Orthogonal Synthesis of Covalent Polydendrimer Frameworks by Fusing Classical and Onion-Peel Phosphorus-Based Dendritic Units

We report novel and new giant three-dimensional polymers having dendrimers as repeating units. The approach is illustrated here for macromolecular synthesis by polymeric condensation of well-defined single phosphorus dendrimers units. Specifically, classical and onion-peel phosphorus dendrimers, constructed by a divergent method from a cyclotriphosphazene core, were fused within the same tectonic nanostructure by several polymeric condensation approaches including hydrazine-to-aldehyde Schiff-base formation and amine-to-carboxylic acid peptide-like coupling. These reticular, easy to run metal-free routes afford a new library of hyperbranched macromolecular materials, featuring various phosphorus layers (both alternated and dissymmetrical), well-defined textured nanospheres, and controllable nanometric ordered substructures. The scope of the concept is successfully expanded to the integration of electro-redox viologen units resulting in the synthesis of new photoactive macromolecular materials

Biological Activity of Mesoporous Dendrimer-Coated Titanium Dioxide: Insight on the Role of the Surface–Interface Composition and the Framework Crystallinity

Hitherto, the field of nanomedicine has been overwhelmingly dominated by the use of mesoporous organosilicas compared to their metal oxide congeners. Despite their remarkable reactivity, titanium oxide-based materials have been seldom evaluated and little knowledge has been gained with respect to their “structure–biological activity” relationship. Herein, a fruitful association of phosphorus dendrimers (both “ammonium-terminated” and “phosphonate-terminated”) and titanium dioxide has been performed by means of the sol–gel process, resulting in mesoporous dendrimer-coated nanosized crystalline titanium dioxide. A similar organo-coating has been reproduced using single branch-mimicking dendrimers that allow isolation of an amorphous titanium dioxide. The impact of these materials on red blood cells was evaluated by studying cell hemolysis. Next, their cytotoxicity toward B14 Chinese fibroblasts and their antimicrobial activity were also investigated. Based on their variants (cationic versus anionic terminal groups and amorphous versus crystalline titanium dioxide phase), better understanding of the role of the surface–interface composition and the nature of the framework has been gained. No noticeable discrimination was observed for amorphous and crystalline material. In contrast, hemolysis and cytotoxicity were found to be sensitive to the nature of the interface composition, with the ammonium-terminated dendrimer-coated titanium dioxide being the most hemolytic and cytotoxic material. This surface-functionalization opens the door for creating a new synergistic machineries mechanism at the cellular level and seems promising for tailoring the biological activity of nanosized organic–inorganic hybrid materials

Biological Properties of New Viologen-Phosphorus Dendrimers

Some biological properties of eight dendrimers incorporating both phosphorus linkages and viologen units within their cascade structure or at the periphery were investigated for the first time. In particular cytotoxicity, hemotoxicity, and antimicrobial and antifungal activity of these new macromolecules were examined. Even if for example all these species exhibited good antimicrobial properties, it was demonstrated that their behavior strongly depends on several parameters as their size and molecular weight, the number of viologen units and the nature of the terminal groups