Phosphorus Dendrimers as Carriers of siRNA—Characterisation of Dendriplexes

There are many types of dendrimers used as nanomolecules for gene delivery but there is still an ongoing search for ones that are able to effectively deliver drugs to cells. The possibility of gene silencing using siRNA gives hope for effective treatment of numerous diseases. The aim of this work was to investigate in vitro biophysical properties of dendriplexes formed by siRNA and cationic phosphorus dendrimers of 3rd and 4th generation. First, using the ethidium bromide intercalation method, it was examined whether dendrimers have an ability to form complexes with siRNA. Next, the characterisation of dendriplexes formed at different molar ratios was carried out using biophysical methods. The effects of zeta potential, size and changes of siRNA conformation on the complexation with dendrimers were examined. It was found that both phosphorus dendrimers interacted with siRNA. The zeta potential values of dendriplexes ranged from negative to positive and the hydrodynamic diameter depended on the number of dendrimer molecules in the complex. Furthermore, using circular dichroism spectroscopy it was found that cationic phosphorus dendrimers changed only slightly the shape of siRNA CD spectra, thus they did not induce significant changes in the nucleic acid secondary structure during complex formation.Studies were funded by the project ―Biological properties and biomedical applications of dendrimers‖ operated within the Foundation for Polish Science Team Programme co-financed by the EU European Regional Development Fund. This work was also supported by the COST TD0802 project and by the CNRS, France

Evaluation of dendronized gold nanoparticles as siRNAs carriers into cancer cells

Gene therapy is one of the most promising approaches for potential application in the treatment of diseases, ranging from cancer and heritable disorders to infectious diseases. Before nucleic acid molecules can reach their site of action inside target cells, they must overcome several obstacles. Thus, to fully exploit the therapeutic potential of nucleic acids, efficient delivery systems are required. We herein evaluated gold nanoparticles (AuNPs) covered with cationic carbosilane dendrons as siRNA delivery systems. Detailed analysis of formation of AuNP:siRNA complexes using circular dichroism, zeta-potential, zeta-size, electron microscopy and gel electrophoresis was performed. The stability of complexes in presence of heparin and RNase was evaluated. Internalization of AuNPs and their complexes with siRNAs into cancer cells was estimated by ultrastructure analysis and confocal microscopy. The cytotoxicity of dendrons, AuNPs and their complexes with siRNAs on 4 cancer cell lines (Caco-2, HeLa, U937 and THP-1) was estimated. We concluded that dendronization of AuNPs is a promising way to develop siRNA carriers for anticancer gene therapyUniversidad de AlcaláMinisterio de Economía y CompetitividadComunidad de MadridJunta de Comunidades de Castilla-La ManchaEuropean Commissio

Effect of PEGylation on the biological properties of cationic carbosilane dendronized gold nanoparticles

Heterofunctionalized gold nanoparticles (AuNPs) were obtained in a one pot reaction of gold precursor with cationic carbosilane dendrons (first to third generations, 1-3G) and (polyethylene)glycol (PEG) ligands in the presence of a reducing agent. The final dendron/PEG proportion on AuNPs depends on the initial dendron/PEG ratio (3/1, 1/1, 1/3) and dendron generation. AuNPs were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), ultraviolet spectroscopy (UV-VIS), thermogravimetric analysis (TGA), nuclear magnetic resonance (H-1 NMR) and zeta potential (ZP). Several assays have been carried out to determine the relevance of PEG/dendron ratio and dendron generation in the biomedical properties of PEGylated AuNPs and the results have been compared with those obtained for non-PEGylated AuNPs. Finally, analyses of PEG recognition by anti-PEG antibodies were carried out. In general, haemolysis, platelet aggregation and toxicity were reduced after PEGylation of AuNPs, the effect being dependent on dendron generation and dendron/PEG ratio. Dendron generation determines the exposure of PEG ligand and the interaction of this ligand with AuNPs environment. On the other hand, increasing PEG proportion diminishes toxicity but also favors interaction with antibodies.Ministerio de Economía, Industria y CompetitividadJunta de Comunidades de Castilla-La ManchaComunidad de MadridCentro de investigación Biomédica en Red. Enfermedades Bioingeniería, Biomateriales y NanomedicinaInstituto Ramón y Cajal de Investigación SanitariaUniversidad de Alcal

Dendritic glycopolymers based on dendritic polyamine scaffolds: view on their synthetic approaches, characteristics and potential for biomedical applications

In this review we highlight the potential for biomedical applications of dendritic glycopolymers based on polyamine scaffolds. The complex interplay of the molecular characteristics of the dendritic architectures and their specific interactions with various (bio)molecules are elucidated with various examples. A special role of the individual sugar units attached to the dendritic scaffolds and their density is identified, which govern ionic and H-bond interactions, and biological targeting, but to a large extent are also responsible for the significantly reduced toxicity of the dendritic glycopolymers compared to their polyamine scaffolds. Thus, the application of dendritic glycopolymers in drug delivery systems for gene transfection but also as therapeutics in neurodegenerative diseases has great promisePublikacja w ramach programu Royal Society of Chemistry "Gold for Gold" 2014 finansowanego przez Uniwersytet Łódzk

Nanotechnology and the Treatment of HIV Infection

Suboptimal adherence, toxicity, drug resistance and viral reservoirs make the lifelong treatment of HIV infection challenging. The emerging field of nanotechnology may play an important role in addressing these challenges by creating drugs that possess pharmacological advantages arising out of unique phenomena that occur at the “nano” scale. At these dimensions, particles have physicochemical properties that are distinct from those of bulk materials or single molecules or atoms. In this review, basic concepts and terms in nanotechnology are defined, and examples are provided of how nanopharmaceuticals such as nanocrystals, nanocapsules, nanoparticles, solid lipid nanoparticles, nanocarriers, micelles, liposomes and dendrimers have been investigated as potential anti-HIV therapies. Such drugs may, for example, be used to optimize the pharmacological characteristics of known antiretrovirals, deliver anti-HIV nucleic acids into infected cells or achieve targeted delivery of antivirals to the immune system, brain or latent reservoirs. Also, nanopharmaceuticals themselves may possess anti-HIV activity. However several hurdles remain, including toxicity, unwanted biological interactions and the difficulty and cost of large-scale synthesis of nanopharmaceuticals

Dendrimer-protein interactions versus dendrimer-based nanomedicine

International audienceDendrimers are hyperbranched polymers belonging to the huge class of nanomedical devices. Their wide application in biology and medicine requires understanding of the fundamental mechanisms of their interactions with biological systems. Summarizing, electrostatic force plays the predominant role in dendrimer-protein interactions, especially with charged dendrimers. Other kinds of interactions have been proven, such as H-bonding, van der Waals forces, and even hydrophobic interactions. These interactions depend on the characteristics of both participants: flexibility and surface charge of a dendrimer, rigidity of protein structure and the localization of charged amino acids at its surface. pH and ionic strength of solutions can significantly modulate interactions. Ligands and cofactors attached to a protein can also change dendrimer-protein interactions. Binding of dendrimers to a protein can change its secondary structure, conformation, intramolecular mobility and functional activity. However, this strongly depends on rigidity versus flexibility of a protein’s structure. In addition, the potential applications of dendrimers to nanomedicine are reviwed related to dendrimer-protein interactions