A flow cytometric approach to study the mechanism of gene delivery to cells by gemini-lipid nanoparticles: an implication for cell membrane nanoporation

Effective gene delivery using size dependant nano core-shell in human cervical cancer cell lines by magnetofection

Biocompatible magnetic nanoparticles are effective for gene delivery in vitro and in vivo transfection. These mediators are mainly used to deliver drugs and genes. It can also be used as probes to diagnose and treat various diseases. Magnetic nanoparticles, primarily iron oxide nanoparticles, are used in various biological applications. However, preparing stable and small-size biocompatible core-shell is crucial in site direct gene delivery. In the present study, superparamagnetic iron oxide nanoparticles were synthesized using the chemical co-precipitation method and were functionalized with starch to attain stable particles. These SPIONs were coated with polyethylenimine to give a net positive charge. The fluorescent plasmid DNA bound to the SPIONs were used as a core shell for gene delivery into the HeLa cells via magnetofection. UV-Visible Spectrophotometry analysis showed a peak at 200 nm, which confirms the presence of FeO nanoparticles. The Scanning Electron Microscopy images revealed the formation of spherical-shaped nanoparticles with an average size of 10 nm. X-ray Diffraction also confirmed FeO as a significant constituent element. Vibrating Sample Magnetometry ensures that the nanoparticles are superparamagnetic. Atomic Force Microscopy images show the DNA bound on the surface of the nanoparticles. The gene delivery and transfection efficiency were analyzed by flow cytometry. These nanoparticles could effectively compact the pDNA, allowing efficient gene transfer into the HeLa cell lines.

Mechanism of endosomal escape by pH-responsive nucleic-acid vectors

Successful intracellular delivery of nucleic acids (NAs) hinges on many factors, one of them being NAs' efficacious escape from endosomes. As competent NA vectors, pH-responsive gemini surfactants (GSs) might achieve high efficacy by facilitating endosomal escape. However, how the GSs assist the escape remains debated as many proposed mechanisms still lack experimental support, which hinders replication and further improvement of the efficient delivery. Here, via UV, fluorescence spectroscopy, and small-angle neutron scattering (SANS), we examined a pH-responsive GS's and a pH-unresponsive GS's capabilities to compact DNA and withstand binding competition, and their interactions with model endosomal and lysosomal membranes, at varied pHs. Acidification-driven enhancement of DNA-compaction capability and of stability against binding competition were found specific to the pH-responsive GS. Alongside the pH-responsive GS's structural perturbation to the membranes as observed with SANS, the features suggest that pH-responsive GSs facilitate endosomal escape by releasing excess GS molecules from DNA-GS complexes upon acidification in endosome maturation, with the released GS molecules disrupting endosomal and lysosomal membranes and thereby assisting the escape. A general design principle for NA vectors is proposed on the basis of this experimental finding.

Materiomically Designed Polymeric Vehicles for Nucleic Acids: Quo Vadis?

Despite rapid advances in molecular biology, particularly in site-specific genome editing technologies, such as CRISPR/Cas9 and base editing, financial and logistical challenges hinder a broad population from accessing and benefiting from gene therapy. To improve the affordability and scalability of gene therapy, we need to deploy chemically defined, economical, and scalable materials, such as synthetic polymers. For polymers to deliver nucleic acids efficaciously to targeted cells, they must optimally combine design attributes, such as architecture, length, composition, spatial distribution of monomers, basicity, hydrophilic-hydrophobic phase balance, or protonation degree. Designing polymeric vectors for specific nucleic acid payloads is a multivariate optimization problem wherein even minuscule deviations from the optimum are poorly tolerated. To explore the multivariate polymer design space rapidly, efficiently, and fruitfully, we must integrate parallelized polymer synthesis, high-throughput biological screening, and statistical modeling. Although materiomics approaches promise to streamline polymeric vector development, several methodological ambiguities must be resolved. For instance, establishing a flexible polymer ontology that accommodates recent synthetic advances, enforcing uniform polymer characterization and data reporting standards, and implementing multiplexed in vitro and in vivo screening studies require considerable planning, coordination, and effort. This contribution will acquaint readers with the challenges associated with materiomics approaches to polymeric gene delivery and offers guidelines for overcoming these challenges. Here, we summarize recent developments in combinatorial polymer synthesis, high-throughput screening of polymeric vectors, omics-based approaches to polymer design, barcoding schemes for pooled in vitro and in vivo screening, and identify materiomics-inspired research directions that will realize the long-unfulfilled clinical potential of polymeric carriers in gene therapy.

Anti-algal activity of the 12-5-12 gemini surfactant results from its impact on the photosynthetic apparatus

A rapid amplification of algal population has a negative impact on the environment and the global economy. Thus, control of algal proliferation is an important issue and effective procedures which reduce algal blooms and control algal fouling are highly desired. Gemini surfactants are considered to have a low environmental impact, therefore they seem to be a promising group of detergents which could reduce algal blooms in water systems. Furthermore, due to their emulsifying properties they could replace algaecides added to antifouling paints and decrease algae adhesion to various surfaces. In this study the toxic effect of the 12-5-12 gemini surfactant was investigated on Chlorella cells and close attention was paid to a potential mechanism of its action. At the high cell density (10.05 × 10⁷ cells/mL) a dose-dependent cell death was found and the IC₅₀ value was reached at the concentration of 19.6 µmol/L after 72-h exposure to the surfactant. The decrease in chlorophyll autofluorescence shows that the photosynthetic apparatus seems to be the target of the tested compound. The presented studies indicate that gemini surfactants could effectively reduce algal blooms in water systems, and if added to paints, they could decrease algal growth on external building walls or other water immersed surfaces.

Dicationic Amino Substituted Gemini Surfactants and their Nanoplexes: Improved Synthesis and Characterization of Transfection Efficiency and Corneal Penetration In Vitro

PURPOSE

To formulate and characterize nanoparticles from m-7NH-m gemini surfactants, synthesized by a new improved method, for non-invasive gene delivery including optimization of composition for transfection efficiency and corneal penetration.

METHODS

A one-pot, solvent-free, DMAP-free method was developed for the synthesis of m-7NH-m (m = 12-18) gemini surfactant series. Lipoplexes (LPXs) and nanoplexes (NPXs) of gemini surfactant-plasmid DNA were formulated with and without DOPE helper lipid, respectively, at various charge ratios and characterized by dynamic light scattering and zeta potential measurements. Transfection efficiency, cellular toxicity, effect of DOPE and gene expression kinetic studies were carried out in A7 astrocytes by flow cytometry and confocal microscopy. Corneal penetration studies of 18-7NH-18 NPXs were carried out using 3D EpiCorneal^® tissue model.

RESULTS

The new synthesis method provides a two-fold improved yield and the production of a pure species of m-7NH-m without DMAP and trimeric m-7N(m)-m surfactants as impurities. Structure and purity was confirmed by ESI-MS, ¹H NMR spectroscopy and surface tension measurements. Particle size of 199.80 ± 1.83 nm ± S.D. and a zeta potential value of +30.18 ± 1.17 mV ± S.D. was obtained for 18-7NH-18 5:1 ratio NPXs showed optimum transfection efficiency (10.97 ± 0.11%) and low toxicity (92.97 ± 0.57% viability) at the 48-h peak expression. Inclusion of DOPE at 1: 0.5 and 1:1 ratios to gemini surfactant reduced transfection efficiency and increased toxicity. Treatment of EpiCorneal^® tissue model showed deep penetration of up to 100 μm with 18-7NH-18 NPXs.

CONCLUSION

Overall, 18-7NH-18 NPXs are potential gene delivery systems for ophthalmic gene delivery and for further in vivo studies.

Photothermal-assisted surface-mediated gene delivery for enhancing transfection efficiency

The development of gene therapy puts forward the requirements for efficient delivery of genetic information into diverse cells. However, in some cases of transfection, especially those for transfecting some primary cells and for delivering large size plasmid DNA (pDNA), the existing conventional transfection methods show poor efficiency. How to further improve transfection efficiency in these hard-to-achieve issues remains a crucial challenge. Here, we report a photothermal-assisted surface-mediated gene delivery based on a polydopamine-polyethylenimine (PDA-PEI) surface. The PDA-PEI surface was prepared through PEI-accelerated dopamine polymerization, which showed efficiency in the immobilization of PEI/pDNA polyplexes and remarkable photothermal properties. Upon IR irradiation, we observed improved transfection efficiencies of two important hard-to-achieve transfection issues, namely the transfection of primary endothelial cells, which are kinds of typical hard-to-transfect cells, and the transfection of cells with large-size pDNA. We demonstrate that the increases of transfection efficiency were due to the hyperthermia-induced pDNA release, the local cell membrane disturbance, and the polyplex internalization. This work highlights the importance of local immobilization and release of pDNA to gene deliveries, showing great potential applications in medical devices in the field of gene therapy.

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.

Targeted Theranostic Nanoparticles for Brain Tumor Treatment

The poor prognosis and rapid recurrence of glioblastoma (GB) are associated to its fast-growing process and invasive nature, which make difficult the complete removal of the cancer infiltrated tissues. Additionally, GB heterogeneity within and between patients demands a patient-focused method of treatment. Thus, the implementation of nanotechnology is an attractive approach considering all anatomic issues of GB, since it will potentially improve brain drug distribution, due to the interaction between the blood⁻brain barrier and nanoparticles (NPs). In recent years, theranostic techniques have also been proposed and regarded as promising. NPs are advantageous for this application, due to their respective size, easy surface modification and versatility to integrate multiple functional components in one system. The design of nanoparticles focused on therapeutic and diagnostic applications has increased exponentially for the treatment of cancer. This dual approach helps to understand the location of the tumor tissue, the biodistribution of nanoparticles, the progress and efficacy of the treatment, and is highly useful for personalized medicine-based therapeutic interventions. To improve theranostic approaches, different active strategies can be used to modulate the surface of the nanotheranostic particle, including surface markers, proteins, drugs or genes, and take advantage of the characteristics of the microenvironment using stimuli responsive triggers. This review focuses on the different strategies to improve the GB treatment, describing some cell surface markers and their ligands, and reports some strategies, and their efficacy, used in the current research.

Recent Advances in Lipid-Based Vesicles and Particulate Carriers for Topical and Transdermal Application

In the recent decade, skin delivery (topical and transdermal) has gained an unprecedented popularity, especially due to increased incidences of chronic skin diseases, demand for targeted and patient compliant delivery, and interest in life cycle management strategies among pharmaceutical companies. Literature review of recent publications indicates that among various skin delivery systems, lipid-based delivery systems (vesicular carriers and lipid particulate systems) have been the most successful. Vesicular carriers consist of liposomes, ultradeformable liposomes, and ethosomes, while lipid particulate systems consist of lipospheres, solid lipid nanoparticles, and nanostructured lipid carriers. These systems can increase the skin drug transport by improving drug solubilization in the formulation, drug partitioning into the skin, and fluidizing skin lipids. Considering that lipid-based delivery systems are regarded as safe and efficient, they are proving to be an attractive delivery strategy for the pharmaceutical as well as cosmeceutical drug substances. However, development of these delivery systems requires comprehensive understanding of physicochemical characteristics of drug and delivery carriers, formulation and process variables, mechanism of skin delivery, recent technological advancements, specific limitations, and regulatory considerations. Therefore, this review article encompasses recent research advances addressing the aforementioned issues.