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Sucrose esters (SEs) have great potential applications in gene delivery because of their low toxicity, excellent biocompatibility, and biodegradability. By using tripeptide-based lipid (CDO) as a model lipid and SEs as helper lipids, a series of liposomes were prepared. The SEs with hydrophilic–lipophilic balance (HLB) values of 1, 6, 11, or 16 and the fatty acids of laurate, stearate, or oleate were used in the liposomes. We investigated the effect of HLB values of SEs and fatty acid types on gene transfection efficiency and toxicity of liposomes. The results showed that transfection efficiencies of the liposomes containing SEs with HLB value of 6 were superior to other liposomes in HeLa, MCF-7, NCI-H460, and A549 tumor cells. For the same HLB value, liposomes of laurate SEs were preferable to transfect cells compared to SEs of stearate and oleate. The liposomes with SEs showed higher cellular uptake than liposome without SEs (LipoCDO). LipoL12-6/Luc-siRNA treatment on tumor-bearing mice exhibited about 60% in vivo gene silencing of luciferase, and LipoL12-6 could mediate IGF-1R siRNA to greatly inhibit tumor growth. Moreover, liposomes with SEs revealed remarkably low toxicity in vitro and in vivo . The illustration of SE structures on gene delivery will promote the use of SEs for clinical trials of liposomes. Statement of Significance This article is the first to study the effects of various chain lengths and hydrophilic–lipophilic balance (HLB) of sucrose esters (SEs) on gene transfection efficiency and safety of liposomes for gene delivery. The in vitro delivery of pDNA and siRNA by lipoplexes against HeLa, MCF-7, NCI-H460, and A549 tumor cells showed that the lipoplexes could lead to better transfection and lower cytotoxicity after the addition of SEs. SEs with shorter chain and a median HLB value could provide the liposomes with much higher gene transfection efficiency than others. The in vivo delivery of siRNA to tumor-bearing mice further confirmed that liposome containing laurate SE (LipoL12-6) could be a potential therapeutic vector, as it delivered siRNA to silence nearly 60% of the luciferase in tumors and also greatly inhibited the tumor growth. Therefore, the addition of SEs to liposomes proved to be relatively safe in vitro and in vivo . These preliminary results demonstrated that SEs show great potential for constructing controlled-release systems for gene delivery. The readers will get insights into a series of gene vectors and deepen their understanding about gene delivery. [ABSTRACT FROM AUTHOR]

Modifying chitosan (CS) with polyethylenimine (PEI) grafts is an effective way to improve its gene transfection performance. However, it is still a challenge to conduct the grafting with fine control and high efficiency, particularly for the modification of water-insoluble CS. Herein, a novel method to graft CS with PEI (1.8 kDa, PEI-1.8) was developed by using ionic liquid 1-butyl-3-methyl imidazolium acetate ([BMIM]Ac) as a reaction solvent, water-insoluble CS as a reaction substrate and 1,1-carbonyldiimidazole (CDI) as a linking agent. The grafting reaction was greatly accelerated and the reaction time was largely shortened to 4 h by taking advantages of the good solubility of CS, the enhanced nucleophilicity of amino groups and the preferential stability of the activated complexes in the ionic liquid. The chitosan-graft-polyethylenimine (CS-g-PEI) products were characterized by 1H NMR, FTIR and GPC. PEI-1.8 was quantitatively grafted to CS through urea linkages, and the grafting degree (GD) was conveniently tuned by varying the molar ratios of PEI-1.8 to D-glucosamine units of CS in the range of 9.0 × 10-3 to 9.0 × 10-2. Compared with CS, the synthesized CS-g-PEI copolymers showed higher pDNA-binding affinity, which increased with the GD as shown in Agarose gel electrophoresis. The dynamic light scattering (DLS) experiment demonstrated that the CS-g-PEI/pDNA polyplexes had suitable particle sizes and proper ζ-potentials for cell transfection. The CS-g-PEI copolymer with a medium GD of 4.5% conferred the best gene transfection, with the efficiency 44 times of CS and 38 times of PEI-1.8 in HEp-2 cells. The cytotoxicity of CS-g-PEI was tested and found nearly as low as that of CS and much lower than that of PEI. [ABSTRACT FROM AUTHOR]

For studying the mechanism of cationic liposome-mediated transmembrane routes for gene delivery, various inhibitors of endocytosis were used to treat human throat epidermis cancer cells, Hep-2, before transfection with Lipofectamine 2000/pGFP-N2 or Lipofectamine 2000/pGL3. To eliminate the effect of inhibitor toxicity on transfection, the RLU/survival rate was used to represent the transfection efficiency. Chlorpromazine and wortmannin, clathrin inhibitors, decreased transfection efficiency by 44 % (100 μM) and 31 % (100 nM), respectively. At the same time, genistein, a caveolin inhibitor, decreased it by 30 % (200 μM). Thus combined transmembrane routes through the clathrin and caveolae-mediated pathways were major mechanisms of cell uptake for the cationic liposome-mediated gene delivery. After entering the cells, microtubules played an important role on gene delivery as vinblastine, a microtubulin inhibitor, could reduce transfection efficiency by 41 % (200 nM). [ABSTRACT FROM AUTHOR]

Background: During the course of gene transfection, the interaction kinetics between liposomes and DNA is speculated to play very important role for blood stability, cellular uptake, DNA release and finally transfection efficiency. Results: As cationic peptide liposomes exhibited great gene transfer activities both in vitro and in vivo, two peptide lipids, containing a tri-ornithine head (LOrn3) and a mono-ornithine head (LOrn1), were chosen to further clarify the process of liposome-mediated gene delivery in this study. The results show that the electrostatically-driven binding between DNA and liposomes reached nearly 100% at equilibrium, and high affinity of LOrn3 to DNA led to fast binding rate between them. The binding process between LOrn3 and DNA conformed to the kinetics equation: y = 1.663631 × exp (− 0.003427x) + 6.278163. Compared to liposome LOrn1, the liposome LOrn3/DNA lipoplex exhibited a faster and more uniform uptake in HeLa cells, as LOrn3 with a tri-ornithine peptide headgroup had a stronger interaction with the negatively charged cell membrane than LOrn1. The efficient endosomal escape of DNA from LOrn3 lipoplex was facilitated by the acidity in late endosomes, resulting in broken carbamate bonds, as well as the "proton sponge effect" of the lipid. Conclusions: The interaction kinetics is a key factor for DNA transfection efficiency. This work provided insights into peptide lipid-mediated DNA delivery that could guide the development of the next generation of delivery systems for gene therapeutics. [ABSTRACT FROM AUTHOR]

In this paper, two novel carbamate-linked quaternary ammonium lipids (MU18: a lipid with a mono-ammonium head; GU18: a lipid with a Gemini-ammonium head) containing unsaturated hydrophobic chains were designed and synthesized. The chemical structures of the synthetic lipids were characterized by infrared spectrum, ESI-MS, 1 H NMR, 13 C NMR, and HPLC. For investigating the effect of unsaturation on gene delivery, the previous reported saturated cationic liposomes (MS18 and GS18) were used as comparison. Cationic liposomes were prepared by using these cationic lipids and neutral lipid DOPE at the molar ratio of 1:1. Particle sizes and zeta potentials of the cationic liposomes were studied to show that they were suitable for gene transfection. The binding abilities of the cationic liposomes were investigated by gel electrophoresis at various N/P ratios from 0.5/1 to 8/1. The results indicated that the binding ability of GU18 was much better than MU18 and the saturated cationic liposomes (MS18 and GS18). DNA transfection of these liposomes comparable to commercially available reagent (DOTAP) was achieved in vitro against Hela, HepG-2 and NCI-H460 cell lines. GU18 showed higher transfection at the N/P ratio of 3/1 than other cationic liposomes and the positive control, DOTAP. All of the liposomes presented a relatively low cytotoxicity, which was measured by MTT. Therefore, the synthetic lipids bearing unsaturated hydrophobic chains and Gemini-head could be promising candidates for gene delivery. [ABSTRACT FROM AUTHOR]

Highlights: [•] Three new carbamate-linked cationic lipids with hydroxyl headgroup were synthesized. [•] These lipids are easy to produce starting from environmentally friendly materials. [•] These liposomes exhibit relatively high transfection efficiency and low toxicity. [•] The inclusion of hydroxyl group in the headgroup can improve transfection efficiency. [ABSTRACT FROM AUTHOR]

Abstract: We have introduced a convenient synthesis method for carbamate-linked cationic lipids. Two cationic lipids N-[1-(2,3-didodecylcarbamoyloxy)propyl]-N,N,N-trimethylammonium iodide (DDCTMA) and N-[1-(2,3-didodecyl carbamoyloxy)propyl]-N-ethyl-N,N-dimethylammonium iodide (DDCEDMA), with identical length of hydrocarbon chains, alternative quaternary ammonium heads, carbamate linkages between hydrocarbon chains and quaternary ammonium heads, were synthesized for liposome-mediated gene delivery. Liposomes composed of DDCEDMA and DOPE in 1:1 ratio exhibited a lower zeta potential as compared to those made of pure DDCEDMA alone, which influences their DNA-binding ability. pGFP-N2 plasmid was transferred by cationic liposomes formed from the above cationic lipids into Hela and Hep-2 cells, and the transfection efficiency of some of cationic liposomes was superior or parallel to that of two commercial transfection agents, Lipofectamine2000 and DOTAP. Combined with the results of the agarose gel electrophoresis and transfection experiment, the DNA-binding ability of cationic lipids was too strong to release DNA from complex in the transfection, which could lead to relative low transfection efficiency and high cytotoxicity. [Copyright &y& Elsevier]

Targeted gene therapy has led to significant breakthroughs in cancer treatment. Heat shock protein gp96 is an emerging target for tumor treatment because of its transfer ability from reticulum to tumor cell surface. CDO14 is a peptide cationic liposome developed in our laboratory with higher gene transfection efficiency and lower toxicity compared with the existing cationic liposomes. In this study, gp96-targeted liposome p37-CDO14 was constructed by modifying cationic liposome CDO14 with a gp96 inhibitor, helical polypeptide p37. Liposome p3 7-CDO14 could specifically bind to breast cancer cells with gp96-overexpression on the cell membrane. Both liposomes CDO14 and p37-CDO14 showed high delivery efficiency for survivin siRNA (siSuvi) to SK-BR-3 and MCF-7 cells via obviously decreased survivin expression level and cell viability. P37-CDO14 significantly increased the accumulation of FAM-siRNA in tumor compared with CDO14. SiSuvi transfected by CDO14 and p37-CDO14 could inhibit the growth of xenograft in mice and the expression of survivin in tumor tissues. The anti-tumor effect of siSuvi delivered by p37-CDO14 was much higher than that delivered by CDO14. This suggests that targeted liposome p37-CDO14 is a potential gene vector for the therapy of gp96 overexpressed breast cancer. Unlabelled Image • A gp96-targeted liposome, p37-CDO14, was constructed by modifying cationic liposome CDO14 with polypeptide p37. • P37-CDO14 showed high delivery efficiency for survivin siRNA to gp96 over-expressed SK-BR-3 and MCF-7 cells. • The anti-tumor effect of survivin siRNA delivered by p37-CDO14 was much higher than that delivered by CDO14. [ABSTRACT FROM AUTHOR]