Heterofunctionalized polyphenolic dendrimers decorated with caffeic acid: Synthesis, characterization and antioxidant activity

Dendrimers, branched polymer structures, have been widely studied as efficient drug carriers. Scientists are trying to find new dendrimer-based formulations with the properties needed for biomedical applications such as improved bioavailability, low toxicity and high transfection profiles. The unique drug delivery properties of carbosilane dendrimers have already been demonstrated. Their efficacy has been further improved by conju-gation with polyphenols, plant secondary metabolites with a wide range of biological activities, including antioxidant effects that are beneficial for human health. The present study focuses on synthesis and character-ization of two new types of carbosilane dendritic systems, one family presents one or two caffeic acid units and ammonium groups on the surface to make them water soluble. The other family has, in addition to the two mentioned functionalities, one or two polyethylene glycol (PEG) chains in the structure to increase the biocompatibility of the system. Carbosilane dendrimers with caffeic acid have low toxicity and protect eryth-rocytes against oxidative hemolysis. These dendrimers also decrease AAPH-induced ROS production in human fibroblasts.Various techniques demonstrating such antioxidant activities have been applied in the current research. The best antioxidant properties were shown for the dendrimer with two PEG-caffeic acid moieties. Further aspects of the biochemical characterization of the dendrimers are also considered and discussed.Ministerio de Ciencia e InnovaciónMinisterio de Economía y CompetitividadJunta de Comunidades de Castilla-La ManchaComunidad de MadridPolish National Agency for Academic Exchang

Gold nanoparticles coated with carbosilane dendrons in protein sample preparation

The feasibility of using carbosilane dendronized gold nanoparticles (GNPs) for protein sample preparation was evaluated. Three different dendrons with three different generations (1G, 2G, and 3G) were employed to modify the GNPs, viz. sulfonate terminated (STC-GNPs), carboxylate terminated (CTC-GNPs), and trimethylammonium terminated (ATC-GNPs)dendrons. The synthesis of the CTC-GNP is described. The other dendronized GNPs were synthesized using previously described routes. Bovine serum albumin, lysozyme, and myoglobin were employed to study the potential of GNPs to interact with proteins. The interaction between the GNPs and the proteins was evaluated using fluorescence spectroscopy and polyacrylamide gel electrophoresis. The CTC-GNPs and STC-GNPs under acidic and neutral conditions, respectively, promoted the establishment of electrostatic interactions with positively charged proteins. Proteins from 10 to 75kDa molecular weights interacted with GNPs at protein: nanoparticle ratios of 1:0.25. The GNPs were applied to the extraction of proteins from a peach seed. In the authors' perception, the method is a clean alternative to established extraction methods based on the use of organic or polluting chemicals.Ministerio de Economía, Comercio y EmpresaUniversidad de AlcaláCentro de investigación Biomédica en Red. Bioingeniería, Biomateriales y Nanomedicin

Antioxidant and Antibacterial Properties of Carbosilane Dendrimers Functionalized with Polyphenolic Moieties

A new family of polyphenolic carbosilane dendrimers functionalized with ferulic, caffeic, and gallic acids has been obtained through a straightforward amidation reaction. Their antioxidant activity has been studied by different techniques such as DPPH (2,2 '-diphenyl-1-picrylhydrazyl) radical scavenging assay, FRAP assay (ferric reducing antioxidant power), and cyclic voltammetry. The antioxidant analysis showed that polyphenolic dendrimers exhibited higher activities than free polyphenols in all cases. The first-generation dendrimer decorated with gallic acid stood out as the best antioxidant compound, displaying a correlation between the number of hydroxyl groups in the polyphenol structure and the antioxidant activity of the compounds. Moreover, the antibacterial capacity of these new systems has been screened against Gram-positive (+) and Gram-negative (-) bacteria, and we observed that polyphenolic dendrimers functionalized with caffeic and gallic acids were capable of decreasing bacterial growth. In contrast, ferulic carbosilane dendrimers and free polyphenols showed no effect, establishing a correlation between antioxidant activity and antibacterial capacity. Finally, a viability assay in human skin fibroblasts cells (HFF-1) allowed for corroborating the nontoxicity of the polyphenolic dendrimers at their active antibacterial concentration.Ministerio de Economía y CompetitividadJunta de Comunidades de Castilla-La ManchaComunidad de Madri

New synthetic procedure for the antiviral sulfonate carbosilane dendrimer G2-S16 and its fluorescein-labelled derivative for biological studies

The anionic carbosilane (CBS) dendrimer with sulfonate groups G2-S16 is a promising compound for the preparation of a microbicide gel to prevent HIV infection. However, until now its synthesis required aggressive conditions. Hence, a reliable synthetic procedure is very important to face GMP conditions and clinical trials. In this study, G2-S16 has been prepared by a new approach that involves the addition of an amine-terminated dendrimer to ethenesulfonyl fluoride (C2H3SO3F, ESF) and then transformation to the sulfonate dendrimer by treatment with a base. This strategy also makes feasible the synthesis of a labelled sulfonate dendrimer (G2-S16-FITC) to be used as a molecular probe for in vivo experiments. Interestingly, G2-S16-FITC enters into human peripheral blood mononuclear cells (PBMCs).Universidad de AlcaláMinisterio de Economía, Industria y CompetitividadComunidad de MadridInstituto de Salud Carlos IIIJunta de Comunidades de Castilla-La Manch

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

Dendronized Anionic Gold Nanoparticles: Synthesis, Characterization and Antiviral Activity

Anionic carbosilane dendrons decorated with sulfonate functions and with a thiol moiety at the focal point have been used to synthesize water soluble gold nanoparticles (AuNPs) by direct reaction of dendrons, gold precursor and reducing agent in water and also by place-exchange reaction. These nanoparticles have been characterized by nuclear magnetic resonance (NMR), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), UV, elemental analysis, and Z potential. Also, the interacting ability of the anionic sulfonate functions was investigated by electron paramagnetic resonance (EPR) using copper(II) as a probe. It was found that the different structures and conformations of the AuNPs modulate the availability of sulfonate and thiol groups to be complexed by copper(II). Toxicity assays of AuNPs showed that those produced by direct reaction were less toxic than those obtained by ligand exchange. Inhibition of HIV-1 infection was higher for dendronized AuNPs than for dendrons.Ministerio de Economía y EmpresaComunidad de MadridUniversidad de Alcal

Antibacterial and antifungal properties of dendronized silver and gold nanoparticles with cationic carbosilane dendrons

Water soluble silver nanoparticles (AgNPs) capped with cationic carbosilane dendrons have been synthesized by direct reaction in water of dendrons, silver precursor and a reducing agent. These nanoparticles have been characterized by nuclear magnetic resonance (NMR), transmission electron microscopy (TEM), dynamic light scattering (DLS), thermogravimetric analysis (TGA), ultraviolet spectroscopy (UV), elemental analysis, and zeta potential (ZP). The antibacterial and antifungal properties of the cationic dendrons and dendronized AgNPs and AuNPs with these dendrons have been evaluated against Gram-negative and Gram-positive bacterial -including resistant strains- and yeast strains, respectively. The results stand out for the activity of AgNPs covered with first generation dendron compared with this free dendron and corresponding dendronized AuNPs.Ministerio de Economía y Empres

Funcionalización de nanopartículas metálicas con dendrones de naturaleza carbosilano y su aplicación en Biomedicina

En los últimos años las nanopartículas de oro (AuNPs) y plata (AgNPs) han recibido especial atención en el campo de la biomedicina. Las propiedades inherentes de las AuNPs sumado a su biocompatibilidad, su citotoxicidad, biodistribución y excreción in vivo han convertido estos sistemas en materiales especialmente atractivos en diferentes campos de la biomedicina. Las AgNPs por su parte han demostrado poseer propiedades antimicrobianas de amplio espectro siendo de especial interés en el desarrollo de nuevos agentes antimicrobianos. La dendronización de este tipo de sistemas permite la introducción de grupos capaces de conferirle propiedades específicas que podrían resultar de interés en medicina. El trabajo recogido en esta Tesis Doctoral está centrado en la obtención de dendrones de naturaleza carbosilano, su uso en la posterior dendronización de AuNPs y AgNPs y la posterior aplicación de dichos sistemas en biomedicina. Se han sintetizado y caracterizado dendrones de naturaleza carbosilano con un grupo -SH en el punto focal y AuNPs/AgNPs dendronizadas con dichos sistemas tanto por el método de intercambio como por el método directo: Los sistemas obtenidos por colaboraciones con diferentes grupos de investigación han sido evaluados como agentes terapéuticos (antibacterianos, anticancerígenos y antivirales) y como agentes de transporte de ácidos nucleicos. Estudios preliminares para su aplicación en la separación de proteínas desde muestras complejas también han sido realizados