Polyelectrolyte Poly Diallyldimethylammonium Chloride Research Articles

Kosmotropes and chaotropes: Specific ion effects to tailor layer-by-layer membrane characteristics and performances

So-called specific ion effects strongly impact physicochemical phenomena in among others, morphologies of polymeric membranes. This can be correlated to the identity of the ions, rather than just to their charge or concentration. We use this effect to tune the properties of layer-by-layer membranes prepared with the polyelectrolytes polydiallyldimethylammonium chloride and polystyrene sodium sulfonate. To systematically study this, membranes were prepared using different salts (NaBr, NH4Cl, MgCl2, NaCl, LiCl, MgSO4, NaH2PO4, (NH4)2SO4, Na2SO4). The specific ion effects were evaluated thanks to the classification of salts and PEs into kosmotropes (well hydrated) and chaotropes (poorly hydrated) following the law of matching water affinities (LMWA). The impact of the type of anions and cations on the multilayer formation and membrane performances was evaluated. Membranes prepared with kosmotropic salts achieved stable performances after only 4 bilayers, and almost 6 times higher water permeabilities than membranes prepared with chaotropic salts without compromising and often even improving the membrane's size exclusion behaviour. The salts used tuned the membranes charge: Kosmotropic salts delivered negatively charged membranes with Na2SO4 and MgCl2 retentions till 97% and 10% respectively, while chaotropic salts formed more positively charged membranes with reversed behaviour with Na2SO4 and MgCl2 rejection of 20 and 89%.

Coaggregation assisted by cationic polyelectrolyte and clay minerals as a strategy for the removal of polystyrene microplastic particles from aqueous solutions

This study aims to test the removal of polystyrene microplastics (PSMPs) from aqueous solution by using the cationic polyelectrolyte polydiallyldimethylammonium chloride (polyDADMAC) to stimulate coaggregation of PSMPs and clay minerals with different shape and surface charge properties, namely kaolinite, montmorillonite, and palygorskite. Colloidal stability, aggregation kinetics and surface charge properties were evaluated simultaneously. For this purpose sedimentation experiments in test tubes were run together with measurements on the course of the hydrodynamic diameter over time by dynamic light scattering and linked with particle charge analyses. In the pH range from 4 to 8, negative surface charge of all clay minerals introduced as well as PSMPs can be neutralized by the addition of polyDADMAC. When being introduced into suspensions of PSMPs and clay minerals, the long-chain poly-DADMAC acts as a bridge to structuralize a matrix of PSMPs and clay particles, by which coaggregation is favoured. The efficiency to remove PSMPs from aqueous solution, follows the order: palygorskite > montmorillonite > kaolinite. Although these clay minerals have been used in water purification for decades, our findings with the amendment of an organic polycation illustrate their extended ability, particularly for palygorskite, to efficiently remove emerging pollutants such as microplastics.

Viscosity of Polyelectrolyte Surfactant Complexes—The Importance of the Choice of the Polyelectrolyte Seen for the Case of PDADMAC Versus JR 400

Some oppositely charged polyelectrolyte (PE) surfactant mixtures show a remarkable increase in viscosity near charge equilibrium, while other very similar systems do not show any appreciable effect. The exact structural prerequisites to achieve a significant increase in viscosity are still unclear. In previous work, we investigated the structure and dynamics of oppositely charged polyelectrolyte surfactant complexes (PESCs) formed from sodium dodecylsulfate (SDS) and the cationically modified hydroxyethyl cellulose JR 400, which does enhance the viscosity around charge equilibrium enormously. Here, we study PESCs consisting of SDS and the cationic PE polydiallyldimethylammonium chloride (PDADMAC) which do not significantly increase the viscosity of solutions under similar conditions. Apparently very similar ingredients in PESCs can lead to largely different macroscopic behavior. Using small-angle neutron scattering, rheology, and neutron spin-echo spectroscopy, we gain insights into the system’s mesoscopic structure and dynamics. Different from that in SDS/JR 400, no intermixed aggregates are formed but instead a cylindrical core–shell structure. In it, the PDADMAC is much less strongly bound and possesses much higher dynamics which explains the much lower viscosity.

Influence of polyelectrolytes on increasing sensitivity of an immunofluorescent analysis based on plasmon silver nanoparticles

It was studied the dependence of the interaction of the components of the immunofluorescence test system for the quantitative determination of prostate specific antigen based on plasmon silver nanoparticles on the physicochemical nature of various polyelectrolytes used to coat films of silver nanoparticles. It has been shown that the use of a weakly charged polycationic polyelectrolyte poly-L-lysine can increase the antigenic binding of the test system by 2.34 times, and the use of a highly charged polycationic polyelectrolyte polydiallyldimethylammonium chloride increases the binding affinity of prostatic specific antigen by 5 times. When developing various immunochemical test systems using films of silver nanoparticles, an important parameter is the choice of a polyelectrolyte for coating a silver nanolayer, since the physicochemical and electrostatic properties of the polyelectrolyte can significantly affect both the sorption capacity of the solid phase and the conformational state functional activity of immobilized protein molecules. Both specificity and sensitivity of the immunochemical test system, as well as the minimum possible detectable concentration of bioanalyte, largely depend on these parameters.

Adsorption of Polyelectrolyte onto Nanosilica Synthesized from Rice Husk: Characteristics, Mechanisms, and Application for Antibiotic Removal.

Adsorption of the polyelectrolyte polydiallyldimethylammonium chloride (PDADMAC) onto nanosilica (SiO2) fabricated from rice husk was studied in this work. Nanosilica was characterized by X-ray diffraction, Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Adsorption of PDADMAC onto SiO2 increased with increasing pH because the negative charge of SiO2 is higher at high pH. Adsorption isotherms of PDADMAC onto silica at different KCl concentrations were fitted well by a two-step adsorption model. Adsorption mechanisms of PDADMAC onto SiO2 are discussed on the basis of surface charge change, evaluation by ζ potential, surface modification by FTIR measurements, and the adsorption isotherm. The application of PDADMAC adsorption onto SiO2 to remove amoxicillin antibiotic (AMX) was also studied. Experimental conditions such as contact time, pH, and adsorbent dosage for removal of AMX using SiO2 modified with PDADMAC were systematically optimized and found to be 180 min, pH 10, and 10 mg/mL, respectively. The removal efficiency of AMX using PDADMAC-modified SiO2 increased significantly from 19.1% to 92.3% under optimum adsorptive conditions. We indicate that PDADMAC-modified SiO2 rice husk is a novel adsorbent for removal of antibiotics from aqueous solution.

Ultrasensitive aptamer biosensor for malathion detection based on cationic polymer and gold nanoparticles

In this work, we have demonstrated a novel sensing strategy for an organophosphorus pesticide namely, malathion, employing unmodified gold nanoparticles, aptamer and a positively charged, water-soluble polyelectrolyte Polydiallyldimethylammonium chloride (PDDA). The PDDA when associated with the aptamer prevents the aggregation of the gold-nanoparticles while no such inhibition is observed when the aptamer specific pesticide is added to the solution, thereby changing the color of the solution from red to blue. This type of biosensor is quite simple and straightforward and can be completed in a few minutes without the need of any expensive equipment or trained personnel. The proposed method was linear in the concentration range of 0.5–1000pM with 0.06pM as the limit of detection. Moreover, the proposed assay selectively recognized malathion in the presence of other interfering substances and thus, can be applied to real samples for the rapid screening of malathion.

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.

Preparation of immuno-probes based on europium-chelate-adsorbed silica nanoparticles and magnetic nanoparticles and their application in detection of hepatitis B surface antigen

In this paper, a simple and reproducible method to synthesize intense fluorescence and photostable silica nanoparticles has been developed. Firstly, silica nanoparticles were prepared based on the Stober method, and hydrophobic europium chelates were adsorbed into their micro-holes by ultrasonication and phase-transfer solvent. Then they were modified by cationic polyelectrolyte polydiallyldimethylammonium chloride (PDAC) and anionic polyelectrolyte poly(acrylic acid) (PAA) layer by layer. Using them as detection probes and magnetic nanoparticles as capture probes, a novel immunoassay for determination of hepatitis B surface antigen (HBsAg) was proposed. Under the optimal experimental conditions, the immuno-probes performed with a good linear range over 10–200 ng mL−1 with a calibration curve equation of y = −549.24 + 652.44x (R = 0.9901). Based on the hydrophobicity and intense fluorescence europium chelates absorbed into silica nanoparticles, one-step fluorescence immunoassay has been realized and may have potential applications in clinical assays.

聚电解质包覆的铕(Ⅲ)配合物@SiO2荧光纳米粒的合成与性质

Uniform silica nanoparticles were synthesized via St(o|¨)ber method,and fluorescent europium complex with three chelate ligands(i.e.dibenzoylmethane,phenanthroline and acrylic acid)has been prepared.The hydrosoluble silica nanoparticles adsorbed liposoluble europium chelate with strong fluorescence in the aid of ultrasonication and phase-transfer solvent,and then were coated by cationic polyelectrolyte polydi-allyldimethylammonium chloride and anionic polyelectrolyte poly(acrylic acid)(PAA)one layer by one layer. The obtained fluorescent nanoparticles were charactered by transmission electron microscopy,ultraviolet spectrophotometer, infrared spectrophotometer,fluorescence spectrophotometer and Zeta potential.These nanoparticles have the advantages of uniform size,strong fluorescence,good photostability and leakage free. Futhermore,the nanoparticles with rich carboxy groups resulting from PAA coated on their surfaces made the surface modification and bioconjugation easier.These properties suggest their great potential in the application field of biology and medicine.

Salt-induced fusion of microcapsules of polyelectrolytes

Fusion of microcapsules of the polyelectrolytes poly-diallyldimethylammonium chloride (PDADMAC) and sodium poly-styrenesulfonic acid (PSS) is achieved during the evaporation of NaCl solution in open chambers. The increasingly concentrated salt solution induces a series of faster and accumulating effects in the structure of the membranes and the cores of microcapsules. It creates defects in the membranes, decreases the electrostatic repulsion of polyelectrolytes in the membranes, causes a conformational change of the polyelectrolytes, increases the osmotic pressure gradient across the microcapsule membranes, and decreases the supporting force of the core by sucking water outwards. Due to the surface tension of the microcapsules and the hydrophobic interaction of the polyelectrolytes, microcapsules decrease the surface area and finally fuse. During fusion, their shapes change from peanut to oblate and then finally to round spheres. The neutral polymer molecules in the core diffuse and mix but do not leak out. The polyelectrolytes in the membranes do not mix due to the molecular entanglement. The work on fusion with salt as a critical parameter is important to approach promising artificial micro-containers, whose novel functions arise from the mixing of the inner content.

Distinctive electrokinetic behavior of nanoporous silica particles treated with cationic polyelectrolyte

In this study we show, for the first time, that the streaming potential of aqueous suspensions of nanoporous silica gel, after treatment with the cationic polyelectrolyte poly-diallyldimethylammonium chloride (poly-DADMAC), can depend very strongly on the concentration of background electrolyte. An increase in the electrical conductivity from 60 to 1000 μS/cm resulted in an approximately 1000-fold increase in the amount of poly-DADMAC that was required to reach an endpoint of zero streaming potential. Results were explained by two contributions to the overall electrokinetic behavior—one due to the outer surfaces and another due to the interior surfaces of nanopore spaces that were inaccessible to the polyelectrolytes. Experiments with cyclical changes in salt content revealed a high degree of reversibility; such observations help to rule out explanations based on salt-induced desorption or enhancement of pore penetration. Supplementary tests with non-porous glass fibers showed no evidence of the distinctive electrokinetic behavior observed in the case of nanoporous particles. Effects of polymer molecular mass and pH, evaluated under similar experimental conditions, agreed with well-established trends.

Enhanced removal of heavy metal ions bound to humic acid by polyelectrolyte flocculation

The enhanced removal of heavy metal ions from solution, such as Pb 2+ and Zn 2+, was studied by binding the ions to humic acid (HA) and then coagulating–flocculating with the cationic polyelectrolyte polydiallyldimethylammonium chloride (PolyDADMAC). The effect of the dosage of PolyDADMAC, the pH level and the concentrations of HA and metal ions were studied. Ultrafiltration was used to separate bound metal ions from free ions in solution. The removal of bound metal ions was found to increase with the extent of coagulation–flocculation of the HA by PolyDADMAC. The pH affects the removal efficiency of bound (complexed) metal, in so much as it affects the binding strength of metal ions to the HA. The removal efficiency of metal also increases with the initial concentration of HA. The effective coagulation–flocculation region of the HA by PolyDADMAC is affected by the initial concentration of the metal ions; an increase in the concentration leads to a decrease in the amount of PolyDADMAC required. Humic substances have the advantage of being naturally occurring, and the results indicate that such a complexation–flocculation process is of potential interest for the removal of heavy metals during water treatment.

Characterization of synthetic polyelectrolytes by capillary electrophoresis

Capillary electrophoresis in entangled polymer solutions was applied to determine the molecular mass and polydispersity of polyelectrolytes. The separation selectivities of different polyethylene glycols as buffer additive can be correlated to their average molecular mass. A universal curve correlating the selectivity and the molecular mass could be obtained by using the instrinsic viscosity of the polyethylene glycol. The separation of poly(2-vinylpyridine) standards was compared to the separation of poly(4-vinylpyridine) standards. An indirect detection system was developed to characterize the cationic polyelectrolyte polydiallyldimethyl ammonium chloride. Various polymers with oppositely charged groups (polycarboxybetaines) were investigated with respect to structure dependence, pH dependence and molecular mass dependence of inter- and intramolecular association.

Preparation of Ultrathin Nanocomposite Films from Exfoliated Aluminosilicate/Coumarin Dye Complexes and Cationic Polyelectrolytes by Layer-by-Layer Deposition

ABSTRACTMultilayer nanocomposite films have been prepared from exfoliated aluminosilicate/coumarin dye complex through layer-by-layer self-assembly using cationic polyelectrolytes. Coumarin dye molecules were intercalated into the layered aluminosilicate by an ion exchange reaction. Particles of the hectorite/dye complex were delaminated by extensive shaking and sonication of their water suspension into 2∼3 nm-thin silicate layers with molecules of the dye adsorbed on their surface. Atomic force microscopy and transmission electron microscopy data are in agreement with such a model. Ultrathin multilayered films were prepared using layer-by-layer self-assembly from the aluminosilicate platelets and a cationic polyelectrolyte polydiallyldimethylammonium chloride (PDAC). Linear build-up of the films up to 20 cycles was demonstrated and investigated using absorption spectroscopy and spectrofluorometer. The resulting transparent films have exhibited strong characteristic blue-green fluorescence due to coumarin dye molecules adhered to the exfoliated hectorite platelets.

Cationic and anionic polymeric additives for wall deactivation and selectivity control in the capillary electrophoretic separation of proteins in food samples

Both cationic and anionic polymeric additives were used for the capillary electrophoretic separation of proteins in food samples. The cationic polyelectrolyte polydiallyldimethylammonium chloride was more effective in minimizing protein–wall interactions at pH 3 than at pH 7, presumably due to greater repulsion between the adsorbed polymer and proteins. Improved resolution was observed in the presence of the co-additive sodium octanesulphonate, presumably due to ion-pairing interactions with protein sample components. The anionic polymer dextran sulfate produced relatively high efficiencies, 120 000–180 000 theoretical plates, for protein separation, presumably because the polymer adsorbed to the capillary wall, rendering the surface more hydrophilic. In addition to reduced protein–wall interactions, improved resolution was observed, presumably due to analyte–polymer ion-exchange/ion-pairing interactions. When poly(vinyl sulphonic acid) was used instead of dextran sulfate, broader profiles were obtained and fewer components were resolved, presumably due to reduced wall deactivation that is related to the lower hydrophilicity of poly(vinyl sulphonic acid).