Direct measurement of the mechanism by which magnesium specifically modifies the mechanical properties of DNA

International audienc

Molecular Recognition and Transport of Active Pharmaceutical Ingredients on Anionic Calix[4]arene-Capped Silver Nanoparticles

A series of six anionic calix[4]arenes, having sulphonate, carboxylate, or phosphonate functions at either the para-aromatic position or the phenolic face were used to cap silver nanoparticles. Their molecular recognition properties were studied with regard to three active pharmaceutical ingredients, chlorhexidine, chloramphenicol, and. gentamycin sulfate. Of these APIs chlorhexidine is known to form cocrystals with the anionic calix[4]arenes, gentamicin sulfate is an aminoglycosidic antibiotic, and chloramphenicol is a neutral antibiotic. As expected the former two APIs show clear complexation behavior as demonstrated by shifts in the visible spectra whereas the last shows no modification in the wavelength of the plasmon resonance of the silver nanoparticles

The N-terminal domains of TRF1 and TRF2 regulate their ability to condense telomeric DNA

TRF1 and TRF2 are key proteins in human telomeres, which, despite their similarities, have different behaviors upon DNA binding. Previous work has shown that unlike TRF1, TRF2 condenses telomeric, thus creating consequential negative torsion on the adjacent DNA, a property that is thought to lead to the stimulation of single-strand invasion and was proposed to favor telomeric DNA looping. In this report, we show that these activities, originating from the central TRFH domain of TRF2, are also displayed by the TRFH domain of TRF1 but are repressed in the full-length protein by the presence of an acidic domain at the N-terminus. Strikingly, a similar repression is observed on TRF2 through the binding of a TERRA-like RNA molecule to the N-terminus of TRF2. Phylogenetic and biochemical studies suggest that the N-terminal domains of TRF proteins originate from a gradual extension of the coding sequences of a duplicated ancestral gene with a consequential progressive alteration of the biochemical properties of these proteins. Overall, these data suggest that the N-termini of TRF1 and TRF2 have evolved to finely regulate their ability to condense DNA

Calix[n]arènes en nano bio-systèmes

Supramolecular assemblies are among the basic biochemical reactions in the cellular functions (e.g. DNA replication, immune response). Calix[n]arenes are macrocyclic molecules that have been reported for interacting with a wide range of biomolecules. As a consequence, they can be found in many biological applications from diagnosis to therapeutic treatment. Their functionalization on silver nanoparticles have produced new nano hybrid compounds with unique optical, electrical and biochemical properties. This thesis has been dedicated to the study of these nano-systems for bio-sensing and for their potent biomedical applications. Cost effective, portable and ultra-sensitive analytical tools are one of the major expectations of the applications of silver nanoparticles capped with calix[n]arenes. Calix[n]arenes nanoparticles have been reported here for following the micellisation process of mixed surfactants or for discriminating a type of molecule such nucleic acid or a serum albumin specie. In a second part, these hybrid nanoparticles have been evaluated for series of biological activities. They’ve been shown to possess anti-oxidant and antibacterial activities, to transport Active Pharmaceutical Ingredient and to reach antiviral and anti-cancer targetsLes assemblages supramoléculaires font parties des réactions biochimiques de base dans les fonctions cellulaires (ex: réplication de l'ADN ou réponse immunitaire). Les calix[n]arènes ont été décrit pour interagir avec une large gamme de biomolécules. En conséquence, ils peuvent être trouvés dans de nombreuses applications biologiques tel qu'en diagnostic ou en traitement thérapeutique. Leurs fonctionnalisations sur des nanoparticules d'argent ont produit de nouveaux nano-composés hybrides ayant des propriétés optique, électrique et biologique uniques. Cette thèse a été dédiée à l'étude de ces nano systèmes pour la bio-détection et leurs potentielles applications biomédicales. Le développement de capteur analytique à bas coût, portable et ultra-sensible représente une des attentes majeures dans les applications des calix[n]arènes sur nanoparticules d'argent. Dans cette thèse, ces nano-composés ont été étudiés selon leurs capacités à suivre la micellisation de surfactant mixtes, et pour discriminer un type moléculaire tel qu'une famille d'acide nucléique ou une espèce d'albumine sérique. Dans une deuxième partie, ces nanoparticules hybrides ont été évaluées pour une série d'activités biologiques. Ils ont montré des facultés antibiotiques et anti-oxydantes, de transporter des Ingrédients Pharmaceutiques Actifs, et d'atteindre des cibles antivirales et anticancéreuse

Bio-Applications of Calix[ n ]arene Capped Silver Nanoparticles

International audienceDuring the 10 last years, there has been a growing interest in calix[n]arene capped silver nanopar-ticles for their uses in biosensing and much more recently for their intrinsic therapeutic properties. Cost effective, portable and ultra-sensitive analytical tools are one of the major expectations of silver nanoparticles capped with calix[n]arenes. Their uses for detecting a wide range of hazardous molecules and biological compounds by different physical approaches (optical or electrical) are reviewed in depth here. A second part deals with their biological activities. These hybrid nanopar-ticles have been shown to possess antibacterial properties, and to reach antiviral and anti-cancer targets

Cellular and in vivo biological activities of the calix[n]arenes

International audienceThe biological activities of the calix[n]arenes have been extensively reported on, with regard to various forms of life ranging from self-replicating systems, such as, viruses, through bacteria, fungi and mammalian cells to human beings. This article reviews more than one hundred different calix[n]arenes classified according to their biological effects directly observed on living species. These macrocyclic molecules have been reported as detoxifying agents, as having antibacterial, antiviral, anticoagulant, anticancer, antifungal activities, as membrane protein modulators / extracters, drug transporters and fluorescent probes. Special in vivo sections, have been inserted when possible for each biological effect showing the impact of the calix[n]arenes on whole living system such as animals or humans

Cellular and in vivo biological activities of the calix[n]arenes

International audienceThe biological activities of the calix[n]arenes have been extensively reported on, with regard to various forms of life ranging from self-replicating systems, such as, viruses, through bacteria, fungi and mammalian cells to human beings. This article reviews more than one hundred different calix[n]arenes classified according to their biological effects directly observed on living species. These macrocyclic molecules have been reported as detoxifying agents, as having antibacterial, antiviral, anticoagulant, anticancer, antifungal activities, as membrane protein modulators / extracters, drug transporters and fluorescent probes. Special in vivo sections, have been inserted when possible for each biological effect showing the impact of the calix[n]arenes on whole living system such as animals or humans

The solid-state structures of the ethanol solvated complexes of para-sulphonato-calix[4]arene with magnesium and calcium ions

International audienc

Mechanical effect of gold nanoparticles labeling used for biochemical sensor applications: A multimode analysis by means of SiNx micromechanical cantilever and bridge mass detectors

International audienceThe effect on mechanical properties of monolithic SiNx micromechanical cantilever and bridge by the adsorption of gold colloids is reported by measuring their resonance frequency shifts. It is experimentally demonstrated that higher resonance modes are more sensitive to the added mass than the fundamental resonance mode leading to increased sensitivity. This is even more significant with monolithic SiNx bridge resonators due to the tensile stress within the SiNx layer. Indeed, resonance frequencies are about ten times higher than calculation without taking into account the tensile stress which was estimated at 500 MPa. Another important result is that the adsorbed colloids do not produce significant change in the stiffness of the SiNx micromechanical resonators. Hence, it is pointed out that only the added mass of Au colloid contributes to the change in the mechanical characteristics of the resonators. Sensitivities up to 20 Hz/pg can be obtained with a minimum detectable density of gold colloids about 2.6×10−2 nanoparticles/μm2

Molecular recognition by gold, silver and copper nanoparticles

International audienceThe intrinsic physical properties of the noble metal nanoparticles, which are highly sensitive to the nature of their local molecular environment, make such systems ideal for the detection of molecular recognition events. The current review describes the state of the art concerning molecular recognition of Noble metal nanoparticles. In the first part the preparation of such nanoparticles is discussed along with methods of capping and stabilization. A brief discussion of the three common methods of functionalization: Electrostatic adsorption; Chemisorption; Affinity-based coordination is given. In the second section a discussion of the optical and electrical properties of nanoparticles is given to aid the reader in understanding the use of such properties in molecular recognition. In the main section the various types of capping agents for molecular recognition; nucleic acid coatings, protein coatings and molecules from the family of supramolecular chemistry are described along with their numerous applications. Emphasis for the nucleic acids is on complementary oligonucleotide and aptamer recognition. For the proteins the recognition properties of antibodies form the core of the section. With respect to the supramolecular systems the cyclodextrins, calix[n]arenes, dendrimers, crown ethers and the cucurbitales are treated in depth. Finally a short section deals with the possible toxicity of the nanoparticles, a concern in public health