Molecular Weight Polyethylenimine Research Articles

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.

Low molecular weight polyethylenimine-conjugated gold nanospheres: a platform for selective gene therapy controlled by near-infrared light.

Whether PEI2k-HAuNS could promote gene transfection efficiency controlled by near-infrared (NIR) light. This safe nonviral gene delivery system was obtained by conjugating low molecular weight (2 kDa) polyethylenimine (PEI) onto hollow gold nanospheres (PEI2k-HAuNS). Upon NIR laser irradiation, there was a conspicuous increase both in the in vitro and in vivo transfection achieved by the nanocomplexes. Furthermore, a plasmid encoding the tumor suppressor TP53 (pTP53) was applied to test antitumor activity. The enhanced gene transfection efficiency and therapy of PEI2k-HAuNS were achieved via the mediation of an NIR laser compared with the other treatments in vitro and in vivo. The application of NIR laser irradiated PEI2k-HAuNS can be used as a promising gene delivery systems in vitro and in vivo.

Polymeric Delivery of siRNA against Integrin-β1 (CD29) to Reduce Attachment and Migration of Breast Cancer Cells.

Cell surface integrins, which play important roles in the survival, proliferation, migration, and invasion of cancer cells, are a viable target for treatment of metastatic breast cancer. This line of therapy still remains challenging due to the lack of proper identification and validation of effective targets as well as the lack of suitable therapeutic agents for treatment. The focus is on one such molecular target for this purpose, namely integrin-β1, and effective lowering of integrin-β1 levels on a breast cancer model (MDA-MB-231 cells) is achieved by delivering a dicer-substrate short interfering RNA (siRNA) targeting integrin-β1 with lipid-modified low molecular weight polyethylenimine polymers. Reduction of integrin-β1 levels leads to reduced adhesion of MDA-MB-231 cells to extracellular matrix component fibronectin as well as to human bone marrow cells. A reduced migration of the breast cancer cells is also observed after integrin-β1 silencing in "scratch" and "transwell" migration assays. These results highlight the importance of integrin-β1 for the migration of metastatic breast cancer cells by effectively silencing this target with a practical dose of siRNA.

Redox-Activatable ATP-Depleting Micelles with Dual Modulation Characteristics for Multidrug-Resistant Cancer Therapy.

A fast adenosine triphosphate (ATP)-depleting micellar system that is activated by intracellular redox for the codelivery of anticancer drug paclitaxel (PTX) and small interference RNA (siRNA) targeting polo-like kinase1 (PLK1) is developed to address the key challenges of multidrug-resistant (MDR) cancer therapy. The ATP-depleting micelle is self-assembled from a redox-responsive amphiphilic polymer (termed as bPEG-SS-P123-PEI (PSPP)) that is composed of biocompatible branched polyethylene glycol (PEG) with 8 arms (bPEG), ATP-depleting Pluronic P123 (P123), and cationic low molecular weight polyethylenimine (PEI) blocks. Upon critical micelle concentration, the PSPP unimer self-assembles into a well-ordered multilayered nanostructure and is able to load PTX and siRNA targeting PLK1. The cleavage of disulfide linkages at intracellular glutathione-rich reduction milieu not only promotes PTX and siRNA release, but also activates the fast ATP-depletion action that is critical in preventing intracellular PTX efflux by multidrug-resistant cancer cells. The combination of ATP depletion and siRNA inhibition by PSPP micelles is found to provide dual modulations for resensitizing multidrug-resistant cancer cells for PTX treatment. As a result, the codelivery of PTX and PLK1 siRNA exerts a stronger combinational effect against tumor growth in MDR tumor models in vivo. The development of fast ATP-depleting nanomicelle represents an original delivery strategy for the distinctive dual modulation of cancer MDR with spatial and temporal control.

The intracellular delivery of plasmid DNA using cationic reducible carbon nanotube — Disulfide conjugates of polyethylenimine

A series of polyethylenimine conjugates of single-walled carbon nanotube (PEI-SWNT) containing bioreducible disulfide bonds was synthesized and evaluated for their transfection efficiency. Different molecular weights of polyethylenimine (PEI) were thiolated with different mole ratio of 2-iminothiolane (2-IT). Single-walled carbon nanotube (SWNT) was first carboxylated and then three different cysteine-functionalized SWNT formulations were synthesized via introduced linkers: a) carbonyl group b) spermidine c) 1,8-diamino 3,6-dioxo octane. The final nanocarriers were fabricated upon conjugation of thiolated PEIs and thiolated SWNT via oxidative disulfide bond formation. All PEI-disulfide-SWNT conjugates were capable of DNA condensation and showed improved viability and transfection efficiency compared to PEI itself. Transfection efficiencies were up to 1500 times greater than PEI 25kDa (C/P=0.8). The results of this study suggest that the synthesized formulations based on SWNT-CO-Cysteine and PEI 1.8kDa were the most efficient carriers. Considering the decreased cytotoxicity and higher transfection levels, the conjugates bear the potential for effective delivery of genetic materials.

The influence of polyethylenimine molecular weight on hydrothermally-synthesised ZnO nanowire morphology

Polyethylenimine (PEI) is a polymer commonly used in the hydrothermal synthesis of ZnO nanowires as an aspect-ratio enhancing agent. To this end, several studies have focused on optimising the PEI concentration to achieve the best results. However, the effect of the polymer's molecular weight on nanowire growth is relatively unstudied. We investigate three different molecular weights of PEI (Mw = 2000, 1300, and 800) at 8 mM, 6 mM, 4 mM and 2 mM concentrations. We find that the Mw = 2000 and Mw = 1300 varieties only yield homogeneous nanowires at 2 mM, while the Mw = 800 variety yields homogeneous nanowires over the entire range of concentrations investigated. The dimensions of the nanowires grown at 2 mM with PEI (Mw = 800, 1300) show minimal variation, with average diameters of 60 nm and average lengths of 2.5 µm, while the nanowires grown at 2 mM PEI (Mw = 2000) have an average diameter of 40 nm and an average length of 4 µm. The nanowires grown with PEI (Mw = 800) at concentrations of 8 mM, 6 mM, and 2 mM show a clear length dependency on concentration, with average lengths of 11 µm, 8 µm and 2.5 µm, respectively. A relationship between concentration and diameter is less clear, with average nanowire diameters of 90 nm, 40 nm and 60 nm, respectively.

Biologically responsive carrier-mediated anti-angiogenesis shRNA delivery for tumor treatment

Small interfering RNA (siRNA) has increased the hope for highly-efficient treatment of gene-related diseases. However, the stable and efficient delivery of therapeutic nucleic acids is a prerequisite for the successful clinical translation of RNA interfering therapy. To achieve this, we condensed the low molecular weight polyethyleneimine (PEI, Mw < 2000) with 2,6-pyridinedicarboxaldehyde (PDA) to synthesize a biologically responsive and degradable cationic polymer (abbreviated to PDAPEI) which was utilized as a gene vector for the delivery of a VEGF-A shRNA expression plasmid DNA (pDNA). The resulting electrostatic interaction between PDAPEI and pDNA led to the self-assembly of nanoscale polyplexes with suitable particle size and stable zeta potential. The PDAPEI/pDNA polyplexes demonstrated an outstanding gene transfection and silencing efficiency at 30 w/w ratio, as well as negligible cytotoxicity. Also, the designed polymer showed no stimulation to the innate immune system. Moreover, compared with PEI 25 KDa, the polyplexes accomplished comparatively better anti-angiogenesis efficacy, which resulted in the inhibition of tumor growth in subcutaneous tumor mice models. In conclusion, PDAPEI has great potential to be a gene delivery vector for cancer therapy.

Effect of high molecular weight polyethyleneimine functionalized graphene oxide coated polyethylene terephthalate film on the hydrogen gas barrier properties

Abstract Fabrication of high-performance graphene-based polymeric composites is challenging due to poor dispersion of graphene caused by restacking, weak interfacial bonding, and incompatibility of graphene with polymers. Herein, reduced graphene oxide (rGO)-based polyethyleneimine (PEI) composite (rGO/PEI) was synthesized by utilizing the unique roles of PEI as reducing agent and surface modifier to overcome the above-mentioned drawbacks of graphene. Composites with different graphene oxide (GO):HPEI ratios were used to prepare rGO-high molecular weight PEI (rGO/HPEI). For potential application as hydrogen gas barrier material, rGO/HPEI composites were coated onto the polyethylene terephthalate (PET) substrates through spray coating technique to prepare gas barrier films. Analogous rGO/LPEI (low molecular weight PEI) coated PET film was also prepared. The rGO/HPEI composite-coated films showed dramatic enhancement in hydrogen gas barrier properties and excellent tensile strength with high elongation at break as compared to PET and rGO/LPEI coated PET films.

Surface-functionalized cation exchange membrane by covalent immobilization of polyelectrolyte multilayer for effective separation of mono- and multivalent cations

ABSTRACTThe existence of numerous non-conductive regions retards the further functionalization of heterogeneous membrane surface. In this report, a modification scheme for covalent immobilization of polyethyleneimine (PEI) multilayer on heterogeneous cation exchange membrane (CEM) was developed by means of diazonium-induced carboxyl group grafting. Of particular note are the influences of some important modification conditions, including the molecular weight of PEI and its deposition times, which were explored and understood. Series of electrodialysis experiments confirmed the achievement of the monovalent cation permselectivity. Furthermore, the results also indicated that the PEI coating can also effectively improve surface homogeneity and then alleviate concentration polarization behaviour during the electrodialysis process.

Characterization of glycol chitosan grafted with low molecular weight polyethylenimine as a gene carrier for human adipose-derived mesenchymal stem cells

Mesenchymal stem cells (MSCs) have a great capacity for self-renewal while still maintaining their multipotency, and can differentiate into a variety of cell types. The delivery of genes to a site of injury is a current and interesting field of gene therapy. In the present study, we describe a nonviral gene delivery carrier, glycol chitosan-methyl acrylate-polyethylenimine (GMP) polymer targeted towards human adipose-derived mesenchymal stem cells (AD-MSCs). Transfection efficiency, using luciferase (Luc) and a pDNA encoding enhanced green fluorescent protein (EGFP), along with cytotoxicity assays, were performed in human AD-MSCs. The results show that the transfection efficiency of the GMP polymer was similar to that of PEI25kD, and the cytotoxicity was lower. Moreover, human AD-MSCs were treated with the GMP polymer/pDNA polyplex and its cellular uptake and distribution were analyzed by flow cytometry and confocal microscopy. Furthermore, we performed endosomal escape analysis using LysoTracker Red, and found that the conjugated GMP polymer could escape from the endosome to the cytosol. Human AD-MSCs treated with the GMP polymer maintained their potential for osteogenic differentiation and phenotypic expression of human AD-MSCs based on flow cytometry analysis. The present study demonstrates that the GMP polymer can be used as a potential targeted–delivery carrier for effective gene delivery.

Abstract 2078: Interleukin-12 gene therapy in combination with bevacizumab and pegylated liposomal doxorubicin for treatment of disseminated ovarian cancer

Abstract Despite recent improvements in treatment options for ovarian cancer patients, notably, the approval of using bevacizumab in combination with chemotherapies including pegylated liposomal doxorubicin (PLD), this disease is still the most deadly of all gynecological malignancies requiring new and novel therapeutics. Interleukin-12 (IL-12) is a highly active cytokine that can induce a potent anti-cancer immunity mediated through activation of cytotoxic T-lymphocytes, natural killer cell proliferation, and secretion of interferon-γ. We are developing an IL-12 based gene therapy for the treatment of gynecological malignancies that have spread into the peritoneal cavity. Our approach utilizes IL-12 plasmid (pIL-12) formulated with the PPC delivery system, which is comprised of a low molecular weight polyethylenimine covalently linked to polyethyleneglycol and cholesterol. Previously we have shown in a mouse model of disseminated ovarian cancer efficacy of a treatment regimen of pIL-12/PPC used in combination with paclitaxel and carboplatin. The combination treatment significantly improved survival compared to either pIL-12/PPC alone or chemotherapy alone and demonstrated the feasibility of using an IL-12 immunotherapy in combination with cytotoxic chemotherapies to achieve additive therapeutic effects. Results from a Phase I clinical trial in platinum resistant patients have shown that intraperitoneal delivery of pIL-12/PPC in combination with PLD produced an overall clinical benefit of 57.1% (PR = 21.4%; SD = 35.7%) in patients with measurable disease. The highest percentage of PRs were found at the highest dose level (28.6%) along with highest percentage of patients achieving SD (57.1%). Here we describe studies evaluating the combination of pIL-12/PPC with bevacizumab and PLD. For these studies 5,000,000 human SKOV3 cells were implanted into the peritoneal cavity of immunocompromised Hsd:Athymic Nude-Foxn1nu mice. Treatment with pIL-12/PPC alone and bevacizumab alone resulted in a 50% and a 39% reduction of animals with visible tumors at the end of the study. Combining pIL-12/PPC + bevacizumab improved the response to 78% of animals with no visible tumors. Further, combining pIL-12/PPC + bevacizumab + PLD resulted in a &amp;gt;98% decrease in tumor burden in animals compared to controls and ∼92% decrease in tumor burden compared to animals treated only with bevacizumab + PLD. All treatments were well tolerated and analysis of serum chemistries and hematology showed normal ranges of all parameters examined for all groups. There were no significant differences in animal weights between groups during the experiment. Together these results suggest synergistic efficacies can be achieved by combining a novel pIL-12/PPC immunotherapy with anti-angiogenesis therapies and cytotoxic chemotherapies in disseminated ovarian cancer. Citation Format: Jason G. Fewell, Majed M. Matar, Jennifer Rice, Diane McClure, Elaine Brunhoeber, Jeff Sparks, Stefanie Greenleaf, Kelley Smith, Khursheed Anwer. Interleukin-12 gene therapy in combination with bevacizumab and pegylated liposomal doxorubicin for treatment of disseminated ovarian cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2078.

Post-Transcriptional Regulation of the GASC1 Oncogene with Active Tumor-Targeted siRNA-Nanoparticles.

Basal-like breast cancer (BLBC) accounts for the most aggressive types of breast cancer, marked by high rates of relapse and poor prognoses and with no effective clinical therapy yet. Therefore, investigation of new targets and treatment strategies is more than necessary. Here, we identified a receptor that can be targeted in BLBC for efficient and specific siRNA mediated gene knockdown of therapeutically relevant genes such as the histone demethylase GASC1, which is involved in multiple signaling pathways leading to tumorigenesis. Breast cancer and healthy breast cell lines were compared regarding transferrin receptor (TfR) expression via flow cytometry and transferrin binding assays. Nanobioconjugates made of low molecular weight polyethylenimine (LMW-PEI) and transferrin (Tf) were synthesized to contain a bioreducible disulfide bond. siRNA complexation was characterized by condensation assays and dynamic light scattering. Cytotoxicity, transfection efficiency, and the targeting specificity of the conjugates were investigated in TfR positive and negative healthy breast and breast cancer cell lines by flow cytometry, confocal microscopy, RT-PCR, and Western blot. Breast cancer cell lines revealed a significantly higher TfR expression than healthy breast cells. The conjugates efficiently condensed siRNA into particles with 45 nm size at low polymer concentrations, showed no apparent toxicity on different breast cancer cell lines, and had significantly greater transfection and gene knockdown activity on mRNA and protein levels than PEI/siRNA leading to targeted and therapeutic growth inhibition post GASC1 knockdown. The synthesized nanobioconjugates improved the efficiency of gene transfer and targeting specificity in transferrin receptor positive cells but not in cells with basal receptor expression. Therefore, these materials in combination with our newly identified siRNA sequences are promising candidates for therapeutic targeting of hard-to-treat BLBC and are currently further investigated regarding in vivo targeting efficacy and biocompatibility.

Reduction of polyethylenimine-coated iron oxide nanoparticles induced autophagy and cytotoxicity by lactosylation.

Superparamagnetic iron oxide (SPIO) nanoparticles are excellent magnetic resonance contrast agents and surface engineering can expand their applications. When covered with amphiphilic alkyl-polyethyleneimine (PEI), the modified SPIO nanoparticles can be used as MRI visible gene/drug delivery carriers and cell tracking probes. However, the positively charged amines of PEI can also cause cytotoxicity and restricts their further applications. In this study, we used lactose to modify amphiphilic low molecular weight polyethylenimine (C12-PEI2K) at different lactosylation degree. It was found that the N-alkyl-PEI-lactobionic acid wrapped SPIO nanocomposites show better cell viability without compromising their labelling efficacy as well as MR imaging capability in RAW 264.7 cells, comparing to the unsubstituted ones. Besides, we found the PEI induced cell autophagy can be reduced via lactose modification, indicating the increased cell viability might rely on down-regulating autophagy. Thus, our findings provide a new approach to overcome the toxicity of PEI wrapped SPIO nanocomposites by lactose modification.

A high affinity kidney targeting by chitobionic acid-conjugated polysorbitol gene transporter alleviates unilateral ureteral obstruction in rats.

Aside from kidney transplantation - a procedure which is exceedingly dependent on donor-match and availability leading to excessive costs - there are currently no permanent treatments available which reverse kidney injury and failure. However, kidney-specific targeted gene therapy has outstanding potential to treat kidney-related dysfunction. Herein we report a novel kidney-specific targeted gene delivery system developed through the conjugation of chitobionic acid (CBA) to a polysorbitol gene transporter (PSGT) synthesized from sorbitol diacrylate and low molecular weight polyethylenimine (PEI) carrying hepatocyte growth factor (HGF) gene to alleviate unilateral ureteral obstruction (UUO) in rats. CBA-PSGT performed exceptionally well for targeted delivery of HGF to kidney tissues compared to its non-targeted counterparts (P<0.001) after systemic tail-vein injection and significantly reduced the UUO symptoms, returning the UUO rats to a normal health status. The kidney-targeted CBA-PSGT-delivered HGF also strikingly reduced various pathologic and molecular markers invivo such as the level of collagens (type I and II), blood urea nitrogen (BUN), creatinine, and the expressions of ICAM-1, TIMP-1 and α-SMA which play a critical role in obstructive kidney functions. Therefore, CBA-PSGT should be further investigated because of its potential to alleviate UUO and kidney-related diseases using high affinity kidney targeting.

Self-Assembled Superparamagnetic Iron Oxide Nanoclusters for Universal Cell Labeling and MRI.

Superparamagnetic iron oxide (SPIO) nanoparticles have been widely used in a variety of biomedical applications, especially as contrast agents for magnetic resonance imaging (MRI) and cell labeling. In this study, SPIO nanoparticles were stabilized with amphiphilic low molecular weight polyethylenimine (PEI) in an aqueous phase to form monodispersed nanocomposites with a controlled clustering structure. The iron-based nanoclusters with a size of 115.3 ± 40.23 nm showed excellent performance on cellular uptake and cell labeling in different types of cells, moreover, which could be tracked by MRI with high sensitivity. The SPIO nanoclusters presented negligible cytotoxicity in various types of cells as detected using MTS, LDH, and flow cytometry assays. Significantly, we found that ferritin protein played an essential role in protecting stress from SPIO nanoclusters. Taken together, the self-assembly of SPIO nanoclusters with good magnetic properties provides a safe and efficient method for universal cell labeling with noninvasive MRI monitoring capability.Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-016-1479-5) contains supplementary material, which is available to authorized users.

Synthesis of intracellular reduction-sensitive amphiphilic polyethyleneimine and poly(ε-caprolactone) graft copolymer for on-demand release of doxorubicin and p53 plasmid DNA

This study aims to present a new intelligent polymeric nano-system used for combining chemotherapy with non-viral gene therapy against human cancers. An amphiphilic copolymer synthesized through the conjugation of low molecular weight polyethyleneimine (LMw-PEI) and poly(ε-caprolactone) (PCL) via a bio-cleavable disulfide linkage was successfully employed for the simultaneous delivery of drug and gene molecules into target cells. Compared to the conventional PCL copolymerization pathway, this paper represents a straightforward and efficient reaction pathway including the activation of PCL-diol hydroxyl end groups, cystamine attachment and LMw-PEI conjugation which are successfully performed at mild conditions as confirmed by FTIR and 1H NMR. Thermal, morphological characteristics as well as biocompatibility of the copolymer were investigated. The copolymer showed great tendency to form positively charged nanoparticles (∼163.1nm, +35.3mV) with hydrophobic core and hydrophilic shell compartments implicating its potential for encapsulation of anti-cancer drug and plasmid DNA, respectively. The gel retardation assay confirmed that the nanoparticles could successfully inhibit the migration of pDNA at ∼5 nanoparticle/pDNAw/w. The in vitro cytotoxicity tests and LDH assay revealed that the cationic amphiphilic copolymer was essentially non-toxic in different carcinoma cell lines in contrast to branched PEI 25K. Moreover, the presence of redox sensitive disulfide linkages provided smart nanoparticles with on-demand release behavior in response to reducing agents such as cytoplasmic glutathione (GSH). Importantly, confocal microscopy images revealed that in contrast to free Dox, the nanoparticles were capable of faster internalizing into the cells and accumulating in the perinuclear region or even in the nucleus. Finally, the co-delivery of Dox and p53-pDNA using the copolymer displayed greater cytotoxic effect compared with the Dox-loaded nanoparticle counterpart as revealed by cell viability and Caspase 3 expression assay. These results suggest the copolymer as a promising candidate for the development of smart delivery systems. Statement of SignificanceWe employed cystamine dihydrochloride as a disulfide linkage for the conjugation of PCL diol and low molecular weight PEI segments through a straightforward and efficient reaction pathway at mild conditions. The new copolymer was essentially non-toxic in different carcinoma cell lines and showed great tendency to form positively charged nanoparticles. Therefore, it can be utilized as a promising platform for simultaneous drug and gene delivery to aggressive cancers. The results of drug and gene co-delivery experiments confirmed the pivotal role of disulfide linkage on the controlled release of both drug and gene molecules in response to glutathione concentration gradient between extracellular and intracellular microenvironments. In addition, the co-delivery of doxorubicin and p53 plasmid DNA using the new copolymer displayed greater cytotoxic effect compared with single agent (i.e. Dox) loaded counterpart, which indicated the significance of rapid dissociation of therapeutic agents from the carrier for synergistic cytotoxic effects on cancer cells.

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.

High molecular weight polyethyleneimine functionalized three dimensional mesoporous silica for regenerable CO2 separation

Polyethylenimine functionalized mesoporous silica is a potential alternative of amine based absorption process for CO2 capture from flue gas. By impregnation of high molecular weight polyethylenimine (PEI) into three dimensional mesoporous KIT-6, a novel sorbent was prepared for highly CO2/N2 selective separation at moderate temperature and low partial pressure with high stability. TEM micrograph shows that, pore is covered with PEI and also a layer of PEI is formed on the surface of adsorbent without disturbing its original structure. TGA analysis confirmed that with increasing molecular weight of PEI, thermal stability of adsorbent was increased. The sorption capacity was increased with increasing the temperature form 30 to 120°C and the adsorption mechanism is elucidated with the help of the nature of CO2 equilibrium isotherms. The very high CO2/N2 selective adsorbent follows the order K/250PEI<K/12PEI<K/8PEI with maximum operating sorption capacity 3.0 mmol CO2/g of K/8PEI at 105°C and 100kPa. Adsorbent showed stable sorption performance at moderate temperature (90–105)A/100D°C during 20 adsorption/desorption cycles. However, K/250PEI gives the maximum benefits in terms of stable sorption performance (2.4mmolCO2/g adsorbent at 105°C and 100kPa) and the necessary thermal stability for practical application.

A novel tyrosine-modified low molecular weight polyethylenimine (P10Y) for efficient siRNA delivery in vitro and in vivo

The delivery of nucleic acids, particularly of small RNA molecules like siRNAs for the induction of RNA interference (RNAi), still represents a major hurdle with regard to their application in vivo. Possible therapeutic applications thus rely on the development of efficient non-viral gene delivery vectors. While low molecular weight polyethylenimines (PEIs) have been successfully explored, the introduction of chemical modifications offers an avenue towards the development of more efficient vectors.In this paper, we describe the synthesis of a novel tyrosine-modified low-molecular weight polyethylenimine (P10Y) for efficient siRNA complexation and delivery. The comparison with the respective parent PEI reveals that knockdown efficacies are considerably enhanced by the tyrosine modification, as determined in different reporter cell lines, without appreciable cytotoxicity. We furthermore identify optimal conditions for complex preparation as well as for storing or lyophilization of the complexes without loss of biological activity. Beyond reporter cell lines, P10Y/siRNA complexes mediate the efficient knockdown of endogenous target genes and, upon knockdown of the anti-apoptotic oncogene survivin, tumor cell inhibitory effects in different carcinoma cell lines. Pushing the system further towards its therapeutic in vivo application, we demonstrate in mice the delivery of intact siRNAs and distinct biodistribution profiles upon systemic (intravenous or intraperitoneal) injection. No adverse effects (hepatotoxicity, immunostimulation/alterations in immunophenotype, weight loss) are observed. More importantly, profound tumor-inhibitory effects in a melanoma xenograft mouse model are observed upon systemic application of P10Y/siRNA complexes for survivin knockdown, indicating the therapeutic efficacy of P10Y/siRNA complexes.Taken together, we (i) establish tyrosine-modified PEI (P10Y) as efficient platform for siRNA delivery in vitro and in vivo, (ii) identify optimal preparation and storage conditions as well as (iii) physicochemical and biological properties of P10Y complexes, and (iv) demonstrate their applicability as siRNA therapeutic in vivo (v) in the absence of adverse effects.

Sialic Acid-Targeted Nanovectors with Phenylboronic Acid-Grafted Polyethylenimine Robustly Enhance siRNA-Based Cancer Therapy.

Small interference RNA (siRNA)-based therapy holds great potential for cancer treatment. However, its clinical application remains unsatisfied due to the lack of a safe and effective RNA delivery system. Aberrantly elevated sialyation on cell membrane has been reported as an attractive target for cancer diagnosis and therapy. In this study, phenylboronic acid (PBA) was conjugated onto low molecular weight polyethylenimine (PEI1.8k) to generate amphiphilic PBA-grafted PEI1.8k (PEI-PBA) nanovector, which was designed to facilitate cancer-targeted RNA delivery through the recognition of sialic structures on a cancer cell membrane. PEI-PBA simultaneously encapsulated siRNA to form PEI-PBA/siRNA nanocomplexes with great biocompatibility, serum stability and RNase resistance. The cell culture study showed that PEI-PBA/siRNA dramatically increased siRNA uptake up to 70-90% in several cancer cell lines, which relied on the interaction between PBA and sialic acid on cell membrane. Moreover, the PEI-PBA nanovector effectively promoted the lysosome escape of siRNA, decreasing the expression of target gene Polo-like kinase 1 (PLK-1) in cancer cells. The systemic administration of PEI-PBA/PLK-1 siRNA (PEI-PBA/siPLK1) nanocomplexes not only facilitated tumor-targeted siRNA delivery but also significantly decreased PLK-1 expression in tumors, thereby robustly inducing tumor apoptosis and cell cycle arrest. Additionally, the administration of PEI-PBA/siPLK1 did not cause significant systemic toxicity or immunotoxicity. Hence, sialic acid-targeted PEI-PBA could be a highly efficient and safe nanovector to improve the efficacy of cancer siRNA therapy.