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1.
It was shown that the block structure of alginate significantly affects the mechanism of formation and properties of its water-soluble polyelectrolyte complexes with cationic derivatives of hydroxyethyl cellulose. Alginate that contains residues of only mannuronic acid remains in solution in the form of coils, and the incorporation of guluronic acid residues gives rise to formation of a network structure. A difference in the structure of polyelectrolyte complexes is explained by different rigidities of blocks formed by residues of mannuronic and guluronic acids having different conformations of the pyranose ring. 相似文献
2.
The build-up of polyelectrolyte multilayers of microfibrillated cellulose and cationic polyelectrolytes 总被引:4,自引:0,他引:4
Wågberg L Decher G Norgren M Lindström T Ankerfors M Axnäs K 《Langmuir : the ACS journal of surfaces and colloids》2008,24(3):784-795
A new type of nanocellulosic material has been prepared by high-pressure homogenization of carboxymethylated cellulose fibers followed by ultrasonication and centrifugation. This material had a cylindrical cross-section as shown by transmission electron microscopy with a diameter of 5-15 nm and a length of up to 1 microm. Calculations, using the Poisson-Boltzmann equation, showed that the surface potential was between 200 and 250 mV, depending on the pH, the salt concentration, and the size of the fibrils. They also showed that the carboxyl groups on the surface of the nanofibrils are not fully dissociated until the pH has reached pH = approximately 10 in deionized water. Calculations of the interaction between the fibrils using the Derjaguin-Landau-Verwey-Overbeek theory and assuming a cylindrical geometry indicated that there is a large electrostatic repulsion between these fibrils, provided the carboxyl groups are dissociated. If the pH is too low and/or the salt concentration is too high, there will be a large attraction between the fibrils, leading to a rapid aggregation of the fibrils. It is also possible to form polyelectrolyte multilayers (PEMs) by combining different types of polyelectrolytes and microfibrillated cellulose (MFC). In this study, silicon oxide surfaces were first treated with cationic polyelectrolytes before the surfaces were exposed to MFC. The build-up of the layers was monitored with ellipsometry, and they show that it is possible to form very well-defined layers by combinations of MFC and different types of polyelectrolytes and different ionic strengths of the solutions during the adsorption of the polyelectrolyte. A polyelectrolyte with a three-dimensional structure leads to the build-up of thick layers of MFC, whereas the use of a highly charged linear polyelectrolyte leads to the formation of thinner layers of MFC. An increase in the salt concentration during the adsorption of the polyelectrolyte results in the formation of thicker layers of MFC, indicating that the structure of the adsorbed polyelectrolyte has a large influence on the formation of the MFC layer. The films of polyelectrolytes and MFC were so smooth and well-defined that they showed clearly different interference colors, depending on the film thickness. A comparison between the thickness of the films, as measured with ellipsometry, and the thickness estimated from their colors showed good agreement, assuming that the films consisted mainly of solid cellulose with a refractive index of 1.53. Carboxymethylated MFC is thus a new type of nanomaterial that can be combined with oppositely charged polyelectrolytes to form well-defined layers that may be used to form, for example, new types of sensor materials. 相似文献
3.
The morphology of aqueous solutions of polyelectrolytes and oppositely charged lipids is the subject of extensive colloid science research, because of their application in industry and medicine, the latter especially for gene therapy. In this work, we show that complexes of two different cationic lipids with the polyelectrolyte sodium poly(acrylic acid), PAA, share similar morphology with the complexes of those lipids with nucleic acids, implying a broader and universal packing phenomenon. We characterized by direct-imaging cryogenic-temperature transmission electron microscopy (cryo-TEM), dynamic light scattering (DLS), and zeta (ζ)-potential two cationic lipids, 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) and bis(11-ferrocenylundecyl) dimethylammonium bromide (BFDMA), which are used in gene transfection, at equivalent lipid/polyelectrolyte charge ratio. Our results revealed that, for both types of complexes, onion-like multilamellar nanostructures formed, which exhibited similar morphology as in complexes of DNA or oligonucleotides (lipoplexes), based on the same lipids. Our findings suggest that the onion-like packing may be energetically favorable for a wide range of polyelectrolyte-liposome systems, from oligonucleotides and DNA to PAA. 相似文献
4.
Baumgart M Lindley M Wright D Anklam MR 《Langmuir : the ACS journal of surfaces and colloids》2005,21(11):4862-4867
Solubilization isotherms for various phenols in cetylpyridinium chloride (CPC)-polyelectrolyte gel aggregates have been determined in order to compare solubilization within these aggregates with that in free micelles and to examine the effects of gel chemistry and structure on solubilization. The isotherms describing solubilization are quite similar to those found for free surfactant in solution. Solutes that are more hydrophobic give rise to larger solubilization constants with trends similar to what is seen for hydrophobic effects in adsorption from aqueous solutions onto hydrophobic solids. The solubilization constants decrease as the fraction of solute in the aggregates increases, indicating that the solutes partition into the palisade region of the aggregates. Solubilization is found to be quite insensitive to changes in gel structure (cross-linker varying from 1% to 3%) and chemistry (poly(acrylic acid) versus poly(methacrylic acid) and neutralization from 50% to 100%). However, the switch from poly(acrylic acid) to poly(methacrylic acid) did give rise to a slight decrease in magnitude of the slope of the isotherm. The most significant factors appear to be the initial concentration of surfactant in solution and the ratio of surfactant solution to gel amount. A decrease in surfactant concentration (especially combined with an increase in solution volume) gives rise to a decrease in solubilization constants. 相似文献
5.
Vesicle aggregation in aqueous mixtures of negatively charged polyelectrolyte and conventional cationic surfactant 总被引:1,自引:0,他引:1
Vesicle aggregation induced by different environmental factors, including the addition of divalent metal ions, decrease of pH, and increase of temperature--was investigated through turbidity measurement, fluorescence measurement, and transmission electron microscope observation in aqueous solutions of hydrolyzed styrene-maleic anhydride copolymer (HSMA) mixed with dodecyltriethylammonium bromide (C(12)Et(3)). The vesicle aggregation can be explained by the dehydration of the vesicle surface through cations addition or temperature increase based on an analysis of the interaction between vesicles. Moreover, the steric repulsion was introduced to the system and the control of vesicle aggregation was achieved. 相似文献
6.
V. E. Dreval’ G. B. Vasil’ev E. A. Litmanovich V. G. Kulichikhin 《Polymer Science Series A》2008,50(7):751-756
The rheological properties of aqueous solutions of poly(acrylic acid), poly(diallyldimethyldiammonium chloride), and their mixtures at 25°C have been studied. The concentrated solutions of the mixtures contain 18 wt % of both polymers taken at different ratios. The ratio of cationogenic and anionogenic groups φ varied from 0 to 0.4 is taken as a criterion for selection of mixture composition. An increase in φ, reflecting a more intense formation of polyelectrolyte complexes in solution, is accompanied by a significant rise in the low-frequency loss modulus and, especially, in the storage modulus, as well as by an increase in viscosity over the entire studied range of shear rates. This behavior may be explained by the presence of an additional spatial structure with junctions formed by interacting complementary charged groups. In the general case, the formation of poly(acrylic acid)-poly(diallyldimethyldiammonium chloride) polyelectrolyte complexes is said to take place in solution. The excess of rheological characteristics of mixture solutions over the corresponding characteristics of poly(acrylic acid) solutions is found to be the power function of parameter φ. The additional spatial network derived from polyelectrolyte complexes and occurring in solution is destroyed at lower shear stresses than is the network of intermolecular entanglements. At high shear stresses, orientational effects may cause phase separation of the systems owing to a change in the hydrophilic-hydrophobic balance between complexes of poly(acrylic acid) with poly(diallyldimethyldiammonium chloride) and water. 相似文献
7.
Wang Y Zhan R Li T Pu KY Wang Y Tan YC Liu B 《Langmuir : the ACS journal of surfaces and colloids》2012,28(1):889-895
We report a simple assay for visual detection of single nucleotide polymorphisms (SNPs) with good sensitivity and selectivity. The selectivity is determined by Escherichia coli (E. coli) DNA ligase mediated circular formation upon recognition of the point mutation on DNA targets. Rolling cycle amplification (RCA) of the perfect-matched DNA target is then initiated using the in situ formed circular template in the presence of Phi29 enzyme. Due to amplification of the DNA target, the RCA product has a tandem-repeated sequence, which is significantly longer than that for the SNP strand. Direct addition of a cationic conjugated polymer of poly[9,9'-bis(6'-(N,N,N-trimethylammonium)hexyl)fluorene-co-9,9'-bis(2-(2-(2-(N,N,N-trimethylammonium)ethoxyl)-ethoxy)-ethyl)fluorene tetrabromide] containing 20 mol% 2,1,3-benzothiadiazole (PFBT(20)) into the RCA solution leads to blue-whitish fluorescent color for SNP strand and yellowish fluorescent color for amplified DNA, due to PFBT(20)/DNA complexation induced intrachain/interchain energy transfer. To further improve the contrast for visual detection, FAM-labeled peptide nucleic acid (PNA) was hybridized to each amplified sequence, which is followed by the addition of poly{2,7-[9,9-bis(6'-N,N,N-trimethylammoniumhexyl)]fluorene-co-2,5-difluoro-1,4-phenylene dibromide} (PFP). The PNA/DNA hybridization brings PFP and FAM-PNA into close proximity for energy transfer, and the solution fluorescent color appears green in the presence of target DNA with a detection limit of 1 nM, which is significantly improved as compared to that for most reported visual SNP assay. 相似文献
8.
Ogawa K Sato S Kokufuta E 《Langmuir : the ACS journal of surfaces and colloids》2005,21(11):4830-4836
Polyelectrolyte complex formation of a strong polyanion, potassium poly(vinyl alcohol) sulfate (KPVS), with positively charged nanogels was studied at 25 degrees C in aqueous solutions with different KCl concentrations (C(s)) as a function of the polyion-nanogel mixing ratio based on moles of anions versus cations. Used as the gel sample was a polyampholytic nanogel consisting of lightly cross-linked terpolymer chains of N-isopropylacrylamide, acrylic acid, and 1-vinylimidazole; thus, the complexation was performed at pH 3 at which the imidazole groups are fully protonated to generate positive charges. Turbidimetric titration was employed to vary the mixing ratio. Also employed for studies of the resulting complexes at different stages of the titration were dynamic light scattering (DLS) and static light scattering (SLS) techniques. It was found from the titration as well as DLS and SLS that there is a critical mixing ratio (cmr) at which both the size and molar mass of the complexed gel particles abruptly increase. The value of the cmr at C(s) = 0 or 0.01 M (mol/L) was observed at approximately 1:1 mixing ratio of anions versus cations but at lower mixing ratios than the 1:1 ratio under conditions of C(s) = 0.05 and 0.1 M. At the mixing ratios less than the cmr, the molar mass of the complex agrees with that of one gel particle with the calculated amount of the bound KPVS ions, indicating the formation of an "intraparticle" KPVS-nanogel complex, by the aggregation of which an "interparticle" complex is formed at the cmr. During the process of the intraparticle complex formation, both the hydrodynamic radius by DLS and the radius gyration by SLS decreased with increasing mixing ratio, demonstrating the gel collapse due to the complexation. At C(s) = 0 or 0.01 M and under conditions where the amount of KPVS bindings was less than half of the nanogel cations, however, the decrease of the hydrodynamic radius was very small, while the radius gyration fell monotonically. These results were discussed in connection with a collapse of dangling chains attached to the nanogel surface by the binding of KPVS. 相似文献
9.
The influence of cationic poly(diallyldimethylammonium chloride) on the morphology and phase behavior of anionic phospholipid vesicles was investigated using differential scanning calorimetry, fluorescent microscopy and light scattering technique. A wide range of polymer concentration has been examined for the first time. The polycation can bind electrostatically to the vesicles to compensate, neutralize and reverse the vesicular charge, depending on the molar ratio of cationic to anionic group R. For R<1, charge compensation weakened the electrostatic repulsion between the lipid molecules, leading to formation of polymer-modified vesicles, each with an increased number of bilayers. The bilayer exhibits a rising main phase transition temperature from a gel to liquid crystalline state. This behavior persisted until R≈1 around the neutralization condition, where the complexes became largest and precipitate. With R>1, charge reversal took place, the complex size reduced. Interestingly, the main phase transition temperature was found for the first time to shift back towards the original value in the absence of polymer for large enough R. Although the thermal behavior was nearly independent of the polymer molecular weight, the complex morphology could be different. 相似文献
10.
Herein, we bring novel insights into a water-soluble conjugated polyelectlyte by deeply studying its properties in cells and observe fl uorescence enhancement of blue emission and turn-on of long-wavelength emission of PFP in HepG2 cells. 相似文献
11.
Zhishuang Ye Li Li Liheng Dai Yunwei Wang Qingsong Yang Regine von Klitzing Xuhong Guo 《Journal of polymer science. Part A, Polymer chemistry》2020,58(21):3018-3030
The selective uptake of bovine serum albumin (BSA) and β-glucosidase (β-G) by annealed and quenched cationic spherical polyelectrolyte brushes (SPB) was systematically studied by combining turbidimetric titration, dynamic light scattering and small angle X-ray scattering (SAXS). These two kinds of SPB consist of a same polystyrene core and a dense shell of poly (2-aminoethyl methacrylate hydrochloride) (PAEMH) and poly [2-(methacryloyloxy) ethyl] trimethylammonium chloride (PMAETA), respectively. Results reveal that the adsorption/desorption of proteins on SPB can be easily controlled by changing external conditions (pH and ionic strength). For a particular annealed or quenched SPB, there is a significant difference of the interaction pH regions between the brush and the two proteins, and this difference can be tuned by ionic strength. At low ionic strength, quenched brushes were more suitable for selective adsorption of BSA and β-G, while annealed brushes performed better at high ionic strength. SAXS analysis demonstrated that volume exclusion effect played a remarkable role in protein uptake by both SPB, and larger proteins were more likely to be adsorbed on the outer layer of the brush. The unique core-shell structure and controllable chain types make SPB an excellent candidate in selective adsorption/separation of proteins of different sizes. 相似文献
12.
A study using coagulation-flocculation and ultrafiltration (UF)methods for pulp and paper mills’ wastewater (WW)was carried
out. The reduction efficiencies of turbidity and chemical oxygen demand (COD), the removal efficiency of total suspended solids
(TSS) and absorbance at 254 nm were the main evaluating parameters. Using coagulation-flocculation, the efficiencies of alum
and polyaluminum chloride (PACl)were studied, when used alone and when coupled with flocculant aids. During the coagulation-flocculation
process, use of a single coagulant, the coagulant dosage, and the pH, play an important role in determining the coagulation
efficiency. At the optimum PACl dosage of 840 mg L−1 and optimum pH of 9.0, turbidity reduction was found to be 94.5%. A combination of inorganic coagulant and flocculant, or
polymer was applied, in which PACl was used coupled with the polyelectrolytes Organopol WPB20 and WPB40. PACl coupled with
Organopol WPB20 by optimal pH 9 gave a 98.3% reduction of turbidity, 91.9% removal of TSS, and a 60.2% reduction in COD. Ultrafiltration
trials were carried out on a pilot scale. A tubular module was used with ceramic membrane. This membrane is a multi-channel
membrane with an active surface layer made of Al2O3 and ZrO2. Within the acidic range, the turbidity and TSS were removed at above 99%. 相似文献
13.
Loading and release behaviors of compressed polyelectrolyte multilayers composed of poly(styrenesulfonate sodium salt) and poly(diallyldimethylammonium chloride) were investigated using fluorescein and rhodamine 6G as indicators by confocal laser scanning microcopy, fluorescence spectroscopy, and UV-vis spectroscopy. Compression of the multilayers resulted in a more densely packed microstructure, leading to the decrease of fluorescence intensity of the incorporated probes to 80% of its initial value, and much slower releasing rate as well as smaller releasing amount regardless of the types of the probes and the presence of salt. Utilizing the difference of loading and release rates between the compressed and the uncompressed regions, arrays of dye reservoirs have been fabricated on a chemical homogeneous but physical heterogeneous multilayer film. 相似文献
14.
Mauricio R. Pinto Chunyan Tan Michael B. Ramey John R. Reynolds Troy S. Bergstedt David G. Whitten Kirk S. Schanze 《Research on Chemical Intermediates》2007,33(1-2):79-90
The quenching behavior of a water-soluble cationic poly (para-phenylene) bearing quaternized ammonium side groups (P-NEt 3 + ) was studied. P-NEt 3 + is efficiently quenched by sodium anthraquinone-2,6-disulfonate (AQS) and sodium 1,4,5,8-naphthalenediimide-N,N’-bis (methylsulfonate) (NDS) in aqueous solution via a photo-induced electron-transfer mechanism. Absorption spectra of the NDS/P-NEt 3 + ion-pair complex indicated formation of a stable charge-transfer complex in the ground state. A large spectral shift and band broadening occurred during AQS/P-NEt 3 + complex formation, which is believed to arise due to P-NEt 3 + conformational changes induced by hydrophobic interactions. Finally, a protein sensor that relies on the quenching behavior of P-NEt 3 + was designed based on the quencher-tether-ligand (QTL) approach. AQS tethered to biotin (AQS-E-Biotin) was used along with P-NEt 3 + to sense avidin. 相似文献
15.
《先进技术聚合物》2018,29(7):1895-1901
This study aimed to develop polyelectrolyte‐structured antimicrobial food packaging materials that do not contain any antimicrobial agents. Cationic hydroxyethyl cellulose was synthesized and characterized by Fourier‐transform infrared, 1H NMR, and 13C NMR spectroscopy. Its nitrogen content was determined by Kjeldahl method. Polyelectrolyte‐structured antimicrobial food packaging materials were prepared using hydroxyethyl cellulose, cationic hydroxyethyl cellulose, and sodium alginate. Antimicrobial activity of materials was defined by inhibition zone method (disc diffusion method). Thermal stability of samples was evaluated by thermal gravimetric analysis and differential scanning calorimetry. Surface morphology of samples was investigated by SEM. The obtained results prove that produced food packaging materials have good thermal and antimicrobial properties, and they can be used as food packaging material in many industries. 相似文献
16.
Bogdanovic G Sennerfors T Zhmud B Tiberg F 《Journal of colloid and interface science》2002,255(1):44-51
The formation and structure of multilayer films containing a cationic polyelectrolyte and anionic silica nanoparticles were studied by means of ellipsometry and atomic force microscopy. Three types of silica particles of different sizes were examined. The density and thickness of the films as well as the adsorption kinetics appear to be strongly dependent on the choice of particle; smaller particles favor the formation of smooth and dense films with a higher content of the inorganic component. 相似文献
17.
Miyake M Ogawa K Kokufuta E 《Langmuir : the ACS journal of surfaces and colloids》2006,22(17):7335-7341
We studied complex formation in an aqueous salt-free system (pH approximately 3 and at 25 degrees C) between nanogel particles having opposite charges. Anionic gel (AG) and cationic gel (CG) particles consist of lightly cross-linked N-isopropylacrylamide (NIPA) copolymers with 2-acrylamido-2-methylpropane sulfonic acid and with 1-vinylimidazole, respectively. The number of charges per particle was -4490 for AG and +20 300 for CG, as estimated from their molar masses (3.33 MD for AG and 11.7 MD for CG) by static light scattering (SLS) and their charge densities (1.35 mmol/g for AG and 1.74 mmol/g for CG) by potentiometric titration. The complexes were formed through the addition of AG to CG and vice versa using a turbidimetric titration technique. At the endpoint of the titration, the aggregate formed was a complex based upon stoichiometric charge neutralization: CG(n)()(+) + xAG(m)()(-) --> CG(n)()(+) (AG(m)()(-))(x)() where x = (n)()/(m)(). At different stages of the titration before the endpoint, the resulting complexes were examined in detail using dynamic light scattering, SLS, and electrophoretic light scattering (ELS). The main results are summarized as follows: (i) When AG with a hydrodynamic radius (R(h)) of 119 nm is added to CG (R(h) approximately 156 nm), the (R(h)) of the complex size decreases from 156 to 80 nm. (ii) In contrast to this (R(h)) change, the molar mass increases from 11.7 MD to 24 MD with increasing amounts of added AG. (iii) Upon addition of CG to AG, the complex formed has the same size ((R(h)) approximately 80 nm) and the same molar mass (55 +/- 2.5 MD) until 55 +/- 5% of AG has been consumed in the complexation. To understand these results, we used the following two models: the random model (RM), in which the added AG particles uniformly bind to all of the CG particles in the system via a strong electrostatic attraction, and the all-or-none model (AONM), in which part of the AG particles in the system preferably bind to the added CG particles to neutralize their electric charges but the other AG particles are uncomplexed and remain in the system. The complex formations upon addition of AG to CG and CG to AG were elucidated in terms of RM and AONM, respectively. 相似文献
18.
Kokufuta E Ogawa K Doi R Kikuchi R Farinato RS 《The journal of physical chemistry. B》2007,111(29):8634-8640
The geometric characteristics of nanogel particles in aqueous solutions were studied by determining their ratios of radius of gyration (mean-square radius; Rg) to hydrodynamic radius (Rh), Rg/Rh, derived from static light scattering and dynamic light scattering experiments, respectively. The various nanogel samples studied included ones composed of lightly cross-linked N-isopropylacrylamide (NIPA) polymer, NIPA-based anionic or cationic copolymers, and amphoteric terpolymers. Polyelectrolyte complexes between anionic or cationic nanogels and oppositely charged polyions or nanogels having opposite charges were also studied. Most NIPA and NIPA-based polyelectrolyte nanogels in a swollen state had Rg/Rh values >0.775, which is the theoretically predicted value for a solid sphere. In a collapsed state, one may expect nanogel particles to be spherical in shape; however, this was not the case for a variety of nanogel samples, either with or without charges. These data were consistent with the idea that the surfaces of these nanogel particles were decorated with attached dangling chains. The Rg/Rh data from polyelectrolyte-nanogel complexes, however, indicated different structures from this. It was found that most of the polyelectrolyte-nanogel complex particles had Rg/Rh approximately 0.775. This suggested that the complexed nanogel particles were spherical in shape and that there were no dangling surface chains. 相似文献
19.
20.
Composite films were prepared by electrophoretic deposition of poly(ethylenimine) or poly(allylamine hydrochloride) combined with cathodic precipitation of zirconia. Films of up to several micrometers thick were obtained on Ni, Pt, stainless-steel, graphite, and carbon-felt substrates. When the concentration of polyelectrolytes in solutions and the deposition time were varied, the amount of the deposited material and its composition can be varied. The electrochemical intercalation of yttria-stabilized zirconia particles into the composite films has been demonstrated. Obtained results pave the way for the electrodeposition of other polymer-ceramic composites. The deposits were studied by thermogravimetric analysis, X-ray diffraction analysis, scanning electron microscopy, and atomic force microscopy. The mechanisms of deposition are discussed. 相似文献