Recent Advance of Liposome Nanoparticles for Nucleic Acid Therapy

Gene therapy, as an emerging therapeutic approach, has shown remarkable advantages in the treatment of some major diseases. With the deepening of genomics research, people have gradually realized that the emergence and development of many diseases are related to genetic abnormalities. Therefore, nucleic acid drugs are gradually becoming a new boon in the treatment of diseases (especially tumors and genetic diseases). It is conservatively estimated that the global market of nucleic acid drugs will exceed $20 billion by 2025. They are simple in design, mature in synthesis, and have good biocompatibility. However, the shortcomings of nucleic acid, such as poor stability, low bioavailability, and poor targeting, greatly limit the clinical application of nucleic acid. Liposome nanoparticles can wrap nucleic acid drugs in internal cavities, increase the stability of nucleic acid and prolong blood circulation time, thus improving the transfection efficiency. This review focuses on the recent advances and potential applications of liposome nanoparticles modified with nucleic acid drugs (DNA, RNA, and ASO) and different chemical molecules (peptides, polymers, dendrimers, fluorescent molecules, magnetic nanoparticles, and receptor targeting molecules). The ability of liposome nanoparticles to deliver nucleic acid drugs is also discussed in detail. We hope that this review will help researchers design safer and more efficient liposome nanoparticles, and accelerate the application of nucleic acid drugs in gene therapy.

Dendrimers as Non-Viral Vectors in Gene-Directed Enzyme Prodrug Therapy

Gene-directed enzyme prodrug therapy (GDEPT) has been intensively studied as a promising new strategy of prodrug delivery, with its main advantages being represented by an enhanced efficacy and a reduced off-target toxicity of the active drug. In recent years, numerous therapeutic systems based on GDEPT strategy have entered clinical trials. In order to deliver the desired gene at a specific site of action, this therapeutic approach uses vectors divided in two major categories, viral vectors and non-viral vectors, with the latter being represented by chemical delivery agents. There is considerable interest in the development of non-viral vectors due to their decreased immunogenicity, higher specificity, ease of synthesis and greater flexibility for subsequent modulations. Dendrimers used as delivery vehicles offer many advantages, such as: nanoscale size, precise molecular weight, increased solubility, high load capacity, high bioavailability and low immunogenicity. The aim of the present work was to provide a comprehensive overview of the recent advances regarding the use of dendrimers as non-viral carriers in the GDEPT therapy.

[12]aneN3-based multifunctional compounds as fluorescent probes and nucleic acids delivering agents

A series of multifunctional compounds (MFCs) 1a-1e based on 1,8-naphthalimide and [12]aneN3 building blocks were designed and synthesized. They were used as not only fluorescent probes for recognition of Cu2+ ions but also as non-viral gene vectors for DNA and RNA delivery. Furthermore, their complexes with Cu2+ (1-Cu) could also selectively stain lysosome in HeLa cells. In order to achieve high performance multifunctional materials, structure-performance relationship of MFCs 1a-1e was studied. It was found that MFCs 1a-1e exhibited highly selective fluorescence turn-off for Cu2+, without interference by other metal ions in aqueous solution. The fluorescence emission of 1a-1e was quenched by a factor of 10-fold, 47-fold, 6-fold, 64-fold, and 15-fold respectively in the presence of Cu2+ ions. Due to high sensitivity, good water solubility, and low cytotoxicity, MFCs 1a-1d were successfully applied in the recognition of Cu2+ and selectively staining lysosome in HeLa cells. Most importantly, MFCs 1a and 1b had excellent HeLa cell selectivity in RNA delivery, and their performances were far better than lipofectamine 2000 and 25 kDa PEI.

Cell-based high-throughput screening of cationic polymers for efficient DNA and siRNA delivery

Development of non-viral gene vectors which can efficiently and safely transfect plasmid DNA and siRNA into cells is of great importance for gene therapy. Despite lots of efforts spent, it is still imperative to develop suitable gene vectors with better transfection efficiency and low cytotoxicity. To this end, we successfully designed, synthesized and screened a library of 120 polymers (via nucleophilic substitution reaction between dihalides and amines). With cell-based transfection screening assays, 120 polymers were tested to evaluate their transfection efficiency of transporting DNA and siRNA into cells. Our results indicated that hydrophobic modification could greatly enhance cationic polymers' transfection efficiency, and polymers with long linkers usually showed better transfection performance, especially for polymers with the linker of 1, 12-dibromododecane (L3 linker). Besides, polyalkylamines exhibited better transfection efficiency with the polymer particle size around 200 nm and the zeta potential in the range of + 40 mV to +50 mV. Interestingly, polymer particles made from N15HL3 not only exhibited better DNA transfection efficiency in HEK 293T cells but also showed higher siRNA transfection efficiency in U87 Luc-GFP cells together with low cell toxicity than Lipofectamine 2000 (one of commercial transfection reagents). Therefore, it is hoped that our study here not only provides promising gene vector candidates for further evaluation in gene therapy, but also provides valuable insights for better understanding of the relationship between the chemical structures and gene transfection efficiency to rationally design better non-viral gene vectors for gene therapy in the future.

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.

Core–shell particles for drug-delivery, bioimaging, sensing, and tissue engineering

Core–shell particles offer significant advantages in their use for bioimaging and biosensors.

Structure-activity relationship of novel low-generation dendrimers for gene delivery

Structure-activity relationship (SAR) studies are very critical to design ideal gene vectors for gene delivery. However, It is difficult to obtain SAR information of low-generation dendrimers due to the lack of easy structural modification ways. Here, we synthesized a novel family of rigid aromatic backbone-based low-generation polyamidoamine (PAMAM) dendrimers. According to the number of primary amines, they were divided into two types: four-amine-containing PAMAM (DL1-DL5) and eight-amine-containing PAMAM (DL6-DL10). Due to the introduction of a rigid aromatic backbone, the low-generation PAMAM could be modified easier by different hydrophobic aliphatic chains. Several assays were used to study the interactions of the PAMAM dendrimers with plasmid DNA, and the results revealed that they not only had good DNA binding ability but also could efficiently condense DNA into spherical-shaped nanoparticles with suitable sizes and zeta potentials. The SAR studies indicated that the gene-transfection efficiency of the synthesized materials depended on not only the structure of their hydrophobic chains but also the number of primary amines. It was found that four-amine-containing PAMAM prepared from oleylamine (DL5) gave the best transfection efficiency, which was 3 times higher than that of lipofectamine 2000 in HEK293 cells. The cellular uptake mechanism mediated by DL5 was further investigated, and the results indicated that DL5/DNA complexes entered the cells mainly via caveolae and clathrin-mediated endocytosis. In addition, these low-generation PAMAMs modified with a single hydrophobic tail showed lower toxicity than lipofectamine 2000 in MC3T3-E1, MG63, HeLa, and HEK293 cells. These results reveal that such a type of low-generation polyamidoamines might be promising non-viral gene vectors, and also give us clues for the design of safe and high-efficiency gene vectors.

Nanocomposites as biomolecules delivery agents in nanomedicine

Nanoparticles (NPs) are atomic clusters of crystalline or amorphous structure that possess unique physical and chemical properties associated with a size range of between 1 and 100 nm. Their nano-sized dimensions, which are in the same range as those of vital biomolecules, such as antibodies, membrane receptors, nucleic acids, and proteins, allow them to interact with different structures within living organisms. Because of these features, numerous nanoparticles are used in medicine as delivery agents for biomolecules. However, off-target drug delivery can cause serious side effects to normal tissues and organs. Considering this issue, it is essential to develop bioengineering strategies to significantly reduce systemic toxicity and improve therapeutic effect. In contrast to passive delivery, nanosystems enable to obtain enhanced therapeutic efficacy, decrease the possibility of drug resistance, and reduce side effects of "conventional" therapy in cancers. The present review provides an overview of the most recent (mostly last 3 years) achievements related to different biomolecules used to enable targeting capabilities of highly diverse nanoparticles. These include monoclonal antibodies, receptor-specific peptides or proteins, deoxyribonucleic acids, ribonucleic acids, [DNA/RNA] aptamers, and small molecules such as folates, and even vitamins or carbohydrates.