Polyethylenimine Copolymers Research Articles

Hierarchical spontaneous self-assembly of polyethylenimine-poly(propylene glycol) copolymer into cationic polyelectrolyte pH-responsive thermogel

Temperature-responsive hydrogels, otherwise known as thermogels, are promising biomaterials which undergo phase change from liquid to a solid-like gel state when warmed. Although poly (ethylene glycol) (PEG) is employed extensively as the hydrophilic segment in thermogelling polymer design, recent years has witnessed development of new families of PEG-free thermogelling copolymers which offer new opportunities in expanding material property profiles for new biomedical applications. Herein, we study the supramolecular self-assembly process of PEG-free amphiphilic branched graft copolymer containing polyethylenimine (PEI) and poly (propylene glycol) (PPG), which shows both thermogelling ability and pH-responsive gelation behaviour. Additionally, we demonstrate the ease of post-synthetic modulation of thermogel properties by amine functionalisation on the PEI copolymer segments through convenient nucleophilic substitution and amide formation reactions. The synthetic platform offered by PEI-PPG thermogels allow facile customisation of these versatile materials for targeted biomedical applications.

Delivery of miR-34a-5p by Folic Acid-Modified β-Cyclodextrin-Grafted Polyethylenimine Copolymer Nanocarriers to Resist KSHV

Kaposi’s sarcoma-associated herpesvirus (KSHV) infection can cause a range of malignancies. The use of microRNA (miRNA) to combat viruses and inhibit tumor development has received increasing attention. However, it is difficult for free miRNA to enter into cells directly and to degrade easily. Therefore, the miRNA therapy alone often fails to achieve the expected effect. The selection of an appropriate delivery system for effective miRNA delivery and anti-KSHV is rarely considered. In this study, a β-cyclodextrin-grafted polyethylenimine (β-CD-PEI) was prepared by the chemical synthesis method, and folic acid was further coupled to a nanocarrier (β-CD-PEI-FA). Gel electrophoresis retardation experiments showed that β-CD-PEI-FA could combine with miR-34a-5p to form a drug-carrying nanocomplex β-CD-PEI-FA/miR-34a-5p, which effectively protected miR-34a-5p from serum and nuclease degradation. The particle size and potential were 203.13 ± 0.41 nm and 27.02 ± 0.72 mV, respectively, which were suitable for endocytosis. The cytotoxicity of the vector to KSHV-positive cells BCBL-1 and SK-RG cells was detected by the CCK-8 assay, which proved that the vector had good biosafety in vitro. Further cell experiments showed that β-CD-PEI-FA/miR-34a-5p not only had the ability to transport miR-34a-5p but also accelerated the G2-phase process of BCBL-1 and SK-RG cells and inhibited the proliferation of KSHV-infected cells. Most importantly, it can significantly reduce the expression levels of KSHV genes ORF26, K8.1A, and LANA. Therefore, the nanocarriers may be a promising antiviral drug delivery system with potential applications in the anti-KSHV therapy.

Synergistically assembled RGO/Si3N4 whiskers hybrid aerogels to endow epoxy composites with excellent thermal and tribological performance

Epoxy resin (EP) composites with satisfactory thermal and tribological performance are highly required for engineering moving components. However, the simple addition of fillers leaded to the serious filler agglomeration and limited promotion in tribological properties. In this work, we constructed a new kind of three-dimensional (3D) reduced graphene oxide (RGO)/Si3N4 hybrid aerogel for EP composites, which was prepared by a facile hydrothermal self-assembly method followed by freeze-drying technique. As a result, the dispersibility of Si3N4 whiskers was greatly improved through wrapping of polydopamine—polyethyleneimine copolymer (PDA—PEI) copolymer and physical spacing of 3D skeleton. Furthermore, benefiting from the synergistic effect of RGO and Si3N4@PDA—PEI in the thermal network, the thermal conductivity of RGO/Si3N4 hybrid aerogel (GSiA)—EP increased by 45.4% compared to that of the neat EP. In addition, the friction coefficient and wear rate of GSiA—EP decreased by 83.7% and 35.8%, respectively. This work is significant for opening a tribological performance enhancement strategy though constructing 3D hybrid architecture.

PH low insertion peptide (pHLIP)-decorated polymeric nanovehicle for efficient and pH-responsive siRNA translocation

As a hallmark of most solid tumors, tumor acidic microenvironment aids tumor survival and progression. Tumor acidity also represents a tumor-specific stimulus that has been harnessed for the design and development of pH-responsive drug delivery systems. Pyruvate kinase M2 (PKM2) functions as an oncoprotein in tumorigenesis, and its overexpression in many tumors promotes metabolic rewiring towards aerobic glycolysis. Herein, a pH low insertion peptide (pHLIP)-functionalized copolymer of polyethylenimine and polylactide (pHLIP-PEI-PLA) was synthesized and self-assembled into a pH-responsive nanovehicle for delivery of siRNA to specifically target PKM2, a rate-limiting enzyme in glycolysis. The delivery of siPKM2 by pHLIP-decorated polymeric nanovehicle sufficiently downregulated the expression of PKM2 and exhibited potent inhibition on HepG2 cell migration. We believe that this strategy of targeting glycolysis-associated PKM2 gene by tumor acidity-responsive RNAi nanovehicle may offer a potential means for anticancer therapy.

Self-assembled polymeric micelle as a novel mRNA delivery carrier

mRNA-based therapy has been evaluated in preclinical and clinical studies for the treatment of a wide variety of disease such as cancer immunotherapies and infectious disease vaccines. However, it remains challenging to development safe and efficient delivery system. Here, we have designed a novel self-assembled polymeric micelle based on vitamin E succinate modified polyethyleneimine copolymer (PVES) to delivery mRNA. In vitro, PVES could transfect mRNA into multiple cell lines such as HEK-293T, HeLa and Vero and the transfection efficiencies were much higher than PEI 25 k. In addition, the cytotoxicity of PVES was much lower than PEI 25 k. Furthermore, mice administered intramuscularly with PVES/SARS-CoV-2 mRNA vaccine induced potent antibody response and show no obvious toxicity. These results demonstrated the potential of PVES as a safe and effective delivery carrier for mRNA.

Modification of Branched Polyethyleneimine Using Mesquite Gum for Its Improved Hemocompatibility.

In the present study, the modification of branched polyethyleneimine (b-PEI) was carried out using mesquite gum (MG) to improve its hemocompatibility to be used in biomedical applications. In the copolymer synthesis process (carboxymethylated mesquite gum grafted polyethyleneimine copolymer (CBX-MG-PEI), an MG carboxymethylation reaction was initially carried out (carboxymethylated mesquite gum (CBX-MG). Subsequently, the functionalization between CBX-MG and b-PEI was carried out using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) as crosslinking agents. The synthesis products were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). Thermogravimetric analysis showed that CBX-MG and CBX-MG-PEI presented a lower decomposition temperature than MG. The CBX-MG-PEI has a high buffer capacity in the pH range of 4 to 7, similar to the b-PEI. In addition, the CBX-MG-PEI showed an improvement in hemocompatibility in comparison with the b-PEI. The results showed a non-hemolytic property at doses lower than 0.1 µg/mL (CBX-MG-PEI). These results allow us to propose that this copolymer be used in transfection, polymeric nanoparticles, and biomaterials due to its physicochemical and hemocompatibility properties.

Electromagnetic Field-Programmed Magnetic Vortex Nanodelivery System for Efficacious Cancer Therapy.

Effective delivery of anticancer drugs into the nucleus for pharmacological action is impeded by a series of intratumoral transport barriers. Despite the significant potential of magnetic nanovehicles in electromagnetic field (EF)‐activated drug delivery, modularizing a tandem magnetoresponsive activity in a one‐nanoparticle system to meet different requirements at both tissue and cellular levels remain highly challenging. Herein, a strategy is described by employing sequential EF frequencies in inducing a succession of magnetoresponses in the magnetic nanovehicles that aims to realize cascaded tissue penetration and nuclear accumulation. This nanovehicle features ferrimagnetic vortex‐domain iron oxide nanorings coated with a thermo‐responsive polyethylenimine copolymer (PI/FVIOs). It is shown that the programmed cascading of low frequency (Lf)‐EF‐induced magnetophoresis and medium frequency (Mf)‐EF‐stimulated magneto‐thermia can steer the Doxorubicin (DOX)‐PI/FVIOs to the deep tissue and subsequently trigger intracellular burst release of DOX for successful nuclear entry. By programming the order of different EF frequencies, it is demonstrated that first‐stage Lf‐EF and subsequent Mf‐EF operation enables DOX‐PI/FVIOs to effectively deliver 86.2% drug into the nucleus in vivo. This nanodelivery system empowers potent antitumoral activity in various models of intractable tumors, including DOX‐resistant MCF‐7 breast cancer cells, triple‐negative MDA‐MB‐231 breast cancer cells, and BxPC‐3 pancreatic cancer cells with poor permeability.

Construction of a specific and efficient antibacterial agent against Pseudomonas aeruginosa based on polyethyleneimine cross-linked fucose

Polyethyleneimine (PEI) is known for its antibacterial properties and ease of modification. How to improve the specific antibacterial activity of PEI with low toxicity is a research hotspot. In this work, the PEI was used to synthesize a fucose-modified polyethyleneimine copolymer particles (Fuc-PEI CPs) via nucleophilic addition between primary amine and aldehyde groups. Fucose (Fuc) can capture Pseudomonas aeruginosa (P. aeruginosa) with LecB, which has a good targeting property toward P. aeruginosa. The Fuc-PEI CPs’ antibacterial activity was investigated by plate counting method. Compared with unmodified PEI, Fuc-PEI CPs (2.5 μg/mL) showed unique bactericidal ability against P. aeruginosa, and less cytotoxicity and excellent biocompatibility. The antimicrobial mechanism indicated that the improvement of PEI antibacterial activity against P. aeruginosa ascribed to the Fuc’s unique recognition of bacteria and PEIs’ ability to destroy the cell membrane of bacteria. The Fuc-PEI CPs as a new antibacterial agent shed light on the constructing a novel antibacterial pathway for killing P. aeruginosa.

Regulation of Lipid Bilayer Ion Permeability by Antibacterial Polymethyloxazoline-Polyethyleneimine Copolymers.

Amphiphilic antimicrobial polymers display activity against the outer bacterial cell membrane, triggering various physiological effects. We investigated the regulation of ion transport across the lipid bilayer to understand differences in biological activity for a series of amphiphilic polymethyloxazoline - polyethyleneimine copolymers. The results confirmed that the tested structures were able to increase the permeability of the lipid bilayer (LB) membrane or its rupture. Black lipid membrane (BLM) experiments show that the triggered conductance profile and its character is strongly correlated with the polymer structure and zeta potential. The polymer exhibiting the highest antimicrobial activity promotes ion transport by using a unique mechanism and step-like characteristics with well-defined discreet openings and closings. The molecule was incorporated into the membrane in a reproducible way, and the observed channel-like activity could be responsible for the antibacterial activity of this molecule.

Amphiphilic Polymethyloxazoline–Polyethyleneimine Copolymers: Interaction with Lipid Bilayer and Antibacterial Properties

Amphiphilic Polymethyloxazoline–Polyethyleneimine Copolymers: Interaction with Lipid Bilayer and Antibacterial Properties

Amphiphilic Polymethyloxazoline-Polyethyleneimine Copolymers: Interaction with Lipid Bilayer and Antibacterial Properties.

Polycations, mimicking activity of antibacterial peptides, belong to an important class of molecules investigated as a support or as an alternative to antibiotics. In this work, studies of modified linear amphiphilic statistical polymethyloxazoline (PMOX) and polyethyleneimine copolymers (PMOX_PEI) series are presented. Variation of PEI content in the structure results in controllable changes of polymeric aggregates zeta potential. The structure with the highest positive charge shows the best antimicrobial activity, well visible in tests against model Gram-positive and Gram-negative bacteria, fungi, and mycobacterium strains. The polymer toxicity is evaluated with MTT and hemolysis assay as a reference. Quartz crystal microbalance (QCM-D) is used to investigate interaction between polycations and a model lipid membrane. Polymer activity correlates well with molecular structure, showing that amphiphilic component is altering polymer behavior in contact with the lipid bilayer.

Antimicrobial Microneedle Patch for Treating Deep Cutaneous Fungal Infection

AbstractSubcutaneous fungal infection is often difficult to be treated by the conventional topical application or oral intake of antifungal agents because of low drug bioavailability to the infection site, lack of sustained therapeutic effect, and development of drug resistance. Here, a new strategy using polymeric microneedle (MN) patches to overcome the skin barrier is reported. MN is made of a biocompatible and biodegradable chitosan–polyethylenimine copolymer, which possesses antimicrobial property immune to drug resistance and allows sustained drug release. Using a fungal infection mouse model, it is demonstrated that MN patches encapsulated with antifungal agent amphotericin B offer outstanding treatment effectiveness. It is attributable to the high bioavailability of therapeutics and synergistic actions of the antifungal polymer and drug.

One-step synthesis of mannose-modified polyethyleneimine copolymer particles as fluorescent probes for the detection of Escherichia coli

Development of effective pathogen detection systems is critical for human health. In this study, Escherichia coli (E. coli) O157:H7 as a model microorganism, mannose-modified polyethyleneimine copolymer particles (Man-PEI CPs) were one-step synthesized through nucleophilic addition between primary amine and aldehyde group, and the fluorescent Man-PEI CPs have been successfully applied for selective and sensitive detection of Escherichia coli. The Man-PEI CPs with highly solubility had an average particle diameter of 54.4 nm. The fluorescence quantum yields of Man-PEI CPs was 0.42. The fluorescent Man-PEIs could provide good targeting ability toward E. coli pili due to the selectively binding to the FimH lectin unit of mannose. In order to get good binding efficiency to E. coli, the ratio of polyethyleneimine to mannose during their synthesis was optimized. The fluorescence emission by Man-PEI CPs/E. coli conjugate is closely related to the content of E. coli. Man-PEI CPs showed selective response towards E. coli and our assay exhibited potential practical applications for E. coli determination in water, beer and human urine. The simple, inexpensive and efficient preparation of Man-PEI CPs showed potential advantages in the detection of bacteria.

Effect of PEI surface modification with PEG on cytotoxicity and transfection efficiency

Polyethylenimine (PEI) is a cationic polymer with high transfection efficiency as non-viral gene delivery agent that exhibits promising features for gene therapy applications due to its cationic charge and thus favourable DNA-condensing abilities; however, its high cytotoxicity restricts its application. The cellular toxicity of PEI molecules depends on their structure, molecular weight and surface charge density. To improve the properties of branched 25 kDa PEI as a non-viral gene delivery agent, this polymer was conjugated to polyethylene glycol (PEG) molecules at three different molar ratios of 10, 20 and 30. The degree of PEG grafting was determined by 2, 4, 6-trinitrobenzene sulphonic acid assay. The effects of various PEGylation degrees on cellular toxicity and transfection ability of PEI polymer were assessed on BT-474 and MCF-10A cell lines. Compared to unmodified PEI, PEG-grafted PEI copolymers demonstrated reduced cytotoxicity, particularly at higher PEG grafting ratios. Among different PEG-grafted PEIs, the PEG-PEI copolymer which grafted to PEG at a molar ratio of 10:1 had the highest transfection efficiency in both cell lines. The findings of this Letter showed that these PEG-grafted PEI copolymers have desirable gene transfection efficiency and favourable biocompatibility for gene delivery.

Lyophilization and stability of antibody-conjugated mesoporous silica nanoparticle with cationic polymer and PEG for siRNA delivery.

IntroductionLong-term stability of therapeutic candidates is necessary toward their clinical applications. For most nanoparticle systems formulated in aqueous solutions, lyophilization or freeze-drying is a common method to ensure long-term stability. While lyophilization of lipid, polymeric, or inorganic nanoparticles have been studied, little has been reported on lyophilization and stability of hybrid nanoparticle systems, consisting of polymers, inorganic particles, and antibody. Lyophilization of complex nanoparticle systems can be challenging with respect to preserving physicochemical properties and the biological activities of the materials. We recently reported an effective small-interfering RNA (siRNA) nanoparticle carrier consisting of 50-nm mesoporous silica nanoparticles decorated with a copolymer of polyethylenimine and polyethyleneglycol, and antibody.Materials and methodsToward future personalized medicine, the nanoparticle carriers were lyophilized alone and loaded with siRNA upon reconstitution by a few minutes of simple mixing in phosphate-buffered saline. Herein, we optimize the lyophilization of the nanoparticles in terms of buffers, lyoprotectants, reconstitution, and time and temperature of freezing and drying steps, and monitor the physical and chemical properties (reconstitution, hydrodynamic size, charge, and siRNA loading) and biological activities (gene silencing, cancer cell killing) of the materials after storing at various temperatures and times.ResultsThe material was best formulated in Tris-HCl buffer with 5% w/w trehalose. Freezing step was performed at −55°C for 3 h, followed by a primary drying step at −40°C (100 µBar) for 24 h and a secondary drying step at 20°C (20 µBar) for 12 h. The lyophilized material can be stored stably for 2 months at 4°C and at least 6 months at −20°C.ConclusionWe successfully developed the lyophilization process that should be applicable to other similar nanoparticle systems consisting of inorganic nanoparticle cores modified with cationic polymers, PEG, and antibodies.

Mannose-Modificated Polyethylenimine: A Specific and Effective Antibacterial Agent against Escherichia coli.

Polyethylenimine (PEI) has antimicrobial activity against Gram-positive (Staphylococcus aureus, S. aureus) and Gram-negative (Escherichia coli, E. coli), bacteria but is highly cytotoxic, and the selective antimicrobial activity against S. aureus is obviously better than that against E. coli. To reduce the cytotoxicity and improve the antibacterial activity against E. coli, we modified PEI with d-mannose through nucleophilic addition between primary amine and aldehyde groups to get mannose-modified polyethylenimine copolymer particles (Man-PEI CPs). The use of mannose may provide good targeting ability toward E. coli pili. The antibacterial activity of Man-PEI CPs was investigated. Man-PEI CPs shows specific and very strong killing capability against E. coli at a concentration of 10 μg/mL, which is the highest antimicrobial efficiency compared to that of unmodified PEI (220 μg/mL). The antibacterial mechanism demonstrated that the enhancement in antibacterial activity is due to specific recognition of the mannose and destroying the cell wall of the bacteria by PEIs. Importantly, the Man-PEI CPs show less cytotoxicity and excellent biocompatibility. The results indicate that Man-PEI CPs have great potential as novel antimicrobial materials to prevent bacterial infections and provide specific applications for killing E. coli.

Specific targeting of human epidermal growth factor receptor 2 (HER2) overexpressing breast cancer cells by polyethylene glycol-grafted polyethyleneimine modified with anti-HER2 single-domain antibody

Polyethyleneimine is one of the most efficient non-viral gene delivery agents. However, some limitations such as non-specific cell binding, interactions with blood components, and relatively high cytotoxicity restrict its in vivo applications. In order to improve the properties of this molecule as a gene transfection vector, in this study, we developed a nano-carrier system based on polyethyleneimine derivatives synthesized by grafting bi-functional polyethylene glycol molecules (MAL-PEG3500-NHS) to 25 kDa branched polyethyleneimine polymer at three different molar ratios of 10, 20, and 30 (polyethylene glycol:polyethyleneimine). Variable domain of heavy-chain antibody against human epidermal growth factor receptor 2 as targeting agent was conjugated to polyethylene glycol–polyethyleneimine copolymer. In order to find the most effective resultant conjugate, the effect of these modifications on physicochemical properties, cytotoxicity, cellular uptake, and gene transfection efficiency of polyethyleneimine polymer was evaluated. According to the findings of this study and compared to unconjugated polyethyleneimine, PEGylated polyethyleneimine copolymers exhibit lower in vitro cytotoxicity. Polyethylene glycol–polyethyleneimine copolymer conjugated at a molar ratio of 10:1 (polyethylene glycol:polyethyleneimine) demonstrated a low cytotoxicity effect and desirable physicochemical properties. Anti-human epidermal growth factor receptor 2 variable domain of heavy-chain antibody conjugation further reduced the cytotoxicity of unmodified polyethyleneimine in all cell lines studied by 1.5- to 2-folds and also resulted in higher cellular uptake and transfection ability of this copolymer in human epidermal growth factor receptor 2 overexpressing breast cancer cell lines versus normal breast cells or human epidermal growth factor receptor 2 negative cell lines. Altogether, our data suggested that variable domain of heavy-chain antibody–polyethylene glycol–polyethyleneimine copolymers might be an efficient nano-carrier system for specific targeting of human epidermal growth factor receptor 2 expressing tumors.

Gene delivery to neuroblastoma cells by poly (l-lysine)-grafted low molecular weight polyethylenimine copolymers

Polyethylenimine (PEI) and poly (l-lysine) (PLL) are among the most investigated non-viral gene carriers. However, both polymers contain deficiencies that restrict their applications. In the present study, we synthesized PLL-alkyl-PEI conjugates via 6-carbon alkyl linker and investigated their possible advantages in gene delivery. Four PLL copolymers were synthesized with different molecular weights and ratios of PEI. The physiochemical properties of synthesized conjugates such as size, zeta potential, DNA condensation ability, buffering capacity and cytotoxicity were investigated. Renilla luciferase assay was employed to evaluate the gene transfection efficiency of pDNA-polymer to Neuro2A cell line. DNA condensation and particle size measurements showed that new PLL-PEI conjugates could form polyplexes in nano-scale size in the range of 99–122 nm and were able to condense DNA at low concentration. While cytotoxicity reduced in some groups, the transfection efficiency increased about 2.8 and 4 fold as compared to the unmodified PEI 1.8 kDa and 10 kDa, respectively. The results of the present study showed that the chemical modifications of PEI with PLL could significantly improve transfection efficiency and PLP10-10% shows the most promise as a new gene carrier.

Synthesis, characterisation and preliminary investigation of the haemocompatibility of polyethyleneimine-grafted carboxymethyl chitosan for gene delivery

The development of safe and efficient gene carriers is the key to the clinical success of gene therapy. In the present study, carboxymethyl chitosan (CMCS) was prepared by chitosan (CS) alkalisation and carboxymethylation reactions. Then polyethyleneimine (PEI) was grafted to the backbone of CMCS by an amidation reaction. The CMCS–PEI copolymer showed strong complexation capability with DNA to form nanoparticles, and achieved lower cytotoxicity and higher transfection efficiency compared with PEI (25kDa) towards 293T and 3T3 cells. Moreover, the haemocompatibility of the CMCS–PEI copolymer was investigated through the aggregation, morphology and lysis of human red blood cells (RBCs), along with the impact on the clotting function with activated partial thromboplastin time (APTT), prothrombin time (PT) and thromboelastographic (TEG) assays. The results demonstrated that the CMCS–PEI copolymer with a concentration lower than 0.05mg/mL had little impact on the aggregation, morphology or lysis of RBCs, or on blood coagulation. Therefore, the copolymer may be a strong alternative candidate as an effective and safe non-viral vector.

Synthesis of a carboxymethylated guar gum grafted polyethyleneimine copolymer as an efficient gene delivery vehicle

In the present study, a carboxymethylated guar gum-grafted-polyethyleneimine copolymer (CMGG-g-PEI) was synthesized and characterized by FT-IR, 1H NMR, XRD and zeta potential analyses.