Poly Acrylic Acid Polyelectrolyte Research Articles

Effect of strong and weak polyelectrolytes on the properties of cationic surfactant with triallyl ammonium head group: Self-assembly and biological assessment

Comprehensive assessment of polymer-colloid systems based on cationic surfactant with triallyl ammonium head group (TAS-16) in the presence of synthetic polyelectrolytes (polyacrylic acid (PAA), sodium polyacrylate (SPA), and sodium polystyrene sulfonate (PSS)) has been carried out. The addition of weak polyelectrolyte PAA significantly reduces the critical micelle concentration of the amphiphile up to 50 times. In conrtrast, strong polyelectrolytes such as PSS and SPA have a much smaller effect on the aggregation threshold of the surfactant. Spherical aggregates with a diameter of 80-230 nm were observed in the surfactant-PAA system using transmission electron microscopy. The mixed compositions exhibited high antitumor activity against the human duodenal adenocarcinoma HuTu 80 cell line (IC50=0.6 μM). The pure polymers do not cause hemolysis and hemagglutination, while TAS-16 exhibits hemolytic activity in both pure and mixed systems. The polymer-colloid complexes containing strong polyelectrolyte SPA were more effective as nanocontainers to enhance the solubility of the hydrophobic antibiotic Amphotericin B.

PH-triggered drug release of ciprofloxacin from layer-by-layer coatings on titanium

Abstract Implant-associated infections are still a major issue in implant surgery. Biofilms tend to form on implant surfaces, like titanium, and can hardly be reached by the immune system. Additionally, systemic treatments with antibiotics often fail and cause severe side effects for the patient. Direct delivery of the antibiotic from the implant surface to the surrounding tissue is one approach to solve this problem. To realize this, the application of pH-sensitive coatings on implant surfaces, which release their cargo only if an infection arises, is a promising option. This can be triggered by the decrease of the pH value occurring in infected tissue. For such pH-sensitive systems with integrated drug loading capacity layer-by-layer coatings with weak polyelectrolytes can be used. Here, we present a coating applied on titanium substrates by dip-coating. As negatively charged polyelectrolyte polyacrylic acid, as positively charged poly(allylamine hydrochloride) is used. As an effective drug, the antibiotic ciprofloxacin is incorporated into the coating and the release profiles are recorded.

PH-Responsive, Thermo-Resistant Poly(Acrylic Acid)-g-Poly(boc-L-Lysine) Hydrogel with Shear-Induced Injectability.

In this study we report the rheological behavior of aqueous solutions of an amphiphilic graft copolymer constituting a polyacrylic acid (PAA) grafted by poly(boc-L-lysine), P(b-LL). Due to the highly hydrophobic nature of the grafted chains, the copolymer self-assembles spontaneously in aqueous media forming three-dimensional (3D) finite size networks (microgels). The rheological analysis demonstrated that the copolymer behaves as a strong elastic hydrogel, showing characteristics of a "frozen" network. Moreover, it is noteworthy that the formulation shows the above-described characteristics in very small concentrations (0.25-1.20 wt%) compared to other naturally cross-linked hydrogels that have been studied so far. Concentration significantly affects the rheological properties of the hydrogel, showing considerable increase in elastic modulus, following the scaling law G'~C1.93. At the same time, the hydrogels can be described as intelligent stimuli-responsive systems, showing pH and shear responsiveness as well as stability with temperature changes. Thanks to the pH dependance of the degree of ionization of the weak polyelectrolyte PAA backbone, stiffness and swelling of the hydrogels can be tuned effectively by adjusting the pH conditions. Simulating conditions such as those of injection through a 28-gauge syringe needle, the gel demonstrates excellent response to shear, due to its remarkable shear thinning behavior. The combination of pH-sensitivity and shear responsiveness leads to excellent injectability and self-healing properties, given that it flows easily upon applying a low stress and recovers instantly in the site of injection. Therefore, the physically cross-linked PAA-g-P(b-LL) hydrogel exhibits remarkable features, namely biocompatibility, biodegradability of cross-links, pH responsiveness, shear-induced injectability and instantaneous self-healing, making it a potential candidate for various biomedical applications.

Electro‐responsive semi‐IPN hydrogel with enhanced responsive property for forward osmosis desalination

AbstractAn electro‐responsive hydrogel with semi‐interpenetrating polymer networks (semi‐IPN) composed of crosslinked poly(2‐acrylamido‐2‐methyl‐l‐propanesulfonic acid‐co‐acrylamide) (P(AMPS‐AM)) and linear polyelectrolyte polyacrylic acid (PAA) was explored. The semi‐IPN hydrogel was characterized with different methods and then used as advanced draw agent toward high water recovery for forward osmosis (FO) desalination. The swelling kinetics of the semi‐IPN hydrogel was investigated, and the electro‐responsive nature of the hydrogel under electric stimulus (in direct contact with electrodes) was determined. Results indicated that in comparison with pure P(AMPS‐AM) hydrogel, the semi‐IPN hydrogel exhibited a loose network structure with more pores. In addition, a higher equilibrium swelling capacity and more pronounced deswelling under electric stimulus can be observed for the semi‐IPN hydrogel. Furthermore, the semi‐IPN hydrogel displayed a similar initial water flux of 2.20 L m−2 h−1 (LMH) from 2 g/L NaCl solution of a lab‐scale FO process. Importantly, the semi‐IPN hydrogel had a 25% increase in water recovery efficiency under the electric stimulus of 15 V, and showed better recyclability during three cycles of regeneration compared with pure P(AMPS‐AM). The mechanism of enhanced dewatering nature for the semi‐IPN hydrogel under electric stimulus was elucidated. These results indicate this new hydrogel's potential as a promising candidate for improving FO performance.

Electrochemiluminescence Enhancement and Particle Structure Stabilization of Polymer Nanoparticle by Doping Anionic Polyelectrolyte and Cationic Polymer Containing Tertiary Amine Groups and Its Highly Sensitive Immunoanalysis

A doped polymer nanoparticle (dPNP) of electrochemiluminescence (ECL) was prepared via doping the anionic polyelectrolyte polyacrylic acid (PAA) and the cationic polymer poly-ethyleneimine (PEI) into the polymer nanoparticle (PNP), which was self-assembled by Ru(bpy)32+ derivative-grafted PAA (PAA–Ru) with both cations and anions. The good electrical conductivity of the doped polyelectrolyte PAA enhanced the ECL intensity of PNP to 109.1%, and the involvement of a large number of tertiary amine groups of the doped PEI further enhanced that to 127.3%; meanwhile, doping low-molecular-weight PEI into PNP, while simultaneously doping high-molecular-weight PAA, avoided the precipitation of PAA and PEI, due to interaction of the two oppositely charged polymers; and these also made the self-assembly procedure more effective and the nanoparticle structure more stable than PNP and also led to the production of rich residual PAA chains on the surface of dPNP. The storage results showed that the average hydrated particle diameter kept almost constant (197.5–213.1 nm) during 15-day storage and that the nanoparticles have rich surface charge of −11.47 mV (zeta potential), well suspension stability and good dispersity without detectable aggregation in the solution during the storage. Therefore, the nanoparticle is quite suitable for the antibody labeling, immunoassay and the storage. As a result, a high-sensitive ECL immunoassay approach with good precision, accuracy and selectivity was established and an ultra-low detection limit of 0.049 pg mL−1 (S/N = 3) for magnetic bead-based detection of Hepatitis B surface antigen was observed.

Bioinspired thermoresponsive nanoscaled coatings: Tailor-made polymer brushes with bioconjugated arginine-glycine-aspartic acid-peptides.

The development of bioengineered surface coatings with stimuli-responsive properties is beneficial for a number of biomedical applications. Environmentally responsive and switchable polymer brush systems have a great potential to create such smart biointerfaces. This study focuses on the bioconjugation of cell-instructive peptides, containing the arginine-glycine-aspartic acid tripeptide sequence (RGD motif), onto well-defined polymer brush films. Herein, the highly tailored end-grafted homo polymer brushes are either composed of the polyelectrolyte poly(acrylic) acid (PAA), providing the reactive carboxyl functionalities, or of the temperature-responsive poly(N-isopropylacrylamide) (PNIPAAm). Of particular interest is the preparation of grafted-to binary brushes using both polymers and their subsequent conversion to RGD-biofunctionalized PNIPAAm-PAA binary brushes by a carbodiimide conjugation method. The bioconjugation process of two linear RGD-peptides Gly-Arg-Gly-Asp-Ser and Gly-Arg-Gly-Asp-Ser-Pro-Lys and one cyclic RGD-peptide cyclo(Arg-Gly-Asp-D-Tyr-Lys) is comparatively investigated by complementary analysis methods. Both techniques, in situ attenuated total reflectance Fourier transform infrared spectroscopy measurements and the in situ spectroscopic ellipsometric analysis, describe changes of the brush surface properties due to biofunctionalization. Besides, the bound RGD-peptide amount is quantitatively evaluated by ellipsometry in comparison to high performance liquid chromatography analysis data. Additionally, molecular dynamic simulations of the RGD-peptides themselves allow a better understanding of the bioconjugation process depending on the peptide properties. The significant influence on the bioconjugation result can be derived, on the one hand, of the polymer brush composition, especially from the PNIPAAm content, and, on the other hand, of the peptide dimension and its reactivity.

Enhanced immunofluorescence detection of a protein marker using a PAA modified ZnO nanorod array-based microfluidic device.

Zinc oxide (ZnO) often serves as protein microarray substrates owing to its outstanding fluorescence enhancement effect. However, the integration of functional substrates with microfluidic technology to detect cancer biomarkers still needs to be optimized and promoted, for example, the optimization of micro/nanostructure and hydrophilic modification strategies for fluorescence immunoassays. Here, ZnO nanorod arrays were constructed on the inner wall of glass capillaries through a microfluidic chemical method, and the electrostatic layer by layer self-assembly was applied to modify the nanorod array with hydrophilic polyelectrolyte-polyacrylic acid (PAA). The effects of the flow rate and the reagent concentration on the morphology of the ZnO nanorod array were investigated. The ZnO nanorod array-based glass capillary, prepared at 25 μL min-1 for 4 min with 50 mM Zn2+ in solution, showed a remarkable enhancement in fluorescence performance. In addition, the introduction of PAA suppressed the interference of nonspecific protein and improved the antibody loading capacity effectively. In the detection of carcinoembryonic antigen, the limit of detection reached 100 fg mL-1, which indicated that the ZnO@PAA nanorod array-based microfluidic device exhibits remarkable fluorescence detection performance towards protein markers and possesses potential to be applied to point-of-care diagnostics and high throughput cancer biomarker detection.

Speciation and equilibria in the H+–Al3+ - polyacrylic acid system

Equilibria between Al3+ and the polyelectrolyte polyacrylic acid (PAA) were studied in 0.1 M NaCl medium at 25 °C (M = mol dm−3). The measurements were performed as precise potentiometric titrations in which OH− was in most cases generated coulometrically. The total concentration of Al(III) and PAA varied within the limits 6.23 × 10−5–2.01 × 10−4 M and 7.20 × 10−4–1.12 × 10−3 M, resp., with a 4–18 fold excess of ligand. The value of − log{[H+]/mol dm−3} varied between 3 and 5–7, the upper limit set by drifting EMF potentials caused by the onset of a precipitation reaction. The constant capacitance model was utilized to model the experimental data. With the objective of finding a model as simple as possible that gives an acceptable fit to data, the two species AlPAA2+ and Al(OH)2PAA are postulated. The polyelectrolyte effect resulting in pH-dependent formation constants is demonstrated. Furthermore a comparison between the stability constant of the 1:1 complexes of Al3+ with acrylate− and PAA−, respectively, shows the logK value of the latter to be five units higher and is ascribed to particular properties of the polyelectrolyte.

Significances of deflocculated sludge flocs as well as extracellular polymeric substances in influencing the compression dewatering of chemically acidified sludge

Abstract Sludge extracellular polymeric substances (EPS) are frequently reported as a main factor determining sludge dewatering, but the role of sludge floc structure in influencing sludge dewatering has not been fully understood. The dewatering of chemically acidified sludge was investigated to reveal the respective role of sludge floc structure and sludge extracellular polymeric substances (EPS) in influencing the removal rate of moisture (i.e., dewatering rate) and the removal amount of moisture (i.e., dewatering extent) of acidified sludge. During the chemical acidification of sludge, serious lysis of microbial cells in sludge was induced to result in a decrease of moisture content in dewatered sludge cake, from 81.8% to only 66.7%, but both the significant increase of sludge outer layer EPS content and the deflocculated sludge flocs led to a serious deterioration of dewatering rate of acidified sludge. Further studies revealed that either decreasing sludge outer layer EPS content or modifying the deflocculated sludge flocs could improve both filtration and expression stages of compression dewatering of acidified sludge to enhance the dewatering rate of acidified sludge. Especially, only 5 mg/g dry solid of anionic synthetic organic polyelectrolyte polyacrylic acid (PAA) could condition acidified sludge to improve its dewatering rate at both filtration and expression dewatering stages through re-flocculating the deflocculated flocs in acidified sludge. Therefore, the deflocculated sludge floc structure is as significant as extracellular polymeric substances in influencing the compression dewatering of acidified sludge, and the treatment of sewage sludge through chemical acidification and followed conditioning using synthetic organic polyelectrolyte PAA can enhance the dewatering extent as well as dewatering rate.

Effective removal of calcium ions from simulated hard water using electrospun polyelectrolyte nanofibrous mats

The development of easily separated from water, high effective mineral ion removal materials is quite required in the hard water treatment system. In this study, water-stable polyelectrolyte polyacrylic acid (PAA) nanofibrous mats were fabricated by electrospinning technology and subsequent thermal crosslinking. Influence factors such as contact time, mat content, temperature and interfering ions strength were experimentally examined. The results indicated that polyelectrolyte PAA nanofibrous mats could be used as high effective Ca(II) ions removal material via complexation to form PAA−COOCa2+complex, with a maximum Ca(II) ion removal capacity of 152.8 mg/g within 60 min at 25 °C. Both equilibrium and kinetic studies showed that the behaviors of Ca(II) ions removal by polyelectrolyte nanofibrous mats followed Freundlich model and fitted pseudo-second-order model, respectively.

Accumulation of small protein molecules in a macroscopic complex coacervate.

To obtain insight into the accumulation of proteins into macroscopic complex coacervate phases, the lysozyme concentration in complex coacervates containing the cationic polyelectrolyte poly-(N,N dimethylaminoethyl methacrylate) and the anionic polyelectrolyte polyacrylic acid was investigated as a function of the mixing ratio, protein concentration and ionic strength. Maximal protein enrichment of the complex coacervate phase was observed to require the presence of all three macromolecules. Under optimized conditions the protein concentrations in the complex coacervate were as high as 200 g L(-1). Such high concentrations are comparable to the protein concentration in the cytosol, suggesting that these interesting liquid phases may serve a suitable model system for the phase behavior of the cytosol and genesis and function of membrane-less organelles. The high stability of the complexes and the salt dependent uptake of protein suggest that complex coacervates may provide a way to store hydrated proteins at high concentrations and might therefore be of interest in the formulation of high protein foods.

Supramolecular systems based on cationic surfactants: an influence of hydrotropic salts and oppositely charged polyelectrolytes

For cationic surfactant 4-aza-1-dodecyl-1-azoniabicyclo[2.2.2]octane bromide (DABCO-16), a significant decrease in the critical micelle concentration (CMC) is shown in the presence of hydrotropic salts, which is due to the efficient binding of organic counterions with the surface of micelles and charge compensation of the head groups. The effect of salts increases in the series sodium benzoate < sodium tosylate < sodium salicylate. In the presence of hydrotropes, the electrokinetic potential decreases and the size of the aggregates increases. For micellar solutions DABCO-16 in the presence of sodium tosylate and sodium salicylate, the viscosity of the solution increases significantly, which is not observed in the case of sodium benzoate. In the presence of strong polyelectrolyte sodium polystyrenesulfonate, an increase in the critical aggregation concentration is observed compared to the CMC of an individual DABCO-16 solution, whereas weak polyelectrolyte polyacrylic acid induces a significant decrease in the aggregation threshold of the surfactant. Both polyelectrolytes exert no substantial effect on the rheological properties of micellar systems.

Synthesis and Characterization of CdTe@CdS Quantum Dots Layered on Silica Nanoparticles

CdTe@CdS quantum dots, cationic polyelectrolyte poly-diallyldimethylammonium chloride, and anionic polyelectrolyte polyacrylic acid were assembled on the surface of silica nanoparticles based on the electrostatic layer-by-layer self-assembly to prepare fluorescent composite nanoparticles. Transmission electron microscopy showed that the particles had a uniform size distribution (approximately 70 nm) and good monodispersity. The fluorescence shielding effect of the silica shell was reduced and the assembled quantum dots were well protected by the sandwich structure. The nanoparticles provided strong fluorescence, high stability for storage, and low photobleaching and leakage. Furthermore, they possessed high fluorescence stability and high-concentration staining for cytoplasm, which enabled them to be used for sensitive cellular imaging analysis. Because of the presence of numerous carboxyl groups, they have potential application for biolabeling and bioanalysis.

Using jet mixing to prepare polyelectrolyte complexes: Complex properties and their interaction with silicon oxide surfaces

The influence of mixing procedure on the properties of polyelectrolyte complexes (PECs) was investigated using two complexation techniques, polyelectrolyte titration and jet mixing, the latter being a new method for PEC preparation. For the low-molecular-weight polyelectrolytes polyacrylic acid (PAA) and polyallyl amine hydrochloride (PAH), shorter mixing times produced smaller PECs, whereas for higher molecular weights of the same polyelectrolytes, PEC size first decreased with decreasing mixing time to a certain level, after which it started increasing again. This pattern was likely due to the diffusion-controlled formation of “pre-complexes”, which, in the case of low-molecular-weight polymers, occurs sufficiently quickly to form stable complexes; when polyelectrolytes are larger, however, non-equilibrium pre-complexes, more prone to aggregation, are formed. Comparing the techniques revealed that jet mixing produced smaller complexes, allowing PEC size to be controlled by mixing time, which was not the case with polyelectrolyte titration. Higher polyelectrolyte concentration during jet mixing led to the formation of larger PECs. It was also demonstrated that PEC size could be changed after preparation: increasing the pH of the PEC dispersion led to an irreversible increase in PEC size, whereas lowering the pH did not influence PEC size. The adsorption behavior of PECs formed from weak polyelectrolytes on model substrates was studied using QCM-D, SPAR, and AFM imaging; the results indicated that increasing the pH increased the amount of PECs adsorbed to model surfaces. However, the amount of PECs adsorbed to the model surfaces was low compared with other systems in all studied cases.

Insoluble complex formation between alpha-amylase from Aspergillus oryzae and polyacrylic acid of different molecular weight

The insoluble complex formation between alpha-amylase and the strong anionic polyelectrolyte polyacrylic acid was studied by using turbidimetric and enzymatic activity. The highest molecular weight polyacrylic acid (100,000 Da and 240,000 Da) proved to be suitable precipitating agents. They were insoluble at pH lower than 4–5, with a stoichiometric ratio polymer mol per protein mol of 1:52 and 1:154, respectively. Electrostatic interactions are not the only factor in the formation of insoluble complexes. High percentage of alpha-amylase enzymatic activity maintains throughout time, even in the presence of polyelectrolyte. The application of precipitation conditions found when applying a bovine homogenate showed that it is not suitable for purification even if it proved to be useful methodology for the concentration of the enzyme and can be used as a first step of purification.

Recognition and effective degradation of 17β-estradiol by anti-estradiol-antibody-immobilized TiO2 nanoparticles

Polyelectrolyte polyacrylic acid (PAA), used in the chemical modification of titanium dioxide (TiO(2)) nanoparticles, allows TiO(2) nanoparticles to remain in suspension at neutral pH. The anti-17beta-estradiol (E2) antibody was immobilized on PAA-modified TiO(2) (PAA-TiO(2)) nanoparticles via covalent bonding between the carboxylic acid of PAA and the amino group of the antibody. The anti-E2-antibody-immobilized TiO(2) (E2Ab-PAA-TiO(2)) nanoparticles can form a suspension at neutral pH, with a particle size of less than 100 nm. The E2-PAA-TiO(2) nanoparticles caused the photocatalytic degradation of a typical TiO(2) substrate, methylene blue. The anti-E2 antibody immobilized on the TiO(2) surface recognized and bound E2 in the solution, thereby improving the efficiency of E2 degradation compared with that of PAA-TiO(2) nanoparticles. These results demonstrate that the E2Ab-PAA-TiO(2) nanoparticles developed in this study can be used in water treatment technology. Furthermore, this strategy of immobilizing proteins on nanoscale TiO(2) particles creates new applications not only in the treatment of environmental waste, but also in medical and public sanitation processes.

Surface modification of hydroxyapatite to introduce interfacial bonding with polyactiveTM 70/30 in a biodegradable composite

A method was developed to improve the interfacial bonding between hydroxyapatite and a biodegradable copolymer PolyactiveTM 70/30. Hydroxyapatite was first surface modified by the polyelectrolytes polyacrylic acid or poly(ethylene-co-maleic acid) in aqueous solutions. Subsequently the surface-modified hydroxyapatite was used as filler in composites with PolyactiveTM 70/30. The strength, elongation at break and elastic modulus of the composite in aqueous environment were significantly improved by this method. Based on these experimental results, it is believed that the interface improvement is due to hydrogen bonding and/or dipole interactions formed between polyelectrolyte molecules and polyethylene glycol segments in the polymer matrix. Due to the introduction of interfacial bonding by using such method, a new biodegradable bone-bonding composite can be made.

Stability of Aqueous Suspensions of High Surface area Zirconia Powders in the Presence of Polyacrylic Acid Polyelectrolyte

ABSTRACTIn this paper results of efforts to prepare stable aqueous suspensions of high surface area (&gt; 100 m2 /gr) yttria stabilized tetragonal zirconia powders are presented using a low molecular weight ammonium polyacrylic acid deflocculant. Zetapotentials, viscosities, agglomerate sizes and sedimentation volumes have been measured to find the optimum pH and deflocculant concentration. It has been found that the optimum pH-value coincides with the pH at which the polyacrylic acid is fully dissociated. Using deflocculant concentrations below the optimum value leads to a highly unstable system, while concentrations above the optimum value influence the stability in a much weaker way.

Nature of interfacial interaction mechanisms between polyacrylic acid macromolecules and oxide metal surfaces

The mechanism for the adhesion of polyacrylic acid (PAA) coatings to oxidized metal surfaces has been studied. The work entailed studies of the mechanical and chemical interactions occurring at the interfaces between PAA polyelectrolyte macromolecules and iron (III) orthophosphate dihydrate or zinc phosphate hydrate (hopeite) crystalline films that were deposited on the metal surfaces. With respect to mechanical interactions, it was determined that the surface topography of the highly crystallized hopeite layers consisted of an open microstructure. This resulted in enhanced wettability of the oxide film by the polyelectrolyte macromolecules, thereby increasing the mechanical interlocking bond forces. Studies of the interfacial chemical reactions indicated that the conformation changes in the PAA macromolecules relate directly to the frequency of the magnitude of acid-base and divalent metallic ion crosslinking interactions between the proton-donating pendent COOH groups in PAA molecules and polar OH groups at hydrated oxide surface sites. Namely, the presence of numerous free nucleophilic ions existing on the deposited oxide film leads to a substantial increase in the coil-up and entanglement macromolecule density. These entangled complex macromolecules at the interfaces result in a decrease in the degree of chemisorption at the oxide film surfaces, whereas regularly oriented COOH groups produce strong interfacial chemisorption with the polar OH groups. Since the polyelectrolyte macromolecules have hydrophilic pendent COOH groups, the polymer structure which appears best for use as an adhesive and coating should have only enough hydrophilic COOH groups to occupy all available polar OH groups at the oxide metal surface sites.