Polyethylenimine-coated Magnetic Nanoparticles Research Articles

Magnetic flocculants and selective adsorbents for the decontamination of radioactive and acidic soil-washing effluent

We demonstrate that radioactive 137Cs-suspended soil and 137Cs+ ions in the effluent can be sequentially removed, enabling the effluent to be reused or released. Specially synthesized coagulant-flocculants and adsorbents were used to remove Cs-suspended soils and Cs+ ions under strongly acidic conditions. Polyethyleneimine coated magnetic nanoparticles (PEI-MNPs) was found to be the best coagulant-flocculants for removing Cs-suspended soil among various coagulant-flocculants, including inorganic, organic, and organic-inorganic ones. To optimize the separation conditions, such as the dosage and composition of the coagulant-flocculants and adsorbents, a nickel potassium hexacyanoferrate -embedded polyacrylonitrile (NiFC/PAN)-3.5, defined as a NiFC/PAN weight ratio of 3.5, was used to successfully remove Cs+ ions in nonradioactive and radioactive tests, meeting the release criterion of 50 Bq L−1 (South Korea). In the first step, the radioactivity of the effluent was reduced from 380 to 300 Bq L−1 by separating 137Cs-suspended soils with PEI-MNP coagulant-flocculants. In the next step, 137Cs ions were substantially removed using NiFC/PAN, resulting in a decrease of the radioactivity from 300 to 20 Bq L−1, which meets the release criterion. These results suggest that the proposed process is a potentially useful and effective method for treating radioactive effluent after soil washing.

Cytotoxic effect of PEI-coated magnetic nanoparticles on the regulation of cellular focal adhesions and actin stress fibres

The biocompatibility of surface-coated magnetic nanoparticles (MNPs) is key to their successful use in biomedical applications. Polyethyleneimine-coated MNPs (MNP-PEIs) provide improved in vitro nucleic acid transfection efficiency and are safer compared to conventional chemicals. Commercial cell toxicity assays are useful for end-point and high-throughput screening, however, they only reports cells that have undergone an extreme toxic response leading to cell death. Cell toxicity is a complex process which can be expressed in many forms, through morphological, metabolic, and epigenetic changes. This study explores the effect of magnetic transfection with MNP-PEIs and an external magnetic field on cell toxicity, by studying particle internalization, changes in cellular morphology, and cell adhesion. We show that MNP-PEIs induce cell stress through a dose-dependent increase in cell adhesion via the overexpression of vinculin and formation of actin stress fibres. While the presence of PEI was the main contributor to increased cell stress, free PEI polyplexes induced higher toxicity compared to PEI bound to MNPs. MNPs without PEI coating however did not adversely affect cells, suggesting a chemical effect instead of a mechanical one. In addition, genes identified as being associated with actin fibre regulation and cell adhesion showed significant increases in expression from MNP-PEI internalization. From these results, we identify anomalous cell behaviour, morphology, and gene expression after interaction with MNP-PEIs, as well as a safe dosage to reduce acute cell toxicity.

Cytotoxic Effect of PEI-Coated Magnetic Nanoparticles on the Regulation of Cellular Focal Adhesions and Actin Stress Fibres

The biocompatibility of surface-coated magnetic nanoparticles (MNPs) is key to their successful use in biomedical applications. Polyethyleneimine-coated MNPs (MNP-PEIs) provide improved in vitro nucleic acid transfection efficiency and are safer compared to conventional chemicals. Commercial cell toxicity assays are useful for end-point and high-throughput screening, however, they only reports cells that have undergone an extreme toxic response leading to cell death. Cell toxicity is a complex process which can be expressed in many forms, through morphological, metabolic, and epigenetic changes. This study explores the effect of magnetic transfection with MNP-PEIs and an external magnetic field on cell toxicity, by studying particle internalization, changes in cellular morphology, and cell adhesion. We show that MNP-PEIs induce cell stress through a dose-dependent increase in cell adhesion via the overexpression of vinculin and formation of actin stress fibres. While the presence of PEI was the main contributor to increased cell stress, free PEI polyplexes induced higher toxicity compared to PEI bound to MNPs. MNPs without PEI coating however did not adversely affect cells, suggesting a chemical effect instead of a mechanical one. In addition, genes identified as being associated with actin fibre regulation and cell adhesion showed significant increases in expression from MNP-PEI internalization. From these results, we identify anomalous cell behaviour, morphology, and gene expression after interaction with MNP-PEIs, as well as a safe dosage to reduce acute cell toxicity.

Selective separation of Cs-contaminated clay from soil using polyethylenimine-coated magnetic nanoparticles

We evaluated the feasibility of using magnetic nanoparticles (MNPs) coated with polyethylenimine (PEI), a cationic polymer, to remediate radioactive contaminated soil by separating Cs-contaminated clay from the soil. The influences of the solution pH, PEI-to-MNPs mass ratio, and the PEI–MNPs dose on the magnetic separation performance were systematically examined. The highest SE% of illite from solution through electrostatic attraction was approximately 100% at a mass ratio of 0.04 g-PEI–MNPs/g-clay. The PEI coating clearly enhanced the adhesion between MNPs and clay minerals by increasing the quantity of functional amine groups available for adsorbing negatively charged clay minerals. In separation experiments using a soil mixture, the PEI-coated MNPs selectively separated clay- and silt-sized fine particles smaller than 0.038 mm even in the presence of a large amount of sand when used at a low dose (mass ratio of 0.05 g-PEI–MNPs/g-clay) and without pH control. We also used the PEI–MNPs to separate 137Cs-contaminated illite from soil under an external magnetic field. After magnetic separation, the highest removal efficiency achieved for 137Cs removal from the treated soil was 81.7% at a low nanoparticle dosage, which resulted in satisfying the reduction of radioactivity and waste volume. The results clearly demonstrate that the selective separation of Cs-contaminated clay using PEI-coated MNPs is a promising technique for remediating radioactive soil.

One-Step Synthesis of Polyethylenimine-Coated Magnetic Nanoparticles and its Demulsification Performance in Surfactant-Stabilized Oil-in-Water Emulsion

In this study, polyethylenimine (PEI)-coated Fe3O4 magnetic nanoparticles (MNPs) were successfully synthesized via a one-step, solvo-thermal method. The synthetic PEI-coated MNPs were characterized by using multiple techniques and their demulsification efficiencies were evaluated in surfactant-stabilized, oil-in-water emulsions. The results showed that the synthesized MNPs successfully adsorbed to the emulsion’s O/W interfaces and, consequently, the oil droplets could be rapidly destabilized under an applied magnetic field. It was found that the demulsification efficiency was enhanced with the increased particle dosage. The opposite effect was found with the increase in pH value and surfactant concentration. The presence of electrolytes facilitated oil removal, presumably by reduction of the electrostatic repulsion or by altering the hydrophobicity of the MNPs. Recovery experiments at various pH levels indicated that the PEI-coated MNPs could be reused for up to ten times without significant reduction in demulsification efficiency. Altogether, the results suggested that the PEI-coated MNPs could provide a simple but powerful tool to remove emulsified oil from aqueous systems.

Transfection by Polyethyleneimine-Coated Magnetic Nanoparticles: Fine-Tuning the Condition for Electrophysiological Experiments.

A non-viral tool for the delivery of nucleic acids termed magnetofection was recently developed as a promising transgenic technique with high transfection efficiency for gene delivery into mammalian cells. Despite the fact that transfection efficiency was the objective in the past, the post-transfection cell morphology and the essential gigaseal formation between cells and patch clamp glass electrodes have not been studied in detail. The cell viability and fluorescent response of Accelerated Sensor of Action Potentials (ASAP1) were studied in somatic HEK293 cells with respect to preserving physiological cell behavior and morphology. The DNA vector (pcDNA3.1/Puro-CAG-ASAP1) was intracellularly delivered by DNA/polyethyleneimine/magnetic nanoparticles and the transfection protocols varied in complex formations were optimized with respect to transfection rate, cytotoxicity of modified nanoparticles and essential gigaseal formation needed for patch clamp technique. A patch clamp study of transfected cells was carried out 72 hours post-transfection. Our results showed the best complex formation in order DNA/magnetic nanoparticle/polyethyleneimine that provides 51.82% transfection efficiency, 83.45% of patch clamp applicable cells, and 90.15% of gigasealed patch clamp applicable cells. A significant difference in fluorescent response of transfected cells was not found compared to control. Thus, these observations suggested that a large amount of the cells were able to create a gigaseal with a glass electrode 72 hours from transfection despite the lower transfection efficiencies.

Harnessing the affinity of magnetic nanoparticles toward dye-labeled DNA and developing it as an universal aptasensor revealed by lipopolysaccharide detection

In current study, we have found that several magnetic nanoparticles (MNPs) are able to absorb DNA molecules, and surface engineering would be beneficial to tune such interaction. We then have focused on the assembly of polyethylenimine (PEI) coated MNPs (PEI-MNPs) with ssDNA (single-stranded DNA) and found this assembly is mediated by two forces, namely the electrostatic interactions of surface charges of MNPs and the phosphate backbones of DNA; as well as the coordination of exterior iron ions (especially Fe3+) of MNPs and DNA phosphate backbones. The fluorescence of dye-labeled DNA is significantly quenched when being complexed with PEI-MNPs, which is proved to be caused by static quenching. This PEI-MNPs interact with DNA, which could be harnessed for devising a novel type of aptasensor. This has been examplified by the selective and sensitive detection of lipopolysaccharide (LPS). The LOD (limit of detection) is ∼35 ng/mL and the linear range from 50 ng/mL to 10 μg/mL. Compared with widely used graphene oxide (GO)‒ssDNA aptamer sensors, we also have demonstrated that the PEI-MNPs based sensor is able to better avoid non-specific DNA displacement by interfering proteins, generating more satisfactory signal-to-background ratio. Our proposed sensor could be a supplement to classic GO‒DNA sensors. In summary, our work provides fundamental understanding of MNPs‒DNA interactions and also paves the way for developing novel MNPs based sensing approaches, which would contribute to nano‒bio interface and DNA-assisted bio-analysis, DNA-coordinated nano-materials and DNA-directed assembly.

A facile method for emulsified oil-water separation by using polyethylenimine-coated magnetic nanoparticles

Oil spills and oily wastewater discharges from ships and industrial activities have serious impacts on the environment and human health. In this study, a class of easy-to-synthesize polyethylenimine (PEI)-coated Fe3O4 magnetic nanoparticles (MNPs) was successfully synthesized via a one-step coprecipitation method. The synthesized PEI-coated Fe3O4 MNPs were characterized by using multiple technologies and applied in emulsified oil-water separation for the first time. It was found that the PEI effectively tuned the surface charge and wettability of MNPs. As a result, the PEI-coated MNPs could successfully assemble at the oil-water interface and promote the coalescence of oil droplets, thereby facilitating the subsequent magnetic separation. Results showed that the oil-water separation performance was superior and enhanced with the increase of ionic strength. Recycling experiment indicated that the PEI-coated MNPs could be reused up to six times without showing a significant decrease in separation efficiency. All of these results suggested that the PEI-coated MNP could potentially be used as a class of promising nanomaterials for emulsified oil-water separation.

Targeting of Magnetic Nanoparticle-coated Microbubbles to the Vascular Wall Empowers Site-specific Lentiviral Gene Delivery in vivo.

In the field of vascular gene therapy, targeting systems are promising advancements to improve site-specificity of gene delivery. Here, we studied whether incorporation of magnetic nanoparticles (MNP) with different magnetic properties into ultrasound sensitive microbubbles may represent an efficient way to enable gene targeting in the vascular system after systemic application. Thus, we associated novel silicon oxide-coated magnetic nanoparticle containing microbubbles (SO-Mag MMB) with lentiviral particles carrying therapeutic genes and determined their physico-chemical as well as biological properties compared to MMB coated with polyethylenimine-coated magnetic nanoparticles (PEI-Mag MMB). While there were no differences between both MMB types concerning size and lentivirus binding, SO-Mag MMB exhibited superior characteristics regarding magnetic moment, magnetizability as well as transduction efficiency under static and flow conditions in vitro. Focal disruption of lentiviral SO-Mag MMB by ultrasound within isolated vessels exposed to an external magnetic field decisively improved localized VEGF expression in aortic endothelium ex vivo and enhanced the angiogenic response. Using the same system in vivo, we achieved a highly effective, site-specific lentiviral transgene expression in microvessels of the mouse dorsal skin after arterial injection. Thus, we established a novel lentiviral MMB technique, which has great potential towards site-directed vascular gene therapy.

Application of Magnetic Nanoparticles to Gene Delivery

Nanoparticle technology is being incorporated into many areas of molecular science and biomedicine. Because nanoparticles are small enough to enter almost all areas of the body, including the circulatory system and cells, they have been and continue to be exploited for basic biomedical research as well as clinical diagnostic and therapeutic applications. For example, nanoparticles hold great promise for enabling gene therapy to reach its full potential by facilitating targeted delivery of DNA into tissues and cells. Substantial progress has been made in binding DNA to nanoparticles and controlling the behavior of these complexes. In this article, we review research on binding DNAs to nanoparticles as well as our latest study on non-viral gene delivery using polyethylenimine-coated magnetic nanoparticles.

Efficient transfection method using deacylated polyethylenimine-coated magnetic nanoparticles

Low efficiencies of nonviral gene vectors, such as transfection reagent, limit their utility in gene therapy. To overcome this disadvantage, we report on the preparation and properties of magnetic nanoparticles [diameter (d)=121.32±27.36nm] positively charged by cationic polymer deacylated polyethylenimine (PEI max), which boosts gene delivery efficiency compare with polyethylenimine (PEI), and their use for the forced expression of plasmid delivery by application of a magnetic field. Magnetic nanoparticles were coated with PEI max, which enabled their electrostatic interaction with negatively charged molecules such as plasmid. We successfully transfected 81.1±4.0% of the cells using PEI max-coated magnetic nanoparticles (PEI max-nanoparticles). Along with their superior properties as a DNA delivery vehicle, PEI max-nanoparticles offer to deliver various DNA formulations in addition to traditional methods. Furthermore, efficiency of the gene transfer was not inhibited in the presence of serum in the cells. PEI max-nanoparticles may be a promising gene carrier that has high transfection efficiency as well as low cytotoxicity.