Gemini surfactants mediate efficient mitochondrial gene delivery and expression

Mitochondrial endogenous substance transport-inspired nanomaterials for mitochondria-targeted gene delivery

Mitochondrial genome (mtDNA) independent of nuclear gene is a set of double-stranded circular DNA that encodes 13 proteins, 2 ribosomal RNAs and 22 mitochondrial transfer RNAs, all of which play vital roles in functions as well as behaviors of mitochondria. Mutations in mtDNA result in various mitochondrial disorders without available cures. However, the manipulation of mtDNA via the mitochondria-targeted gene delivery faces formidable barriers, particularly owing to the mitochondrial double membrane. Given the fact that there are various transport channels on the mitochondrial membrane used to transfer a variety of endogenous substances to maintain the normal functions of mitochondria, mitochondrial endogenous substance transport-inspired nanomaterials have been proposed for mitochondria-targeted gene delivery. In this review, we summarize mitochondria-targeted gene delivery systems based on different mitochondrial endogenous substance transport pathways. These are categorized into mitochondrial steroid hormones import pathways-inspired nanomaterials, protein import pathways-inspired nanomaterials and other mitochondria-targeted gene delivery nanomaterials. We also review the applications and challenges involved in current mitochondrial gene editing systems. This review delves into the approaches of mitochondria-targeted gene delivery, providing details on the design of mitochondria-targeted delivery systems and the limitations regarding the various technologies. Despite the progress in this field is currently slow, the ongoing exploration of mitochondrial endogenous substance transport and mitochondrial biological phenomena may act as a crucial breakthrough in the targeted delivery of gene into mitochondria and even the manipulation of mtDNA.

Gemini surfactants as next-generation drug carriers in cancer management

INTRODUCTION

Gemini surfactants (GS) are an elite class of amphiphilic molecules that have shown up as a potential candidate in the field of drug delivery because of their exceptional physicochemical properties. They comprise two hydrophilic headgroups connected by an adaptable spacer and hydrophobic tails that has shown promising results in delivering different therapeutic agents to cancer cells at preclinical level. However further studies are in demand to unlock the full potential of GS in this field.

AREAS COVERED

This review summarizes the new advancements in GS as drug carriers in cancer therapy, their capacity to overcome conventional shortcomings and the demand for innovative approaches in disease treatment. A detailed list of GS-based formulations along with a brief description on oligomeric surfactants have also been provided in this review. This article summarizes data from studies identified through literature database searches including PubMed and Google Scholar (2010-2023).

EXPERT OPINION

There are major challenges that need to be addressed in this field which restrict their progression toward clinical phase. Further research can focus on developing a theranostic system that can provide simultaneous real-time monitoring along with treatment care. Nevertheless, ensuring the safety parameters of these nanocarriers followed by their regulatory approval is a time-consuming and expensive process. A collaborative approach between regulatory bodies, research institutions, and pharmaceutical companies can speed up the process in the upcoming years.

Mitochondrial adaptation in cancer drug resistance: prevalence, mechanisms, and management

Drug resistance represents a major obstacle in cancer management, and the mechanisms underlying stress adaptation of cancer cells in response to therapy-induced hostile environment are largely unknown. As the central organelle for cellular energy supply, mitochondria can rapidly undergo dynamic changes and integrate cellular signaling pathways to provide bioenergetic and biosynthetic flexibility for cancer cells, which contributes to multiple aspects of tumor characteristics, including drug resistance. Therefore, targeting mitochondria for cancer therapy and overcoming drug resistance has attracted increasing attention for various types of cancer. Multiple mitochondrial adaptation processes, including mitochondrial dynamics, mitochondrial metabolism, and mitochondrial apoptotic regulatory machinery, have been demonstrated to be potential targets. However, recent increasing insights into mitochondria have revealed the complexity of mitochondrial structure and functions, the elusive functions of mitochondria in tumor biology, and the targeting inaccessibility of mitochondria, which have posed challenges for the clinical application of mitochondrial-based cancer therapeutic strategies. Therefore, discovery of both novel mitochondria-targeting agents and innovative mitochondria-targeting approaches is urgently required. Here, we review the most recent literature to summarize the molecular mechanisms underlying mitochondrial stress adaptation and their intricate connection with cancer drug resistance. In addition, an overview of the emerging strategies to target mitochondria for effectively overcoming chemoresistance is highlighted, with an emphasis on drug repositioning and mitochondrial drug delivery approaches, which may accelerate the application of mitochondria-targeting compounds for cancer therapy.

Rational Designs at the Forefront of Mitochondria-Targeted Gene Delivery: Recent Progress and Future Perspectives

Mitochondria play an essential role in cellular metabolism and generate energy in cells. To support these functions, several proteins are encoded in the mitochondrial DNA (mtDNA). The mutation of mtDNA causes mitochondrial dysfunction and ultimately results in a variety of inherited diseases. To date, gene delivery systems targeting mitochondria have been developed to ameliorate mtDNA mutations. However, applications of these strategies in mitochondrial gene therapy are still being explored and optimized. Thus, from this perspective, we herein highlight recent mitochondria-targeting strategies for gene therapy and discuss future directions for effective mitochondria-targeted gene delivery.

Gemini and Bicephalous Surfactants: A Review on Their Synthesis, Micelle Formation, and Uses

The use of surfactants in polymerization reactions is particularly important, mainly in emulsion polymerizations. Further, micelles from biocompatible surfactants find use in pharmaceutical dosage forms. This paper reviews recent developments in the synthesis of novel gemini and bicephalous surfactants, micelle formation, and their applications in polymer and nanoparticle synthesis, oil recovery, catalysis, corrosion, protein binding, and biomedical area, particularly in drug delivery.

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.

Peptide-Based Drug Delivery Systems

Peptide-based drug delivery systems have many advantages when compared to synthetic systems in that they have better biocompatibility, biochemical and biophysical properties, lack of toxicity, controlled molecular weight via solid phase synthesis and purification. Lysosomes, solid lipid nanoparticles, dendrimers, polymeric micelles can be applied by intravenous administration, however they are of artificial nature and thus may induce side effects and possess lack of ability to penetrate the blood-brain barrier. An analysis of nontoxic drug delivery systems and an establishment of prospective trends in the development of drug delivery systems was needed. This review paper summarizes data, mainly from the past 5 years, devoted to the use of peptide-based carriers for delivery of various toxic drugs, mostly anticancer or drugs with limiting bioavailability. Peptide-based drug delivery platforms are utilized as peptide–drug conjugates, injectable biodegradable particles and depots for delivering small molecule pharmaceutical substances (500 Da) and therapeutic proteins. Controlled drug delivery systems that can effectively deliver anticancer and peptide-based drugs leading to accelerated recovery without significant side effects are discussed. Moreover, cell penetrating peptides and their molecular mechanisms as targeting peptides, as well as stimuli responsive (enzyme-responsive and pH-responsive) peptides and peptide-based self-assembly scaffolds are also reviewed.

Pathologically Responsive Mitochondrial Gene Therapy in an Allotopic Expression-Independent Manner Cures Leber's Hereditary Optic Neuropathy

Leber's hereditary optic neuropathy (LHON) is a rare inherited blindness caused by mutations in the mitochondrial DNA (mtDNA). The disorder is untreatable and tricky, as the existing chemotherapeutic agent Idebenone alleviates symptoms rather than overcoming the underlying cause. Although some studies have made progress on allotopic expression for LHON, in situ mitochondrial gene therapy remains challenging, which may simplify delivery procedures to be a promising therapeutic for LHON. LHON becomes more difficult to manage in the changed mitochondrial microenvironment, including increasing reactive oxygen species (ROS) and decreasing mitochondrial membrane potential (MMP). Herein, a pathologically responsive mitochondrial gene delivery vector named [triphenylphosphine-terminated poly(sulfur-containing thioketal undecafluorohexylamine histamine) and Ide-terminated poly(sulfur-containing thioketal undecafluorohexylamine histamine)] (TISUH) is reported to facilitate commendable in situ mitochondrial gene therapy for LHON. TISUH directly targets diseased mitochondria via triphenylphosphine and fluorination addressing the decreasing MMP. In addition, TISUH can be disassembled by high mitochondrial ROS levels to release functional genes for enhancing gene transfection efficiency and fundamentally correcting genetic abnormalities. In both traditional and gene-mutation-induced LHON mouse models, TISUH-mediated gene therapy shows satisfactory curative effect through the sustained therapeutic protein expression in vivo. This work proposes a novel pathologically responsive in situ mitochondrial delivery platform and provides a promising approach for refractory LHON as well as other mtDNA mutated diseases treatments.

A review of the tortuous path of nonviral gene delivery and recent progress

Gene therapy encompasses the transfer of exogenous genetic materials into the patient's target cells to treat or prevent diseases. Nevertheless, the transfer of genetic material into desired cells is challenging and often requires specialized tools or delivery systems. For the past 40 years, scientists are mainly pursuing various viruses as gene delivery vectors, and the overall progress has been slow and far from the expectation. As an alternative, nonviral vectors have gained substantial attention due to their several advantages, including superior safety profile, enhanced payload capacity, and stealth abilities. Since nonviral vectors encounter multiple extra- and intra-cellular barriers limiting the transfer of genetic payload into the target cell nucleus, we have discussed these barriers in detail for this review. A direct approach, utilizing physical methods like electroporation, sonoporation, gene gun, eliminate the requirement for a specific carrier for gene delivery. In contrast, chemical methods of gene transfer exploit natural or synthetic compounds as carriers to increase cellular targeting and gene therapy effectiveness. We have also emphasized the recent advancements aimed at enhancing the current nonviral approaches. Therefore, in this review, we have focused on discussing the current evolving state of nonviral gene delivery systems and their future perspectives.

Development of Peptide-Based Nanoparticles for Mitochondrial Plasmid DNA Delivery

A mitochondrion is a cellular organelle able to produce cellular energy in the form of adenosine triphosphate (ATP). As in the nucleus, mitochondria contain their own genome: the mitochondrial DNA (mtDNA). This genome is particularly susceptible to mutations that are at the basis of a multitude of disorders, especially those affecting the heart, the central nervous system and muscles. Conventional clinical practice applied to mitochondrial diseases is very limited and ineffective; a clear need for innovative therapies is demonstrated. Gene therapy seems to be a promising approach. The use of mitochondrial DNA as a therapeutic, optimized by peptide-based complexes with mitochondrial targeting, can be seen as a powerful tool in the reestablishment of normal mitochondrial function. In line with this requirement, in this work and for the first time, a mitochondrial-targeting sequence (MTS) has been incorporated into previously researched peptides, to confer on them a targeting ability. These peptides were then considered to complex a plasmid DNA (pDNA) which contains the mitochondrial gene ND1 (mitochondrially encoded NADH dehydrogenase 1 protein), aiming at the formation of peptide-based nanoparticles. Currently, the ND1 plasmid is one of the most advanced bioengineered vectors for conducting research on mitochondrial gene expression. The formed complexes were characterized in terms of pDNA complexation capacity, morphology, size, surface charge and cytotoxic profile. These data revealed that the developed carriers possess suitable properties for pDNA delivery. Furthermore, in vitro studies illustrated the mitochondrial targeting ability of the novel peptide/pDNA complexes. A comparison between the different complexes revealed the most promising ones that complex pDNA and target mitochondria. This may contribute to the optimization of peptide-based non-viral systems to target mitochondria, instigating progress in mitochondrial gene therapy.

Mixing behaviour of Pluronics with gemini surfactant/plasmid DNA condensates: effect of Pluronic composition

Nanoparticles prepared from plasmid DNA (pDNA) and N,N-bis(dimethylhexadecyl)-1,3-propanediammonium bromide (16-3-16) have been mixed with various Pluronic block copolymers and investigated as binary surfactant systems in water using the previously demonstrated critical aggregation concentration of the surfactant-DNA complex. Surface tensiometry was used to determine critical micelle concentrations of mixed micelles formed within these Pluronic/16-3-16/pDNA mixtures. Use of mixed micelle theories reveals that mixed micelle composition and the interaction parameter, β, are influenced by the structure, in particular hydrophobicity, of the Pluronic component. Ethidium bromide fluorescence studies demonstrate the ability of the Pluronics to de-condense the plasmid DNA from the cationic 16-3-16 gemini surfactant complex, and show some relationship to the interaction parameter and Pluronic composition.

Power of mitochondrial drug delivery systems to produce innovative nanomedicines

Mitochondria carry out various essential functions including ATP production, the regulation of apoptosis and possess their own genome (mtDNA). Delivering target molecules to this organelle, it would make it possible to control the functions of cells and living organisms and would allow us to develop a better understanding of life. Given the fact that mitochondrial dysfunction has been implicated in a variety of human disorders, delivering therapeutic molecules to mitochondria for the treatment of these diseases is an important issue. To date, several mitochondrial drug delivery system (DDS) developments have been reported, but a generalized DDS leading to therapy that exclusively targets mitochondria has not been established. This review focuses on mitochondria-targeted therapeutic strategies including antioxidant therapy, cancer therapy, mitochondrial gene therapy and cell transplantation therapy based on mitochondrial DDS. A particular focus is on nanocarriers for mitochondrial delivery with the goal of achieving mitochondria-targeting therapy. We hope that this review will stimulate the accelerated development of mitochondrial DDS.

Endocytosis: The Nanoparticle and Submicron Nanocompounds Gateway into the Cell

Nanoparticles (NPs) and submicron particles are increasingly used as carriers for delivering therapeutic compounds to cells. Their entry into the cell represents the initial step in this delivery process, being most of the nanoparticles taken up by endocytosis, although other mechanisms can contribute to the uptake. To increase the delivery efficiency of therapeutic compounds by NPs and submicron particles is very relevant to understand the mechanisms involved in the uptake process. This review covers the proposed pathways involved in the cellular uptake of different NPs and submicron particles types as well as the role that some of the physicochemical nanoparticle characteristics play in the uptake pathway preferentially used by the nanoparticles to gain access and deliver their cargo inside the cell.

Synergistic Catalytic Synthesis of Gemini Lipoamino Acids Based on Multiple Hydrogen-Bonding Interactions in Natural Deep Eutectic Solvents-Enzyme System

In the previous studies, gemini lipoamino acids (GLAA) were always synthesized by complex multistep organic synthesis, which involved a large number of byproducts and organic solvents. To develop a straightforward, efficient, and renewable synthesis strategy for GLAA, in this study, a type of novel green solvents, natural deep eutectic solvents (NADESs), were adopted as the solvents for these reactions. Five commercial enzymes were involved in the enzyme screening section, and Candida antarctica lipase B (CALB) tended to have the best performance in NADESs systems. The optimization procedure was performed using the Taguchi crossed array method and the highest yield of GLAA (59.14 ± 0.51%) was obtained in choline chloride-glycerol (C-Gly). The purification procedure was carried out with ethyl acetate and water, and the isolate yield ranged from 86.31 ± 2.36 to 91.34 ± 2.26%. With 10 times recycling, the yield of GLAA in C-Gly decreased from 59.14 ± 0.51 to 51.31 ± 0.68%. Interestingly, a synergistic effect of CALB and NADESs was found in the enzymatic synthesis of GLAA, which can be attributed to fatty acids being activated by chloride ions via hydrogen-bonding interactions and resulting in an enhancement in its electron-attracting ability.

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.

Effect of hydrophobic tails of plier-like cationic lipids on nucleic acid delivery and intracellular trafficking

In the optimization of transfection efficacy, one of the crucial barriers to effective gene delivery is in fact the intracellular trafficking of nucleic acids, besides the first and the last steps of gene transfer, i.e., delivery to the cell and transcription. Modifications of cationic lipid structure have been reported to have a significant effect on gene delivery. Therefore, the plier-like cationic lipids (PCLs) have been synthesized and the effect of the different types of hydrophobic tails (chain length and unsaturated hydrocarbon) on physicochemical properties, cellular uptake, trafficking process, transfection, and silencing efficiency has been investigated. In this study, the plier-like cationic niosomes (PCNs) containing PCL (A, B, and C) were evaluated their performance to deliver pDNA and siRNA to HeLa cells. Among the PCNs, PCN-B with saturated asymmetric hydrocarbon tails (C18 and C12) provided the highest efficiency for pDNA and siRNA delivery. Furthermore, the results revealed that the structure of the cationic lipids affected the internalization pathway and the intracellular trafficking. PCL-B and PCL-C with asymmetric tails preferred clathrin- and caveolae-mediated endocytosis as the predominant internalization pathways and were also involved in the polymerization process for transfection. However, PCL-A with symmetry hydrocarbon tails (C12) was predominantly taken up via macropinocytosis. All PCNs were able to escape from endosomal-lysosomal systems through facilitation of acidification. Results obtained from the cytotoxicity test revealed that the PCNs were safe in vitro. Therefore, PCNs provide a great prospect as an alternative effective gene delivery system.

Cellular Uptake and Distribution of Gemini Surfactant Nanoparticles Used as Gene Delivery Agents

Gemini surfactants are promising molecules utilized as non-viral gene delivery vectors. However, little is known about their cellular uptake and distribution after they release their therapeutic cargo. Therefore, we quantitatively evaluated the cellular uptake and distribution of three gemini surfactants: unsubstituted (16-3-16), with pyridinium head groups (16(Py)-S-2-S-16(Py)) and substituted with a glycyl-lysine di-peptide (16-7N(GK)-16). We also assessed the relationship between cellular uptake and distribution of each gemini surfactant and its overall efficiency and toxicity. Epidermal keratinocytes PAM 212 were treated with gemini surfactant nanoparticles formulated with plasmid DNA and harvested at various time points to collect the enriched nuclear, mitochondrial, plasma membrane, and cytosolic fractions. Gemini surfactants were then extracted from each subcellular fraction and quantified using a validated flow injection analysis-tandem mass spectrometry (FIA-MS/MS) method. Mass spectrometry is superior to the use of fluorescent tags that alter the physicochemical properties and pharmacokinetics of the nanoparticles and can be cleaved from the gemini surfactant molecules within biological systems. Overall, a significantly higher cellular uptake was observed for 16-7N(GK)-16 (17.0%) compared with 16-3-6 (3.6%) and 16(Py)-S-2-S-16(Py) (1.4%), which explained the relatively higher transfection efficiency of 16-7N(GK)-16. Gemini surfactants 16-3-16 and 16(Py)-S-2-S-16(Py) displayed similar subcellular distribution patterns, with major accumulation in the nucleus, followed by the mitochondrion, cytosol, and plasma membrane. In contrast, 16-7N(GK)-16 was relatively evenly distributed across all four subcellular fractions. However, accumulation within the nucleus after 5 h of treatment was the highest for 16(Py)-S-2-S-16(Py) (50.3%), followed by 16-3-16 (41.8%) and then 16-7N(GK)-16 (33.4%), possibly leading to its relatively higher toxicity. Graphical Abstract.

Surface charge tunable catanionic vesicles based on serine-derived surfactants as efficient nanocarriers for the delivery of the anticancer drug doxorubicin

Self-assembled vesicles composed of amino acid-based cationic/anionic surfactant mixtures show promise as novel effective drug nanocarriers. Here, we report the in vitro performance of vesicles based on cationic (16Ser) and anionic (8-8Ser) serine-based surfactants using a cancer cell model for the delivery of the anticancer drug doxorubicin (DOX). This catanionic mixture yields both negatively (0.20 in the cationic surfactant molar fraction, x16Ser) and positively (x16Ser = 0.58) charged vesicles, hence providing a surface charge tunable system. Low toxicity is confirmed for concentration ranges below 32 μM in both formulations. DOX is successfully encapsulated in the vesicles, resulting in a surface charge switch to negative for the (0.58) system, making both (0.20) and (0.58) DOX-loaded vesicles highly interesting for systemic administration. High uptake by cells was demonstrated using flow cytometry and confocal microscopy. Drug accumulation results in an increase of cell uptake up to 250% and 200% for the (0.20) and (0.58) vesicles, respectively, compared to free DOX and with localizations near the nuclear regions in the cells. The in vitro cytotoxicity studies show that DOX-loaded vesicles induce cell death, confirming the therapeutic potential of the formulations. Furthermore, the efficient accumulation of the drug inside the cell compartments harbors the potential for optimization strategies including phased delivery for prolonged treatment periods or even on-demand release.

Solid Lipid Nanoparticles Surface Modification Modulates Cell Internalization and Improves Chemotoxic Treatment in an Oral Carcinoma Cell Line

Solid lipid nanoparticles (SLN) present low toxicity, versatility to incorporate both lipophilic and hydrophilic drugs, controlled drug release and they are easy to scale-up. It is well known that the endocytosis pathway by which SLN are taken up and the subsequent subcellular distribution are crucial for the biological effect of the incorporated drug. In addition, interactions between SLN and cells depend on many factors, such as, the composition of nanoparticle surface. In this work different amounts of phosphatidylethanolamine polyethylene glycol (PE–PEG) were added to SLN composed of stearic acid, Epikuron 200 and sodium taurodeoxycholate. Characterization of obtained nanoparticle suspensions were performed by the analysis of particle size, polydispersity index, ζ-potential, cell toxicity and cell internalization pathway. We have observed that the presence of PE–PEG improves active cell internalization of the nanoparticles in an oral adenocarcinoma cell line, reducing non-specific internalization mechanisms. Finally, we have tested the effect of surface coating on the efficiency of incorporated drugs using all-trans retinoic acid as a model drug. We have observed that delivery of this drug into PE–PEG coated SLN increases its chemotoxic effect compared to non-coated SLN. Therefore, it can be concluded that surface modification with PE–PEG improves the efficiency and the specificity of the SLN-loaded drug.

The determination of gemini surfactants used as gene delivery agents in cellular matrix using validated tandem mass spectrometric method

A simple, reliable flow injection analysis (FIA)-tandem mass spectrometric (MS/MS) method was developed for the determination of gemini surfactants, designated as 16-3-16, 16(Py)-S-2-S-(Py)16 and 16-7N(GK)-16, as gene delivery agents in cellular matrix. 16-3-16 is a conventional gemini surfactant bearing two quaternary amines, linked by a 3-carbon spacer region, 16(Py)-S-2-S-(Py)16 contains two pyridinium head groups, while 16-7N(GK)-16 bears a glycine-lysine di-peptide in the space region. The method was fully validated according to USFDA guidelines. It is the first time that FIA-MS/MS method was developed for the quantification of gemini surfactants, belonging to different structural families. The method was superior to existing liquid chromatographic (LC)-MS/MS methods in terms of sensitivity and time of analysis. Positive electrospray ionization (ESI) in the multiple reaction monitoring (MRM) mode were used on a triple quadrupole-linear ion trap (4000 QTRAP^®) instrument. Deuterated internal standards were used to correct for matrix effects and variations in ionization within the ESI source. Isotope dilution standard curves were established in cellular matrix, with a linear range of 10 nM-1000 nM for 16-3-16 and 16(Py)-S-2-S-(Py)16, and 20 nM-2000 nM for 16-7N(GK)-16. The precision, accuracy, recovery and stability were all within the acceptable ranges as per the USFDA guidelines. The method was successfully applied for the quantification of target gemini surfactants in the nuclear fraction of PAM 212 keratinocyte cells treated with nanoparticles, which varied significantly and may explain differences in the observed efficiency and/or toxicity of these gemini surfactants in gene delivery.

Mitochondria targeting two-photon fluorescent molecules for gene transfection and biological tracking

Mitochondria targeting two-photon fluorescent organic molecules are applied in gene transfection in vitro and in vivo.

Recent Advances in Mitochondria-Targeted Gene Delivery

Mitochondria are the energy-producing organelles of cells. Mitochondrial dysfunctions link to various syndromes and diseases including myoclonic epilepsy and ragged-red fiber disease (MERRF), Leigh syndrome (LS), and Leber hereditary optic neuropathy (LHON). Primary mitochondrial diseases often result from mutations of mitochondrial genomes and nuclear genes that encode the mitochondrial components. However, complete intracellular correction of the mutated genetic parts relevant to mitochondrial structures and functions is technically challenging. Instead, there have been diverse attempts to provide corrected genetic materials with cells. In this review, we discuss recent novel physical, chemical and biological strategies, and methods to introduce genetic cargos into mitochondria of eukaryotic cells. Effective mitochondria-targeting gene delivery systems can reverse multiple mitochondrial disorders by enabling cells to produce functional mitochondrial components.

Aggregate evolution in aqueous solutions of a Gemini surfactant derived from dehydroabietic acid

Innovations in surfactant structure are a feasible way to probe molecular self-assembly principles. Herein, the solution behaviour of a newly synthesized Gemini surfactant derived from dehydroabietic acid, abbreviated R-(EO)-E-R, was investigated using surface tension, fluorescence, isothermal titration calorimetry (ITC), rheology, freeze-fracture transmission electron microscopy (FF-TEM) and cryogenic transmission electron microscopy (cryo-TEM) methods. R-(EO)-E-R has two large, rigid hydrophobic groups. At low concentrations, R-(EO)-E-R forms micelles with an aggregation number of approximately 10, which is smaller than those of Gemini surfactants containing flexible alkyl tails. In addition, the micellization process is less exothermic because of the rigidity of the hydrophobic portions. As the concentration increases, R-(EO)-E-R without any additives forms wormlike micelles, endowing the solution with an obvious viscoelasticity. Further increases in the concentration lead to the coexistence of single-walled vesicles, double-walled vesicles and rarely observed long, tubular vesicles. This behaviour is attributed to the two large, rigid hydrophobic groups of R-(EO)-E-R, which increase the density of the hydrophobic portion around the ionic head groups and facilitate the formation of aggregates with lower curvatures and asymmetric morphology. Surfactants containing rigid hydrophobic portions are expected to result in more delicate, self-assembled morphologies with broad applications.

Self-assembly of cationic gemini surfactants, alkanediyl-bis-(dimethyldodecyl-ammonium bromide), in cyclohexane: effects of spacer length on their association into reverse lyotropic liquid crystalline or reverse vesicles

Herein, homogeneous solutions of cationic gemini surfactants, alkanediyl-α,ω-bis(dimethyldodecylammonium bromide), referred to as 12-s-12 where s = 2, 4, 6, 8, and 10, in cyclohexane have been prepared with the help of sodium hexanoate (SH) or sodium laurate (SL). These surfactants self-assembled in cyclohexane to form various aggregating structures, which were characterised by small-angle X-ray scattering (SAXS) together with polarised microscopy observations. The results showed that 12-2-12/SH, where the gemini had the shortest spacer among this series, formed an inverse micellar cubic liquid crystalline phase of the Fd3m structure. 12-s-12/SL, including s = 4, 6, and 8, which contained an adequate length spacer, formed an inverse hexagonal liquid crystalline phase packed by the cylindrical assemblies of surfactants. 12-10-12/SL, in which the gemini had a longer spacer, formed dispersed reverse vesicles (a lamellar structure). The rheological properties of liquid crystalline phases in a linear visco-elastic regime were studied. 12-2-12/SH formed a hard gel, whereas 12-s-12/SL formed soft gels. Dynamic light scattering and steady-state viscosity analyses were performed for the reverse vesicle solutions formed by 12-10-12/SL. In all these systems, the amount of added water W₀, denoting the mole ratio of water to the gemini surfactant, was demonstrated to influence the properties.

Advances in the synthesis, molecular architectures and potential applications of gemini surfactants

Gemini surfactants have been the subject of intensive scrutiny by virtue of their unique combination of physical and chemical properties and being used in ordinary household objects to multifarious industrial processes. In this review, we summarize the recent developments of gemini surfactants, highlighting the classification of gemini surfactants based on the variation in headgroup polarity, flexibility/rigidity of spacer, hydrophobic alkyl chain and counterion along with potential applications of gemini surfactants, depicting the truly remarkable journey of gemini surfactants that has just come of age. We have focused on those objectives which will act as suitable candidates to take the field forward. The preceding information will permit us to estimate the effect of structural variation on the aggregation behavior of gemini surfactants for nanoscience and biological applications like antimicrobial, anti-fungal agent, better gene and drug delivery agent with low cytotoxicity and biodegradability, which makes them more advantageous for a number of technological processes and hence reduces the impact of these gemini surfactants on the environment.

Gemini-Type Tetraphenylethylene Amphiphiles Containing [12]aneN3 and Long Hydrocarbon Chains as Nonviral Gene Vectors and Gene Delivery Monitors

Four gemini amphiphiles decorated with triazole-[12]aneN₃ as the hydrophilic moiety and various long hydrocarbons as hydrophobic moieties, 1-4, were designed to form micelles possessing the aggregation-induced emission (AIE) property for gene delivery and tracing. All four amphiphiles give ultralow critical micelle concentrations, are pH-/photostable and biocompatible, and completely retard the migration of plasmid DNAs at low concentrations. The DNA-binding abilities of the micelles were fully assessed. The coaggregated nanoparticles of 1-4 with DNAs could convert back into AIE micelles. In vitro transfections indicated that lipids 1 and 2 and their originated liposomes bearing decent delivering abilities have great potentials as nonviral vectors. Finally, on the basis of the transfection and the transitions between condensates and micelles, lipid 2 was singled out as the first example for real-time tracing of the intracellular deliveries of nonlabeled DNA, which provides spatiotemporal messages about the processes of condensate uptake and DNA release.

Mitochondrial Gene Therapy: Advances in Mitochondrial Gene Cloning, Plasmid Production, and Nanosystems Targeted to Mitochondria

Mitochondrial gene therapy seems to be a valuable and promising strategy to treat mitochondrial disorders. The use of a therapeutic vector based on mitochondrial DNA, along with its affinity to the site of mitochondria, can be considered a powerful tool in the reestablishment of normal mitochondrial function. In line with this and for the first time, we successfully cloned the mitochondrial gene ND1 that was stably maintained in multicopy pCAG-GFP plasmid, which is used to transform E. coli. This mitochondrial-gene-based plasmid was encapsulated into nanoparticles. Furthermore, the functionalization of nanoparticles with polymers, such as cellulose or gelatin, enhances their overall properties and performance for gene therapy. The fluorescence arising from rhodamine nanoparticles in mitochondria and a fluorescence microscopy study show pCAG-GFP-ND1-based nanoparticles' cell internalization and mitochondria targeting. The quantification of GFP expression strongly supports this finding. This work highlights the viability of gene therapy based on mitochondrial DNA instigating further in vitro research and clinical translation.

Facile construction of mitochondria-targeting nanoparticles for enhanced phototherapeutic effects

An illustration of the preparation of ICG/rPAA@SWCNT nanoparticles which target mitochondria for amplifying photodynamic therapeutic effects.