Low Molecular Weight Oligomers with Aromatic Backbone as Efficient Nonviral Gene Vectors

Poly(l-glutamic acid) augments the transfection performance of lipophilic polycations by overcoming tradeoffs among cytotoxicity, pDNA delivery efficiency, and serum stability

Polycations are scalable and affordable nanocarriers for delivering therapeutic nucleic acids. Yet, cationicity-dependent tradeoffs between nucleic acid delivery efficiency, cytotoxicity, and serum stability hinder clinical translation. Typically, the most efficient polycationic vehicles also tend to be the most toxic. For lipophilic polycations-which recruit hydrophobic interactions in addition to electrostatic interactions to bind and deliver nucleic acids-extensive chemical or architectural modifications sometimes fail to resolve intractable toxicity-efficiency tradeoffs. Here, we employ a facile post-synthetic polyplex surface modification strategy wherein poly(l-glutamic acid) (PGA) rescues toxicity, inhibits hemolysis, and prevents serum inhibition of lipophilic polycation-mediated plasmid (pDNA) delivery. Importantly, the sequence in which polycations, pDNA, and PGA are combined dictates pDNA conformations and spatial distribution. Circular dichroism spectroscopy reveals that PGA must be added last to polyplexes assembled from lipophilic polycations and pDNA; else, PGA will disrupt polycation-mediated pDNA condensation. Although PGA did not mitigate toxicity caused by hydrophilic PEI-based polycations, PGA tripled the population of transfected viable cells for lipophilic polycations. Non-specific adsorption of serum proteins abrogated pDNA delivery mediated by lipophilic polycations; however, PGA-coated polyplexes proved more serum-tolerant than uncoated polyplexes. Despite lower cellular uptake than uncoated polyplexes, PGA-coated polyplexes were imported into nuclei at higher rates. PGA also silenced the hemolytic activity of lipophilic polycations. Our work provides fundamental insights into how polyanionic coatings such as PGA transform intermolecular interactions between lipophilic polycations, nucleic acids, and serum proteins, and facilitate gentle yet efficient transgene delivery.

ROS-Responsive Bola-Lipid Nanoparticles as a Codelivery System for Gene/Photodynamic Combination Therapy

The nonviral delivery systems that combine genes with photosensitizers for multimodal tumor gene/photodynamic therapy (PDT) have attracted much attention. In this study, a series of ROS-sensitive cationic bola-lipids were applied for the gene/photosensitizer codelivery. Zn-DPA was introduced as a cationic headgroup to enhance DNA binding, while the hydrophobic linking chains may facilitate the formation of lipid nanoparticles (LNP) and the encapsulation of photosensitizer Ce6. The length of the hydrophobic chain played an important role in the gene transfection process, and 14-TDZn containing the longest chains showed better DNA condensation, gene transfection, and cellular uptake. 14-TDZn LNPs could well load photosensitizer Ce6 to form 14-TDC without a loss of gene delivery efficiency. 14-TDC was used for codelivery of p53 and Ce6 to achieve enhanced therapeutic effects on the tumor cell proliferation inhibition and apoptosis. Results showed that the codelivery system was more effective in the inhibition of tumor cell proliferation than individual p53 or Ce6 monotherapy. Mechanism studies showed that the production of ROS after Ce6 irradiation could increase the accumulation of p53 protein in tumor cells, thereby promoting caspase-3 activation and inducing apoptosis, indicating some synergistic effect. These results demonstrated that 14-TDC may serve as a promising nanocarrier for gene/PDT combination therapy.

Combination of Backbone Rigidity and Richness in Aryl Structures Enables Direct Membrane Translocation of Polymer Scaffolds for Efficient Gene Delivery

The development of cell-penetrating polymers with endocytosis-independent cell uptake pathways has emerged as a prominent strategy to enhance the transfection efficiency. Inspired by the rigid α-helical structure that endows polypeptides with cell-penetrating ability, we propose that a rigid backbone can facilitate the corresponding polymer vector's performance in gene delivery by bypassing the difficult endosomal escape process. Meanwhile, the installation of aromatic domains, as a way to promote gene transfection efficiency, is employed through the construction of a poly(benzyl ether) (PBE)-based scaffold in this work. We demonstrate that the direct membrane translocation capability of the synthesized PBE contributes to its enhanced transfection performance and excellent biocompatibility profile, rendering the imidazolium-functionalized PBE scaffold with higher activity and biocompatibility. Molecular details of the PBE-lipid interaction are also revealed in molecular dynamics simulations, indicating the important roles of individual structural elements on the polymeric scaffold in the membrane penetration process.

Nuclear-targeted carbon quantum dot mediated CRISPR/Cas9 delivery for fluorescence visualization and efficient editing

Nuclear targeted delivery has great potential in improving the efficiency of non-viral carrier mediated genome editing. However, direct and efficient delivery of CRISPR/Cas9 plasmid into the nucleus remains a challenge. In this study, a nuclear targeted gene delivery platform based on fluorescent carbon quantum dots (CQDs) was developed. Polyethylenimine (PEI) and polyethylene glycol (PEG) synergistically passivated the surface of CQDs, providing an excitation-independent green-emitting fluorescent CQDs-PEI-PEG conjugate (CQDs-PP) with an ultra-small size and positive surface charge. Here we show that CQDs-PP could bind CRISPR/Cas9 plasmid to form a nano-complex by electrostatic attraction, which can bypass lysosomes and enter the nucleus by passive diffusion, and thereby improve the transfection efficiency. Also, CQDs-PP could deliver CRISPR/Cas9 plasmid into HeLa cells, resulting in the insertion/deletion mutation of the target EFHD1 gene. More importantly, CQDs-PP exhibited a considerably higher gene editing efficiency as well as comparable or lower cytotoxicity relative to Lipo2000 and PEI-passivated CQDs-PEI (CQDs-P). Thus, the nuclear-targeted CQDs-PP is expected to constitute an efficient CRISPR/Cas9 delivery carrier in vitro with imaging-trackable ability.

One-step fabrication of functional carbon dots with long wavelength emission for gene delivery and bio-imaging

As a new-type of fluorescent material, carbon dots (CDs) are promising nanoscale reagents with the potential to integrate the functions of bio-imaging and gene/drug delivery. Most of the reported CDs for nucleic acid delivery only emitted short-wavelength (blue and green) fluorescence, making them unsuitable for in vivo application. Herein, a one-step solvothermal method was applied to prepare CDs with long wavelength emission from low molecular weight PEI and rhodamine dyes for both bio-imaging and gene delivery. The structure of the CDs was confirmed by several analytical methods including ¹H NMR, FT-IR, TEM, and XPS. The results showed that the CDs possess excellent fluorescence properties, which enable their application in both in vitro and in vivo bio-imaging. Meanwhile, the CDs could also be used for the intracellular tracking of the gene delivery process. In vitro transfection results revealed that the CDs possessed high transfection efficiency, which was up to 162 times higher than that of the "golden standard" transfection reagent PEI 25 kDa. Besides, these CDs also exhibited better serum tolerance and lower cytotoxicity than PEI. A mechanistic study suggested that the CD/DNA complexes may release the nucleic acid cargo more effectively. This work provides a new method to prepare multi-functional CDs with non-viral gene delivery and long wavelength bio-imaging abilities.

A Fluorescent Self-Reporting Vector with GSH Reduction Responsiveness for Nucleic Acid Delivery

Nonviral gene vectors with stimulus responsiveness and self-reporting properties have broad application prospects in gene therapy. Herein, we developed a nanosized reduction-responsive cationic liposomal vector formed from DNS(Zn), in which a naphthalimide-sulfonamide group was used as the glutathione (GSH)-responsive group to generate a blue fluorescence signal at 458 nm. Macrocyclic polyamine (cyclen) was used as a cationic headgroup to facilitate Zn(II) coordination, which may reduce the cytotoxicity and improve transfection efficiency. The Zn-free and nonresponsive analogues were used for comparison. Fluorescent assays revealed that the GSH response of DNS(Zn) could increase the blue fluorescence signal and improve the DNA release in cells. The title material also showed higher positive ζ-potential than its nonresponsive analogue, resulting in stronger DNA binding ability and better cellular uptake. These advantages made DNS(Zn) a good candidate for nonviral gene delivery, and the transfection efficiency in HeLa cells was distinctly higher than that of its analogue and the commercially available transfection reagent. Besides plasmid DNA, DNS(Zn) could also deliver small interfering RNA (siRNA) with good gene silencing efficiency, extending the application of the liposomes. These results suggest that DNS(Zn) can serve as a highly efficient nucleic acid delivery vector with reduction-responsive fluorescence self-reporting ability in tumor cells.

Quinine copolymer reporters promote efficient intracellular DNA delivery and illuminate a protein-induced unpackaging mechanism

Polymeric vehicles that efficiently package and controllably release nucleic acids enable the development of safer and more efficacious strategies in genetic and polynucleotide therapies. Developing delivery platforms that endogenously monitor the molecular interactions, which facilitate binding and release of nucleic acids in cells, would aid in the rational design of more effective vectors for clinical applications. Here, we report the facile synthesis of a copolymer containing quinine and 2-hydroxyethyl acrylate that effectively compacts plasmid DNA (pDNA) through electrostatic binding and intercalation. This polymer system poly(quinine-co-HEA) packages pDNA and shows exceptional cellular internalization, transgene expression, and low cytotoxicity compared to commercial controls for several human cell lines, including HeLa, HEK 293T, K562, and keratinocytes (N/TERTs). Using quinine as an endogenous reporter for pDNA intercalation, Raman imaging revealed that proteins inside cells facilitate the unpackaging of polymer-DNA complexes (polyplexes) and the release of their cargo. Our work showcases the ability of this quinine copolymer reporter to not only facilitate effective gene delivery but also enable diagnostic monitoring of polymer-pDNA binding interactions on the molecular scale via Raman imaging. The use of Raman chemical imaging in the field of gene delivery yields unprecedented insight into the unpackaging behavior of polyplexes in cells and provides a methodology to assess and design more efficient delivery vehicles for gene-based therapies.

Novel Polymeric Hybrid Nanocarrier for Curcumin and Survivin shRNA Co-delivery Augments Tumor Penetration and Promotes Synergistic Tumor Suppression

A major barrier for co-delivery of gene medicine with small molecular chemotherapeutic drugs in solid tumors is the inadequate tumor penetration and transfection. In this study, a novel polymeric nanocarrier with integrated properties of tumor penetration, nuclear targeting, and pH-responsive features was designed, and further used to achieve the synergistic anti-tumor effect of curcumin (CUR) and survivin shRNA (pSUR). The polymeric hybrid nanocarrier was constructed from the FDA-approved polymer PLGA and a novel conjugated triblock polymer W5R4K-PEG_2K-PHIS (WPH). CUR and pSUR were simultaneously encapsulated in the dual-drug-loaded nanoparticles (CUR/pSUR-NPs) by a modified double-emulsion solvent evaporation (W/O/W) method. The obtained nanoparticles exhibited better pharmaceutical properties with a uniform spherical morphology and sustained release manners of CUR and pSUR. Excellent features including preferable cellular uptake, efficient endosomal escape, enhanced tumor penetration, and elevated transfection efficiency were further proven. Additionally, a markedly enhanced anti-tumor efficacy for CUR/shRNA-NPs was achieved on SKOV-3 and Hela cells. The synergistic anti-tumor effect involved the inhibition of tumor cell proliferation, induction of cell apoptosis, and the activation of caspase-3 pathways. This work sets up an innovative co-delivery nanosystem to suppress tumor growth, contributing to the development of a comprehensive nanoparticulate strategy for future clinical applications.

Cationic polymer-derived carbon dots for enhanced gene delivery and cell imaging

Carbon dots have attracted rapidly growing interest in recent years. In this report, we prepared two cationic polymer-derived carbon dots (Taea-CD and Cyclen-CD, collectively called C-dots) via a hydrothermal method. Transmission electron microscopy (TEM) results show that the C-dots were sphere-like and the size distribution was 1.8 ± 0.4 nm for Taea-CD and 5.4 ± 2 nm for Cyclen-CD. The C-dots emitted bright blue fluorescence under UV light (365 nm). Confocal laser scanning microscopy (CLSM) assay indicates that the C-dots-mediated transfection process could be detected in real time, and their tunable fluorescence emission under different wavelengths could satisfy varying requirements. Luciferase assay indicates that the transformation from the polymer to CD is an effective strategy to improve the transfection efficiency (TE) of the materials. Moreover, the C-dots also exhibit higher serum tolerance and cell viability than commercially available polyethyleneimine (PEI). These results demonstrate that the preparation of carbon dots from polymers is a promising method for developing multifunctional gene vectors with high TE and biocompatibility.

Zn(ii) coordination to cyclen-based polycations for enhanced gene delivery

Zn²⁺ coordination greatly improved the gene transfection efficiency of cyclen-based polycations.

Zn(ii)-cyclen complex-based liposomes for gene delivery: the advantage of Zn coordination

Zn-Coordination significantly improves the gene transfection efficiency and reduces the cytotoxicity of cyclen-based cationic liposomes.

Anti-tumour activity of low molecular weight heparin doxorubicin nanoparticles for histone H1 high-expressive prostate cancer PC-3M cells

Nucleus-targeting drug delivery systems (NTDDs) deliver chemotherapeutic agents to nuclei in order to improve the efficacy of anti-tumour therapy. Histone H1 (H1) plays a key role in establishing and maintaining higher order chromatin structures and could bind to cell membranes. In the present study, we selected H1 as a target to prepare a novel H1-mediated NTDD. Low molecular weight heparin (LMHP) and doxorubicin (DOX) were combined to form LMHP-DOX. Then, a novel NTDD consisting of LMHP-DOX nanoparticles (LMHP-DOX NPs) was prepared by self-assembly. The characteristics of LMHP-DOX and LMHP-DOX NPs were investigated. Histone H1 high-expressive prostate cancer PC-3M cell line was selected as the cell model. Cellular uptake, and the in vitro and in vivo anti-tumour activity of LMHP-DOX NPs were evaluated on H1 high-expressive human prostate cancer PC-3M cells. Our results indicated that intact LMHP-DOX NPs mediated by H1 could be absorbed by H1 high-expressive PC-3M cells, escape from the lysosomes to the cytoplasm, and localize in the perinuclear region via H1-mediated, whereby DOX could directly enter the cell nucleus and quickly increase the concentration of DOX in the nuclei of H1 high-expressive PC-3M cells to enhance the apoptotic activity of cancer cells. The anti-coagulant activity of LMHP-DOX NPs was almost completely diminished in rat blood compared with that of LMHP, indicating the safety of LMHP-DOX NPs. Compared to traditional NTDD strategies, LMHP-DOX NPs avoid the complicated modification of nucleus-targeting ligands and provide a compelling solution for the substantially enhanced nuclear uptake of chemotherapeutic agents for the development of more intelligent NTDDs.

Low molecular weight PEI-based fluorinated polymers for efficient gene delivery

Fluorinated biomaterials have been reported to have promising features as non-viral gene carriers. In this study, a series of fluorinated polymeric gene carriers were synthesized via Michael addition from low molecular weight polyethyleneimine (PEI) and fluorobenzoic acids (FBAs)-based linking compounds with different numbers of fluorine atoms. The structure-activity relationship (SAR) of these materials was systematically investigated. SAR studies showed that fluorine could screen the positive charge of these polymers. However, this shielding effect of fluorine would endow fluorinated polymers with good balance between DNA condensation and release. In vitro transfection results suggested that these fluorinated polymers could mediate efficient gene delivery. Flow cytometry and confocal microscopy studies demonstrated that more efficient cell uptake could be achieved by fluorinated materials with more fluorine atoms. Cytotoxicity assays showed that these fluorinated materials exhibited very low cytotoxicity even at high mass ratios. This study demonstrates that FBA-based fluorinated biopolymers have the potential for practical application.

Construction of a High-Efficiency Drug and Gene Co-Delivery System for Cancer Therapy from a pH-Sensitive Supramolecular Inclusion between Oligoethylenimine- graft-β-cyclodextrin and Hyperbranched Polyglycerol Derivative

Introducing genes into drug-delivery system for a combined therapy has become a promising strategy for cancer treatment. However, improving the in vivo therapy effect resulted from the high delivery efficiency, low toxicity, and good stability in the blood remains a challenge. For this purpose, the supramolecular inclusion was considered to construct a high-efficiency drug and gene co-delivery system in this work. The oligoethylenimine-conjugated β-cyclodextrin (β-CD-PEI600) and benzimidazole-modified four-arm-polycaprolactone-initiated hyperbranched polyglycerol (PCL-HPG-BM) were synthesized as the host and guest molecules, respectively, and then the co-delivery carrier of PCL-HPG-PEI600 was formed from the pH-mediated inclusion interaction between β-CD and BM. PCL-HPG-PEI600 showed the improved drug (doxorubicin, DOX) and gene (MMP-9 shRNA plasmid, pMMP-9) delivery ability in vivo, and their cellular uptake and intracellular delivery were investigated. Particularly, PCL-HPG-PEI600 showed excellent pMMP-9 delivery ability with significantly higher transfection efficiency than PEI25k due to its excellent serum resistance. For the combined therapy to breast cancer MCF-7 tumor, the co-delivery system of PCL-HPG-PEI600/DOX/pMMP-9 resulted in a much better inhibition effect on MCF-7 cell proliferation and migration in vitro as well as the suppression effect on MCF-7 tumors in vivo compared to those of single DOX or pMMP-9 formulation used. Moreover, PCL-HPG-PEI600 displayed nontoxicity and excellent blood compatibility, suggesting a promising drug and gene co-delivery carrier in combined therapy to tumors.

Dynamic constitutional chemistry towards efficient nonviral vectors

Dynamic constitutional chemistry has been used to design nonviral vectors for gene transfection. Their design has been thought in order to fulfill ab initio the main requirements for gene therapy. As building blocks were used hyperbranched PEI as hydrophilic part and benzentrialdehyde and a diamine linear siloxane as hydrophobic part, connected through reversible imine linkages. The obtaining of the envisaged structures has been confirmed by NMR and FTIR spectroscopy. The dynamic synthesized amphiphiles proved to be able to self-assemble in nano-sized spherical entities as was demonstrated by TEM and DLS, characterized by a narrow dimensional polydispersity. Agarose gel electrophoresis proved the ability of the synthesized compounds to bind DNA, while TEM revealed the spherical morphology of the formed polyplexes. As a proof of the concept, the nonviral vectors promoted an efficient transfection on HeLa cells, demonstrating that dynamic constitutional chemistry can be an important tool in the development of this domain.

Biodegradable Gene Carriers Containing Rigid Aromatic Linkage with Enhanced DNA Binding and Cell Uptake

The linking and modification of low molecular weight cationic polymers (oligomers) has become an attracted strategy to construct non-viral gene carriers with good transfection efficiency and much reduced cytotoxicity. In this study, PEI 600 Da was linked by biodegradable bridges containing rigid aromatic rings. The introduction of aromatic rings enhanced the DNA-binding ability of the target polymers and also improved the stability of the formed polymer/DNA complexes. The biodegradable property and resulted DNA release were verified by enzyme stimulated gel electrophoresis experiment. These materials have lower molecular weights compared to PEI 25 kDa, but exhibited higher transfection efficiency, especially in the presence of serum. Flow cytometry and confocal laser scanning microscopy results indicate that the polymers with aromatic rings could induce higher cellular uptake. This strategy for the construction of non-viral gene vectors may be applied as an efficient and promising method for gene delivery.

Aromatic Thioacetal-Bridged ROS-Responsive Nanoparticles as Novel Gene Delivery Vehicles

In this report, a series of polycations are designed and synthesized by conjugating reactive oxygen species (ROS)-responsive thioacetal-linkers to low molecular weight (LMW) polyethylenimine (PEI) via ring-opening polymerization. Their structure⁻activity relationships (SARs) as gene delivery vectors are systematically studied. Although the MWs of the target polymers are only ~9 KDa, they show good DNA binding ability. The formed polyplexes, which are stable toward serum but decomposed under ROS-conditions, have appropriate sizes (180~300 nm) and positive zeta-potentials (+35~50 mV). In vitro experiments reveal that these materials have low cytotoxicity, and higher transfection efficiency (TE) than controls. Furthermore, the title polymers exhibit excellent serum tolerance. With the present of 10% serum, the TE of the polymers even increases up to 10 times higher than 25 KDa PEI and 9 times higher than Lipofectamine 2000. The SAR studies also reveal that electron-withdrawing groups on the aromatic ring in 4a may benefit to balance between the DNA condensation and release for efficient gene transfection.

Functionalized Asymmetric Bola-Type Amphiphiles for Efficient Gene and Drug Delivery

The studies of bolaamphiphile-based nanoparticles as delivery vectors are still rudimentary and under development. In this study, several asymmetric bolaamphiphiles containing lysine and another moiety with special functions, such as pH-sensitive or cell-targeting property, were designed and synthesized. The potentials of these bolaamphiphile-based nanoparticles as versatile vectors for both nucleic acids and chemical drugs were studied. With the presence of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), these amphiphiles could be prepared into bolasomes, which showed good DNA binding ability and could condense plasmid DNA into nanoparticles with appropriate size and surface potential. Lys-His, which has a pH-sensitive histidine on one head, exhibited higher transfection efficiency than the symmetric counterpart and comparable efficiency to commercially available transfection reagent. Mechanism studies confirmed that the bolaplexes formed from Lys-His might induce the highest cellular uptake and the best endosomal escape ability. On the other hand, these bolaamphiphiles also exhibited good drug loading ability. The self-assembly vesicles could efficiently encapsulate the hydrophobic anti-cancer drug doxorubicin (DOX) in aqueous solution with high drug loading content and encapsulation efficiency. Confocal laser scanning microscopy (CLSM) experiment and cell viability assay exhibited a controlled release of the drug with the assistance of bolasomes. It was shown that such bolaamphiphiles have great potential as nano-vectors for both drug and gene or their co-delivery.

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.

Engineering the Aromaticity of Cationic Helical Polypeptides toward "Self-Activated" DNA/siRNA Delivery

The development of potent yet nontoxic membrane-penetrating materials is in high demand for effective intracellular gene delivery. We have recently developed α-helical polypeptides which afford potent membrane activities to facilitate intracellular DNA delivery via both endocytosis and the nonendocytic "pore formation" mechanism. Endocytosis will cause endosomal entrapment of the DNA cargo, while excessive "pore formation" would cause appreciable cytotoxicity. Additionally, helical polypeptides with stiff, rodlike structure suffer from low siRNA binding affinity. To address such critical issues, we herein incorporated various aromatic domains (benzyl, naphthyl, biphenyl, anthryl, and pyrenyl) into the side-chain terminals of guanidine-rich, helical polypeptides, wherein the flat-rigid shape, π-electronic structures of aromatic motifs "self-activated" the membrane-penetrating capabilities of polypeptides to promote intracellular gene delivery. Benzyl (Bn)- and naphthyl (Naph)-modified polypeptides demonstrated the highest DNA uptake level that outperformed the unmodified polypeptide, P2, by ∼4 fold. More importantly, compared with P2, Bn- and Naph-modified polypeptides allowed more DNA cargos to be internalized via the nonendocytic pathway, which significantly bypassed the endosomal entrapment and accordingly enhanced the transfection efficiency by up to 42 fold, outperforming PEI 25k as the commercial reagent by 3-4 orders of magnitude. The aromatic modification also improved the siRNA condensation capability of polypeptides, achieving notably enhanced gene-silencing efficiency against tumor necrosis factor-α to treat acute hepatic inflammation. Furthermore, we revealed that aromaticity-augmented membrane activity was accompanied by comparable or even significantly reduced "pore formation" capability, thus leading to diminished cytotoxicity at high concentrations. This study therefore provides a promising approach to manipulate the membrane activities and penetration mechanisms of polycations, which overcomes the multiple critical barriers preventing effective and safe gene delivery.

Biodegradable Poly(Amino Ester) with Aromatic Backbone as Efficient Nonviral Gene Delivery Vectors

The development of gene delivery vectors with high efficiency and biocompatibility is one of the critical points of gene therapy. Two biodegradable poly(amino ester)s were synthesized via ring-opening polymerization between low molecular weight (LMW) PEI and diepoxide. The molecular weights of poly(amino ester)s were measured by GPC. Agarose gel retardation assays showed that these materials have good DNA-binding ability and can retard the electrophoretic mobility of plasmid DNA (pDNA) at a weight ratio of 1. The formed polyplexes have proper sizes of around 200 nm and zeta-potential values of about 30-40 mV for cellular uptake. In vitro experiments revealed that polymer P2 gave higher transfection efficiency than PEI 25KDa and Lipofectamine 2000 with less toxicity, especially in 293 cells. Results demonstrate that such a type of degradable poly(amino ester) may serve as a promising non-viral gene vector.

Cationic lipids with a cyclen headgroup: synthesis and structure–activity relationship studies as non-viral gene vectors

The structure–activity relationships of cyclen-based cationic lipids as non-viral gene delivery vectors were studied and clarified.

A Facile Strategy to Prepare Hyperbranched Hydroxyl-Rich Polycations for Effective Gene Therapy

For effective gene therapy, nonviral gene carriers with low toxicity and high transfection efficiency are of much importance. In this work, we developed a facile strategy to prepare hyperbranched hydroxyl-rich polycations (denoted by TE) by the one-pot method involving ring-opening reactions between two commonly used reagents, ethylenediamine (ED) with two amino groups and 1,3,5-triglycidyl isocyanurate (TGIC) with three epoxy groups. The hyperbranched TEs with different molecular weights were investigated on their DNA condensation ability, protein absorption property, biocompatibility, transfection efficiency, and in vivo cancer therapy and toxicity. TE exhibited low cytotoxicity and protein absorption property due to the plentiful hydroxyl groups. The optimal transfection efficiency of TE was significantly higher than that of the gold standard polycationic gene carrier branched polyethylenimine (PEI, 25 kDa). Furthermore, TE was applied for in vivo tumor inhibition by the delivery of antioncogene p53, which showed good antitumor efficiency with low adverse effects. The present work provides a new concept for the facile preparation of hyperbranched hydroxyl-rich polycationic carriers with good transfection performances.