Cationic Poly Diallyldimethylammonium Chloride Research Articles

The distribution of poly-DADMAC additive in the inkjet coating layer and its influence on the print quality

Maximizing the functionality of cationic polydiallyldimethylammonium chloride (poly-DADMAC) additive with minimal dosage in inkjet coatings can contribute to both an improvement in quality and a cost reduction. To do this, it is essential to understand how the cationic additive is distributed in the coating layer and how it affects the print quality. This study presents a three-step investigation to enhance the understanding of the distribution of poly-DADMAC, as well as its effect on inkjet print quality. First, the adsorption behavior of poly-DADMAC on silica pigments was investigated by measuring the surface charge of silica and the adsorption of the cationic additive. Second, the influence of poly-DADMAC on the printability of binder films was investigated. Finally, the effect of poly-DADMAC on the print quality of inkjet paper was examined. The addition of poly-DADMAC improved the print quality of the inkjet paper because of the improved holdout of the negatively charged colorants in the ink.

Azo modified hyaluronic acid based nanocapsules: CD44 targeted, UV-responsive decomposition and drug release in liver cancer cells

Herein, we demonstrate a novel UV-induced decomposable nanocapsule of natural polysaccharide (HA-azo/PDADMAC). The nanocapsules are fabricated based on layer-by-layer co-assembly of anionic azobenzene functionalized hyaluronic acid (HA-azo) and cationic poly diallyl dimethylammonium chloride (PDADMAC). When the nanocapsules are exposed to 365 nm light, ultraviolet photons can trigger the photo-isomerization of azobenzene groups in the framework. The nanocapsules could decompose from large-sized nanocapsules to small fragments. Due to their optimized original size (~180 nm), the nanocapsules can effectively avoid biological barriers, provide a long blood circulation and achieve high tumor accumulation. It can fast eliminate nanocapsules from tumor and release the loaded drugs for chemotherapy after UV-induced dissociation. Besides, HA is an endogenous polysaccharide that shows intrinsic targetability to CD44 receptors on surface of cancer cells. The intracellular experiment shows that the HA-azo/PDADMAC nanocapsules with CD44 targeting ability and UV-controlled intracellular drug release are promising for cancer chemotherapy.

Structure of polymer-capped gold nanorods binding to model phospholipid monolayers

We report an experimental study of the structure of polymer-capped gold nanorods (AuNRs) binding to model phospholipid monolayers to elucidate the mechanism that drives the insertion of the AuNRs into phospholipid membranes. The experimental system consists of four different cases of AuNRs interacting with lipid monolayers: cationic and anionic polymer-capped AuNRs suspended in the pure water subphase of Langmuir monolayers of zwitterionic and anionic phospholipids, separately. Liquid surface x-ray reflectivity was used to measure in situ the structure of the lipids and AuNRs at the air-water interface with sub-nanometer resolution, yielding quantitatively the amount, orientation, as well as depth of AuNR insertion into the monolayer. In the case of a zwitterionic monolayer composed of 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine, cationic Poly-diallyldimethylammonium chloride (PDC) capped AuNRs (PDC-AuNRs) adsorbed peripherally at the water-lipid interface whereas the anionic Poly-sodium 4-styrenesulfonate (PSS) capped AuNRs (PSS-AuNRs) penetrated deeply into the lipid monolayer. In the case of an anionic monolayer composed of 1-stearoyl-2-oleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (SOPG), PDC-AuNRs inserted into the monolayer whereas PSS-AuNRs were not even attracted to the monolayer. The results suggest that the adsorption process of AuNRs to model membranes may proceed through different mechanisms. In the presence of a charged membrane, electrostatic interactions drove the AuNRs to or away from the membrane depending on the nature of the charge of the lipid film and the AuNRs, while in the presence of a zwitterionic membrane, both electrostatic interactions and hydrophobic interactions mediated the insertion of the AuNRs into the membrane.

Lower molecular weight fractions of PolyDADMAC coagulants disproportionately contribute to N-nitrosodimethylamine formation during water treatment

N-nitrosodimethylamine (NDMA) is a chloramine disinfection by-product, and its formation in drinking waters can increase due to the addition of cationic polydiallyldimethylammonium chloride (polyDADMAC). PolyDADMAC is a cationic polymer added as a coagulant or coagulant aid to enhance turbidity removal during sedimentation and filtration. This paper answers two central questions to understanding the nature of the NDMA precursors in polyDADMAC. First, what is the reactivity of different molecular weight (MW) fractions of polyDADMAC with chloramines? NDMA formation potential (NDMAFP) and kinetic experiments with chloramines were conducted for non-fractionated (raw) and size-excluded fractions (<3K, 3–10K, and >10K Da.) of polyDADMAC. The lower MW fraction (<3K Da.) of polyDADMAC solutions was responsible for forming 64 ± 6% of the NDMA, despite containing only 8.7 and 9.8% of the carbon or nitrogen present in the bulk polymer. The chloramine demand kinetics of the lowest MW fraction were also >2× faster than the higher MW fractions. Therefore, in a water treatment application the lower MW polyDADMAC likely contributes to most of the NDMA attributed to the use of polyDADMAC. The second question was: can 1H and 13C nuclear magnetic resonance spectroscopy (NMR) be used to characterize the molecular structures in polyDADMAC that react with chloramines? A peak for 1H NMR dimethylamine (DMA), a known low MW NDMA precursor, was found in a commercial polyDADMAC solution and decreased upon chloramination. The estimated DMA alone could not account for the observed NDMAFP, indicating the presence of other low MW precursors. Diffusion order spectroscopy (DOSY) NMR also showed multiple lower MW organics in polyDADMAC that change upon chloramination, including a 1.5× decrease in MW, suggesting chloramines cleave CC or CN bonds. These reactions may produce intermediates responsible for NDMA formation. Polymer manufacturers could use NMR to synthesize polyDADMAC with less DMA and other low MW compounds that produce NDMA upon chloramination.

Electrical conductivity enhancement and wettability modification of (PDDA/PEDOT:PSS)n multilayer film

Conductive polyelectrolyte multilayer films composed of conductive anionic poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) and insulating cationic polydiallyldimethylammonium chloride (PDDA) were successfully prepared by layer-by-layer method. The (PDDA/PEDOT:PSS)n multilayer thickness is affected by the PDDA concentration ranging from 0.25 g.L−1 to 1 g.L−1 as well as the number of deposited bilayers and the type of salts used as electrolyte (BaCl2 or NaCl). More precisely, film thickness measured by profilometry increases with PDDA concentration, number of adsorbed bilayers and with the presence of Ba2+ cations. From UV–Visible absorbance spectroscopy, we showed that the amount of adsorbed PEDOT:PSS is greater when PDDA concentration increases and that PEDOT is still incorporated into the multilayer film especially when divalent ions are employed to improve the film growth. Water contact angles were measured on (PDDA/PEDOT:PSS)n films with PEDOT:PSS as the outerlayer. Films are more hydrophobic in the presence of Ba2+ which is probably due to a modification of the PEDOT:PSS core/shell structure. A percolation threshold leading to electrical conduction was determined as a function of the number of adsorbed bilayers. The effect of several parameters such as PDDA concentration, type of salt and temperature on conductivity and activation energy was investigated.

Fabrication of sensitive enzymatic biosensor based on multi-layered reduced graphene oxide added PtAu nanoparticles-modified hybrid electrode.

A highly sensitive amperometric glucose sensor was developed by immobilization of glucose oxidase (GOx) onto multi-layer reduced graphene oxide (MRGO) sheets decorated with platinum and gold flower-like nanoparticles (PtAuNPs) modified Au substrate electrode. The fabricated MRGO/PtAuNPs modified hybrid electrode demonstrated high electrocatalytic activities toward oxidation of H2O2, to which it had a wide linear response that ranged from 0.5 to 8 mM (R2 = 0.997), and high sensitivity of 506.25 μA/mMcm2. Furthermore, glucose oxidase-chitosan composite and cationic polydiallyldimethylammonium chloride (PDDA) were assembled by a casting method on the surface of MRGO/PtAuNPs modified electrode. This as-fabricated hybrid biosensor electrode exhibited high electrocatalytic activity for the detection of glucose in PBS. It demonstrated good analytical properties in terms of a low detection limit of 1 μM (signal-to-noise ratio of 3), short response time (3 s), high sensitivity (17.85 μA/mMcm2), and a wide linear range (0.01–8 mM) for glucose sensing. These results reveal that the newly developed sensing electrode offers great promise for new type enzymatic biosensor applications.

The fiber charge measurement depending on the poly-DADMAC accessibility to cellulose fibers

Cellulose fiber charge is a significant parameter for porous cellulose fibers, and strongly affects the swelling ability of cellulose fibers and the properties of cellulose-based materials as well. Actually, it includes surface charge and inner charge. The surface charge is mentioned often in papermaking wet-end chemistry, however, the inner charge or the total charge is paid less attention to. In this study, the cationic polydiallyldimethyl ammonium chloride (poly-DADMAC) with different molecular weight (Mw) was applied for the accessibility evaluation to the cellulose fiber charges by using polyelectrolyte adsorption technique. Results showed that higher fiber charge was detected by lower Mw poly-DADMAC (7.5–15 kDa) due to its highly efficient penetration into the fiber cell walls and neutralization with inner charges, while lower fiber charge was obtained by using higher Mw poly-DADMAC (higher than 100 kDa) because of its adsorption onto fiber surface. As a consequence, high-Mw poly-DADMAC was used to determine the surface charge of cellulose fibers, and low-Mw poly-DADMAC could be used to measure the total charge under the saturated adsorption and low ionic strength (or salts concentration). This was confirmed by SEM–EDS analysis. The low-Mw poly-DADMAC adsorption had a good agreement with conventional conductometric titration, and a linear regression equation with slope of 1.03 and regression coefficient of 0.99 was obtained.

Evaluation of candidate biocides to control the biofouling Asian clam in the drinking water treatment industry: An environmentally friendly approach

The biofouling Asian clam Corbicula fluminea greatly affects freshwater-dependent facilities in Europe and North America, including in the Great Lakes region. As chlorination has become increasingly restricted, finding alternative control agents is a priority. Due to the species' epifaunal nature, the body of knowledge on Dreissena polymorpha is larger than that on the Asian clam, and there is a tendency to assume that mitigation methods should work similarly for both species. However, this generalisation is inaccurate, and the optimisation of Asian clam control relies on species-specific toxicological data. This paper reports information on the potential of three candidate biocides for C. fluminea control: (i) the cationic polydiallyldimethylammonium chloride (polyDADMAC), (ii) potassium chloride and (iii) aluminum sulphate. While these chemicals may be employed in a range of contexts, they are particularly suitable for the highly regulated drinking water industry. LT50 values ranging from 284.3h, for polyDADMAC applied at 10mg/L, to 855.1h, for an aluminum sulphate concentration of 11mg/L, were obtained. Ecotoxicological standard tests with Pseudokirchneriella subcapitata and Daphnia magna suggested that, amongst the three biocides, potassium chloride is the one representing lower potential environmental hazard (with, for example, 48h-EC50 higher than 1g/L for Daphnia immobilisation, which compares to values of 20.2 and 112.5mg/L for polyDADMAC and aluminum sulphate, respectively). The three chemicals are promising control agents at dosages compatible with waterworks' operational requirements with polyDADMAC having the highest biocidal activity, but also posing more environmental risks.

The role of surface chemistry in determining in vivo biodistribution and toxicity of CdSe/ZnS core–shell quantum dots

To examine the effect of surface chemistry and surface charge on in vivo biodistribution and toxicity of CdSe/ZnS core–shell quantum dots (QDs), QDs with positive, negative, or PEG coating are used in this study for in vivo evaluation in a mouse model. The results suggest that QDs coated with cationic polydiallyldimethylammonium chloride (PDDA) preferentially deposit in the lung other than in the liver, while the negative and PEGylated QDs render abundant accumulation in the liver. At higher doses positive QDs with PDDA coating show severe acute toxicity due to pulmonary embolism. Independent of their surface coatings, all QDs cause injuries in specific tissues like liver, spleen, lung, and kidney, after acute and long-term exposure, and the degree of injuries is dominated by their surface properties. For the positively charged QDs, the acute phase toxicity is primarily contributed by the coating material PDDA, while coating on QDs may amplify both in vitro and in vivo toxicity of PDDA. PEGylated QDs display the slightest chronic injuries in the long-term toxicity examination in comparison to positive or negative ones.

Novel Uric Acid Sensor Based on Enzyme Electrode Modified by ZnO Nanoparticles and Multiwall Carbon Nanotubes

In this work, we report the development of a highly sensitive and stable uric acid sensor based on the synergic action of multiwalled carbon nanotubes (MWNTs) and ZnO nanoparticles. MWNTs were first cast on pyrolytic graphite (PG) wafers. ZnO nanoparticles were then decorated onto the negatively charged MWNTs via the Vapor Liquid Solid (VLS) growth. Uricase was immobilized on the ZnO nanoparticles surface because of their large differences in the isoelectric point (IEP). Last, a cationic polydiallyldimethylammonium chloride (PDDA) layer was coated onto the uricase-contained ZnO nanoparticle layer and resulted in the PDDA/uricase/ZnO/MWNTs multilayer structure. The unique multilayer structure provides a favorable microenvironment to keep the bioactivity of uricase, which led to rapid amperometric response toward uric acid. Amperometric detection of uric acid was carried out at 320 mV (vs. SCE) in 0.05 mol/L (M) phosphate buffer solution (pH 6.8). For the sensor, a wide linear response range of 5.0 µM to 1 mM with a linear sensitivity of 393 mA cm−2M−1, a detection limit of 2.0 µM (3σ), and a long-term stability of 160 days can be obtained by using differential pulse voltammetry (DPV). Testing results in human urine obtained from the sensors were also compared with the data obtained by spectrometry. For five samples with different concentrations of urine, the relative deviations between them were smaller than 3.8%. The recovery was between 96.5 and 104.0%.

Improved enzyme immobilization for enhanced bioelectrocatalytic activity of glucose sensor

In this work, we report the development of a highly sensitive and stable glucose sensor based on the synergetic effect of multi-walled carbon nanotubes (MWNTs) and ZnO nanoparticles. Since the isoelectric point (IEP) of glucose oxidase (GOx) is significantly different from that of ZnO nanoparticles, GOx was electrostatically bound to ZnO nanoparticles decorated onto a negatively charged MWNTs layer at the electrode surface via VLS growth. A cationic polydiallyldimethylammonium chloride (PDDA) layer was further coated onto the GOx-contained ZnO nanoparticle layer to prevent the leakage of GOx. This unique multi-layer structure (PDDA/GOx/ZnO/MWNTs) provided a favorable microenvironment to maintain the bioactivity of GOx, which led to rapid amperometric response toward glucose. By loading 0.5-U GOx at the sensor surface, we obtained a wide linear response range of 0.1–16 mM for this sensor. High sensitivity of 50.2 mA cm −2 M −1 was obtained with increased loading of GOx (2.0 U), leading to an even lower detection limit of 250 nM. This nanomaterials-based glucose sensor was highly sensitive and showed favorable stability over a relatively long-term storage (160 days). Importantly, we challenged our sensor with 100 human blood serum samples, and obtained consistent results with the classic spectrometric assay (correlation coefficient, 0.997).

Floc structural characteristics using conventional coagulation for a high doc, low alkalinity surface water source

Removal of natural organic matter (NOM) is well established using metal salt coagulants. In addition, flocculant aids are also commonly used to improve solid removal. The objectives of this paper is to describe the impacts of both NOM and polymer on floc structure. The study offeres a comparison of floc physical characteristics for coagulant precipitate flocs, organic-coagulant flocs and organic-coagulant-polymer flocs for optimum coagulant and polymer doses. A ferric sulphate-based coagulant was used as the primary coagulant and the polymer selected was a high molecular weight (MW) cationic polydiallyldimethylammonium chloride (polyDADMAC). Floc size, breakage, re-growth and settling characteristics were measured. Precipitate flocs were larger than organic flocs and had better settling characteristics when compared to NOM-coagulant flocs. When polymer was added, floc size and compaction was seen to further reduce. An explanation was offered in terms of the mode of flocculation involved. Floc breakage behaviour showed that polymer reduced the rate of floc degradation but did not greatly improve floc re-growth potential after breakage, which was generally poor for all of the suspensions.

Amperometric glucose biosensor based on self-assembling glucose oxidase on carbon nanotubes

A flow injection amperometric glucose biosensor based on electrostatic self-assembling glucose oxidase (GOx) on a carbon nanotube (CNT) – modified glassy carbon transducer is described. GOx is immobilized on the negatively charged CNT surface by alternatively assembling a cationic polydiallyldimethylammonium chloride (PDDA) layer and a GOx layer. The unique sandwich-like layer structure (PDDA/GOx/PDDA/CNT) formed by self-assembling provides a favorable microenvironment to keep the bioactivity of GOx and to prevent enzyme molecule leakage. The excellent electrocatalytic activity toward H 2O 2 of the fabricated PDDA/GOx/PDDA/CNT electrode indicated that the polyelectrolyte-protein multilayer does not affect the electrocatalytic properties of CNT, enabling sensitive determination of glucose. Flow injection amperometric detection of glucose is carried out at −100 mV (vs. Ag/AgCl) in 0.05 M phosphate buffer solution (pH 7.4) with a wide linear response range of 15 μM to 6 mM and a detection limit of 7 μM. The PDDA/GOx/PDDA/CNT/GC biosensor showed excellent properties for the sensitive determination of glucose with good reproducibility, remarkable stability, and freedom of interference from other co-existing electroactive species.

Giant Magnetoresistance of Electrostatic Self-Assembled Fe3O4Nanocluster and Polymer Thin-Films

ABSTRACTGiant magnetoresistance (GMR) as large as 25% at 25°C has been observed for multilayer ultrathin films of iron oxide (Fe3O4) nanoclusters and polyimide molecules alternately adsorbed onto single crystal silicon and quartz substrates using a novel self-assembly technique. This process involves the alternate dipping of a substrate into an aqueous solution of anionic polyimide precursor (polyamic salt, PAA) followed by dipping it into an aqueous solution of cationic polydiallyldimethylammonium chloride (PDDA)-coated Fe3O4, nanoparticles. The regular formation of alternating monolayers is verified by UV-vis spectroscopy and contact angle measurements. Vibrating sample magnetometry indicates the formation of ultrasoft films.