2010
In the present work, the results of polyelectrolyte multilayers and hybrid multilayers, which were formed by the assembling colloidal particles and polyelectrolytes, have been presented. They are built by the alternate deposition of materials with charges of opposite signs. The kinetics of the adsorption of the materials onto charged surfaces are discussed using dissipative quartz crystal balance and ellipsometry techniques. The effect of the ionic strength and of the charge density of the polymer on the thickness of the multilayer per adsorbed layer is discussed. The water content of the polymer film and the real and imaginary components of its shear modulus have been measured as a function of the thickness and of the ionic strength. Finally, we analyzed how the multilayers are modified by the substitution of the polymeric components by colloidal particles.
Journal of Chromatography A
Protein adsorption on the inner wall of the fused silica capillary wall is an important concern for capillary electrophoresis (CE) analysis since it is mainly responsible for separation efficiency reduction. Successive Multiple Ionic-polymer Layers (SMIL) are used as capillary coatings to limit protein adsorption, but even low residual adsorption strongly impacts the separation efficiency, especially at high separation voltages. In this work, the influence of the chemical nature and the PEGylation of the polyelectrolyte deposited in the last layer of the SMIL coating was investigated on the separation performances of a mixture of four model intact proteins (myoglobin (Myo), trypsin inhibitor (TI), ribonuclease a (RNAse A) and lysozyme (Lyz)). Poly(allylamine hydrochloride) (PAH), polyethyleneimine (PEI), ε-poly(L-lysine) (εPLL) and αpoly(L-lysine) (αPLL) were compared before and after chemical modification with polyethyleneglycol (PEG) of different chain lengths. The experimental results obtained by performing electrophoretic separations at different separation voltages allowed determining the residual retention factor of the proteins onto the capillary wall via the determination of the plate height at different solute velocities and demonstrated a strong impact of the polycationic last layer on the electroosmotic mobility, the separation efficiency and the overall resolution. Properties of SMIL coatings were also characterized by quartz microbalance and atomic force microscopy, demonstrating a glassy structure of the films.
Journal of Colloid and Interface Science, 1998
In this investigation surface force, X-ray photoelectron spectroscopy and ellipsometry techniques have been used to study the adsorption of a low-charge-density cationic polyelectrolyte on negatively charged surfaces. It is shown that the low cationicity of this polyelectrolyte induces an adsorption behavior which is limited by steric factors rather than by the substrate surface charge or potential. It is also established that an increase in ionic strength of the solution results in desorption of the polyelectrolyte accompanied by an increase in layer thickness. This phenomenon is typical of a screening-reduced adsorption regime where electrostatic interactions predominate in the adsorption process. An increase in layer thickness most often occurs as a result of an increased adsorbed amount. Here, however, the increase in layer thickness occurs despite a reduction in the adsorbed amount. This can be understood as resulting from a reduced polyelectrolyte-surface affinity and a swelling of the adsorbed layer. Finally, it is demonstrated that the employed techniques complement each other and reveal new information on the interaction forces and conformation of polyelectrolytes at the solid-liquid interface.