Amount Of Polyethyleneimine Research Articles

Gene Delivery Efficacy of Polyethyleneimine-Introduced Chitosan Shell/Poly(methyl Methacrylate) Core Nanoparticles for Rat Mesenchymal Stem Cells

This work investigated polyethyleneimine (PEI)-introduced chitosan (CS) (CS/PEI) nanoparticles as non-viral carrier of plasmid DNA for rat mesenchymal stem cells (MSCs). The CS/PEI nanoparticles were prepared by the emulsifier-free emulsion polymerization of methyl methacrylate monomer induced by a small amount of t-butyl hydroperxide in the presence of different concentrations of PEI mixed with CS. The resulting nanoparticles were characterized by their surface properties and buffering capacity. In vitro gene transfection was also evaluated. The introduction of PEI affected the surface charge, dispersing stability and buffering capacity of the nanoparticles. The CS/PEI nanoparticles formed a complex upon mixing with a plasmid DNA of luciferase. The complex enhanced the level of gene transfection and prolonged the time period of expression for MSCs, compared with those of plasmid DNA–original CS and PEI nanoparticles. Cytotoxicity of CS/PEI complexes with plasmid DNA was significantly low, depending on the amount of PEI introduced. It is concluded that the CS/PEI nanoparticle was a promising carrier for gene delivery of MSCs.

Application of polyethyleneimine‐modified scaffolds to the regeneration of cartilaginous tissue

In this study, we analyzed the physicochemical and biophysical properties of three-dimensional scaffolds modified using polyethyleneimine (PEI) and applied these scaffolds to the cultivation of bovine knee chondrocytes (BKCs). PEI was crosslinked in the bulk or on the surface of the ternary scaffolds comprising polyethylene oxide, chitin and chitosan. The results revealed that when the concentration of PEI was less than 300 microg/mL, the cytotoxicity of a scaffold was on the same order in the two method of modification. An increase in the concentration of PEI favored the adhesion of BKCs. When the amount of PEI in scaffolds is fixed, the surface-modified scaffolds exhibited a higher adhesion efficiency of BKCs than the bulk-modified scaffolds. For the regeneration of cartilaginous components, a higher amount of PEI in a scaffold yielded larger amounts of proliferated BKCs, secreted glycosaminoglycans, and produced collagen. In addition, the formation of neocartilage in the surface-modified scaffolds was more effective than that in the bulk-modified scaffolds. These tissue-engineered scaffolds, modified by an appropriate concentration of PEI, can be potentially applied to cartilage repair in clinical trials.

Polyethyleneimine impregnation on activated carbon: Effects of impregnation amount and molecular number on textural characteristics and metal adsorption capacities

This paper presents findings on polyethyleneimine (PEI) impregnation on palm shell activated carbon (AC) with regards to effects of impregnation amount and types of PEI used on surface characteristics as well as metal ions adsorption capacities of the AC. Fundamental interactions between PEI molecules and metal ions on textural surface (micro- and mesopores) of the AC are elucidated. Three types of low molecular weight PEI distinguished by their molecular numbers, Mn (423, 600 and 1200) are used for the impregnation process. Impregnation at 8.41 wt% 423-PEI/AC provides optimum increases for nickel and copper adsorption capacities by factors of 2.6 and 1.5 respectively at 49% reduction of Brunauer–Emmett–Teller (BET) surface area as compared to virgin AC. Only 423-PEI molecules are shown to have considerably filled the micropores of AC whereas the 600- and 1200-PEI molecules are too large (in terms of molecular sizes) to infiltrate the micropores.

Adsorption capacities of carbon dioxide, oxygen, nitrogen and methane on carbon molecular basket derived from polyethyleneimine impregnation on microporous palm shell activated carbon

In this study, palm shell-based activated carbon (AC) was used as precursor in the production of carbon molecular basket (CMB) via impregnation of polyethyleneimine (PEI). The effects of amount of PEI impregnated on AC on carbon dioxide (CO 2), oxygen (O 2), nitrogen (N 2), and methane (CH 4) adsorption capacities of CMB were investigated. Molecular basket was produced at PEI weight percentages of 0.06, 0.11, 0.13, 0.26, 0.27 and 0.28 wt%. Adsorption capacities of CO 2, O 2, N 2 and CH 4 were enhanced with increasing PEI impregnation from virgin AC to 0.26 wt% PEI/AC before the capacities decreased onwards for 0.28 and 0.29 wt% PEI/AC. The amount of PEI impregnation determined for optimum uptake of gas adsorption was 0.26 wt% PEI/AC. The maximum adsorption capacity for the gases follows the sequence: CO 2 ≫ CH 4 > O 2 > N 2 for all the CMB samples.

Buildup of Polyelectrolyte Multilayers of Polyethyleneimine and Microfibrillated Cellulose Studied by in Situ Dual-Polarization Interferometry and Quartz Crystal Microbalance with Dissipation

Polyethyleneimine (PEI) and Microfibrillated cellulose (MFC) have been used to buildup polyelectrolyte multilayers (PEM) on silicone oxide and silicone oxynitride surfaces at different pH values and with different electrolyte and polyelectrolyte/colloid concentrations of the components. Consecutive adsorption on these surfaces was studied by in situ dual-polarization interferometry (DPI) and quartz crystal microbalance measurements. The adsorption data obtained from both the techniques showed a steady buildup of multilayers. High pH and electrolyte concentration of the PEI solution was found to be beneficial for achieving a high adsorbed amount of PEI, and hence of MFC, during the buildup of the multilayer. On the other hand, an increase in the electrolyte concentration of the MFC dispersion was found to inhibit the adsorption of MFC onto PEI. The adsorbed amount of MFC was independent of the bulk MFC concentration in the investigated concentration range (15-250 mg/L). Atomic force microscopy measurements were used to image a MFC-treated silicone oxynitride chip from DPI measurements. The surface was found to be almost fully covered by randomly oriented microfibrils after the adsorption of only one bilayer of PEI/MFC. The surface roughness expressed as the rms-roughness over 1 microm2 was calculated to be 4.6 nm (1 bilayer). The adsorbed amount of PEI and MFC and the amount of water entrapped by the individual layers in the multilayer structures were estimated by combining results from the two analytical techniques using the de Feijter formula. These results indicate a total water content of ca. 41% in the PEM.

Hydrothermal synthesis of ZnO nanorod arrays with the addition of polyethyleneimine

ZnO nanorod arrays were synthesized on glass substrates coated by a ZnO seeding layer via a hydrothermal technique by adding polyethyleneimine (PEI) to the growth solution. The XRD and SEM results show that the ZnO nanorods have the single crystal wurtzite structure with the (0 0 2) direction normal to the substrates. In 50 ml growth solution of 0.05 M zinc salts, the average diameter of the nanorods was reduced drastically from 300 nm to 40 nm with the PEI amount increasing from 0 ml to 6 ml. The diameter distribution and the polycrystalline layer at the bottom of the nanorods were improved. Longer nanorods were obtained by prolonging the growth time. Based on the results, possible mechanisms that PEI adsorbs on the non-polar facets of ZnO nanorods and its coordination to zinc ions were proposed to elucidate the effect of PEI on reducing the diameters and improving the morphologies of nanorods.

Adsorption of phenol on a novel adsorption material PEI/SiO 2

In this paper, functional macromolecule polyethyleneimine (PEI) was grafted onto the surfaces of silica gel particles via the coupling effect of γ-chloropropyl trimethoxysilane (CP), and the novel adsorption material PEI/SiO 2 with strong adsorption ability for phenol was prepared. The adsorption properties of PEI/SiO 2 for phenol were researched by both static and dynamic methods. The experimental results show that PEI/SiO 2 possesses very strong adsorption ability for phenol, and the saturated adsorption amount could reach to 160 mg g −1. The empirical Freundlich isotherm was found to describe well the equilibrium adsorption data. pH and grafting amount of PEI have great influence on the adsorption amount. Diluted sodium hydroxide solution is used as eluent, and the adsorbed phenol is eluted easily from PEI/SiO 2.

Cytosolic Aspartate Aminotransferase, a New Partner in Adipocyte Glyceroneogenesis and an Atypical Target of Thiazolidinedione

We show that cytosolic aspartate aminotransferase (cAspAT) is involved in adipocyte glyceroneogenesis, a regulated pathway that controls fatty acid homeostasis by promoting glycerol 3-phosphate formation for fatty acid re-esterification during fasting. cAspAT activity, as well as the incorporation of [(14)C]aspartate into the neutral lipid fraction of 3T3-F442A adipocytes was stimulated by the thiazolidinedione (TZD) rosiglitazone. Conversely, the ratio of fatty acid to glycerol released into the medium decreased. Regulation of cAspAT gene expression was specific to differentiated adipocytes and did not require any peroxisome proliferator-activated receptor gamma (PPARgamma)/retinoid X receptor-alpha direct binding. Nevertheless, PPARgamma is indirectly necessary for both cAspAT basal expression and TZD responsiveness because they are, respectively, diminished and abolished by ectopic overexpression of a dominant negative PPARgamma. The cAspAT TZD-responsive site was restricted to a single AGGACA hexanucleotide located at -381 to -376 bp whose mutation impaired the specific RORalpha binding. RORalpha ectopic expression activated the cAspAT gene transcription in absence of rosiglitazone, and its protein amount in nuclear extracts is 1.8-fold increased by rosiglitazone treatment of adipocytes. Finally, the amounts of RORalpha and cAspAT mRNAs were similarly increased by TZD treatment of human adipose tissue explants, confirming coordinated regulation. Our data identify cAspAT as a new member of glyceroneogenesis, transcriptionally regulated by TZD via the control of RORalpha expression by PPARgamma in adipocytes.

Effects of polyethylenimine on the dispersibility of hollow silica nanoparticles

In this study, two different methods were applied to disperse hollow silica nanoparticles (HSNP); one employed polyethylenimine (PEI) as the dispersant during the synthesis processes for preparing HSNP, while the other added PEI into suspensions of the prepared HSNP and used milling treatment to achieve the desired dispersion. It was found that adding PEI during the synthesis process of HSNP had no noticeable improvement in the dispersion, while adding PEI into suspensions of the prepared HSNP and utilizing milling treatment resulted in remarkable dispersion improvement. Therefore, the latter was chosen as the method in dispersing HSNP suspensions. The adsorption of PEI on the surface of HSNP and the stability of the aqueous suspensions was investigated. The results indicated that the adsorption of PEI on the surface of HSNP would increase the repulsive energy among particles, hence reducing the agglomeration of HSNP and improving the stability of the aqueous suspensions. The change of HSNP’s ζ potential after adding PEI and the relationship between the adsorbed amount of PEI and pH were also investigated.

Impregnation of palm shell activated carbon with polyethyleneimine and its effects on Cd 2+ adsorption

Palm shell activated carbon (AC) was impregnated with low (LMW) and high molecular weight (HMW) polyethyleneimine (PEI) via batch adsorption. The maximum amount of LMW PEI adsorbed on AC was determined to be approximately 425 mg/g carbon while the maximum adsorbed HMW PEI was 2.8 mg/g carbon. The LMW PEI adsorption data fitted the Langmuir isotherm better than the Freundlich isotherm. The PEI impregnated AC were characterized via nitrogen adsorption, scanning electron microscopy, elemental analysis, thermogravimetric, Fourier transform infra red and pH drift analyses. Only LMW PEI could be successfully impregnated as monolayers on the surface of the micropores. This impregnation leads to drastic reduction of surface area and pore volume whereas impregnation of HMW PEI does not significantly affect the physical characteristics of the AC. LMW PEI impregnation appears to enhance Cd 2+ adsorption capacity of the AC while HMW PEI impregnation is found to have an opposite effect. This result shows that LMW PEI impregnation technique may have the potential to improve the batch adsorption capacity of AC for other transition metal ion adsorption as well.

Effect of Polyethylenimine on Hydrolysis and Dispersion Properties of Aqueous Si3N4 Suspensions

The roles of polyethylenimine (PEI) in the hydrolysis and dispersion properties of aqueous Si3N4 suspensions were studied in terms of the hydrolysis, adsorption, electrokinetic, and rheological measurements. It was found that the pH change of the suspensions in the acidic environment could be minimized in the presence of ≥0.5 dwb% PEI. The ammonia and oxygen measurements suggest that this phenomenon is primarily attributed to the buffer mechanism generated by the ionized PEI, instead of the protection mechanism. The constant pH enables the suspensions to retain a better stability with time at acidic pH. The adsorption of PEI on Si3N4 is a high‐affinity type at highly basic pH, but is a low‐affinity type at acidic pH. As the PEI amount increases, the adsorption shifts the isoelectric point (IEP) of Si3N4 from pH 5.9 to pH ∼11 until complete coverage is attained. The stability of Si3N4 suspensions is found to depend strongly on the saturated adsorption of PEI, which is as a function of the pH and PEI amount. Once the saturated adsorption limit is reached, the excess free PEI molecules become more detrimental to the stability with increased solid loading. The stabilization mechanisms of Si3N4 suspensions by PEI were discussed in detail.

Aqueous Processing of Textured Silicon Nitride Ceramics by Slip Casting in a Strong Magnetic Field

Recently, textured microstructure has received particular interest in the processing of advanced Si3N4 ceramics because of significant improvement in the mechanical properties and thermal conductivity. This work will report a highly textured β-Si3N4 ceramic by aqueous slip casting in a magnetic field and subsequent pressureless sintering, using commercial α-Si3N4 raw powder and a mixture of Y2O3 and Al2O3 as sintering aids. To obtain the well-dispersed Si3N4- Y2O3-Al2O3 slurries, polyethylenimine (PEI) was chosen as a dispersant. Effects of the sintering aids, PEI amount, pH and stirring time on the stability of the Si3N4 slurries were studied. It is shown that PEI is an effective dispersant for stabilizing the Si3N4-Y2O3-Al2O3 slurries that does not show a time-dependent behavior at an optimum pH ≈ 10, compared to the case in the absence of PEI. Using the 30 vol% Si3N4-Y2O3-Al2O3 slurries stabilized with 1.5 dwb% PEI at pH 10, the highly textured β-Si3N4 with 97 % relative density could be obtained by slip casting in a magnetic field of 12 T and subsequent sintering at 1800 oC for 1 h. The textured microstructure is featured by the alignment of c-axis of β-Si3N4 crystals perpendicular to the magnetic field, and the Lotgering orientation factor, f, is determined to be 0.8.

Polyethyleneimine functionalized iron oxide nanoparticles as agents for DNA delivery and transfection

A novel, efficient DNA delivery and transfection agent has been developed by chemically attaching short chain polyethyleneimine (PEI) molecules (M.W. = 423 and 1800) to the surface of composite iron oxide nanoparticles (250 nm in diameter). These particles are not only capable of delivering DNA but also can be driven by an external magnetic field. During DNA binding experiments, a remarkably low N : P ratio of <1 was recorded. This is due to the more effective distribution of the PEI molecules across the surface of the nanoparticles in comparison to particles where PEI is attached to the surface via simple electrostatic interactions. This new attachment strategy allows the use of smaller amounts of PEI with potential reduction in toxic side-effects.

Chelating adsorption properties of PEI/SiO 2 for plumbum ion

In this paper, a novel adsorption material PEI/SiO 2 with strong adsorption ability towards heavy-metal ions was prepared. In preparation of PEI/SiO 2, functional macromolecule polyethyleneimine (PEI) was grafted onto the surfaces of silica gel particles via the coupling effect of γ-chloropropyl trimethoxysilane (CP). The adsorption properties of PEI/SiO 2 for Pb 2+ ion were studied by both static and dynamic methods. The experimental results show that PEI/SiO 2 possesses very strong adsorption ability for Pb 2+ ion, the saturated adsorption amount could reach to 17.5 mg g −1, and the empirical Langmuir isotherm was found to describe well the equilibrium adsorption data. The pH and grafting amount of PEI have great influence on the adsorption amount. The Pb 2+ ions adsorbed on PEI/SiO 2 are eluted easily by diluted hydrochloric acid solution.

Physicochemical characterization of poly( l-lactic acid) and poly( d, l-lactide-co-glycolide) nanoparticles with polyethylenimine as gene delivery carrier

Polymer nanoparticles have been used as non-viral gene delivery systems and drug delivery systems. In this study, biodegradable poly( l-lactic acid) (PLA)/polyethylenimine (PEI) and poly( d, l-lactide-co-glycolide) (PLGA)/PEI nanoparticles were prepared and characterized as gene delivery systems. The PLA/PEI and PLGA/PEI nanoparticles, which were prepared by a diafiltration method, had spherical shapes and smooth surface characteristics. The size of nanoparticles was controlled by the amount of PEI, which acted as a hydrophilic moiety, which effectively reduced the interfacial energy between the particle surface and the aqueous media. The nanoparticles showed an excellent dispersive stability under storage in a phosphate-buffered saline solution for 12 days. The positive zeta-potentials for the nanoparticles decreased and changed to negative values with increasing plasmid DNA (pDNA) content. Agarose gel electrophoresis showed that the complex formation between the nanoparticles and the pDNA coincided with the zeta-potential results. The results of in vitro transfection and cell viability on HEK 293 cells indicated that the nanoparticles could be used as gene delivery carriers.

Evaluation of transferrin-polyethylenimine conjugate for targeted gene delivery

With the aim to improve the specificity and to reduce the cytotoxicity of polyethylenimine (PEI), we have synthesized the conjugates of the branched PEI (25 kDa) with transferrin. The transferrin-PEI (TP) conjugates with five compositions were synthesized using periodate oxidation method and confirmed by FT-IR spectroscopy and gel permeation chromatography. The free amine contents of TP conjugates, which were able to condense and deliver DNA, increased as the amount of PEI increased. TP/DNA polyplexes were characterized by measuring gel electrophoresis, ethidium bromide fluorescence quenching, particle size and zeta potential of complexes. Complete complexation of the polyplexes was observed above the N/P ratio of 5 in TP/ DNA, and above 3 in PEI/DNA, respectively. The zeta potential of the complexes decreased as the amount of transferrin in TP conjugates increased. Transfection efficiency of TP conjugates was evaluated in HeLa cell and Jurkat cell systems. Among the five compositions of TP conjugates, TP-2 system mediated a higher beta-galactosidase gene expression than PEI system in Jurkat cell which was known to express elevated numbers of transferrin receptors. From the results of the cell viability based on MTT assay, TP conjugates showed lower cytotoxicity compared with the PEI system. We expect that the TP conjugate can be used efficiently as a nonviral gene delivery vector.

The effect of polyelectrolyte on fabrication of macroporous ZrO2 ceramics

The effect of polyethylenimine (PEI) on preparing macroporous ZrO2 materials via heterocoagulation coating process was investigated, using ZrO2 nanoparticles as the building materials and polystyrene spheres as the organic templates. When PEI was applied to modify the surface charge of ZrO2 nanoparticles, it was found that 40–50% of initial PEI amount remained excess in the suspensions. Adsorption of excess PEI on the surface of polystyrene spheres resulted in partial coating of the polystyrene spheres by ZrO2 nanoparticles at 1 wt% PEI and even no coating at 3 wt% PEI. Microstructure studies revealed that ZrO2 ceramics prepared without using PEI had quite ordered macropores, while the ZrO2 framework was partially collapsed at 1 wt% PEI and disordered macropores were observed at 3 wt% PEI.

Effect of polyethylenimine on the dispersion and electrophoretic deposition of nano-sized titania aqueous suspensions

The dispersion and electrophoretic deposition (EPD) behavior of an aqueous suspension of nano-sized titania particles stabilized with a dispersant of polyethylenimine (PEI) were systematically investigated. The adsorption behavior of PEI on the titania surfaces indicated a high affinity adsorption of PEI at a high pH value while a low affinity adsorption was observed at a low pH value, which is consistent with the viscosity behavior of the suspension. The influences of the suspension pH, the added amount of PEI and the salt addition on the electrophoretic deposition behavior of the suspensions were studied.

Dispersion of SiC Suspensions with Cationic Dispersant of Polyethylenimine

The influences of suspension pH and the added amount of the cationic polyethylenimine (PEI) dispersant on the stability of SiC suspensions have been investigated by measuring their zeta potential, rheological properties and adsorption behavior. The PEI adsorption state on the SiC surfaces under different pH conditions played a key role in the modification of the particle surface charges and the stability of suspensions. The pH range of stable suspensions was determined depending on the added amount of PEI.

Adsorption of polyethyleneimine characterized by spectroscopic ellipsometry

Abstract Polyethyleneimine (PEI) is a well known gene transfection reagent that has been extensively studied in the pass two decades. In this work, we have explored its physiochemical properties by examining its interfacial absorption at the hydrophilic silicon oxide/water interface and its ability to immobilize bioactive DNA under physiological conditions. Its surface excess was found to show a gradual increase with pH between pH 3 and pH 10. At pH 7 the surface absorbed amount increased with increasing salt concentaration. The amount of DNA immobilzed was found to be controlled by the charge ratio between PEI and DNA under these physiological conditions. Thus, the amount of bioactive DNA immobilized can be tuned by badjusting the amount of PEI preadsorbed. This study provides useful information for fabrication of biosensors and gene chips via interfacial adsorption.