Propylene Imine Research Articles

Obtaining of highly-active catalysts of unsaturated compounds hydrogenation by using supercritical carbon dioxide

Polymer frameworks have been for the first time impregnated with rhodium and palladium compounds in a supercritical carbon dioxide medium. The polymeric carriers were the mesoporous phenol-formaldehyde resin and cross-linked dendrimer networks, based on poly(propylene imine) and poly(amido amine) dendrimers. The metal compounds were rhodium acetylacetonate and palladium carboxylates including their fluoro-substituted derivatives and palladium hexafluoroacetylacetonate. Using the IR-spectroscopy method, we have shown that the metal content in the polymers was in the range of 0.3–2.0 wt.% depending on the polymer nature, cross-linking agent type and cross-linking degree. We have obtained the samples of polymer supports with nanosized metal particles through hydrogen reduction of immobilized rhodium and palladium compounds at P(H2) = 6–10 MPa, T = 60 °C, 4 h time. The average rhodium particle size was 1–2 nm. It has been shown that the obtained nanocomposites were extremely active catalysts for hydrogenation of unsaturated hydrocarbons.

Cationic amphiphilic dendrimers with tunable hydrophobicity show in vitro activity

The widespread use of antibiotics has led to an increase in the number of strains resistant to major antibacterial pharmaceuticals. Many synthesized quaternary ammonium compounds possess antibacterial, antifungal and antiviral properties. Incorporation of quaternary ammonium moieties into dendrimers represents a promising strategy for the preparation of novel antimicrobial biomaterials. Here, poly(quaternary ammonium) chloride dendrimers were synthesized by functionalizing poly(propylene imine) (PPI) dendrimer with various lengths of alkyl chains. In vitro antimicrobial assays indicate that the amphiphilic dendrimers are potent antimicrobial agents with activity against multidrug-resistant pathogens such as the methicillin-resistant Staphylococcus aureus.

Effect of nanoparticle metal composition: mono- and bimetallic gold/copper dendrimer stabilized nanoparticles as solvent-free styrene oxidation catalysts

A range of mono- and bimetallic AumCun nanoparticles (NPs), with varying metal compositions, was prepared by using a third-generation diaminobutane poly(propylene imine) (G3 DAB-PPI) dendrimer, modified with alkyl chains, as a stabilizer. It was found that the length of the peripheral alkyl chain, (M1 (C15), M2 (C11), and M3 (C5)), had a direct influence on the average nanoparticle size obtained, confirming the importance of the nanoparticle stabilizer during synthesis. The Au NPs showed the highest degree of agglomeration and polydispersity, whereas the Cu NPs were the smallest and most monodisperse of the NPs. The bimetallic NPs sizes were found to vary between those of the monometallic NPs, depending on the metal composition. Interestingly, the bimetallic NPs were found to be the most stable, showing very little variation in size over time, even up to 9 months. The DSNs were evaluated in the catalytic oxidation of styrene, using either H2O2 or TBHP as oxidant. Here, we show that the bimetallic DSNs are indeed the superior catalysts when compared to their monometallic analogues, under the same reaction conditions, since a good compromise between stability and activity can be achieved where the Au provides catalytic activity and the Cu serves as a stabilizer. These AumCun bimetallic DSNs present a less expensive and more stable catalyst with negligible loss of activity, opening the door to green catalysis.

Redox-sensitive, cholesterol-bearing PEGylated poly(propylene imine)-based dendrimersomes for drug and gene delivery to cancer cells.

Stimuli-responsive nanocarriers have attracted increased attention as materials that can facilitate drug and gene delivery in cancer therapy. The present study reports the development of redox-sensitive dendrimersomes comprising disulfide-linked cholesterol-bearing PEGylated dendrimers, which can be used as drug and gene delivery systems. Two disulfide-linked cholesterol-bearing PEGylated generation 3 diaminobutyric polypropylenimine dendrimers have been successfully synthesized via an in situ two-step reaction. They were able to spontaneously self-assemble into stable, cationic, nanosized vesicles (or dendrimersomes) with lower critical aggregation concentration values for high-cholesterol-bearing vesicles. These dendrimersomes were able to entrap both hydrophilic and hydrophobic dyes, and they also showed a redox-responsive sustained release of the entrapped guests in the presence of a glutathione concentration similar to that of a cytosolic reducing environment. The high-cholesterol-bearing dendrimersomes were found to have a higher melting enthalpy, increased adsorption tendency on mica surface, entrapping ability for a larger amount of hydrophobic drugs, and increased resistance to redox-responsive environments in comparison with their low-cholesterol counterpart. In addition, both dendrimersomes were able to condense more than 85% of the DNA at all the tested ratios for the low-cholesterol vesicles, and at dendrimer : DNA weight ratios of 1 : 1 and higher for the high-cholesterol vesicles. These vesicles resulted in an enhanced cellular uptake of DNA, by up to 15-fold when compared with naked DNA with low-cholesterol vesicles. As a result, they increased the gene transfection on the PC-3 prostate cancer cell line, with the highest transfection being obtained with low-cholesterol vesicle complexes at a dendrimer : DNA weight ratio of 5 : 1 and high-cholesterol vesicle complexes at a dendrimer : DNA weight ratio of 10 : 1. These transfection levels were about 5-fold higher than those observed when treated with naked DNA. These cholesterol-bearing PEGylated dendrimer-based vesicles are, therefore, promising as redox-sensitive drugs and gene delivery systems for potential applications in combination cancer therapies.

Dendrimer supported Fe/Ni bimetallic composites immobilized in polyethersulfone membranes for effective degradation of arginine containing microcystins

The degradation study on arginine containing microcystins (MCY – LR, MCY – YR and MCY - RR) was conducted using poly (propylene imine) dendrimers (G2 and G3) supported Fe/Ni bimetallic composites immobilized in polyethersulfone (PES) membrane. The membrane composites namely PES/G21FeNi, PES/G22FeNi, PES/G31FeNi and PES/G32FeNi were synthesized characterized for FTIR, SEM (with EDS) and AFM studies. Batch degradation studies to remove microcystins from standard and extracted solutions were carried out at the pH of 7.2 ± 0.03 for an equilibrium time of 90 min. The degradation efficiency greater than 80% was achieved for the standard solutions of all the three microcystin congeners and extracted solution of MCY – LR. The compliance of pseudo – first – order kinetics was approved from the regression coefficients. The linear model applied using JMP software implied the validation of 96.7% due to variables. The possible degradation mechanism was explored in the study based on the adsorption followed by degradation of microcystins as a consequence of Fe/Ni participation on the platform of dendrimers.

Synthesis and hydrogenation application of Pt-Pd bimetallic nanocatalysts stabilized by macrocycle-modified dendrimer.

Different generations of poly(propylene imine) (Gn-PPI) terminated with N-containing 15-membered triolefinic macrocycle (GnM) (n = 2, 3, 4, 5) were prepared. The bimetallic nanoparticle catalysts GnM-(Ptx/Pd10−x) (x = 0, 3, 5, 7, 10) were prepared by the synchronous ligand-exchange reaction between GnM and the complexes of Pt(PPh3)4 and Pd(PPh3)4. The structure and catalytic properties of GnM-(Ptx/Pd10−x) were characterized via Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, energy-dispersive spectroscopy and inductively coupled plasma atomic emission spectroscopy. The novel bimetallic Pd–Pt nanoparticle catalysts stabilized by dendrimers (DSNs) present higher catalytic activities for the hydrogenation of dimeric acid (DA) than that of nitrile butadiene rubber (NBR). It can be concluded that bimetallic Pd–Pt DSNs possess alloying and synergistic electronic effects on account of the hydrogenation degree (HD) of DA and NBR. Furthermore, the HD of DA and NBR shows a remarkable decrease with the incremental generations (n) of GnM-(Pt3/Pd7) (n = 2, 3, 4, 5).

Selective Levulinic Acid Hydrogenation in the Presence of Hybrid Dendrimer‐Based Catalysts. Part I: Monometallic

AbstractHybrid Ru‐containing catalysts, based on poly(propylene imine) (PPI) dendrimers, immobilized in silica pores, were synthesized and characterized by transmission electron microscopy and X‐ray photoelectron spectroscopy. The synthesized Ru catalysts proved their efficiency in the selective hydrogenation of levulinic acid and its esters at 80 °C, 30 bar of H2, and 50 % volume substrate concentration in water. Quantitative yields of γ‐valerolactone were obtained for both micro‐ and mesoporous Ru catalysts within 2 h with catalytic activity as high as 1610 h−1. The reaction rate and selectivity on γ‐valerolactone were found to depend on several factors such as carrier structure, temperature, presence of water, and substrate/Ru ratio. The novelty of these hybrid materials is the presence of both weak acid (SiO2) and organic base centers (dendrimer amino groups), enhancing the dispersion of Ru nanoparticles. The presence of amino groups in the catalyst stabilizes the Ru nanoparticles during the synthesis and promotes the adsorption of levulinic acid on the surface of Ru nanoparticles during the reaction. Synthesized hybrid Ru catalysts can be reused several times without significant loss of activity.

A Dendrimer Supported Electrochemical Immunosensor for the Detection of Alpha‐feto protein – a Cancer Biomarker

AbstractThe electrochemical detection of alpha‐feto protein based on novel gold nanoparticles‐ poly(propylene imine) dendrimer platform is reported. The platform was prepared by co‐electrodeposition of gold nanoparticles and generation 3 poly (propylene imine) dendrimer on a glassy carbon electrode. Each modifying step was characterised by cyclic voltammetry and electrochemical impedance spectroscopy. The electrochemical measurements showed that the platform was stable, conducting and exhibited reversible electrochemistry. Results obtained from the electrochemical impedance spectroscopy interrogation in [Fe(CN)63−/4−] redox probe showed a marked reduction in charge transfer resistance (Rct) after each modification step. The immunosensor was prepared by immobilisation of a probe anti‐alpha feto protein (AFP) on the platform for 3 hrs at 35 °C followed by blocking the surface with bovine serum albumin to minimise non‐specific binding. The prepared immunosensor was used to detect AFP over a wide concentration range from 0.005 to 500 ng/mL and detection limits of 0.0022 and 0.00185 ng/mL were obtained for SWV and EIS measurements respectively. The immunosensor gave good stability over a period of fourteen days when stored at 4 °C.

Структура жидкокристаллических поли(пропилениминовых) дендримеров низших генераций по данным рентгеновского рассеяния

Структура жидкокристаллических поли(пропилениминовых) дендримеров низших генераций по данным рентгеновского рассеяния

Modification of wool protein fiber with plasma and dendrimer: Effects on dyeing with cochineal

In this study, plasma treatment and a poly(propylene imine) dendrimer were employed to improve the dyeability of wool fibers with cochineal natural dye. FESEM, EDX, AFM and FTIR techniques were employed to investigate the effects of these treatments on chemical and physical properties of wool fibers. The etching of the surface layer of wool fibers and increased roughness after plasma treatment was confirmed by FESEM and AFM images. EDX and FTIR analyses confirmed the creation of oxygen-containing groups and attachment of dendrimer molecules on wool fibers after plasma and dendrimer treatments respectively. The effects of different dyeing parameters on dye absorption and the applicability of different isotherm and kinetic models on the dyeing process were investigated. The results showed that the kinetics of absorption of cochineal on raw, plasma-treated and dendrimer-treated fibers was best fitted with the pseudo-second-order model and the isotherms of the dyeing processes followed the Freundlich model.

Palladium nanoparticles on dendrimer-containing supports as catalysts for hydrogenation of unsaturated hydrocarbons

A method for the synthesis of encapsulated palladium nanoparticles of size to 5nm in the pores of specially prepared supports, which are polymer networks based on poly(amidoamine) (PAMAM) and poly(propylene imine) (PPI) dendrimers, is proposed. It was found that particle size distributions, as well as catalytic activity and selectivity of the resulting materials in hydrogenation of unsaturated compounds significantly depend on the structure features of the support (nature and generation of dendrimer, size and rigidity of a crosslinking agent, and the use of a template in the synthesis). The best values of specific activity were achieved for styrene (86,000h−1), phenylacetylene (103,700h−1) and 1,3-cyclohexadiene (65,000h−1). It was established that the catalysts based on PAMAM dendrimers, synthesized in the presence of template, were superior to their analogues, synthesized without template, in terms of activity. An inverse relationship was observed for catalysts, based on PPI dendrimers, for all substrates with the exception of phenylacetylene. The catalysts based on palladium nanoparticles, encapsulated into dendrimer networks, can be repeatedly used without a noticeable loss of activity.

Blockage of Wnt/β-Catenin Signaling by Nanoparticles Reduces Survival and Proliferation of CLL Cells In Vitro-Preliminary Study.

The Wnt/β-catenin signaling pathway is shown to play a significant role in the control of the survival, proliferation, and differentiation of hematopoietic cells. Studies have confirmed that aberrant activation of canonical Wnt signaling occurs in various forms of leukemia, and is crucial for chronic lymphocytic leukemia (CLL) pathogenesis. The aim of the study is to evaluate the influence of maltotriose (M3) modified fourth generation poly(propylene imine) dendrimers (PPI-G4) on Wnt/β-catenin pathway gene expression in CLL (MEC-1) cells and to compare these findings with those obtained with fludarabine (FA). Microarray data analysis reveals seven of 19 Wnt/β-catenin pathway genes whose expression changes significantly during dendrimer and FA treatment: WNT10A, WNT6, and CDH1 among others. PPI-G4-M3 is already known to influence MEC-1 cell apoptosis and proliferation. The obtained results suggest that the reduction in cell survival under the influence of glycodendrimers and FA may be due to loss of Wnt signaling.

Hybrid graphene oxide/DAB-Am-16 dendrimer: Preparation, characterization chemical reactivity and their electrocatalytic detection of l-Dopamine

Graphene oxide (GO) was chemically modified with a poly(propylene)imine Generation 3.0 dendrimer (DAB-Am-16). The characterization, structure and properties of hybrid graphene oxide/DAB-Am-16 dendrimer was studied by Raman spectroscopy, Fourier-Transforming Infrared Spectroscopy (FT-IR), X-Ray Photoelectron Spectroscopic (XPS), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Thermogravimetric analysis. After functionalized the hybrid material (GOD) can interact with copper and subsequently with hexacyanoferrate (III) ions (GODHCu). The GODHCu incorporated into a graphite paste electrode (20% w/w) was applied to an electrocatalytic detection of neurotransmitter l-dopamine using differential pulse voltammetry. The analytical curve showed a linear response in the concentration range from 1.0 × 10−7 to 1.0 × 10−5 mol L−1 with a corresponding equation Y(A) = 1.706 × 10−5 + 0.862 [l-dopamine] and a correlation coefficient r2 = 0.998. The detection limit was 6.36 × 10−7 mol L−1 with a relative standard deviation of ±4% (n = 3) and an amperometric sensitivity of 0.862 A/mol L−1.

Diglycolamide-functionalized dendrimers: Studies on Americium(III) pertraction from radioactive waste

Abstract Diglycolamide (DGA)-functionalized poly(propylene imine) diaminobutane dendrimers were evaluated as the carrier in supported liquid membranes (SLMs) for selective recovery of trivalent actinides over uranium. The 0, 1st, and 2nd generation dendrimers with 2, 4, and 8 DGA moieties, termed as L I , L II , and L III , respectively, gave D Am values of 0.11 ± 0.02, 41.9 ± 3.21 and 109.4 ± 6.22 in solvent extraction studies using 1 mmol/L ligand solutions in a diluent mixture of 95% n -dodecane + 5% iso -decanol. SLM studies using polytetrafluoroethylene flat sheet membrane filters impregnated with 1 mmol solutions of L II and L III suggested quantitative mass transfer of Pu 4+ , Am 3+ , and Eu 3+ from 3 mol/L HNO 3 in about 5 h. Various diffusional parameters affecting SLM transport have been calculated for better understanding the transport data. The stability of the SLM was also studied over a period of five days.

EPR detection of presumable quantum behavior of iron oxide nanoparticles in dendrimeric nanocomposite

The superparamagnetic γ-Fe2O3 nanoparticles (average diameter of 2.5nm) encapsulated in poly(propylene imine) dendrimer have been investigated by Electron Magnetic Resonance (EMR). EMR measurements have been recorded in perpendicular and parallel configurations in the wide temperature range (4.2–300K). It has been shown that the model based on the spin value S=30, corresponding to the total magnetic moment of the nanoparticle, can be used to interpret the experimental results and the proof of the quantum behavior of γ-Fe2O3 nanoparticles.

Poly(propylene imine) dendrimer-grafted nanocrystalline cellulose: Doxorubicin loading and release behavior

4th-generation poly(propylene imine) (PPI)-grafted nanocrystalline cellulose (NCC) is prepared via iterative Michael addition of acrylonitrile onto amine-functionalized NCC as initial core and homogeneous hydrogenation of nitrile groups to primary amines. Successful grafting of dendrimers onto NCCs is confirmed by TEM, FT-IR, XPS, TGA and elemental analyses. Also, peripheral primary amines of dendrimer-grafted NCCs are conjugated with folic acid (FA) to investigate bioconjugation effect on drug release behavior of nanostructures. FA-conjugated and nonconjugated nanostructures are loaded with DOX and exposed to environments with different pH values to examine release behavior. Also, drug release kinetics is studied by fitting of experimental data with release models. At different pH values, nonconjugated nanostructures show higher cumulative drug release than FA-conjugated systems while loading content was higher for conjugated systems. Drug release from nonconjugated nanostructures is modeled using Korsmeyer-Peppas model that describes release from polymeric matrix. However, in conjugated system, Higuchi model is the best one due to the better solubility of DOX in release media than cavities of grafted dendrimers.

Synthesis and characterization of poly(propylene imine)-dendrimer-grafted gold nanoparticles as nanocarriers of doxorubicin

The aim of current work is synthesis 4th-generation-poly(propylene imine) (PPI)-dendrimer modified gold nanoparticles (Au-G4A) as nanocarriers for doxorubicin (DOX) and studying in vitro drug release kinetics from nanocarriers into different media. Accordingly, AuNPs were synthesized by reduction of chloroauric acid (HAuCl4) aqueous solution with trisodium citrate and modified with cysteamine to obtain amine-functionalized (Au-NH2) nanoparticles. Au-NH2 nanoparticles were used as multifunctional cores and participated in Michael addition of acrylonitrile and reduction process by lithium aluminum hydride (LAH) to synthesize Au-G4A nanoparticles. Also, peripheral primary amine groups of Au-G4A were conjugated with folic acid (FA) (Au-G4F) to study the bioconjugation effect on drug release behavior of nanostructures. Ultraviolet spectroscopy (UV–vis), atomic force microscopy (AFM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and thermal gravimetric analysis (TGA) were used to approve the synthesis of different nanostructures. Finally, Au-G4A and Au-G4F samples were loaded with DOX and exposed to environments with different pH values to examine the release properties of nanostructures. Also, drug release kinetics was investigated by fitting of experimental data with different release models. As a result, synthesized dendritic structures showed Higuchi and Korsmeyer-Peppas models release behavior due to better solubility of drug in release media with respect to dendrimer cavities and drug release through polymeric matrix respectively.

Synthesis of poly(propylene imine) dendrimers via homogeneous reduction process using lithium aluminium hydride: Bioconjugation with folic acid and doxorubicin release kinetics

The heterogeneous reduction process for synthesis of poly(propylene imine) (PPI) dendrimer has been replaced by a novel and homogeneous process. Accordingly, to prepare half generations, acrylonitrile was added to amine groups via Michael addition reaction. Then, nitrile groups were reduced via homogeneous hydrogenation using lithium aluminium hydride to synthesize fifth‐generation PPI dendrimers with ethylenediamine core. Also, peripheral primary amine groups were conjugated with folic acid (FA). Fourier transform infrared and 13C NMR spectroscopies and gel permeation chromatograph y were used to prove the synthesis of the various structures. Finally fifth‐generation and FA‐conjugated fifth‐generation PPI dendrimers were loaded with doxorubicin and exposed to environments with different pH values to examine the release properties of the structures. Also, drug release kinetics was investigated by fitting experimental data with various release models. The synthesized dendritic structures showed Higuchi model release behaviour due to better solubility of drug in release media with respect to dendrimer cavities.

Dendrimer-Stabilized Ru Nanoparticles Immobilized in Organo-Silica Materials for Hydrogenation of Phenols

New hybrid catalysts based on Ru nanoparticles, encapsulated into poly(propylene imine dendrimers), immobilized into silica pores, were synthesized and examined for the hydrogenation of alkyl-substituted phenols. The corresponding alkyl-substituted cyclohexanols were presented as the major reaction products, while incomplete hydrogenation products appeared to be minor. A competition between the sterical factors of dendrimer-containing carriers and the electronic factors of substrate substituents influenced the hydrogenation rate of the alkyl-substituted phenols. The carrier structure was found to have a significant influence on both the physical and chemical properties of the catalysts and their hydrogenation activity. The synthesized hybrid catalysts appeared to be stable after recycling and could be re-used several times without significant loss of activity.

Preparation of Rh metallic nanoparticle stabilized by 15-membered nitrogen-containing triolefinic macrocycle-ended poly(propylene imine) dendrimer and its catalytic hydrogenation for nitrile-butadiene rubber

Two different generations of poly(propylene imine) dendrimers (GnPPI, n = 2, 3) terminated by 15-membered nitrogen-containing triolefinic macrocycle (15-MAC) on the periphery (Gn-M) were synthesized. The structure and composition of Gn-M were characterized by FT-IR, 1H NMR, and elemental analysis. The Rh metallic dendrimer-stabilized nanoparticles (Rh DSNs) were prepared by utilizing Gn-M as stabilizers and analyzed by UV-vis spectroscopy. Transmission electron microscopy (TEM) was adopted to characterize the size and particle morphology of Rh DSNs. The G3-(Rh) DSNs demonstrated higher catalytic activity than G2-(Rh) DSNs for the hydrogenation of nitrile-butadiene rubber (NBR).