Interactions gold/phosphorus dendrimers. Versatile ways to hybrid organic–metallic macromolecules

Interplay between Nanoparticles and Phosphorus Dendrimers, and Their Properties

This review presents the state of the art of interactions between two different families of nanoobjects: nanoparticles-mainly metal nanoparticles, and dendrimers-mainly phosphorhydrazone dendrimers (or dendrons). The review firstly presents the encapsulation/protection of existing nanoparticles (organic or metallic) by phosphorus-based dendrimers and dendrons. In the second part, several methods for the synthesis of metal nanoparticles, thanks to the dendrimer that acts as a template, are presented. The properties of the associations between dendrimers and nanoparticles are emphasized throughout the review. These properties mainly concern the elaboration of diverse types of hybrid materials, some of them being used as sensitive chemosensors or biosensors. Several examples concerning catalysis are also given, displaying in particular the efficient recovery and reuse of the catalytic entities.

Phosphorus-carrying cascade molecules: inner architecture to biomedical applications

Cascade molecules are nearly uniform-sized macromolecules of small molecules or linear polymer cores built around symmetric branching units. A wide range of biological properties can be achieved with phosphorus-containing dendrimers, depending on their terminal functions, ranging from biomaterials to imaging, drug delivery, and acting as a drug by themselves. This feature article presents significant examples of phosphorus-containing dendrimers used to develop biochips, support cell cultures, carry or deliver biomacromolecules and drugs, bioimaging, and combinational benefits. Because of the thermal stability, ferrocene function, and physical and chemical properties of phosphorus, dendrimers show greater rigidity, mobility, and strength. These dendrimers will be discussed as having a favorable effect on cell growths, especially on neuronal cells, as well as human immune cells like natural killer cells and monocytes, which have a crucial part in preventing cancerous and viral infections. Several phosphorus dendrimers are effective as drugs by themselves (drug per se) and show their activity against neurodegenerative diseases, cancer, inflammation, ocular hypertension, and transmissible spongiform encephalopathies (TSEs) in both in vivo and in vitro. The present review discusses the synthetic route, fabrications, and biomedical applications of phosphorus-containing dendrimers. The toxicity of these dendrimers was also reported.

The Backbone of Success of P,N-Hybrid Ligands: Some Recent Developments

Organophosphorus ligands are an invaluable family of compounds that continue to underpin important roles in disciplines such as coordination chemistry and catalysis. Their success can routinely be traced back to facile tuneability thus enabling a high degree of control over, for example, electronic and steric properties. Diphosphines, phosphorus compounds bearing two separated P^III donor atoms, are also highly valued and impart their own unique features, for example excellent chelating properties upon metal complexation. In many classical ligands of this type, the backbone connectivity has been based on all carbon spacers only but there is growing interest in embedding other donor atoms such as additional nitrogen (–NH–, –NR–) sites. This review will collate some important examples of ligands in this field, illustrate their role as ligands in coordination chemistry and highlight some of their reactivities and applications. It will be shown that incorporation of a nitrogen-based group can impart unusual reactivities and important catalytic applications.

Engineered non-invasive functionalized dendrimer/dendron-entrapped/complexed gold nanoparticles as a novel class of theranostic (radio)pharmaceuticals in cancer therapy

Nanomedicine represents a very significant contribution in current cancer treatment; in addition to surgical intervention, radiation and chemotherapeutic agents that unfortunately also kill healthy cells, inducing highly deleterious and often life-threatening side effects in the patient. Of the numerous nanoparticles used against cancer, gold nanoparticles had been developed for therapeutic applications. Inter alia, a large variety of dendrimers, i.e. soft artificial macromolecules, have turned up as non-viral functional nanocarriers for entrapping drugs, imaging agents, and targeting molecules. This review will provide insights into the design, synthesis, functionalization, and development in biomedicine of engineered functionalized hybrid dendrimer-tangled gold nanoparticles in the domain of cancer theranostic. Several aspects are highlighted and discussed such as 1) dendrimer-entrapped gold(0) hybrid nanoparticles for the targeted imaging and treatment of cancer cells, 2) dendrimer encapsulating gold(0) nanoparticles (Au DENPs) for the delivery of genes, 3) Au DENPs for drug delivery applications, 4) dendrimer encapsulating gold radioactive nanoparticles for radiotherapy, and 5) dendrimer/dendron-complexed gold(III) nanoparticles as technologies to take down cancer cells.

Multivalent Copper(II)-Conjugated Phosphorus Dendrimers with Noteworthy In Vitro and In Vivo Antitumor Activities: A Concise Overview

Dendrimers are macromolecules with well-defined, homogeneous, and monodispersed structures that form a branch-like structure. In general, they have a symmetric core, inner shells, and an outer shell. Over the past decade, metallodendritic architectures have developed into a new area in nanomedicine. Due to their versatility and facile customization, phosphorus dendrimers represent interesting platforms for biomedical applications. Metallo-conjugated phosphorus dendrimers have been developed within the dendrimer space, an important part of the chemical space. The first investigation was made using phosphorus dendrimers bearing copper(II) groups on their surface as the original anticancer drug candidates. The aim of this minireview is to present our powerful strategy to find and develop original multivalent copper(II)-conjugated phosphorus dendrimers. The most potent of them is G3 dendrimers with N-(pyridine-2-ylmethylene)ethanamine as the chelating motif complexed with Cu(II) (1G3-Cu), showing very good in vitro and in vivo antiproliferative efficacy. On the basis of these results, 1G3-Cu is a potential clinical candidate having progressed from hit to preclinical candidate status.

From Riluzole to Dexpramipexole via Substituted-Benzothiazole Derivatives for Amyotrophic Lateral Sclerosis Disease Treatment: Case Studies

The 1,3-benzothiazole (BTZ) ring may offer a valid option for scaffold-hopping from indole derivatives. Several BTZs have clinically relevant roles, mainly as CNS medicines and diagnostic agents, with riluzole being one of the most famous examples. Riluzole is currently the only approved drug to treat amyotrophic lateral sclerosis (ALS) but its efficacy is marginal. Several clinical studies have demonstrated only limited improvements in survival, without benefits to motor function in patients with ALS. Despite significant clinical trial efforts to understand the genetic, epigenetic, and molecular pathways linked to ALS pathophysiology, therapeutic translation has remained disappointingly slow, probably due to the complexity and the heterogeneity of this disease. Many other drugs to tackle ALS have been tested for 20 years without any success. Dexpramipexole is a BTZ structural analog of riluzole and was a great hope for the treatment of ALS. In this review, as an interesting case study in the development of a new medicine to treat ALS, we present the strategy of the development of dexpramipexole, which was one of the most promising drugs against ALS.

Integrated POSS-dendrimer nanohybrid materials: current status and future perspective

Polyhedral oligomeric silsesquioxane (POSS)-dendrimer hybrid materials have attracted great interest in the past ten years. The integration of inorganic POSS and organic dendrimer blocks in a single-phase material offers numerous possibilities to access desirable mechanical, optical, and biomedical properties for various applications. In this review article, we describe several kinds of POSS-dendrimer hybrid materials (POSS as the core, surface functionality, repeating unit of dendrimers and the POSS-dendron conjugates) with an emphasis on their synthetic strategies, tunable macroscopic properties, and potential applications. Moreover, the current trends, challenges and future directions of POSS-dendrimer hybrid materials are elaborated.

Nano-antimicrobials: A New Paradigm for Combating Mycobacterial Resistance

BACKGROUND

Mycobacterium group contains several pathogenic bacteria including M. tuberculosis where the emergence of multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) is alarming for human and animal health around the world. The condition has further aggravated due to the speed of discovery of the newer drugs has been outpaced by the rate of resistance developed in microorganisms, thus requiring alternative combat strategies. For this purpose, nano-antimicrobials have emerged as a potential option.

OBJECTIVE

The current review is focused on providing a detailed account of nanocarriers like liposome, micelles, dendrimers, solid lipid NPs, niosomes, polymeric nanoparticles, nano-suspensions, nano-emulsion, mesoporous silica and alginate-based drug delivery systems along with the recent updates on developments regarding nanoparticle-based therapeutics, vaccines and diagnostic methods developed or under pipeline with their potential benefits and limitations to combat mycobacterial diseases for their successful eradication from the world in future.

RESULTS

Distinct morphology and the underlying mechanism of pathogenesis and resistance development in this group of organisms urge improved and novel methods for the early and efficient diagnosis, treatment and vaccination to eradicate the disease. Recent developments in nanotechnology have the potential to meet both the aspects: nano-materials are proven components of several efficient targeted drug delivery systems and the typical physicochemical properties of several nano-formulations have shown to possess distinct bacteriocidal properties. Along with the therapeutic aspects, nano-vaccines and theranostic applications of nano-formulations have grown in popularity in recent times as an effective alternative means to combat different microbial superbugs.

CONCLUSION

Nanomedicine holds a bright prospect to perform a key role in global tuberculosis elimination program.

Straightforward synthesis of gold nanoparticles by adding water to an engineered small dendrimer

A small water-soluble phosphorus-containing dendrimer was engineered for the complexation of gold(I) and for its reduction under mild conditions. Gold nanoparticles were obtained as colloidal suspensions simply and only when the powdered form of this dendrimer was dissolved in water, as shown by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX) analyses. The dendrimers acted simultaneously as mild reducers and as nanoreactors, favoring the self-assembly of gold atoms and promoting the growth and stabilization of isolated gold nanoparticles. Thus, an unprecedented method for the synthesis of colloidal suspensions of water-soluble gold nanoparticles was proposed in this work.

Constitutional isomers of dendrimer-like pyrene substituted cyclotriphosphazenes: synthesis, theoretical calculations, and use as fluorescence receptors for the detection of explosive nitroaromatics

Two constitutionally isomeric bis-pyrenyl phenol dendrons (4 and 6) and their dendrimer-like cyclotriphosphazene derivatives (5 and 7) are designed, synthesized and fluorescence detection behaviors are evaluated for nitro aromatic compounds (NACs).

New Ways to Treat Tuberculosis Using Dendrimers as Nanocarriers

Tuberculosis (TB) is a contagious infection that usually attacks not only the lungs, but also brain and spine. More than twenty drugs have been developed for the treatment of TB, but most of them were developed some years ago. They are used in different combinations. Isoniazid and Rifampicin are examples of the five first line TB drugs, whereas, for instance, Levofloxacin, Kanamycin and Linezolid belong to the second line drugs that are used for the treatment of drug resistant TB. Several new bicyclic nitroimidazoles (e.g., Delamanid) without mutagenic effects were developed. New TB drugs need to provide several main issues such as more effective, less toxic, and less expensive for drug resistant TB. Besides polymeric, metal-based nanoparticles, polymeric micelles and polymers, dendrimer nanostructures represent ideal delivery vehicles and offer high hopes for the future of nanomedicine. In this original review, we present and analyze the development of anti-TB drugs in combination with dendrimers. Few articles have highlighted the encapsulation of anti-TB drugs with dendrimers. Due to their unique structure, dendrimers represent attractive candidates for the encapsulation and conjugation of other anti-TB drugs presenting important drawbacks (e.g., solubility, toxicity, low bioavailability) that hinder their development, including clinic trials.

Synthesis of dissymmetric phosphorus dendrimers using an unusual protecting group

We report the synthesis of neutral and polycationic dissymmetric phosphorus dendrimers bearing branches of different generations on the core.