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

Applications des films Langmuir-Blodgett à base de phosphonates de zirconium pour la préparation de puces à oligonucléotides (synthèse de ligands hybrides P/N chiraux. Étude de leurs propriétés de coordination)

Ce mémoire traite d'un procédé de préparation de puces à ADN utilisant un support de verre recouvert d'une couche de phosphonate de zirconium déposée par la technique de Langmuir-Blodgett. Les oligonucléotides sondes modifiés par un phosphate terminal sont déposés sur la surface de zirconium et s'y fixent en formant des liaisons à caractère fortement covalent. Les performances de ce nouveau type de puce à ADN ont été étudiées dans des conditions biologiques. Une augmentation de la fluorescence est observée lors de l'introduction d'un espaceur polyguanine entre la sonde et le phosphate terminal. Puis la synthèse de ligands P/N chiraux est décrite via la désymétrisation du squelette méso et achiral d'une diamine de symétrie C2 par l'introduction sélective d'un groupement diphénylphosphine sur un des deux centres azotés. La coordination du ligand (L) avec des précurseurs métalliques à base de Rh(I) ou de Pd(0) permet l'obtention de complexes potentiellement utilisables en catalyse.This report deals with a new process for preparing DNA microarrays using glass slides covered by a zirconium phosphonate monolayer deposited by Langmuir-Blodgett method. Oligonucleotides probes modified with a terminal phosphate were spotted onto the zirconated surface where they bound by formation of metal-oxygen covalent bonds. Performances of this new type of DNA microarrays were studied in biological conditions. An increase of the fluorescence intensity was observed when using a polyguanine spacer between the probe oligomer and the terminal phosphate. Then the synthesis of novel chiral P,N-ligands by desymmetrization of the achiral meso N,N'-dimethyl-1,2-diphenylethane-1,2-diamine backbone is described. This transformation was achieved by the selective introduction of a diphenylphosphine moiety on one of the two nitrogen centers. The coordination of this ligand (L) with Rh(I) and Pd(0) precursors led to the formation of complexes which can be of potential interest for catalysis.NANTES-BU Sciences (441092104) / SudocSudocFranceF

Antimicrobial molecules impregnation of nanocellulose-based structures in supercritical carbon dioxide

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Antimicrobial molecules impregnation of nanocellulose-based structures in supercritical carbon dioxide

International audienc

A DNA array based on clickable lesion-containing hairpin probes for multiplexed detection of base excision repair activities

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Combining chemistry and topography to produce antifouling surfaces, a review

International audienceDespite decades of research on the reduction of surface fouling from biomolecules like proteins or micro-organisms like bacteria, viruses or fungi, the ultimate antifouling surface remains undiscovered. Our strongly expanding, but still incomplete, understanding of micro-organisms interactions with surfaces, and biofilm formation partly impedes the development of fully biopassive surface treatments. In parallel, the recent covid-19 pandemic strengthened the crucial need for such treatments. Among the numerous approaches that are able to provide surfaces with antifouling properties, chemical, biological and topographical strategies have been implemented for instance in marine, medical or food industries. While chemical and biological approaches either prevent the non-specific adsorption of micro-organisms, or kill them, topographical strategies are often designed to generate a mechanical stress upon their membranes. Active Principle Ingredient (API) release can be efficient; however, as well as being limited in time, bioresistance is increasing and thus the use of antibiotics should be reconsidered. Therefore, reducing non-specific adsorption and limiting micro-organism attachment is necessary for long-term solutions. Bio-inspired strategies, combining both organic chemistry and topography, are currently at the heart of the best innovative and sustainable solutions. The simultaneous effect of micro/nano-structuration, together with engineered chemical or biological functionalization is believed to contribute to the development of ever-increasing antibiofouling surfaces. This review aims to present approaches combining hydrophobic or hydrophilic chemistry and structured surfaces to avoid biofouling in different fields of interest

Highly absorbent cellulose nanofibrils aerogels prepared by supercritical drying

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Aptasensors based on silicon nanowire field-effect transistors for electrical detection of thrombin

International audienceArrays of silicon nanowire field-effect transistors (Si NWFETs) were built to detect thrombin (a model biomarker) electrically. The Si NWFETs were created using a conventional top-down CMOS process, allowing them to be co-integrated with CMOS readout circuits in the future. EHTES organosilane was then used to graft aptamer probes onto the HfO2 gate oxide of Si nanowires. We investigated the influence of aptamer grafting and thrombin recognition on the electrical transfer capabilities of Si NWFET aptasensors in details. Our technique was evaluated on a significant number of Si NWFETs, including two distinct chips with 30 aptasensors apiece. According to the findings, aptamer grafting increased the threshold voltage by a positive range of +28.8 mV to +87.7 mV, depending on the aptasensor employed. Thrombin identification, on the other hand, resulted in a negative shift of the threshold voltage between −26.6 and − 23.8 mV. These opposing voltage shifts coincide with the aptamer probes' and thrombin molecules' electric charges, respectively. These findings provide unique demonstration of Si NWFETs manufactured utilizing typical top-down CMOS processing methods, allowing these devices to be used in various biomedical and biosensing applications

Functionalization of silicon oxide using supercritical fluid deposition of 3,4-epoxybutyltrimethoxysilane for the immobilization of amino-modified oligonucleotide

International audienceThe functionalization of silicon oxide based substrates using silanes is generally performed through liquid phase methodologies. These processes involve a huge quantity of potentially toxic solvents and present some important disadvantages for the functionalization of microdevices or porous materials, for example the low diffusion. To overcome this drawback, solvent-free methodologies like molecular vapor deposition (MVD) or supercritical fluid deposition (SFD) have been developed. In this paper, the deposition process of 3,4-epoxybutyltrimethoxysilane (EBTMOS) on silicon oxide using supercritical carbon dioxide (scCO2) as a solvent is studied for the first time. The oxirane ring of epoxy silanes readily reacts with amine group and is of particular interest for the grafting of amino-modified oligonucleotides or antibodies for diagnostic application. Then the ability of this specific EBTMOS layer to react with amine functions has been evaluated using the immobilization of amino-modified oligonucleotide probes. The presence of the probes is revealed by fluorescence using hybridization with a fluorescent target oligonucleotide. The performances of SFD of EBTMOS have been optimized and then compared with the dip coating and molecular vapor deposition methods, evidencing a better grafting efficiency and homogeneity, a lower reaction time in addition to the eco-friendly properties of the supercritical carbon dioxide. The epoxysilane layers have been characterized by surface enhanced ellipsometric contrast optical technique, atomic force microscopy, multiple internal reflection infrared spectroscopy and X-ray photoelectron spectroscopy. The shelf life of the 3,4-epoxybutyltrimethoxysilane coating layer has also been studied. Finally, two different strategies of NH2-oligonucleotide grafting on EBTMOS coating layer have been compared, i.e. reductive amination and nucleophilic substitution, SN2. This EBTMOS based coating layer can be used for a wide range of applications such as the preparation of new supported and recoverable catalysts and new integrated silicon microdevices for healthcare purposes