Ammonium Gemini Surfactants Form Complexes with Model Oligomers of siRNA and dsDNA

Multiheaded Cationic Surfactants with Dedicated Functionalities: Design, Synthetic Strategies, Self-Assembly and Performance

Contemporary research concerning surfactant science and technology comprises a variety of requirements relating to the design of surfactant structures with widely varying architectures to achieve physicochemical properties and dedicated functionality. Such approaches are necessary to make them applicable to modern technologies, such as nanostructure engineering, surface structurization or fine chemicals, e.g., magnetic surfactants, biocidal agents, capping and stabilizing reagents or reactive agents at interfaces. Even slight modifications of a surfactant's molecular structure with respect to the conventional single-head-single-tail design allow for various custom-designed products. Among them, multicharge structures are the most intriguing. Their preparation requires specific synthetic routes that enable both main amphiphilic compound synthesis using appropriate step-by-step reaction strategies or coupling approaches as well as further derivatization toward specific features such as magnetic properties. Some of the most challenging aspects of multicharge cationic surfactants relate to their use at different interfaces for stable nanostructures formation, applying capping effects or complexation with polyelectrolytes. Multiheaded cationic surfactants exhibit strong antimicrobial and antiviral activity, allowing them to be implemented in various biomedical fields, especially biofilm prevention and eradication. Therefore, recent advances in synthetic strategies for multiheaded cationic surfactants, their self-aggregation and performance are scrutinized in this up-to-date review, emphasizing their applications in different fields such as building blocks in nanostructure engineering and their use as fine chemicals.

Pegylated Gold Nanoparticles Conjugated with siRNA: Complexes Formation and Cytotoxicity

Drug delivery systems such as dendrimers, liposomes, polymers or gold/silver nanoparticles could be used to advance modern medicine. One significant pharmacological problem is crossing biological barriers by commonly used drugs, e.g., in the treatment of neurodegenerative diseases, which have a problem of the blood-brain barrier (BBB) restricting drug delivery. Numerous studies have been conducted to find appropriate drug carriers that are safe, biocompatible and efficient. In this work, we evaluate pegylated gold nanoparticles AuNP14a and AuNP14b after their conjugation with therapeutic siRNA directed against APOE4. This genetic risk factor remains the strongest predictor for late-onset Alzheimer’s disease. The study aimed to assess the biophysical properties of AuNPs/siAPOE complexes and to check their biological safety on healthy cells using human brain endothelial cells (HBEC-5i). Techniques such as fluorescence polarization, circular dichroism, dynamic light scattering, ζ-potential measurements and gel retardation assay showed that AuNPs form stable complexes with siRNA. Subsequently, cytotoxicity assays proved the biological safety of formed conjugates. Obtained results enabled us to find effective concentrations of AuNPs when complexes are formed and non-toxic for healthy cells. One of the studied nanoparticles, AuNP14b complexed with siRNA, displayed lower cytotoxicity (MTT assay, cells viability −74.8 ± 3.1%) than free nanoparticles (44.7 ± 3.6%). This may be promising for further investigations in nucleic acid delivery and could have practical use in treating neurodegenerative diseases.

Complexation of Oligo- and Polynucleotides with Methoxyphenyl-Functionalized Imidazolium Surfactants

Interaction between cationic surfactants and nucleic acids attracts much attention due to the possibility of using such systems for gene delivery. Herein, the lipoplexes based on cationic surfactants with imidazolium head group bearing methoxyphenyl fragment (MPI-n, n = 10, 12, 14, 16) and nucleic acids (oligonucleotide and plasmid DNA) were explored. The complex formation was confirmed by dynamic/electrophoretic light scattering, transmission electron microscopy, fluorescence spectroscopy, circular dichroism, and gel electrophoresis. The nanosized lipoplex formation (of about 100-200 nm), contributed by electrostatic, hydrophobic interactions, and intercalation mechanism, has been shown. Significant effects of the hydrocarbon tail length of surfactant and the type of nucleic acid on their interaction was revealed. The cytotoxic effect and transfection ability of lipoplexes studied were determined using M-HeLa, A549 cancer cell lines, and normal Chang liver cells. A selective reduced cytotoxic effect of the complexes on M-HeLa cancer cells was established, as well as a high ability of the systems to be transfected into cancer cells. MPI-n/DNA complexes showed a pronounced transfection activity equal to the commercial preparation Lipofectamine 3000. Thus, it has been shown that MPI-n surfactants are effective agents for nucleic acid condensation and can be considered as potential non-viral vectors for gene delivery.

Tetraethylenepentamine-Coated β Cyclodextrin Nanoparticles for Dual DNA and siRNA Delivery

Nucleic acid reagents, including plasmid-encoded genes and small interfering RNA (siRNA), are promising tools for validating gene function and for the development of therapeutic agents. Native β-cyclodextrins (BCDs) have limited efficiency in gene delivery due to their instable complexes with nucleic acid. We hypothesized that cationic BCD nanoparticles could be an efficient carrier for both DNA and siRNA. Tetraethylenepentamine-coated β-cyclodextrin (TEPA-BCD) nanoparticles were synthesized, characterized, and evaluated for targeted cell delivery of plasmid DNA and siRNA. The cationic TEPA coating provided ideal zeta potential and effective nucleic acid binding ability. When transfecting plasmid encoding green fluorescent protein (GFP) by TEPA-BCD, excellent GFP expression could be achieved in multiple cell lines. In addition, siRNA transfected by TEPA-BCD suppressed target GFP gene expression. We showed that TEPA-BCD internalization was mediated by energy-dependent endocytosis via both clathrin-dependent and caveolin-dependent endocytic pathways. TEPA-BCD nanoparticles provide an effective means of nucleic acid delivery and can act as potential carriers in future pharmaceutical application.

The Process of Binding and Releasing of Genetic Material from Lipoplexes Based on Trimeric Surfactants and Phospholipids

Nonviral vectors for gene therapy such as lipoplexes are characterized by low toxicity, high biocompatibility, and good transfection efficiency. Specifically, lipoplexes based on polymeric surfactants and phospholipids have great potential as gene carriers due to the increased ability to bind genetic material (multiplied positive electric charge) while lowering undesirable effects (the presence of lipids makes the system more like natural membranes). This study aimed to test the ability to bind and release genetic material by lipoplexes based on trimeric surfactants and lipid formulations of different compositions and to characterize formed complexes by circular dichroism (CD) spectroscopy and atomic force microscopy (AFM). The cytotoxicity of studied lipoplexes was tested on HeLa cells by the MTT cell viability assay and the dye exclusion test (trypan blue). The presence of lipids in the system lowered the surfactant concentration required for complexation (higher efficiency) and reduced the cytotoxicity of lipoplexes. Surfactant/lipids/DNA complexes were more stable than surfactant/DNA complexes. Surfactant molecules induced the genetic material condensation, but the presence of lipids significantly intensified this process. Systems based on trimeric surfactants and lipid formulations, particularly TRI_N and TRI_IMI systems, could be used as delivery carrier, and have proven to be highly effective, nontoxic, and universal for DNA of various lengths.