Efficient Cellular Knockdown Mediated by siRNA Nanovectors of Gemini Cationic Lipids Having Delocalizable Headgroups and Oligo-Oxyethylene Spacers

Lipid nanoparticles as nano-Trojan-horses for siRNA delivery and gene-knockdown

The therapeutic messenger RNA strategies, such as those using small interfering RNAs, take several advantages (versatility, efficiency and selectivity) over plasmid DNA-based strategies. However, the challenge remains to find nanovectors capable of properly loading the genetic material, transporting it through troublesome environments, like a tumoral site, and delivering it into the cytoplasm of target cells. Here, lipid nanoparticles, consisting of a gemini cationic/neutral helper lipid mixture, are proposed as siRNA nanovector. Cells from cervical and brain cancer overexpressing the green fluorescent protein (GFP) were chosen to analyse the biological response as well as the efficiency and safety of the siRNA-loaded nanovector according to the cell phenotype. Flow cytometry and epifluorescence or confocal microscopy were used to follow the gene knockdown in these overexpressed cells. The effect of the nanovector on cellular proliferation was evaluated with cytotoxicity assays while their potential oxidative stress generation was determined by quantifying the generation of reactive oxygen species. To explore the mechanism of cellular uptake, different inhibitors of endocytic pathways were used during incubation with cells. Finally, nanovectors were incubated in 3D-grown cells (spheroids) to see whether they can penetrate the complex tumoral microenvironments, their efficiency to knockdown GFP expression being monitored by confocal microscopy.

DNA-amphiphilic nanostructures: synthesis, characterization and applications

DNA's extraordinary potential reaches far beyond its role as a carrier of genetic information. It serves as a remarkably adaptable structural foundation for constructing intricate nanostructures with a diverse range of functionalities. This inherent programmability sets DNA apart from other biomolecules like peptides, proteins, and small molecules. By covalently attaching DNA to synthetic hydrophobic moieties, researchers create DNA amphiphiles capable of interacting with artificial lipid bilayers and cell membranes. These hybrid structures have rapidly gained prominence due to their promising potential in the medical field. This review provides a comprehensive overview of the latest advancements in the synthesis of DNA amphiphiles and their assembly into well-defined nanostructures. It explores the diverse applications of these nanostructures across various medical domains, including targeted drug delivery, innovative immunotherapies, and gene-silencing techniques. Moreover, the review delves into the current challenges and prospects of this rapidly evolving field, highlighting the potential of DNA hybrid materials to revolutionize medical treatments and diagnostics. By addressing the limitations and exploring new avenues of research, scientists aim to unlock the full potential of DNA nanotechnology for the benefit of human health.

Effective delivery and selective insecticidal activity of double-stranded RNA via complexation with diblock copolymer varies with polymer block composition

BACKGROUND

Chemical insecticides are an important tool to control damaging pest infestations. However, lack of species specificity, the rise of resistance and the demand for biological alternatives with improved ecotoxicity profiles means that chemicals with new modes of action are required. RNA interference (RNAi)-based strategies using double-stranded RNA (dsRNA) as a species-specific bio-insecticide offer an exquisite solution that addresses these issues. Many species, such as the fruit pest Drosophila suzukii, do not exhibit RNAi when dsRNA is orally administered due to degradation by gut nucleases and slow cellular uptake pathways. Thus, delivery vehicles that protect and deliver dsRNA are highly desirable.

RESULTS

In this work, we demonstrate the complexation of D. suzukii-specific dsRNA for degradation of vha26 mRNA with bespoke diblock copolymers. We study the ex vivo protection of dsRNA against enzymatic degradation by gut enzymes, which demonstrates the efficiency of this system. Flow cytometry then investigates the cellular uptake of Cy3-labelled dsRNA, showing a 10-fold increase in the mean fluorescence intensity of cells treated with polyplexes. The polymer/dsRNA polyplexes induced a significant 87% decrease in the odds of survival of D. suzukii larvae following oral feeding only when formed with a diblock copolymer containing a long neutral block length (1:2 cationic block/neutral block). However, there was no toxicity when fed to the closely related Drosophila melanogaster.

CONCLUSION

We provide evidence that dsRNA complexation with diblock copolymers is a promising strategy for RNAi-based species-specific pest control, but optimisation of polymer composition is essential for RNAi success. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The development of highly dense highly protected surfactant ionizable lipid RNA loaded nanoparticles

The long quest for efficient drug administration has been looking for a universal carrier that can precisely transport traditional drugs, new genomic and proteic therapeutic agents. Today, researchers have found conditions to overcome the two main drug delivery dilemmas. On the one side, the versatility of the vehicle to efficiently load, protect and transport the drug and then release it at the target place. On the other hand, the questions related to the degree of PEGylation which are needed to avoid nanoparticle (NP) aggregation and opsonization while preventing cellular uptake. The development of different kinds of lipidic drug delivery vehicles and particles has resulted in the development of ionizable lipid nanoparticles (iLNPs), which can overcome most of the typical drug delivery problems. Proof of their success is the late approval and massive administration as the prophylactic vaccine for SARS-CoV-2. These ILNPs are built by electrostatic aggregation of surfactants, the therapeutic agent, and lipids that self-segregate from an aqueous solution, forming nanoparticles stabilized with lipid polymers, such as PEG. These vehicles overcome previous limitations such as low loading and high toxicity, likely thanks to low charge at the working pH and reduced size, and their entry into the cells via endocytosis rather than membrane perforation or fusion, always associated with higher toxicity. We herein revise their primary features, synthetic methods to prepare and characterize them, pharmacokinetic (administration, distribution, metabolization and excretion) aspects, and biodistribution and fate. Owing to their advantages, iLNPs are potential drug delivery systems to improve the management of various diseases and widely available for clinical use.

Efficient Delivery of DNA Using Lipid Nanoparticles

DNA vaccination has been extensively studied as a promising strategy for tumor treatment. Despite the efforts, the therapeutic efficacy of DNA vaccines has been limited by their intrinsic poor cellular internalization. Electroporation, which is based on the application of a controlled electric field to enhance DNA penetration into cells, has been the method of choice to produce acceptable levels of gene transfer in vivo. However, this method may cause cell damage or rupture, non-specific targeting, and even degradation of pDNA. Skin irritation, muscle contractions, pain, alterations in skin structure, and irreversible cell damage have been frequently reported. To overcome these limitations, in this work, we use a microfluidic platform to generate DNA-loaded lipid nanoparticles (LNPs) which are then characterized by a combination of dynamic light scattering (DLS), synchrotron small-angle X-ray scattering (SAXS), and transmission electron microscopy (TEM). Despite the clinical successes obtained by LNPs for mRNA and siRNA delivery, little is known about LNPs encapsulating bulkier DNA molecules, the clinical application of which remains challenging. For in vitro screening, LNPs were administered to human embryonic kidney 293 (HEK-293) and Chinese hamster ovary (CHO) cell lines and ranked for their transfection efficiency (TE) and cytotoxicity. The LNP formulation exhibiting the highest TE and the lowest cytotoxicity was then tested for the delivery of the DNA vaccine pVAX-hECTM targeting the human neoantigen HER2, an oncoprotein overexpressed in several cancer types. Using fluorescence-activated cell sorting (FACS), immunofluorescence assays and fluorescence confocal microscopy (FCS), we proved that pVAX-hECTM-loaded LNPs produce massive expression of the HER2 antigen on the cell membrane of HEK-293 cells. Our results provide new insights into the structure-activity relationship of DNA-loaded LNPs and pave the way for the access of this gene delivery technology to preclinical studies.

Principles for optimization and validation of mRNA lipid nanoparticle vaccines against COVID-19 using 3D bioprinting

BioNTech/Pfizer's Comirnaty and Moderna's SpikeVax vaccines consist in mRNA encapsulated in lipid nanoparticles (LNPs). The modularity of the delivery platform and the manufacturing possibilities provided by microfluidics let them look like an instant success, but they are the product of decades of intense research. There is a multitude of considerations to be made when designing an optimal mRNA-LNPs vaccine. Herein, we provide a brief overview of what is presently known and what still requires investigation to optimize mRNA LNPs vaccines. Lastly, we give our perspective on the engineering of 3D bioprinted validation systems that will allow faster, cheaper, and more predictive vaccine testing in the future compared with animal models.

A polytherapy based approach to combat antimicrobial resistance using cubosomes

A depleted antimicrobial drug pipeline combined with an increasing prevalence of Gram-negative ‘superbugs’ has increased interest in nano therapies to treat antibiotic resistance. As cubosomes and polymyxins disrupt the outer membrane of Gram-negative bacteria via different mechanisms, we herein examine the antimicrobial activity of polymyxin-loaded cubosomes and explore an alternative strategy via the polytherapy treatment of pathogens with cubosomes in combination with polymyxin. The polytherapy treatment substantially increases antimicrobial activity compared to polymyxin B-loaded cubosomes or polymyxin and cubosomes alone. Confocal microscopy and neutron reflectometry suggest the superior polytherapy activity is achieved via a two-step process. Firstly, electrostatic interactions between polymyxin and lipid A initially destabilize the outer membrane. Subsequently, an influx of cubosomes results in further membrane disruption via a lipid exchange process. These findings demonstrate that nanoparticle-based polytherapy treatments may potentially serve as improved alternatives to the conventional use of drug-loaded lipid nanoparticles for the treatment of “superbugs”.

An increasing prevalence of Gram-negative bacteria increases the interest in nanotherapies to treat antibiotic resistance. Here, the authors examine the antimicrobial activity of polymyxin-loaded cubosomes and explore a polytherapy treatment of pathogens with cubosomes in combination with polymyxin.

Transgene expression in mice of the Opa1 mitochondrial transmembrane protein through bicontinuous cubic lipoplexes containing gemini imidazolium surfactants

BACKGROUND

Lipoplexes are non-viral vectors based on cationic lipids used to deliver DNA into cells, also known as lipofection. The positively charge of the hydrophilic head-group provides the cationic lipids the ability to condensate the negatively charged DNA into structured complexes. The polar head can carry a large variety of chemical groups including amines as well as guanidino or imidazole groups. In particular, gemini cationic lipids consist of two positive polar heads linked by a spacer with different length. As for the hydrophobic aliphatic chains, they can be unsaturated or saturated and are connected to the polar head-groups. Many other chemical components can be included in the formulation of lipoplexes to improve their transfection efficiency, which often relies on their structural features. Varying these components can drastically change the arrangement of DNA molecules within the lamellar, hexagonal or cubic phases that are provided by the lipid matrix. Lipofection is widely used to deliver genetic material in cell culture experiments but the simpler formulations exhibit major drawbacks related to low transfection, low specificity, low circulation half-life and toxicity when scaled up to in vivo experiments.

RESULTS

So far, we have explored in cell cultures the transfection ability of lipoplexes based on gemini cationic lipids that consist of two C16 alkyl chains and two imidazolium polar head-groups linked with a polyoxyethylene spacer, (C16Im)2(C4O). Here, PEGylated lipids have been introduced to the lipoplex formulation and the transgene expression of the Opa1 mitochondrial transmembrane protein in mice was assessed. The addition of PEG on the surface of the lipid mixed resulted in the formation of Ia3d bicontinuous cubic phases as determined by small angle X-ray scattering. After a single intramuscular administration, the cubic lipoplexes were accumulated in tissues with tight endothelial barriers such as brain, heart, and lungs for at least 48 h. The transgene expression of Opa1 in those organs was identified by western blotting or RNA expression analysis through quantitative polymerase chain reaction.

CONCLUSIONS

The expression reported here is sufficient in magnitude, duration and toxicity to consolidate the bicontinuous cubic structures formed by (C16Im)2(C4O)-based lipoplexes as valuable therapeutic agents in the field of gene delivery.

A functional and self-assembling octyl-phosphonium-tagged esculetin as an effective siRNA delivery agent

Herein, we document a self-assembling octyl-TPP tagged esculetin (Mito-Esc) as functionally active and as a novel small molecule siRNA delivery vector. While Mito-Esc itself induces selective breast cancer cell death, the amphiphilic nature of Mito-Esc delivers therapeutic siRNAs intracellularly without the need for any excipient to exacerbate the anti-proliferative effects.

Lipids and Lipid Derivatives for RNA Delivery

RNA-based therapeutics have shown great promise in treating a broad spectrum of diseases through various mechanisms including knockdown of pathological genes, expression of therapeutic proteins, and programmed gene editing. Due to the inherent instability and negative-charges of RNA molecules, RNA-based therapeutics can make the most use of delivery systems to overcome biological barriers and to release the RNA payload into the cytosol. Among different types of delivery systems, lipid-based RNA delivery systems, particularly lipid nanoparticles (LNPs), have been extensively studied due to their unique properties, such as simple chemical synthesis of lipid components, scalable manufacturing processes of LNPs, and wide packaging capability. LNPs represent the most widely used delivery systems for RNA-based therapeutics, as evidenced by the clinical approvals of three LNP-RNA formulations, patisiran, BNT162b2, and mRNA-1273. This review covers recent advances of lipids, lipid derivatives, and lipid-derived macromolecules used in RNA delivery over the past several decades. We focus mainly on their chemical structures, synthetic routes, characterization, formulation methods, and structure-activity relationships. We also briefly describe the current status of representative preclinical studies and clinical trials and highlight future opportunities and challenges.

Cationic Liposomes as Vectors for Nucleic Acid and Hydrophobic Drug Therapeutics

Cationic liposomes (CLs) are effective carriers of a variety of therapeutics. Their applications as vectors of nucleic acids (NAs), from long DNA and mRNA to short interfering RNA (siRNA), have been pursued for decades to realize the promise of gene therapy, with approvals of the siRNA therapeutic patisiran and two mRNA vaccines against COVID-19 as recent milestones. The long-term goal of developing optimized CL-based NA carriers for a broad range of medical applications requires a comprehensive understanding of the structure of these vectors and their interactions with cell membranes and components that lead to the release and activity of the NAs within the cell. Structure-activity relationships of lipids for CL-based NA and drug delivery must take into account that these lipids act not individually but as components of an assembly of many molecules. This review summarizes our current understanding of how the choice of the constituting lipids governs the structure of their CL-NA self-assemblies, which constitute distinct liquid crystalline phases, and the relation of these structures to their efficacy for delivery. In addition, we review progress toward CL-NA nanoparticles for targeted NA delivery in vivo and close with an outlook on CL-based carriers of hydrophobic drugs, which may eventually lead to combination therapies with NAs and drugs for cancer and other diseases.

Cancer Stem Cell-Targeted Gene Delivery Mediated by Aptamer-Decorated pH-Sensitive Nanoliposomes

A new pH-responsive cationic co-liposomal formulation was prepared in this study using the twin version of the amphiphile palmitoyl homocysteine, TPHC; natural zwitterionic lipid, DOPE; and cholesterol-based twin cationic lipid, C5C, at specified molar ratios. This co-liposome was further decorated with a newly designed fluorescently tagged, cholesterol-tethered EpCAM-targeting RNA aptamer for targeted gene delivery. This aptamer-guided nanoliposomal formulation, C5C/DOPE/TPHC at 8:24:1 molar ratio, could efficiently transport the genes in response to low pH of cellular endosomes selectively to the EpCAM overexpressing cancer stem cells. This particular observation was extended using siRNA against GFP to validate their transfection capabilities in response to EpCAM expression. Overall, the aptamer-guided nanoliposomal formulation was found to be an excellent transfectant for in vitro siRNA gene delivery.

Protein Expression Knockdown in Cancer Cells Induced by a Gemini Cationic Lipid Nanovector with Histidine-Based Polar Heads

A histidine-based gemini cationic lipid, which had already demonstrated its efficiency as a plasmid DNA (pDNA) nanocarrier, has been used in this work to transfect a small interfering RNA (siRNA) into cancer cells. In combination with the helper lipid monoolein glycerol (MOG), the cationic lipid was used as an antiGFP-siRNA nanovector in a multidisciplinary study. Initially, a biophysical characterization by zeta potential (ζ) and agarose gel electrophoresis experiments was performed to determine the lipid effective charge and confirm siRNA compaction. The lipoplexes formed were arranged in Lα lamellar lyotropic liquid crystal phases with a cluster-type morphology, as cryo-transmission electron microscopy (cryo-TEM) and small-angle X-ray scattering (SAXS) studies revealed. Additionally, in vitro experiments confirmed the high gene knockdown efficiency of the lipid-based nanovehicle as detected by flow cytometry (FC) and epifluorescence microscopy, even better than that of Lipofectamine2000*, the transfecting reagent commonly used as a positive control. Cytotoxicity assays indicated that the nanovector is non-toxic to cells. Finally, using nano-liquid chromatography tandem mass spectrometry (nanoLC-MS/MS), apolipoprotein A-I and A-II followed by serum albumin were identified as the proteins with higher affinity for the surface of the lipoplexes. This fact could be beyond the remarkable silencing activity of the histidine-based lipid nanocarrier herein presented.

Biocompatible Nanovector of siRNA Consisting of Arginine-Based Cationic Lipid for Gene Knockdown in Cancer Cells

Despite the use of small interfering RNAs (siRNAs) as therapeutic agents through the knockdown expression of pathogenic proteins, transportation and delivery of such siRNAs into cells continue to be under investigation. Within nonviral vectors, cationic lipids that include amino acid residues in their structures, and that have already demonstrated their suitability as plasmid DNA nanocarriers, may be also considered as potential siRNA vehicles. A double-chain cationic lipid based on the amino acid arginine mixed with a helper lipid has been the object of this biophysical study. First, ζ-potential measurements and agarose gel electrophoresis experiments confirmed the siRNA compaction, while small-angle X-ray scattering analysis (SAXS) revealed the structural pattern of the lipoplexes. Two bicontinuous cubic phases were found to coexist: the double-gyroid phase (Q_II^G) and the double-diamond phase (Q_II^D), with Pn3m and Ia3d as crystallographic space groups, respectively; the siRNA is known to be located inside their bicontinuous aqueous channels. Second, in vitro studies in HeLa-green fluorescent protein (GFP) and T731-GFP cell lines (modified for GFP overexpression) showed moderate to high gene knockdown levels (determined by flow cytometry and epifluorescence microscopy) with remarkable cell viabilities (CCK-8 assay). Finally, nano-liquid chromatography/mass spectrometry (nanoLC-MS/MS) was used to identify the nature of the proteins adhered to the surface of the lipoplexes after incubation with human serum, simulating their behavior in biological fluids. The abundant presence of lipoproteins and serum albumin in such protein corona, together with the coexistence of the bicontinuous cubic phases, may be behind the remarkable silencing activity of these lipoplexes. The results reported herein show that the use of amino-acid-based cationic lipids mixed with a suitable helper lipid, which have already provided good results as DNA plasmid nanocarriers in cellular transfection processes, may also be a biocompatible option, and so far little investigated, in gene silencing in vitro strategies.

Lipid-based Vehicles for siRNA Delivery in Biomedical Field

BACKGROUND

Genetic drugs have aroused much attention in the past twenty years. RNA interference (RNAi) offers novel insights into discovering potential gene functions and therapies targeting genetic diseases. Small interference RNA (siRNA), typically 21-23 nucleotides in length, can specifically degrade complementary mRNA. However, targeted delivery and controlled release of siRNA remain a great challenge.

METHODS

Different types of lipid-based delivery vehicles have been synthesized, such as liposomes, lipidoids, micelles, lipoplexes and lipid nanoparticles. These carriers commonly have a core-shell structure. For active targeting, ligands may be conjugated to the surface of lipid particles.

RESULTS

Lipid-based drug delivery vehicles can be utilized in anti-viral or anti-tumor therapies. They can also be used to tackle genetic diseases or discover novel druggable genes.

CONCLUSION

In this review, the structures of lipid-based vehicles and possible surface modifications are described, and applications of delivery vehicles in biomedical field are discussed.

Gemini-Based Lipoplexes Complement the Mitochondrial Phenotype in MFN1-Knockout Mouse Embryonic Fibroblasts

Mitochondria form a dynamic network of constantly dividing and fusing organelles. The balance between these antagonistic processes is crucial for normal cellular function and requires the action of specialized proteins. The mitochondrial membrane proteins mitofusin 1 (Mfn1) and mitofusin 2 (Mfn2) are responsible for the fusion of the outer membrane of adjacent mitochondria. Mutations within Mfn1 or Mfn2 impair mitochondrial fusion and lead to some severe mitochondrial dysfunctions and mitochondrial diseases (MDs). A characteristic phenotype of cells carrying defective Mfn1 or Mfn2 is the presence of a highly fragmented mitochondrial network. Here, we use a biocompatible mixture of lipids, consisting on synthetic gemini cationic lipids (GCLs) and the zwitterionic phospholipid (DOPE), to complex, transport, and deliver intact copies of MFN1 gene into MFN1-Knockout mouse embryonic fibroblasts (MFN1-KO MEFs). We demonstrate that the GCL/DOPE-DNA lipoplexes are able to introduce the intact MFN1 gene into the cells and ectopically produce functional Mfn1. A four-fold increase of the Mfn1 levels is necessary to revert the MFN1-KO phenotype and to partially restore a mitochondrial network. This phenotype complementation was correlated with the transfection of GCL/DOPE-MFN1 lipoplexes that exhibited a high proportion of highly packaged hexagonal phase. GCL/DOPE-DNA lipoplexes are formulated as efficient therapeutic agents against MDs.

A Non-Viral Plasmid DNA Delivery System Consisting on a Lysine-Derived Cationic Lipid Mixed with a Fusogenic Lipid

The insertion of biocompatible amino acid moieties in non-viral gene nanocarriers is an attractive approach that has been recently gaining interest. In this work, a cationic lipid, consisting of a lysine-derived moiety linked to a C12 chain (LYCl) was combined with a common fusogenic helper lipid (DOPE) and evaluated as a potential vehicle to transfect two plasmid DNAs (encoding green fluorescent protein GFP and luciferase) into COS-7 cells. A multidisciplinary approach has been followed: (i) biophysical characterization based on zeta potential, gel electrophoresis, small-angle X-ray scattering (SAXS), and cryo-transmission electronic microscopy (cryo-TEM); (ii) biological studies by fluorescence assisted cell sorting (FACS), luminometry, and cytotoxicity experiments; and (iii) a computational study of the formation of lipid bilayers and their subsequent stabilization with DNA. The results indicate that LYCl/DOPE nanocarriers are capable of compacting the pDNAs and protecting them efficiently against DNase I degradation, by forming Lα lyotropic liquid crystal phases, with an average size of ~200 nm and low polydispersity that facilitate the cellular uptake process. The computational results confirmed that the LYCl/DOPE lipid bilayers are stable and also capable of stabilizing DNA fragments via lipoplex formation, with dimensions consistent with experimental values. The optimum formulations (found at 20% of LYCl content) were able to complete the transfection process efficiently and with high cell viabilities, even improving the outcomes of the positive control Lipo2000*.

Triggered RNAi Therapy Using Metal Inorganic Nanovectors

The administration of small interfering RNA (siRNA) is a very interesting therapeutic option to treat genetic diseases such as Alzheimer's or some types of cancer, but its effective delivery still remains a challenge. Herein, Au nanorod (GNR)-based platforms functionalized with polyelectrolyte layers were developed and analyzed as potential siRNA nanocarriers. The polymeric layers were successfully assembled on the particle surfaces by means of the layer-by-layer assembly technique through the alternating deposition of oppositely charged poly(styrene)sulfonate, PSS, poly(lysine), PLL, and siRNA biopolymers, with a final hyaluronic acid layer in order to provide the nanoconstructs with a potential targeting ability as well as colloidal stability in physiological medium. Once the hybrid nanocarriers were obtained, the cargo release, their colloidal stability in physiological-relevant media, cytotoxicity, cellular internalization and uptake, and knockdown activity were studied. The present hybrid particles release the genetic material inside cells by means of a protease-assisted and/or a light-triggered release mechanism in order to control the delivery of the oligonucleotides on demand. In addition, the hybrid nanovectors were observed to be nontoxic to cells and could efficiently deliver the genetic material in the cell cytoplasms. The GNR-based nanocarriers proposed here can provide a suitable environment to load and protect a sufficient amount of the genetic material to allow an efficient and sustained knockdown gene expression for long (up to 93% for 72 h), thanks to the slow degradation of PLL, without the observation of adverse side toxic effects. It was also found that the silencing activity was enhanced with the number of siRNA layers assembled in the nanoplatforms.

PLGA nanoparticle-based docetaxel/LY294002 drug delivery system enhances antitumor activities against gastric cancer

Docetaxel (TXT) is acknowledged as one of the most important chemotherapy agents for gastric cancer (GC). PI3K/AKT signaling is frequently activated in GC, and its inhibitor LY294002 exerts potent antitumor effects. However, the hydrophobicity of TXT and the poor solubility and low bioavailability of LY294002 limit their clinical application. To overcome these shortcomings, we developed poly(lactic acid/glycolic) (PLGA) nanoparticles loaded with TXT and LY294002. PLGA facilitated the accumulation of TXT and LY294002 at the tumor sites. The in vitro functional results showed that PLGA(TXT+LY294002) exhibited controlled-release and resulted in a markedly reduced proliferative capacity and an elevated apoptosis rate. An in vivo orthotopic GC mouse model and xenograft mouse model confirmed the anticancer superiority and tumor-targeting feature of PLGA(TXT+LY294002). Histological analysis indicated that PLGA(TXT+LY294002) was biocompatible and had no toxicity to major organs. Characterized by the combined slow release of TXT and LY294002, this novel PLGA-based TXT/LY294002 drug delivery system provides controlled release and tumor targeting and is safe, shedding light on the future of targeted therapy against GC.

DNA Delivery Systems Based on Peptide-Mimicking Cationic Lipids-The Effect of the Co-Lipid on the Structure and DNA Binding Capacity

In continuation of previous work, we present a new promising DNA carrier, OO4, a highly effective peptide-mimicking lysine-based cationic lipid. The structural characteristics of the polynucleotide carrier system OO4 mixed with the commonly used co-lipid DOPE and the saturated phospholipid DPPE have been studied in two-dimensional and three-dimensional model systems to understand their influence on the physical-chemical properties. The phase behavior of pure OO4 and its mixtures with DOPE and DPPE was studied at the air-water interface using a Langmuir film balance combined with infrared reflection-absorption spectroscopy. In bulk, the self-assembling structures in the presence and absence of DNA were determined by small-angle and wide-angle X-ray scattering. The amount of adsorbed DNA to cationic lipid bilayers was measured using a quartz crystal microbalance. The choice of the co-lipid has an enormous influence on the structure and capability of binding DNA. DOPE promotes the formation of nonlamellar lipoplexes (cubic and hexagonal structures), whereas DPPE promotes the formation of lamellar lipoplexes. The correlation of the observed structures with the transfection efficiency and serum stability indicates that OO4/DOPE 1:3 lipoplexes with a DNA-containing cubic phase encapsulated in multilamellar structures seem to be most promising.

Trehalose-based Siamese twin amphiphiles with tunable self-assembling, DNA nanocomplexing and gene delivery properties

Trehalose Siamese twin vectors, encompassing gemini and facial amphiphilicity, promote pDNA compaction into core–shell nanocomplexes and selective delivery in the lungs.

A Gemini Cationic Lipid with Histidine Residues as a Novel Lipid-Based Gene Nanocarrier: A Biophysical and Biochemical Study

This work reports the synthesis of a novel gemini cationic lipid that incorporates two histidine-type head groups (C₃(C16His)₂). Mixed with a helper lipid 1,2-dioleoyl-sn-glycero-3-phosphatidyl ethanol amine (DOPE), it was used to transfect three different types of plasmid DNA: one encoding the green fluorescence protein (pEGFP-C3), one encoding a luciferase (pCMV-Luc), and a therapeutic anti-tumoral agent encoding interleukin-12 (pCMV-IL12). Complementary biophysical experiments (zeta potential, gel electrophoresis, small-angle X-ray scattering (SAXS), and fluorescence anisotropy) and biological studies (FACS, luminometry, and cytotoxicity) of these C₃(C16His)₂/DOPE-pDNA lipoplexes provided vast insight into their outcomes as gene carriers. They were found to efficiently compact and protect pDNA against DNase I degradation by forming nanoaggregates of 120⁻290 nm in size, which were further characterized as very fluidic lamellar structures based in a sandwich-type phase, with alternating layers of mixed lipids and an aqueous monolayer where the pDNA and counterions are located. The optimum formulations of these nanoaggregates were able to transfect the pDNAs into COS-7 and HeLa cells with high cell viability, comparable or superior to that of the standard Lipo2000*. The vast amount of information collected from the in vitro studies points to this histidine-based lipid nanocarrier as a potentially interesting candidate for future in vivo studies investigating specific gene therapies.

Interactions of Cationic Lipids with DNA: A Structural Approach

Colloidal nucleic acid carrier systems based on cationic lipids are a promising pharmaceutical tool in the implementation of gene therapeutic strategies. This study demonstrates the complex behavior of DNA at the lipid-solvent interface facilitating structural changes of the lyotropic liquid-crystalline phases. For this study, the structural properties of six malonic acid based cationic lipids were determined using small- and wide-angle X-ray scattering (SAXS and WAXS) as well as differential scanning calorimetry (DSC). Selected lipids (lipid 3 and lipid 6) with high nucleic acid transfer activity have been investigated in detail because of the strong influence of the zwitterionic helper lipid 1,2-di(9 Z-octadecenoyl)- sn-glycero-3-phosphoethanolamine (DOPE) on the structural properties as well as of the complex formation of lipid-DNA complexes (lipoplexes). In the case of lipid 3, DNA stabilizes a metastable cubic mesophase with Im3 m symmetry and an Im3 m Q_α^c lipoplex is formed, which is rarely described for DNA lipoplexes in literature. In the case of lipid 6, a cubic mesophase with Im3 m symmetry turns into a fluid lamellar phase while mixing with DOPE and complexing DNA.

Transfection by cationic gemini lipids and surfactants

Diseases that are linked to defective genes or mutations can in principle be cured by gene therapy, in which damaged or absent genes are either repaired or replaced by new DNA in the nucleus of the cell. Related to this, disorders associated with elevated protein expression levels can be treated by RNA interference via the delivery of siRNA to the cytoplasm of cells. Polynucleotides can be brought into cells by viruses, but this is not without risk for the patient. Alternatively, DNA and RNA can be delivered by transfection, i.e. by non-viral vector systems such as cationic surfactants, which are also referred to as cationic lipids. In this review, recent progress on cationic lipids as transfection vectors will be discussed, with special emphasis on geminis, surfactants with 2 head groups and 2 tails connected by a spacer.

Characterization of the complexation phenomenon and biological activity in vitro of polyplexes based on Tetronic T901 and DNA

The complexation process and underlying mechanisms that rule the interaction of DNA with the cationic block copolymer Tetronic T901 to form polyplexes and their potential transfection efficiency have been studied under different solution conditions. We noted that T901 favors the formation of self-assembled structures with partially condensed DNA at smaller polymer concentrations than other Pluronic™/Tetronic™-type copolymers previously analysed. The observed polyplexes display sizes from the nano- to the micro- range as derived from DLS, electronic and optical microscopies. Also, copolymer micelles are observed at concentrations below the copolymer critical micellar concentration (cmc) induced by the presence of DNA. The complexation process is dependent on solution conditions, with electrostatic and ionic interactions being more important at acidic pH thanks to the predominant diprotonated form of the block copolymer which is less aggregation-prone, whilst dispersive forces are increasingly enhanced under basic conditions or when rising the solution temperature. Whatever the case, the complexation is mainly governed by entropic contributions, as denoted from ITC data. In vitro transfection experiments after complexing T901 with a pDNA encoding the expression of green fluorescein protein, GFP, show a relative successful fluorescence of transfected HeLa cells, which confirms the uptake, internalization and release of the genetic material within the cells at suitable [N]/[P] ratios with relatively low cytotoxicity. Despite the observed successful outcomes, the obtained transfection efficacies are slightly lower than those obtained with Lipofectamine2000, so further optimization of the polyplex formation conditions is envisaged in future studies.

Multidisciplinary Approach to the Transfection of Plasmid DNA by a Nonviral Nanocarrier Based on a Gemini-Bolaamphiphilic Hybrid Lipid

A multidisciplinary strategy, including both biochemical and biophysical studies, was proposed here to evaluate the potential of lipid nanoaggregates consisting of a mixture of a gemini-bolaamphiphilic lipid (C6C22C6) and the well-known helper lipid 1,2-dioleoyl-sn-glycero-3-phosphatidylethanolamine (DOPE) to transfect plasmid DNA into living cells in an efficient and safe way. For that purpose, several experimental techniques were employed, such as zeta potential (phase analysis light scattering methodology), agarose gel electrophoresis (pDNA compaction and pDNA protection assays), small-angle X-ray scattering, cryo-transmission electron microscopy, atomic force microscopy, fluorescence-assisted cell sorting, luminometry, and cytotoxicity assays. The results revealed that the cationic lipid and plasmid offer only 70 and 30% of their nominal positive () and negative charges (), respectively. Upon mixing with DOPE, they form lipoplexes that self-aggregate in typical multilamellar Lα lyotropic liquid-crystal nanostructures with sizes in the range of 100-200 nm and low polydispersities, very suitably fitted to remain in the bloodstream and cross the cell membrane. Interestingly, these nanoaggregates were able to compact, protect (from the degrading effect of DNase I), and transfect two DNA plasmids (pEGFP-C3, encoding the green fluorescent protein, and pCMV-Luc, encoding luciferase) into COS-7 cells, with an efficiency equal or even superior to that of the universal control Lipo2000*, as long as the effective +/- charge ratio was maintained higher than 1 but reasonably close to electroneutrality. Moreover, this transfection process was not cytotoxic because the viability of COS-7 cells remained at high levels, greater than 80%. All of these features make the C6C22C6/DOPE nanosystem an optimal nonviral gene nanocarrier in vitro and a potentially interesting candidate for future in vivo experiments.

Transfection of plasmid DNA by nanocarriers containing a gemini cationic lipid with an aromatic spacer or its monomeric counterpart

This study performed a biophysical characterization (electrochemistry, structure and morphology) and assessment of the biological activity and cell biocompatibility of GCL/DOPE-pDNA lipoplexes comprised of plasmid DNA and a mixed lipid formed by a DOPE zwitterionic lipid and a gemini cationic lipid N-N'-(1,3-phenylene bis (methylene)) bis (N,N-dimethyl-N-(1-dodecyl) ammonium dibromide (12PH12) containing an aromatic spacer or its monomeric counterpart surfactant, N-benzyl-N,N-dimethyl-N-(1-dodecyl) ammonium bromide (12PH). Electrochemical results reveal that i) the gemini cationic lipid (12PH12) and the plasmid pDNA yield effective charges less than their nominal charges (+2 and -2/bp, respectively) and that ii) both vectors (12PH12/DOPE and 12PH/DOPE) could compact pDNA and protect it from DNase I degradation. SAXS and cryo-TEM experiments indicate the presence of a lamellar lyotropic liquid crystal phase represented as alternating layers of mixed lipid and plasmid. Transfection efficiency (by FACS and luminometry) and cell viability assay in COS-7 cells, performed with two plasmid DNAs (pEGFP-C3 and pCMV-Luc VR1216), confirm the goodness of the proposed formulations (12PH12/DOPE and 12PH/DOPE) to transport genetic material, with efficiencies and biocompatibilities comparable to or better than those exhibited by the control Lipofectamine 2000*. In conclusion, although major attention has been paid to gemini cationic lipids in the literature, due to the large variety of modifications that their structures may support to improve the biological activity of the resulting lipoplexes, it is remarkable that the monomeric counterpart surfactant with an aromatic group analyzed in the present work also exhibits good biological activity. The in vitro results reported here indicate that the optimum formulations of the gene vectors studied in this work efficiently transfect plasmid DNA with very low toxicity levels and, thus, may be used in forthcoming in vivo experiments.

Advances in structural design of lipid-based nanoparticle carriers for delivery of macromolecular drugs, phytochemicals and anti-tumor agents

The present work highlights recent achievements in development of nanostructured dispersions and biocolloids for drug delivery applications. We emphasize the key role of biological small-angle X-ray scattering (BioSAXS) investigations for the nanomedicine design. A focus is given on controlled encapsulation of small molecular weight phytochemical drugs in lipid-based nanocarriers as well as on encapsulation of macromolecular siRNA, plasmid DNA, peptide and protein pharmaceuticals in nanostructured nanoparticles that may provide efficient intracellular delivery and triggered drug release. Selected examples of utilisation of the BioSAXS method for characterization of various types of liquid crystalline nanoorganizations (liposome, spongosome, cubosome, hexosome, and nanostructured lipid carriers) are discussed in view of the successful encapsulation and protection of phytochemicals and therapeutic biomolecules in the hydrophobic or the hydrophilic compartments of the nanocarriers. We conclude that the structural design of the nanoparticulate carriers is of crucial importance for the therapeutic outcome and the triggered drug release from biocolloids.

A biophysical study of gene nanocarriers formed by anionic/zwitterionic mixed lipids and pillar[5]arene polycationic macrocycles

A multivalent cationic macrocycle is used as a mediator between plasmid DNAs and anionic lipids (ALs) to build an efficient and safe gene nanocarrier.