Molecular Weight Polyethylenimine Research Articles

Cholic acid-modified polyethylenimine: in vitro and in vivo studies.

Low-molecular-weight polyethylenimine has lower cytotoxicity than high molecular weight polyethylenimine, but it is not an efficient transfection agent because of limitations of DNA delivery into the cytoplasm. Therefore, in the present study, the hydrophobic modification of low-molecular-weight polyethylenimine (PEI 2 kDa [PEI2]) by cholic acid (ChA) was performed to form PEI2-ChA, and in vitro and in vivo studies were performed. Results indicate that the nanoplexes of PEI2-ChA with gWIZ-GFP have greater transfection efficiency (27%) in NT8e cell lines as evaluated by flow cytometry and also observed by fluorescence imaging. The present study concluded that the transferrin-containing nanoplexes of PEI2-ChA conjugates with plasmid p53 warrant clinical trials in humans after exhaustive animal studies for use as a novel gene delivery system.

Enhanced CO2/N2 separation performance by using dopamine/polyethyleneimine-grafted TiO2 nanoparticles filled PEBA mixed-matrix membranes

Mixed matrix membranes (MMMs) were fabricated by incorporating synthesized titanium dioxide (TiO2) nanoparticles into polyether block amide (PEBA) matrix to fabricate TiO2/PBEA MMMs for CO2/N2 separation. The mesoporous channels of TiO2 increased the density of active sites with high accessibility and also facilitate the diffusion of CO2 in the gas separation process. Furthermore, amine groups are grafted onto the TiO2 fillers via one step reaction with dopamine (DA) and polyethyleneimine (PEI). The modified TiO2 fillers with abundant amine groups are conductive to transfer CO2 owing to the reversible reaction occurred between CO2 and amine groups. The effects of TiO2 loading, DA/PEI modification on the morphology and CO2/N2 separation performance of the resulting TiO2/PBEA MMMs were systematically studied. The results showed that the MMMs filled with 3 wt% DA-PEI-TiO2 synthesized with DA/PEI mass ratio of 1/1 and PEI molecular weight of 1800 exhibited optimal separation performance with CO2 permeability of 67 Barrer and CO2/N2 selectivity of 101, surpassing the 2008 Robeson upper-bound.

Charge reduction: an efficient strategy to reduce toxicity and increase the transfection efficiency of high molecular weight polyethylenimine

With high potency in treatment of various diseases, gene therapy is mainly hindered by lack of safe and efficient gene delivery vectors. The current study was aimed to develop an efficient non-viral vector with adequate cytotoxicity. To this end, alkylcarboxylate chains (6C, 10C, 16C) were exploited to ameliorate the characteristics of PEI 750 kDa. Briefly, alkylcarboxylate chains with three different lengths (6C, 10C, 16C) were chemically grafted to the primary amine groups of PEI 750 kDa in three percentages (10, 50, and 100%). After evaluating the physicochemical properties of prepared vectors including surface charge, size, buffering capacity, and DNA condensing, their transfection efficiency and cytotoxicity were investigated in Neuro2A cells. The polyplexes size were 158.9–264.5 nm and their zeta potentials were 14–30 mV, while their buffering capacity and DNA condensing were not significantly decreased. The highest transfection efficiency in term of C/P ratio was observed in PEI750-10C-68%, PEI750-10C-7%, and PEI750-6C-7% at C/P ratios of 2, 4, and 6, respectively. Altogether, the decanoylcarboxylate-modified PEI with medium grafting percentages showed promising results as gene delivery vector. To sum up, the modification of high molecular weight PEIs by alkylcarboxylate chains is an efficient approach for development of more efficient non-viral vectors.

Probing the effect of polymer molecular weight on penetration into the wood cell wall using polyethylenimine (PEI) as a model compound

Decking is one of the largest applications for the treated wood market. The most challenging property to obtain for treated wood is dimensional stability, which can be achieved, in part, by cell wall bulking, cell wall polymer crosslinking and removal of hygroscopic components in the cell wall. A commonly accepted key requirement is for the actives to infuse through the cell wall, which has a microporosity of ∼5-13 nm. Equally as challenging is being able to measure and quantify the cell wall penetration. Branched polyethylenimine (PEI) was studied as a model polymer for penetration due to its water solubility, polarity, variable molecular weight ranges, and ability to form a chelation complex with preservative metals to treat lumbers. Two different molecular weight polyethylenimines (PEI), one with a weight average molecular weight (Mw) equal to 800 Da and the other 750000 Da, were investigated for penetration by microscopy and spectroscopy techniques. Analytical methods were developed to both create smooth interfaces and for relative quantitation and visualisation of PEI penetration into the wood. The results showed both PEI with Mw of 800 Da and PEI with Mw of 750000 Da coated the lumens in high density. However, only the PEI with Mw of 800 appeared to penetrate the cell walls in sufficient levels. Literature has shown the hydrodynamic radii of PEI 750000 is near 29 nm, whereas a smaller PEI at 25 K showed 4.5 nm. Most importantly the results, based on methods developed, show how molecular weight and tertiary structure of the polymer can affect its penetration, with the microporosity of the wood being the main barrier.

Tween 85-Modified Low Molecular Weight PEI Enhances Exon-Skipping of Antisense Morpholino Oligomer InVitro and in mdx Mice.

We investigated a series of Tween 85 modified low molecular weight polyethylenimine (LPEI, 0.8k/1.2k/2.0k)-copolymers (Zs) through simple formulation and covalent conjugation with phosphorodiamidate morpholino oligomer (PMO) for their potential to enhance delivery in vitro and in dystrophic mdx mice. Z polymers significantly enhanced PMO-induced exon-skipping in a GFP reporter-based cell culture system. Application of optimized formulations of Zs with PMO targeted to dystrophin exon 23 demonstrated a significant increase in exon-skipping efficiency in mdx mice. Consistent with our observations in vitro, optimization of molecular size and hydropholic-lipopholic balance (HLB) of polymers are important factors to achieve enhanced PMO delivery in vivo. The best formulation of Zs enhanced PMO delivery with 20- and 6-fold over PMO alone in vitro and in vivo, respectively. Further, chemical conjugation of the polymer and PMO exhibits greater benefit than polymer/PMO simple formulation in PMO delivery efficiency. Observed cytotoxicity of the Zs was lower than Endo-porter and PEI 25k in vitro, and no tissue toxicity was clearly detected with the Zs at the dosage tested. These results indicate the potential of the Zs as effective and safe PMO delivery carriers for treating diseases such as muscular dystrophy.

Self-replicating RNA vaccine functionality modulated by fine-tuning of polyplex delivery vehicle structure

The major limitations with large and complex self-amplifying RNA vaccines (RepRNA) are RNase-sensitivity and inefficient translation in dendritic cells (DCs). Condensing RepRNA with polyethylenimine (PEI) gave positive in vitro readouts, but was largely inferior to virus-like replicon particles (VRP) or direct electroporation. In the present study, we improved such polyplex formulation and determined that fine-tuning of the polyplex structure is essential for ensuring efficacious translation. Thereby, three parameters dominate: (i) PEI molecular weight (MW); (ii) RepRNA:PEI (weight:weight) ratio; and (iii) inclusion of cell penetrating peptides (CPPs). Seven commercially available linear PEIs (MW 2,500–250,000) were classified as strong, intermediate or low for their aptitude at complexing and protecting RepRNA for delivery into porcine blood DCs. Inclusion of (Arg)9 or TAT(57-57) CPPs further modified the translation readouts, but varied for different gene expressions. Dependent on the formulation, translation of the gene of interest (GOI) inserted into the RepRNA (luciferase, or influenza virus hemagglutinin or nucleoprotein) could decrease, while the RepRNA structural gene (E2) translation increased. This was noted in the porcine SK6 cell line, as well as both porcine and, for the first time, human DCs. Two formulations – [Rep/PEI-4,000 (1:3)] and [Rep/PEI-40,000 (1:2)/(Arg)9] were efficacious in vivo in mice and pigs, where specific CD8+ T and CD4+ T-cell responses against the GOI-encoded antigen were observed for the first time. The results demonstrate that different polyplex formulations differ in their interaction with the RepRNA such that only certain genes can be translated. Thus, delivery of these large self-replicating RNA molecules require definition with respect to translation of different genes, rather than just the GOI as is the norm, for identifying optimal delivery for the desired immune activation in vivo.

Aromatic Modification of Low Molecular Weight PEI for Enhanced Gene Delivery.

Low molecular weight polyethylenimine (1800 Da, also referred to as oligoethylenimines, OEI) was modified with amino acids, including two aromatic amino acids (tryptophan, phenylalanine) and an aliphatic amino acid (leucine). The substitution degree of amino acids could be controlled by adjusting the feeding mole ratio of the reactants. Fluorescence spectroscopy and circular dichroism experiments demonstrated that the indole ring of tryptophan may intercalate into the DNA base pairs and contribute to efficient DNA condensation. In vitro gene expression results revealed that the modified OEIs (OEI-AAs) may provide higher transfection efficiency even than high molecular weight polyethylenimine (25 kDa, PEI), especially the aromatic tryptophan substituted OEI. Moreover, OEI-AAs exhibited excellent serum tolerance, and up to 137 times higher transfection efficiency than PEI 25 kDa that was obtained in the presence of serum. The cytotoxicity of OEI-AAs is much lower than PEI 25 kDa. This study may afford a new method for the development of low molecular weight oligomeric non-viral gene vectors with both high efficiency and biocompatibility.

Biodegradable Carriers for Delivery of VEGF Plasmid DNA for the Treatment of Critical Limb Ischemia.

The safe and efficient delivery of therapeutic nucleic acid is a prerequisite for an effective DNA therapy. In this study, we condensed the low molecular weight polyethylenimine (PEI, 1.8k Da) with 2,6-pyridinedicarboxaldehyde (PDA), both of which are degradable in vivo, to synthesize a biodegradable polycationic material (PDAPEI) to deliver vascular endothelial growth factor (VEGF) plasmid DNA (pDNA). Particle size and zeta potential of this novel degradable PEI derivatives-pDNA nanoparticle were investigated and in vitro cytotoxicity was estimated on human umbilical vein endothelial cells (HUVECs). Using pDNA-encoding VEGF-A and green fluorescence protein (GFP), we also checked transfection efficiency of the vector (PDAPEI) and found its excellent performance at 40 w/w ratio. We successfully established peripheral ischemia animal model on C57/BL6J mice to evaluate the therapeutic effect of PDAPEI/pVEGF-A polyplex system on ischemic disease and a conclusion was made that PDAPEI is a promising gene vector in the treatment of peripheral ischemic artery disease (PAD).

MoS2-LA-PEI nanocomposite carrier for real-time imaging of ATP metabolism in glioma stem cells co-cultured with endothelial cells on a microfluidic system

Stimuli-responsive carriers have extensively attracted attention in recent years. However, long-term and real-time tracking ability with stimuli-responsive carrier is still in its infant stage due to the limitations such as, low efficacy, instability and cytotoxicity in a bio-environment. In this work, we developed a reduction-sensitive carrier composed of lipoic acid-modified low molecular weight polyethyleneimine (LA-PEI) and large surface ratio MoS2 nanosheet integrated via disulfide bond to mimic a high molecular weight PEI. The positively charged carriers loading negatively charged aptamer enter the cells for a real time long-term tracking of adenosine triphosphate (ATP) metabolism in glioma stem cells (GSCs) when stimulated by TGFβ factor secreted from HUVECs. We envision that MoS2-LA-PEI carrier has a promising potential for delivery and monitoring the changes in live cells with low cytotoxicity and high efficiency.

Elucidation of siRNA complexation efficiency by graphene oxide and reduced graphene oxide

Gene therapy has attracted tremendous attention as a promising method for the treatment of many diseases. Graphene oxide (GO), the oxidized form of graphene, is showing lot of potential in this field. Indeed, the polar GO oxygenated functional groups make this material highly hydrophilic, leading to a good dispersibility in water. Until now, the interaction of small interference RNA (siRNA) with graphene materials has not been elucidated. The main goal of this work was to develop a novel platform to complex siRNA molecules and to rationalize the supramolecular interactions between GO surface and the double strand RNA. Our study focused first on green and facile methods such as hydrothermal or vitamin C treatments to prepare graphene oxides at various percentage of oxygen. Epoxidation was also explored to reintroduce epoxide groups on reduced GO for further functionalization. Subsequently, we performed the covalent functionalization of GO with triethyleneglycoldiamine (TEG) and with low molecular weight polyethyleneimine (PEI) via the epoxy ring opening reaction. Finally, by gel electrophoresis, we were able to correlate the GO complexation ability with the graphene surface chemistry. In addition, ozonated GO functionalized with PEI showed a high complexing capacity for siRNA, proving to be a promising candidate for gene silencing.

Structure–performance study of polyamide composite nanofiltration membranes prepared with polyethyleneimine

Polyethyleneimine (PEI) of various molecular weights and trimesoyl chloride (TMC) were utilized to prepare composite nanofiltration (NF) membranes via interfacial polymerization. The changes in the surface structure and chemical composition of the prepared membranes were evaluated using SEM, ATR-FTIR, XPS and surface potential measurements. The pure-water flux and rejection rates of the inorganic salts (MgCl2, MgSO4, Na2SO4 and NaCl) through the resultant NF membranes were also investigated. The results showed that the performance of the composite NF membranes was significantly affected by the molecular weight of the PEI. Notably, the permeate flux and rejection rate of the NF membranes increased with the PEI molecular weight. In addition, when the NF membranes were used to treat actual wastewater from the electroplating industry, the NF membranes presented high-efficiency separation properties for heavy metal ions. The rejection rates of the NF membranes at 0.4 MPa for chromium, nickel, zinc and copper ions reached 92.6, 89.6, 89.2 and 86.3%, respectively.

Acid-labile poly(amino alcohol ortho ester) based on low molecular weight polyethyleneimine for gene delivery.

A series of acid-labile poly(amino alcohol ortho ester) (POEeis) were synthesized through ring-opening polymerization between diglycidyl ethers with ortho ester bonded and low molecular weight polyethyleneimine by various feed molar ratios. The obtain POEei 1 and POEei 2 exhibited clear kinetic of degradation and condensed plasmid DNA into nanoparticles of suitable sizes (250-300 nm) and positive zeta potentials (+20-30 mV) while protecting DNA from enzymatic digestion. Further, these polymers have uniform distribution of abundant hydroxyl groups, which could improve their water solubility, biocompatibility, and lower protein adsorption. Significantly, ortho ester groups in POEeis main-chains could hydrolyze rapidly at acidic endosomal pH, resulting in intracellular DNA release and diminished material toxicity. MTT assay revealed that all the polymers exhibited much lower cytotoxicity than 25 kDa PEI in the human neuroblastoma SH-SY5Y cells. Moreover, the transfection efficiency of POEei 1 was higher than 25 kDa PEI in serum-free medium or 10% serum medium.

Improving catalytic activity of laccase immobilized on the branched polymer chains of magnetic nanoparticles under alternating magnetic field

AbstractBACKGROUNDImmobilization of laccase may cause more or less mass transfer limitation in practical applications. In order to enhance the reaction rate, there is great interest in developing an effective way to increase the rate of diffusion in reactions catalyzed by immobilized laccase.RESULTSThe laccase from Trametes versicolor (p‐diphenol: dioxygen oxidoreductases, EC 1.10.3.2) immobilized on different molecular weight polyethylenimine (PEI) modified amine‐functionalized Fe3O4 nanoparticles [Fe3O4–NH2–PEI (1200/10 000/60 000)–laccase] was separately fabricated. The oxidation reaction rate of catechol catalyzed by Fe3O4–NH2–PEI (1200)–laccase under an alternating magnetic field (600 Hz, 10 Gs) was separately 2.10 times and 1.16 times higher than the control without any external force and with mechanical stirring at 150 rpm. This was a larger increase than for Fe3O4–NH2–PEI (10 000/60 000)–laccase. In addition, the reaction rate catalyzed by Fe3O4–NH2–PEI (1200)–laccase was enhanced as the magnetic field frequency, strength and Fe3O4–NH2–PEI (1200)–laccase or catechol concentration was increased. The immobilized laccase retained 85% of its initial activity after six consecutive operations.CONCLUSIONUsing an alternating magnetic field was a powerful way to intensify the reaction rate catalyzed by laccase immobilized on branched polymer chains of magnetic nanoparticles and showed potential for large‐scale catalytic reaction. © 2017 Society of Chemical Industry

Layer-by-layer assembly of graphene on polyimide films via thermal imidization and synchronous reduction of graphene oxide

To investigate the effects of holding time after deposition of polyethylenimine (PEI) solution and molecular weight of PEI on the surface morphology of multi-layer films prepared by layer-by-layer (LbL) method, polyamic acid (PAA)/PEI/graphene oxide (GO) films were prepared using different holding times and different molecular weights of PEI. To convert PAA into polyimide (PI), the films were thermally imidized after film deposition. In this process, GO was also converted into partially reduced GO (rGO). The effects of holding time and molecular weight of PEI on the surface morphology and the sheet resistance of PI/PEI/rGO films were investigated. Also, to investigate the effect of rGO on the barrier properties of PI based multilayer films, (PI/PEI/rGO/PEI)6 films were prepared by LbL method. Longer holding time (10 min) and smaller molecular weight (25,000) of PEI lead to relatively flat surfaces, but shorter holding time (5 min) and larger molecular weight (75,000) result in wrinkled and overlapped surfaces. The sheet resistance of PI/PEI25K/rGO films prepared with holding time 10 and 5 min is 502.1 kΩ/sq and out of range (> 2000 kΩ/sq), respectively. The sheet resistance of PI/PEI75K/rGO films prepared with holding time 10 min is out of range (> 2000 kΩ/sq). Gas transmission rate (GTR) and permeability coefficient of (PI/PEI25K/rGO/PEI25K)6 are lower than those of (PI/PEI75K/rGO/PEI75K)6, respectively.

Biodegradable and biocompatible cationic polymer delivering microRNA-221/222 promotes nerve regeneration after sciatic nerve crush.

MicroRNA (miRNA) has great potential to treat a wide range of illnesses by regulating the expression of eukaryotic genes. Biomaterials with high transfection efficiency and low toxicity are needed to deliver miRNA to target cells. In this study, a biodegradable and biocompatible cationic polymer (PDAPEI) was synthetized from low molecular weight polyethyleneimine (PEI1.8kDa) cross-linked with 2,6-pyridinedicarboxaldehyde. PDAPEI showed a lower cytotoxicity and higher transfection efficiency than PEI25kDa in transfecting miR-221/222 into rat Schwann cells (SCs). The upregulation of miR-221/222 in SCs promoted the expression of nerve growth factor and myelin basic protein in vitro. The mouse sciatic nerve crush injury model was used to evaluate the effectiveness of PDAPEI/miR-221/222 complexes for nerve regeneration in vivo. The results of electrophysiological tests, functional assessments, and histological and immunohistochemistry analyses demonstrated that PDAPEI/miR-221/222 complexes significantly promoted nerve regeneration after sciatic nerve crush, specifically enhancing remyelination. All these results show that the use of PDAPEI to deliver miR-221/222 may provide a safe therapeutic means of treating nerve crush injury and may help to overcome the barrier of biomaterial toxicity and low efficiency often encountered during medical intervention.

Local Delivery of CTGF siRNA with Poly(sorbitol-co-PEI) Reduces Scar Contraction in Cutaneous Wound Healing.

Healing process in scarring inevitably produces a considerable amount of non-organized dense collagen-rich matrix called scar thus impairing the native structure of skin. Connective tissue growth factor (CTGF) overexpression within healing tissues is known to play an imperative role in collagen production stimulated by transforming growth factor-beta in cutaneous wound healing. Undoubtedly, the knockdown of CTGF expression through siRNA-mediated gene silencing could simply impede the scarring process. However, the less stability and low transfection of siRNAs themselves urge a safe carrier to protect and transfect them into cells at a high rate avoiding toxicities. Here, we developed a degradable poly(sorbitol-co-PEI) (PSPEI), prepared by polymerization of sorbitol diacrylate with low molecular weight polyethylenimine, which has high transfection efficiency but low cytotoxicity, and utilized it in siCTGF delivery to silence the expression of CTGF in an animal model of cutaneous wound healing. Unlike contracted scar in normal healing, there was no or less contraction in the healed skin of mice treated with siCTGF using PSPEI. Histologically, the healed tissues also had distinct papillary structures and dense irregular connective tissues that were lacking in the control scar tissues. This study exemplifies a successful treatment of cutaneous wound healing using a polymer system coupled with RNA interference. Hence, the approach holds a great promise for developing new treatments with novel targets in regenerative medicines.

Performance enhancement of TFC FO membranes with polyethyleneimine modification and post-treatment

In this work, simple and effective second interfacial polymerization (SIP) of thin-film composite (TFC) membranes is performed with polyethyleneimine (PEI) of various molecular weights, in order to improve the separation performance for forward osmosis (FO) applications. Various characterization techniques are employed to examine the modification mechanism. Compared to the control TFC membrane, PEI-modified membranes exhibit higher water permeabilities, acceptable salt rejection and lower fouling propensity. The effects of PEI molecular weight on the membrane morphology and separation performance are investigated systematically with various characterizations. Post-treatment of PEI-modified membranes in alkaline and acidic aqueous solutions is further investigated, and its effects on the FO performance, intrinsic separation properties and antifouling properties of these post-treated membranes are studied. In comparison with pristine PEI-modified TFC membranes, the post-treated TFC membranes show further enhanced water flux and improved anti-fouling properties.

High performance and stable naphthalene diimide based n-channel organic field-effect transistors by polyethylenimine doping

In this paper, we study the effect of the structure and molecular weight of polyethylenimine (PEI) on doping efficiency of n-type organic semiconductors based on poly[[N, N 9-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,59-(2,29-bithiophene)] (P(NDI2OD-T2)). Linear and branched PEI with low (Mw = 2 and 3 kDa) and high molecular weights (Mw = 25 kDa) are used. It is found that the low molecular weight PEI shows higher doping efficiency than high molecular weight PEI due to better mix-ability between the dopant and the host. Doped P(NDI2OD-T2) OFETs show highly improved mobility up to 0.85 cm2/V·s (linear) at 0.1 wt% doping concentration from 0.21 cm2/V·s for pristine devices with enhanced air and operational stability.

In situ biodegradable crosslinking of cationic oligomer coating on mesoporous silica nanoparticles for drug delivery

Although layer-by-layer assembly using anionic and cationic polymer has been a popular way to develop core-shell nanoparticles, the strong electrostatic interactions may limit shell degradability, thus hampering their application as a platform for controlled therapeutic delivery. In this study, we demonstrate a simple approach to developing mesoporous nanohybrids via a process of pre-drug loading (using doxorubicin (DOX) as a model drug) into mesoporous silica nanoparticles (MSN), followed by surface functionalization with a kind of cationic oligomer (low molecular weight polyethylene imine, LPEI) and in situ crosslinking by degradable N,N′-bis(acryloyl)cystamine (BAC). The presence of LPEI shell affords the nanohybrids with charge-reversal ability, which means that the acidic tumor extracellular microenvironment can transform the negative surface charge at neutral conditions into positive-charged ones. The nanohybrids displayed a pH- and redox-dual sensitivity in DOX release under conditions that mimic intracellular reductive conditions and acidic tumor microenvironments. The nanohybrids can be effectively internalized into A549 cells (a carcinomic human alveolar basal epithelial cell line), resulting in a high DOX intracellular accumulation and an improved anticancer cytotoxicity when compared with free DOX, suggesting their high potential as a new platform for therapeutic delivery.

Hydrophobically modified polyethylenimine-based ternary complexes for targeting brain tumor: stability, in vitro and in vivo studies

Hydrophobic modification of low molecular weight polyethylenimine (PEI 2 kDa) by cholic acid (ChA) was done to obtain PEI2-ChA. The nanoplexes of PEI2-ChA with gWIZ-GFP demonstrated increase transfection efficiency (∼27%) in NT8e cell lines. The cell-cycle analysis of NT8e cells (p53 mutant) treated with transferrin containing nanoplexes showed increased apoptosis of cells. In vitro protein expression revealed expression of exogenous p53 protein. In vivo imaging of mice showed localized signal for GFP protein in brain region. The tumors of mice treated with transferrin containing nanoplexes of PEI2-ChA were ∼5 times smaller in size than the tumor of untreated animals.