Novel phosphate–phosphonate hybrid nanomaterials applied to biology

International audienceA new process for preparing oligonucleotide arrays is described that uses surface grafting chemistry which is fundamentally different from the electrostatic adsorption and organic covalent binding methods normally employed. Solid supports are modified with a mixed organic/inorganic zirconium phosphonate monolayer film providing a stable, well-defined interface. Oligonucleotide probes terminated with phosphate are spotted directly to the zirconated surface forming a covalent linkage. Specific binding of terminal phosphate groups with minimal binding of the internal phosphate diesters has been demonstrated. On the other hand, the reaction of a bisphosphonate bone resorption inhibitor (Zoledronate) with calcium deficient apatites (CDAs) was studied as a potential route to local drug delivery systems active against bone resorption disorders. A simple mathematical model of the Zoledronate/CDA interaction was designed that correctly described the adsorption of Zoledronate onto CDAs. The resulting Zoledronate-loaded materials were found to release the drug in different phosphate-containing media, with a satisfactory agreement between experimental data and the values predicted from the model

Fabrication of colloidosomes at low temperature for the encapsulation of thermally sensitive compounds.

International audienceA method using safe and mild conditions to prepare water-core colloidosomes of a few micrometers in size is examined. Using poly(styrene-co-butylacrylate) colloidal particles of 180 nm in size, with a low-temperature glass transition of 30 or 42 degrees C, the self-assembly into micrometer-sized water-core polymer shell particles is demonstrated. The effect of oil phase type, surfactant and cosolvent, sintering time, and the method of transfer into an aqueous phase are all examined. The work demonstrates the production of water-core rigid-shell colloidosomes at low temperatures, between 35 and 65 degrees C

Fabrication of colloidosomes at low temperature for the encapsulation of thermally sensitive compounds

A method using safe and mild conditions to prepare water-core colloidosomes of a few micrometers in size is examined. Using poly(styrene-co-butylacrylate) colloidal particles of 180 nm in size, with a low-temperature glass transition of 30 or 42[thin space]°C, the self-assembly into micrometer-sized water-core polymer shell particles is demonstrated. The effect of oil phase type, surfactant and cosolvent, sintering time, and the method of transfer into an aqueous phase are all examined. The work demonstrates the production of water-core rigid-shell colloidosomes at low temperatures, between 35 and 65[thin space]°C

Marquage chimique de dérivés cellulosiques pour un suivi in vivo chez l'animal. Incorporation d'agents anti-ostéoporotiques sur des matrices phosphocalciques

Le projet vise à mettre au point un nouveau dispositif médical pour traiter les dérèglements de la résorption osseuse. Les biomatériaux à développer sont des substituts osseux constitués de granules de phosphate de calcium et de dérivés cellulosiques hydrosolubles. Une première thématique repose sur le marquage chimique covalent de la phase organique du matériau par des complexes ruthénium tris-bipyridine. Les polymères seront détectés par microfluorescence X après implantation chez l'animal, l'objectif étant de mieux comprendre leur influence sur la bioactivité du matériau. La deuxième thématique repose sur la compréhension des modes d'association et de dissociation possibles entre un gem-bisphosphonate (BP) et différents phosphates de calcium (PCas). Il est notamment présenté un modèle mathématique prédictif décrivant un processus de chimisorption basé sur un échange phosphate/phosphonate entre les deux constituants. L'évaluation biologique des systèmes BP/PCas est également décrite.The purpose of the project is to design a new drug-delivery system to treat bone resorption disorders. This work is based on the development of biomaterials made of calcium phosphates and hydrosoluble cellulosic derivatives. The first topic concerns a covalent chemical labelling of the polymers by tris-bipyridine ruthenium complexes derivatives. The probe will be detected by micro X-Ray fluorescence scanning of tissue sections performed after animal implantations. The aim is to localize the polymers during bone formation for a better understanding of their influence on the bioactivity of the biomaterials. The second part is focus on comprehensive studies about the formation and the dissociation of gem-bisphosphonate-coated (BP) calcium phosphate matrices (PCas). In particular, a mathematical modelling of the chemical sorption process is described, which is based on phosphate/phosphonate exchange between the two compounds. Biological evaluations of PCas/BP systems are also reported.NANTES-BU Médecine pharmacie (441092101) / SudocNANTES-Bib.Odontologie (441092219) / SudocSudocFranceF

Novel biomaterials for bisphosphonate delivery.

One type of gem-bisphosphonate (Zoledronate) has been chemically associated onto calcium phosphate (CaP) compounds of various compositions. For that purpose,CaP powders of controlled granulometry have been suspended in aqueous Zoledronate solutions of variable concentrations. Using mainly 31P NMR spectroscopy,two different association modes have been observed, according to the nature of the CaP support and/or the initial concentration of the Zoledronate solution. b-tricalcium phosphate (b- TCP) and mixtures of hydroxyapatite and b-TCP (BCPs) appear to promote Zoledronate-containing crystals formation. On the other hand,at concentrations o0.05 mol l1 CDAs (calcium deficients apatites) seem to undergo chemisorption of the drug through a surface adsorption process,due to PO3 for PO4 exchange,that is well described by Freundlich equations. At concentrations >0.05 mol l1,crystalline needles of a Zoledronate complex form onto the CDAs surface. The ability of such materials to release Zoledronate,resulting in the inhibition of osteoclastic activity,was shown using a specific in vitro bone resorption model

The in vivo degradation of a ruthenium labelled polysaccharide-based hydrogel for bone tissue engineering

In this paper we report a new method that permitted for the first time to selectively track a polysaccharide-based hydrogel on bone tissue explants, several weeks after its implantation. The hydrogel, which was developed for bone healing and tissue engineering, was labelled with a ruthenium complex and implanted into rabbit bone defects in order to investigate its in vivo degradation. 1, 2, 3 and 8 weeks after surgery, the bone explants were analyzed by synchrotron X-ray microfluorescence, infrared mapping spectroscopy, scanning electron microscopy, and optical microscopy after histological coloration. The results showed that the labelled polysaccharide-based hydrogel was likely to undergo phagocytosis that seemed to occur from the edge to the center of the implantation site up to at least the 8th week