Polyethylene Glycol-polyethylenimine Research Articles

Enhanced antitumor effects of follicle-stimulating hormone receptor-mediated hexokinase-2 depletion on ovarian cancer mediated by a shift in glucose metabolism

BackgroundMost cancers favor glycolytic-based glucose metabolism. Hexokinase-2 (HK2), the first glycolytic rate-limiting enzyme, shows limited expression in normal adult tissues but is overexpressed in many tumor tissues, including ovarian cancer. HK2 has been shown to be correlated with the progression and chemoresistance of ovarian cancer and could be a therapeutic target. However, the systemic toxicity of HK2 inhibitors has limited their clinical use. Since follicle-stimulating hormone (FSH) receptor (FSHR) is overexpressed in ovarian cancer but not in nonovarian healthy tissues, we designed FSHR-mediated nanocarriers for HK2 shRNA delivery to increase tumor specificity and decrease toxicity.ResultsHK2 shRNA was encapsulated in a polyethylene glycol-polyethylenimine copolymer modified with the FSH β 33–53 or retro-inverso FSH β 33–53 peptide. The nanoparticle complex with FSH peptides modification effectively depleted HK2 expression and facilitated a shift towards oxidative glucose metabolism, with evidence of increased oxygen consumption rates, decreased extracellular acidification rates, and decreased extracellular lactate and glucose consumption in A2780 ovarian cancer cells and cisplatin-resistant A2780CP counterpart cells. Consequently, cell proliferation, invasion and migration were significantly inhibited, and tumor growth was suppressed even in cisplatin-resistant ovarian cancer. No obvious systemic toxicity was observed in mice. Moreover, the nanoparticle complex modified with retro-inverso FSH peptides exhibited the strongest antitumor effects and effectively improved cisplatin sensitivity by regulating cisplatin transport proteins and increasing apoptosis through the mitochondrial pathway.ConclusionsThese results established HK2 as an effective therapeutic target even for cisplatin-resistant ovarian cancer and suggested a promising targeted therapeutic approach.

Multimodal theranostics augmented by transmembrane polymer-sealed nano-enzymatic porous MoS2 nanoflowers.

Developing an all-in-one multimodal theranostic platform that can synergistically integrate sensitive photoacoustic (PA) imaging, enhanced photothermal therapy (PTT) and photodynamic therapy (PDT) as well as the nano-enzyme activated chemodynamic therapy (CDT) presents a great challenge for the current nanomedicine design. Herein, a simple hydrothermal method was used to prepare porous molybdenum disulfide (MoS2) nanoflowers. These nanoflowers were assembled by three dimensional (3D)-stacked MoS2 nanosheets with plentiful pores and large surfaces, which thus exhibited enhanced photothermal conversion via light trapping and peroxidase (POD)-like activity via active defects exposure. Consequently, this 3D-MoS2 nanostructure could be well-sealed by polyethylene glycol-polyethylenimine polymer modified with nucleolar translocation signal sequence of the LIM Kinase 2 protein (LNP) via strong electrostatic interaction, which not only benefited to stably deliver anticancer drug doxorubicin (DOX) into the tumor cells for pH/NIR-responsive chemotherapy, but also provided strong photoacoustic, photothermal performances and stimulated generation of reactive oxygen species (ROS) for imaging-guided PTT/PDT/CDT combined therapy. This work promised a simple all-in-one multimodal theranostic platform to augment the potential antitumoral therapeutic outcomes.

Functionally modified magnetic nanoparticles for effective siRNA delivery to prostate cancer cells in vitro.

Different types of siRNA delivery vehicles including nanoparticles have been synthesized and utilized for prostate cancer gene therapy. However, one of the most common limitations being faced is the toxicity of cationic polymers toward the cells. In the current study, magnetic nanoparticles were prepared and conjugated with cationic polymer, polyethylenimine. Then polyethylene glycol was conjugated with polyethylenimine to improve the biocompatibility of nanoparticles. The transmission electron microscopy size of nanoparticles was found to be 15.82 (±9.07) nm, while hydrodynamic size was about 79.20 (±0.68) nm. Zeta potential analysis of polyethylenimine and polyethylene glycol-coated nanoparticles was +31.4 (±0.62) and +5.65 (±0.76) mV, respectively. Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance confirmed the presence of polyethylene glycol and polyethylenimine polymers in magnetic nanoparticles. Cell viability test in mouse fibroblast NIH 3T3 and prostate cancer PC3 cells showed an increased in biocompatibility of functionally modified polyethylene glycol–polyethylenimine–Fe3O4 nanoparticles. siRNA targeting a disintegrin and metalloproteinase 10 (ADAM10) was successfully loaded into the polyethylene glycol–polyethylenimine–Fe3O4 nanoparticles and delivered to PC3 cells. The results clearly demonstrated a significant decrease in cell viability, which increased within a certain siRNA concentration. The inhibitory concentration (IC50) value for ADAM10 siRNA was calculated to be 15.83 nM after 72 h. Confocal microscopy confirmed the delivery of siRNA-loaded nanoparticles intracellularly to the tumor cells cytosol. This magnetic system can be used as a powerful platform to inhibit cancer cells progression.

Polyethylene Glycol (PEG) Addition to Polyethylenimine (PEI)-Impregnated Silica Increases Amine Accessibility during CO2 Sorption

Amine-impregnated sorbents can be applied in CO2 sequestration, but they suffer from low amine utility due to slow diffusion of CO2, leading to reduced accessibility of buried amines. We examined silica-supported polyethylenimine (PEI) sorbents and blended them with polyethylene glycol (PEG) as an additive to study the role of PEG in modifying sorption performance. We report an increase in amine efficiency, a decrease in the heat of sorption and regeneration temperature, and a change CO2 amine speciation with the addition of PEG. The increase in viscosity due to CO2 sorption leads to greater diffusion resistance; increases in viscosity were lower during CO2 sorption in blends with higher PEG composition. 13C NMR results on CO2-saturated PEI–PEG blends revealed the formation of carbamic acid and carbamate and showed a larger fraction of carbamic acid in PEG-rich samples. We propose PEG increases the amine efficiency by enabling the diffusion of CO2 due to viscosity reduction and changes in the CO2-amine speciation (carbamate versus carbamic acid), which modifies the theoretical CO2/amine stoichiometry.

A Versatile Naphthalimide–Sulfonamide‐Coated Tetraphenylethene: Aggregation‐Induced Emission Behavior, Mechanochromism, and Tracking Glutathione in Living Cells

A tetraphenylethene (TPE) derivative substituted with a sulfonyl-based naphthalimide unit (TPE-Np) was designed and synthesized. Its optical properties in solution and in the solid state were investigated. Photophysical properties indicated that the target molecule, TPE-Np, possessed aggregation-induced emission (AIE) behavior, although the linkage between TPE and the naphthalimide unit was nonconjugated. Additionally, it exhibited an unexpected, highly reversible mechanochromism in the solid state, which was attributed to the change in manner of aggregation between crystalline and amorphous states. On the other hand, a solution of TPE-Np in a mixture of dimethyl sulfoxide/phosphate-buffered saline was capable of efficiently distinguishing glutathione (GSH) from cysteine and homocysteine in the presence of cetyltrimethylammonium bromide. Furthermore, the strategy of using poly(ethylene glycol)-polyethylenimine (PEG-PEI) nanogel as a carrier to cross-link TPE-Np to obtain a water-soluble PEG-PEI/TPE-Np nanoprobe greatly improved the biocompatibility, and this nanoprobe could be successfully applied in the visualization of GSH levels in living cells.

Notch-1 siRNA and Methotrexate towards a Multifunctional Approach in Rhematoid Arthritis Management: a Nanomedicine Approach.

Rheumatoid arthritis (RA) is a chronic inflammatory disease and Notch pathway plays a pivotal role in synoviocytes involved in progression of RA. Herein, we have designed a self-assembled polymeric micelles based on polycaprolactone-polyethylene glycol (PCL-PEG) and polyethylenimine-polyethylene glycol (PEI-PEG) was prepared and loaded with methotrexate and Notch-1 siRNA for the effective treatment of rheumatoid arthritis. The MTX/siRNA-loaded polymeric micelles (siM-PM) showed appreciable cellular uptake in Raw264.7 cells which were activated with LPS and did not exhibit any toxicity to Raw264.7 and HUVEC cells. The AUC of siM-PM was 4-fold higher compared to that of free MTX while t1/2 was 6 fold for siM-PM compared to that of free drug indicating the superior pharmacokinetic parameters. Importantly, siM-PM significantly reduced the paw thickness and slowed the disease progression remarkably, indicating that siM-PM is very effective in recovering the edema in arthritic animals. Importantly, 2-fold decrease in arthritic score was observed in siM-PM treated group at the end of day 24. The data clearly reveals anti-inflammatory effect of combinational nanoparticle due to the sequence specific downregulation of Notch-1 expression in the RA clinical models. Overall, nanomedicine-based delivery of MTX and siRNA could overcome the side effects of small molecules and could improve the therapeutic effect of siRNA in rheumatoid arthritis.

Co-expression of mFat-1 and pig IGF-1 genes by recombinant plasmids in modified chitosan nanoparticles and its synergistic effect on mouse immunity

To develop a cost-effective molecular regulator to improve growth metabolism and immunity of animals, a recombinant plasmid co-expressing fatty acid desaturase (mFat-1) and pig insulin growth like factor 1 (IGF-1) genes was constructed by the 2 A self-cleavage technique. After entrapment within modified chitosan nanoparticles (chitosan modified with polyethyleneglycol–polyethylenimine, CPP), the recombinant plasmid was injected intramuscularly into mice. Compared with controls, co-expression of mFat-1 and IGF-1 significantly raised the level of serum IGF-1, and increased the liver and muscle docosa hexaenoic acid (DHA) content. Th and Tc cell levels were also elevated, as were expression levels of serum IL-4 and IL-6 genes. These results demonstrate that the immunity and metabolism of an animal can be effectively improved by co-expression of mFat-1 and IGF-1 genes in vivo, which may contribute to further development of novel immunomodulators with beneficial effects on growth metabolism and immunity.

Co-delivery of microRNA-21 antisense oligonucleotides and gemcitabine using nanomedicine for pancreatic cancer therapy.

Tumor metastasis occurs naturally in pancreatic cancer, and the efficacy of chemotherapy is usually poor. Precision medicine, combining downregulation of target genes with chemotherapy drugs, is expected to improve therapeutic effects. Therefore, we developed a combined therapy of microRNA‐21 antisense oligonucleotides (ASO‐miR‐21) and gemcitabine (Gem) using a targeted co‐delivery nanoparticle (NP) carrier and investigated the synergistic inhibitory effects on pancreatic cancer cells metastasis and growth. Polyethylene glycol–polyethylenimine–magnetic iron oxide NPs were used to co‐deliver ASO‐miR‐21 and Gem. An anti‐CD44v6 single‐chain variable fragment (scFvCD 44v6) was used to coat the particles to obtain active and targeted delivery. Our results showed that the downregulation of the oncogenic miR‐21 by ASO resulted in upregulation of the tumor‐suppressor genes PDCD4 and PTEN and the suppression of epithelial–mesenchymal transition, which inhibited the proliferation and induced the clonal formation, migration, and invasion of pancreatic cancer cells in vitro. The co‐delivery of ASO‐miR‐21 and Gem induced more cell apoptosis and inhibited the growth of pancreatic cancer cells to a greater extent than single ASO‐miR‐21 or Gem treatment in vitro. In animal tests, more scFvCD 44v6‐PEG‐polyethylenimine/ASO‐magnetic iron oxide NP/Gem accumulated at the tumor site than non‐targeted NPs and induced a potent inhibition of tumor proliferation and metastasis. Magnetic resonance imaging was used to observed tumor homing of NPs. These results imply that the combination of miR‐21 gene silencing and Gem therapy using an scFv‐functionalized NP carrier exerted synergistic antitumor effects on pancreatic cancer cells, which is a promising strategy for pancreatic cancer therapy.

Co-Delivery of Epirubicin and siRNA Using Functionalized Mesoporous Silica Nanoparticles Enhances In vitro and In vivo Drug Efficacy.

Development of drug resistance to anticancer drugs is an important challenge for cancer treatment. Recent studies focus on co-delivery of anticancer drugs and siRNA to overcome this challenge. Mesoporous silica nanoparticles (MSNs) are one of the promising nanoparticles that enable the delivery of drugs and siRNA simultaneously. MSNs coated with copolymer capable of co-delivery of drug and siRNA were prepared and characterized. In the present study, MSNs functionalized with polyethylenimine-polyethylene glycol (PEI-PEG) copolymer were prepared. MSNs were characterized using dynamic light scattering (DLS), Transmission Electron Microscopy (TEM) and elemental analysis. Nanoparticles were loaded with epirubicin hydrochloride (EPI) and anti B-cell lymphoma 2 (BCL-2) siRNA. The in vitro cytotoxicity and in vivo efficacy of different formulations were evaluated. Mean size of MSNs ranged from 98 to 247 nm. EPI release from MSNs was pH-dependent. MSNs loaded with EPI and siRNA showed better in vitro cytotoxicity with 1 μg/mL EPI and 50-400 ng/mL siRNA, besides MSNs loaded with 9 mg/kg EPI and 1.2 mg/kg siRNA resulted in improved in vivo effects compared to EPI or MSNs containing EPI or siRNA alone. The results of in vitro and in vivo studies indicated the synergistic effect of EPI and anti BCL-2 siRNA. This formulation could be a promising nanoparticle for codelivery of drug and siRNA in cancer cells.

Multifunctional targeting vinorelbine plus tetrandrine liposomes for treating brain glioma along with eliminating glioma stem cells.

Malignant brain glioma is the most lethal and aggressive type of cancer. Surgery and radiotherapy cannot eliminate all glioma stem cells (GSCs) and blood–brain barrier (BBB) restricts the movement of antitumor drugs from blood to brain, thus leading to the poor prognosis with high recurrence rate. In the present study, the targeting conjugates of cholesterol polyethylene glycol polyethylenimine (CHOL-PEG2000-PEI) and D-a-tocopheryl polyethylene glycol 1000 succinate vapreotide (TPGS1000-VAP) were newly synthesized for transporting drugs across the BBB and targeting glioma cells and GSCs. The multifunctional targeting vinorelbine plus tetrandrine liposomes were constructed by modifying the targeting conjugates. The studies were undertaken on BBB model, glioma cells, GSCs, and glioma-bearing mice. In vitro results showed that multifunctional targeting drugs-loaded liposomes with suitable physicochemical property could enhance the transport drugs across the BBB, increase the intracellular uptake, inhibit glioma cells and GSCs, penetrate and destruct the GSCs spheroids, and induce apoptosis via activating related apoptotic proteins. In vivo results demonstrated that multifunctional targeting drugs-loaded liposomes could significantly accumulate into brain tumor location, show the specificity to tumor sites, and result in a robust overall antitumor efficacy in glioma-bearing mice. These data suggested that the multifunctional targeting vinorelbine plus tetrandrine liposomes could offer a promising strategy for treating brain glioma.

Peptide GE11-Polyethylene Glycol-Polyethylenimine for targeted gene delivery in laryngeal cancer.

The objective of this study was to evaluate the possibility of using GE11-polyethylene glycol-polyethylenimine (GE11-PEG-PEI) for targeted gene delivery to treat epidermal growth factor receptor (EGFR)-overexpressing laryngeal cancer. This study described the design, characterization, and in vitro and in vivo study of the nanocarrier GE11-PEG-PEI for gene delivery to treat laryngeal cancer. Analysis of the sizes and zeta potentials indicated that the formation of PEGylated complexes was dependent on the N/P ratio, and these complexes were capable of binding plasmid DNA and condensing DNA into small positively charged nanoparticles. The results also revealed that GE11-PEG-PEI had a weaker effect on cell survival in vitro. Gene transfection was performed on human laryngeal cancer Hep-2 cells in vitro and in vivo. Both the in vitro and in vivo results demonstrated that GE11-PEG-PEI had greater transfection efficiency than mPEG-PEI. Compared with mPEG-PEI/pORF-hTRAIL and saline, GE11-PEG-PEI/pORFh-TRAIL significantly (p < 0.05) reduced tumor growth in nude mice with laryngeal cancer. Moreover, the GE11-PEG-PEI/pORF-hTRAIL-treated groups showed more apoptosis than the mPEG-PEI/pORF-hTRAIL-treated groups. Therefore, our results showed that the peptide GE11 conjugated to PEG-PEI delivered significantly more genes to EGFR-overexpressing laryngeal cancer cells in vivo, indicating that GE11-PEG-PEI may be a suitable gene vector for treating EGFR-overexpressing laryngeal cancer.

Surface functionalized mesoporous silica nanoparticles as an effective carrier for epirubicin delivery to cancer cells

Recent studies with inorganic nanoparticles modified with functional groups have demonstrated improvement in drug delivery into cancer cells. In the present study, we prepared, characterized, and evaluated mesoporous silica nanoparticles (MSNs) as carriers for epirubicin hydrochloride (EPI) in order to improve the antitumor efficacy of this drug. MSNs were prepared and functionalized with phosphonate, polyethylene glycol (PEG) and polyethylenimine–polyethylene glycol (PEI–PEG) groups. Different nanoparticulate formulations were loaded with EPI. The in vitro cytotoxicity and the in vivo antitumor efficacy of MSNs containing EPI were evaluated versus free EPI. The EPI release from nanoparticles was shown to be pH-dependent. The size of MSNs functionalized with polyethyleneimine-polyethylene glycol (MSN–PEI–PEG) was 123.8±4.8nm. This formulation showed the best antitumor effects at an EPI dose of 9mg/kg in C-26 colon carcinoma model. The biodistribution results proved that MSN–PEI–PEG–EPI had a higher tumor accumulation compared to free EPI, 3h after drug administration. The results indicated that this formulation could be effective nanocarriers for anti-tumor therapies.

PinX1-siRNA/mPEG-PEI-SPION combined with doxorubicin enhances the inhibition of glioma growth.

Resistance to chemotherapy and the side effects of anticancer drugs are the major obstacles for glioma treatment. The aim of the present study was to develop a novel approach for the treatment of gliomas that improved the therapeutic effect; the anticancer drug, doxorubicin (DOX), was combined with short interfering (si)RNA and monomethoxy polyethylene glycol polyethylenimine superparamagnetic iron oxide nanoparticle (mPEG-PEI-SPION), a magnetic resonance imaging (MRI)-visible nanoparticle. Specific siRNA molecules, delivered by mPEG-PEI-SPION, were employed to knockdown the PIN2-interacting protein 1 (PinX1) gene in C6 glioma cells. PinX1 is a nucleolar protein associated with telomere and telomerase. C6 cells were treated with DOX and/or PinX1-siRNA. The results of the transfection experiments revealed that siRNA/mPEG-PEI-SPION was transfected into C6 cells with high efficiency. PinX1-siRNA was unable to inhibit C6 cells, while in the PinX1-siRNA + DOX group, the same dose of DOX caused an increased loss of cell viability. Therefore, mPEG-PEI-SPION was shown to be viable for siRNA delivery into C6 cells and coadministration of DOX with PinX1-siRNA may be a potential therapeutic method for inhibiting gliomas.

Design of polyethylene glycol–polyethylenimine nanocomplexes as non‐viral carriers: mir‐150 delivery to chronic myeloid leukemia cells

MicroRNAs (miRNAs) are acknowledged as indispensable regulators relevant in many biological processes, and they have been pioneered as therapeutic targets for curing disease. miRNAs are single-stranded, small (19-22 nt) regulatory non-coding RNAs whose deregulation of expression triggers human cancers, including leukemias, mainly through dysregulation of expression of leukemia genes. miRNAs can function as tumour suppressors (suppressing malignant potential) or oncogenes (activating malignant potential) like actors of complex diseases. To address the issue of overcoming instability and low transfection efficiency in vitro, the polyethylene glycol-polyethyleneimine (PEG-PEI) nanoparticle was used as non-viral vector carrier for miR-150 transfection, which is downregulated in chronic myeloid leukemia. PEG-PEI [PEG(550)3 -g-PEI(1800) ]/miRNA nanocomplexes were synthesised and characterised by particle size distribution (PSD), polydispersity index (PDI) and zeta potential, surface charge, their cytotoxicity, and transfection efficiency. Interaction with human leukemia cells (K-562 and KU812) and control cells NCI-BL2347 with them has been investigated. The transfection efficiency of PEG-PEI/miRNA at N/P 26 rose 6.7-fold above the control by qRT-PCR. The size of homogenous nanocomplexes (PBI < 0.5) was 160.8 ± 11 nm. The data indicate that PEG-PEI may be an encouraging non-viral carrier for altering miRNA expression in the treatment of chronic myeloid leukemia, with many advantages such as relatively high miRNA transfection efficiency and low cytotoxicity.

Polyethylene Glycol - Polyethylenimine Nanoparticle-Mediated Transfection of Mir-150 Into the Leukemia Cells and Determination of the Expression Pattern Changes in Apoptosis and Cell Cycle Genes

AbstractAbstract 4679The aims of this study are transfection of tumor suppressor miR-150 that is down-regulated in leukemogenesis into leukemia cells mediated by Polyethylene Glycol - Polyethylenimine (PEG-PEI) nanoparticle and determine the changes in gene expression pattern in chronic myeloid leukemia model cell lines; K-562 and KU812 and non-leukemia cell lines NCI-BL2347 and NCI-BL2171.Characterization studies and stability studies of PEG-PEI copolymers were performed and by using these copolymers 9 nanoparticle formulations were prepared. Three copolymers (named T1, T3 and T9) were eligible for further analysis and nanoparticle complex (named F1, F2 and F3) formulations, particles that their size less than 300 nM have been evaluated.Nanoparticle-mediated substitution of miR-150 reduced the expressions of cell cycle control genes CDK2 and CCNG2, CDK6 7-fold and 2-fold, respectively in K562 leukemia cell model.Nanoparticle-mediated substitution of miR-150 has been evaluated KU812 leukemia cell model and reduced the expression of cell cycle control genes CHEK2, CDK5RAP1 and CCNG2 and CDKN1A 6- fold 5 –fold and 2-fold, respectively.Substitution of deregulated tumor suppressor miR-150 to leukemia cells with non-viral transfection yielded promising results for the treatment of leukemia. Taking into account these results, it should be supported by preclinical studies in animal models, which would add benefit to current treatment protocols in clinical application. Disclosures:No relevant conflicts of interest to declare.

Cyclic RGD–Polyethylene Glycol–Polyethylenimine for Intracranial Glioblastoma‐Targeted Gene Delivery

Even though the blood-brain barrier (BBB) is compromised for angiogenesis, therapeutic agents for glioblastoma multiforme (GBM) are particularly inefficient due to the existence of a blood-tumor barrier (BTB), which hampers tumor accumulation and uptake. Integrin α(v)β(3) is overexpressed on glioblastoma U87 cells and neovasculture, thus making its ligands such as the RGD motif target glioblastoma in vitro and in vivo. In the present work, we have designed a modified polyethylene glycol-polyethylenimine (PEG-PEI) gene carrier by conjugating it with a cyclic RGD sequence, c(RGDyK) (cyclic arginine-glycine-aspartic acid-D-tyrosine-lysine). When complexed with plasmid DNA, this gene carrier, termed RGD-PEG-PEI, formed homogenous nanoparticles with a mean diameter of 73 nm. These nanoparticles had a high binding affinity with U87 cells and facilitated targeted gene delivery against intracranial glioblastoma in vivo, thereby leading to a higher gene transfer efficiency compared to the PEG-PEI gene carrier without RGD decoration. This intracranial glioblastoma-targeted gene carrier also enhanced the therapeutic efficacy of pORF-hTRAIL, as evidenced by a significantly prolonged survival of intracranial glioblastoma-bearing nude mice. Considering the contribution of glioblastoma neovasculature to the BBB under angiogenic conditions, our results demonstrated the therapeutic feasibility of treating a brain tumor through mediation of integrin α(v)β(3), as well as the potential of using RGD-PEG-PEI as a targeted gene carrier in the treatment of intracranial glioblastoma.

Combination of Nanogel Polyethylene Glycol-Polyethylenimine and 6(hydroxymethyl)-1,4-anthracenedione as an Anticancer Nanomedicine

Polyethylene glycol-polyethylenimine (PEG-PEI) nanogels have been used to deliver nucleic acids and oligonucleotides into cells. First, we synthesized PEG-PEI nanogels with methylene proton ratios (CH2O:CH2N) in PEG-PEI ranging from approximately 6.8:1 to 4:1 and less, as shown by 1H NMR spectra. We first synthesized various nanogels with varying ratios of CH2O:CH2N (methylene proton) in PEG-PEI as shown by 1H NMR spectra and tested their cytotoxicity using a rodent pancreatic adenocarcinoma cell line (Pan 02). We showed that the nanogel PEG-PEI with methylene proton ratio of 4:1 was strongly cytotoxic to Pan 02 cells in vitro, while the nanogel with the methylene proton ratio of 6.8:1 was not toxic. We incorporated a novel anti-cancer drug, 6-(hydroxymethyl)-1,4-anthracenedione (AQ) analogue (AQ10) into nontoxic nanogel PEG-PEI and tested the effect of AQ10 loaded nanogel PEG-PEI (AQ10-nanogel PEG-PEI) and AQ10 dissolved in DMSO on Pan 02 cell growth. The size of this AQ10-nanogel PEG-PEI was characterized using atomic force microscopy (AFM). Our studies showed that the AQ10-nanogel PEG-PEI is readily taken up by Pan 02 cells. Growth attenuation of Pan 02 cells treated with AQ10-nanogel PEG-PEI was three to four times that of cells treated with AQ10 dissolved in DMSO. These results suggest that PEG-PEI, usually used to deliver nucleic acids into cells, can also be used to deliver an insoluble small molecule anticancer drug, AQ10.

Evaluation of the transfection property of a peptide ligand for the fibroblast growth factor receptor as part of PEGylated polyethylenimine polyplex

Purpose: Experiments were conducted to evaluate the utility of a peptide receptor ligand to improve transfection efficiency as part of a polyethylenimine-polyethylene glycol (PEI-PEG) polyplex. The 7-mer peptide (MQLPLAT), targeted toward the fibroblast growth factor 2 (FGF2) receptor, was recently identified using a phage-display library method as possessing a high degree of specificity for the FGF2 receptor without the mutagenicity associated with FGF itself. Two approaches (pre-modification or post-modification) to incorporate the peptide into the PEGylated polyplex were compared in terms of their effect on particle size, surface charge, DNA condensation ability, toxicity, cellular uptake and transfection efficiency.Methods: The peptide was conjugated to branched PEI (25 kDa) via a PEG spacer either before (pre-modified) or after (post-modified) complexation of PEI with DNA. Polyethyleneimine was conjugated to the PEG spacer (N-hydroxy succinimide (NHS) -PEG-maleimide (Mal)) through the NHS group. The FGF2 peptide was synthesized to contain a cysteine at the carboxyl end (MQLPLATC) and conjugated to the PEG spacer via the Maleimide group. Conjugates were evaluated using 1H NMR, amino acid analysis, and picrylsulfonic acid assay. DNA condensation was evaluated using agarose gel electrophoresis and cellular toxicity was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cellular uptake was measured using flow cytometry and transfection efficiency was determined using a luciferase reporter gene assay.Results: Both pre- and post-modification approaches led to a decrease in the zeta potential of the resulting polyplexes but did not alter their size. The pre-modification of PEI did not affect its ability to condense DNA. However, polyplexes formed with the pre-conjugated PEI did not improve cell uptake or transfection efficiency. In contrast, polyplexes that were post-modified with the FGF2 peptide resulted in a 3-fold increase in cell uptake and a 6-fold increase in transfection efficiency. Both pre- and post-modified polyplexes resulted in lower toxicity compared with unmodified PEI.Conclusions: The results indicate that the FGF2 peptide improves transfection efficiency when used as part of post-modified PEI/PEG polyplex. When used with pre-modified PEI/PEG, the beneficial effect of the peptide on transfection is not evident, probably because, in this case, the peptide ligand is not readily accessible to the FGF receptor.

Direct force measurement of the stability of poly(ethylene glycol)-polyethylenimine graft films.

The stability and passivity of poly(ethylene glycol)-polyethylenimine (PEG-PEI) graft films are important for their use as antifouling coatings in a variety of biotechnology applications. We have used AFM colloidal-probe force measurements combined with optical reflectometry to characterize the surface properties and stability of PEI and dense PEG-PEI graft films on silica. Initial contact between bare silica probes and PEI-modified surfaces yields force curves that exhibit a long-range electrostatic repulsion and short-range attraction between the surfaces, indicating spontaneous desorption of PEI in the aqueous medium. Further transfer of PEI molecules to the probe occurs with subsequent application of forces between FR = 300 and 500 microN/m. The presence of PEG reduces the adhesive properties of the PEI surface and prevents transfer of PEI molecules to the probe with continuous contact, though an initial desorption of PEI still occurs. Glutaraldehyde crosslinking of the graft films prevents both the initial desorption and subsequent transfer of the PEI, resulting in sustained attractive interaction forces of electrostatic origin between the negatively charged probe and the positively charged copolymer graft films.

Genuine DNA/polyethylenimine (PEI) Complexes Improve Transfection Properties and Cell Survival

Polyethylenimine (PEI) has been described as one of the most efficient cationic polymers for in vitro gene delivery. Systemic delivery of PEI/DNA polyplexes leads to a lung-expression tropism. Selective in vivo gene transfer would require targeting and stealth particles. Here, we describe two strategies for chemically coupling polyethylene glycol (PEG) to PEI, to form protected ligand-bearing particles. Pre-grafted PEG–PEI polymers lost their DNA condensing property, hence their poor performances. Coupling PEG to pre-formed PEI/DNA particles led to the expected physical properties. However, low transfection efficacies raised the question of the fate of excess free polymer in solution. We have developed a straightforward a purification assay, which uses centrifugation-based ultrafiltration. Crude polyplexes were purified, with up to 60% of the initial PEI dose being removed. The resulting purified and unshielded PEI/DNA polyplexes are more efficient for transfection and less toxic to cells in culture than the crude ones. Moreover, the in vivo toxicity of the polyplexes was greatly reduced, without affecting their efficacy.