Inflammation is an essential component of many lung diseases, including asthma, chronic obstructive pulmonary disease (COPD), or acute lung injury. Our purpose was to design efficient carriers for lung delivery of small interfering RNA (siRNA) targeting tumor necrosis factor (TNF-α) in an acute lung injury model. To achieve this goal, two different types of phosphorus-based dendrimers with either pyrrolidinium or morpholinium as terminal protonated amino groups were selected for their better biocompatibility compared to other dendrimers. Dendriplexes containing pyrrolidinium surface groups demonstrated a stronger siRNA complexation, a higher cellular uptake, and enhanced in vitro silencing efficiency of TNF-α in the lipopolysaccharide (LPS)-activated mouse macrophage cell line RAW264.7, compared to morpholinium-containing dendriplexes. The better performance of the pyrrolidium dendriplexes was attributed to their higher pK value leading to a stronger siRNA complexation and improved protection against enzymatic degradation resulting in a higher cellular uptake. The superior silencing effect of the pyrrolidinium dendriplexes, compared to noncomplexed siRNA, was confirmed in vivo in an LPS-induced murine model of short-term acute lung injury upon lung delivery via nasal administration. These data suggest that phosphorus dendriplexes have a strong potential in lung delivery of siRNA for treating inflammatory lung diseases.

Novel multivalent copper(II)-conjugated phosphorus dendrimers and their corresponding mononuclear copper(II) complexes were synthesized, characterized, and screened for antiproliferative activity against human cancer cell lines. Selected copper ligands were grafted on the surface of phosphorus dendrimers of generation G(n) (n = 1 to 3): N-(pyridin-2-ylmethylene)ethanamine for dendrimers 1G(n), N-(di(pyridin-2-yl)methylene)ethanamine for dendrimers 2G(n), and 2-(2-methylenehydrazinyl)pyridine for dendrimers 3G(n). The results indicated that the most potent derivatives are 1G(n) and 1G(n)-Cu versus 2G(n), 2G(n)-Cu, and 3G(n), 3G(n)-Cu. A direct relationship between the growth inhibitory effect and the number of terminal moieties or the amount of copper complexed to the dendrimer was observed in copper-complexed 1 series and noncomplexed 1 series. These data clearly suggested that cytotoxicity increased with the number of terminal moieties available and was boosted by the presence of complexed Cu atoms. Importantly, no cytotoxic effect was observed with CuCl2 at the same concentrations. Finally, 1G3 and 1G3-Cu have been selected for antiproliferative studies against a panel of tumor cell lines: 1G3 and 1G3-Cu demonstrated potent antiproliferative activities with IC50 values ranging 0.3-1.6 μM. Interestingly, the complexation of the terminal ligands of 1G3 dendrimers by copper(II) metal strongly increased the IC50 values in noncancer cells lines referred to as "safety" cell lines.

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Original metallophosphorus dendrimers (generation 3, 48 terminal groups) have been prepared via the complexation of phosphorus dendrimers bearing imino-pyridino end groups with Au(III) or with both Au(III) and Cu(II). The complexation of the dendrimer with Au(III), leading to 1G3-[Au][AuCl], strongly increased the antiproliferative activities against both KB and HL-60 tumoral cell lines, showing ICs in the low nanomolar range. It can be noticed also that this gold conjugated phosphorus dendrimer displayed low activity on the quiescent cell line EPC versus its potent antiproliferative activity against actively dividing cells. In order to evaluate the potential synergistic effect between Au(III) and Cu(II) and the influence of the number of Au(III) moieties on the surface of dendrimer against the proliferative activities, nine other original dendrimers with several surface modifications have been prepared. Whatever the number of Au(III) moieties introduced on the surface of dendrimers, all the dendrimers prepared displayed similar potency (nanomolar range) to 1G3-[Au][AuCl] against KB and HL60. In marked contrast synergistic effects on the antimicrobial activity of some of these phosphorus dendrimers are observed when both Au(III) and Cu(II) are present on the dendritic structure.

This report aims to review the advances made in C–H arylation of 5,6, 6,6 and 5,5 fused-heterocyclic systems.

The preparation of novel families of phosphorus-based macromolecular architectures called "onion peel" phosphorus nanodendritic systems is reported. This construct is based on the versatility of methods of synthesis using several building blocks and on the capability of these systems to undergo regioselective reactions within the cascade structure. Sustainable metal-free routes such as the Staudinger reaction or Schiff-base condensation, involving only water and nitrogen as byproducts, allow access to several dendritic macromolecules bearing up to seven different phosphorus units in their backbone, each of them featuring specific reactivity. The presence of the highly aurophilic P=N-P=S fragment enables selective ligation of Au(I) within the dendritic framework.

In the field of dendrimers targeting small interfering RNA (siRNA) delivery, dendrimer structural properties, such as the flexibility/rigidity ratio, play a crucial role in the efficiency of complexation. However, advances in organic chemistry have enabled the development of dendrimers that differ only by a single atom on their surface terminals. This is the case for cationic phosphorus dendrimers functionalized with either pyrrolidinium (DP) or morpholinium (DM) terminal groups. This small change was shown to strongly affect the dendrimer-siRNA complexation, leading to more efficient anti-inflammatory effects in the case of DP. Reasons for this different behavior can hardly be inferred only by biological in vitro and in vivo experiments due to the high number of variables and complexity of the investigated biological system. However, an understanding of how small chemical surface changes may completely modify the overall dendrimer-siRNA complexation is a significant breakthrough towards the design of efficient dendrimers for nucleic acid delivery. Herein, we present experimental and computational approaches based on isothermal titration calorimetry and molecular dynamics simulations to elucidate the molecular reasons behind different efficiencies and activities of DP and DM. Results of the present research highlight how chemical surface modifications may drive the overall dendrimer-siRNA affinity by influencing enthalpic and entropic contributions of binding free energy. Moreover, this study elucidates molecular reasons related to complexation stoichiometry that may be crucial in determining the dendrimer complexation efficiency.

Inflammation is part of the physiological response of the organism to infectious diseases caused by organisms such as bacteria, viruses, fungi, or parasites. Innate immunity, mediated by mononuclear phagocytes, including monocytes and macrophages, is a first line of defense against infectious diseases and plays a key role triggering the delayed adaptive response that ensures an efficient defense against pathogens. Monocytes and macrophages stimulation by pathogen antigens results in activation of different signaling pathways leading to the release of proinflammatory cytokines. However, inflammation can also participate in the pathogenesis of several diseases, the autoimmune diseases that represent a relevant burden for human health. Dendrimers are branched, multivalent nanoparticles with a well-defined structure that have a high potential for biomedical applications. To explore new approaches to fight against the negative aspects of inflammation, we have used neutral high-generation phosphorus dendrimers bearing 48 (G3) or 96 (G4) bisphosphonate groups on their surface. These dendrimers show no toxicity and have good solubility and chemical stability in aqueous solutions. Here, we present data indicating that neutral phosphorus dendrimers show impressive antiinflammatory activities both in vitro and in vivo. In vitro, these dendrimers reduced the secretion of proinflammatory cytokines from mice and human monocytederived macrophages. In addition, these molecules present efficient antiinflammatory activity in vivo in a mouse model of subchronic inflammation. Taken together, these data suggest that neutral G3-G4 phosphorus dendrimers have strong potential applications in the therapy of inflammation and, likely, of autoimmune diseases.dendrimers | inflammation | innate immunity | air pouch | macrophage