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.

Gene therapy is a promising approach in cancer treatment; however, current methods have a number of limitations mainly due to the difficulty in delivering therapeutic nucleic acids to their sites of action. The application of non-viral carriers based on nanomaterials aims at protecting genetic material from degradation and enabling its effective intracellular transport. We proposed the use of silver nanoparticles (AgNPs) surface-modified with carbosilane dendrons as carriers of anticancer siRNA (siBcl-xl). Using gel electrophoresis, zeta potential and hydrodynamic diameter measurements, as well as transmission electron microscopy, we characterized AgNP:siRNA complexes and demonstrated the stability of nucleic acid in complexes in the presence of RNase. Hemolytic properties of free silver nanoparticles and complexes, their effect on lymphocyte proliferation and cytotoxic activity on HeLa cells were also examined. Confocal microscopy proved the effective cellular uptake of complexes, indicating the possible use of this type of silver nanoparticles as carriers of genetic material in gene therapy.

Gold nanoparticles (AuNPs) and polycationic macromolecules are used as gene carriers. Their behaviour is dependent on several factors, such as the size and type of the framework, charge, etc. We have combined both types of systems and prepared AuNPs covered with cationic carbosilane dendrons with the aim to evaluate their biocompatibility. Water soluble dendronized cationic AuNPs were prepared following a straightforward procedure from dendrons, a gold precursor and a reducing agent in water and were characterized by ¹H NMR, transmission electron microscopy (TEM), dynamic light scattering (DLS), thermogravimetric analysis (TGA), ultraviolet spectroscopy (UV), and zeta potential (ZP). The biological properties of dendrons and AuNPs were determined by hemolysis, platelet aggregation and lymphocyte proliferation. These assays reflect modification of dendron properties when covering nanoparticles. For dendrons, hemolysis and platelet aggregation are generation dependent whilst, for AuNPs these properties are related to the bigger size of NPs. On the other hand, none of the systems induced lymphocyte proliferation. Selected cationic dendrons and AuNPs were chosen for gene delivery experiments employing a small interference RNA (siRNA Nef) against human immunodeficiency virus (HIV).

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.