Search

International audience; The preparation of two cyclens both possessing two triethoxysilyl groups through click chemistry is described. These two cyclens were incorporated into bis(triethoxysilyl)ethenylene‐based periodic mesoporous organosilica nanoparticles (PMO NPs) at different proportions of bis(triethoxysilyl)ethenylene/cyclens (90/10, 75/25). The obtained nanorods were analyzed with different techniques and showed high specific surface areas at low proportion of cyclens. The nanorods containing free amino groups of cyclen were then used for Ni(II) and Co(II) removal from model solutions. The kinetics and isotherms of adsorption of Ni(II) and Co(II) were determined, and the materials showed high uptake of metals (up to 3.9 mmol ⋅ g−1). They demonstrated pronounced selectivity in separation of rare earth elements from late transition metals, e. g. Ni(II) and Co(II) by adsorption and even more so by controlled desorption..

Organosilica nanoparticles hold great promise for nanomedicine applications. These nanoparticles are synthesized from polytrialkoxysilylated precursors without any silica source. In this work we present two kinds of organosilica nanoparticles with either amine or ammonium walls constituting their structure. Both types of nanoparticles are very efficient for gemcitabine monophosphate delivery, a small hydrophilic anticancer drug whose encapsulation is still a challenge. The nanoparticles are endocytosed by MCF-7 breast cancer cells as monitored by confocal microscopy. They are efficient and lead to 60% cancer cell death.

Gemcitabine hydrochloride is an FDA-approved chemotherapeutic drug used in the treatment of various cancers. Several drawbacks of gemcitabine including its short in vivo half-life of 8-17 min associated with a rapid excretion by the kidneys and its poor membrane permeability have inspired research on a nanodelivery approach. In this study, we report ethylene-based periodic mesoporous organosilica nanoparticles (PMOs) for photodynamic therapy and the autonomous delivery of gemcitabine in cancer cells. Porphyrins were used as photosensitizers and were localized in the walls of the PMOs while a high loading capacity of gemcitabine was observed in the porous structure. Depending on the nature of the photosensitizer, and its aggregation state, we were able to perform one or two-photon photodynamic therapy. Two-photon excited photodynamic therapy combined with gemcitabine delivery led to a synergy and a very efficient cancer cell killing.

International audience; Background: Bridged silsesquioxane nanoparticles (BSNs) recently described represent a new class of nanoparticles exhibiting versatile applications and particularly a strong potential for nanomedicine.Aims: In this work, we describe the synthesis of BSNs from an octasilylated functional porphyrin precursor (PORBSNs) efficiently obtained through a click reaction. These innovative and very small-sized nanoparticles were functionalized with PEG and mannose (PORBSNs-mannose) in order to target breast tumors in vivo. Methods and Results: The structure of these nanoparticles is constituted of porphyrins J aggregates that allow two-photon spatiotemporal excitation of the nanoparticles. The therapeutic potential of such photoactivable nanoparticles was first studied in vitro, in human breast cancer cells in culture and then in vivo on zebrafish embryos bearing human tumors. These animal models were intravenously injected with 5 nL of a solution containing PORBSNs-mannose. An hour and half after the injection of photoactivable and targeted nanoparticles, the tumor areas were excited for few seconds with a two-photon beam induced focused laser. We observed strong tumor size decrease, with the involvement of apoptosis pathway activation.onclusion: We demonstrated the high targeting, imaging, and therapeutic potential of PORBSNs-mannose injected in the blood stream of zebrafish xenografted with human tumors.

International audience; Periodic mesoporous organosilica nanorods and nanospheres are synthesized from 1,4-bis(triethoxysilyl)ethylene and bis(3-ethoxysilylpropyl)disulfide. The nanosystems present the long-range order of the hexagonal nanostructure. They are degraded in simulated physiological conditions. The loading and release of doxorubicin with these nanosystems are both pH dependent. These nanoparticles are endocytosed by breast cancer cells and are very efficient for doxorubicin delivery in these cells.

International audience

A feasible method of grafting complex amine structures (methyl ester of glycine, Rho-Lys-Arg-NH2, amine-terminated oligonucleotide and 7,8,11,12-tetrahydro-5-hexahelicenamine) onto a silicon wafer surface is described. The two step process comprises (1) anchoring 10-isocyanatodecyltrichlorosilane to a 1.8–2-nm thin silica layer on a single silicon wafer crystal (100) and (2) the attachment of amine substrates through a urea linkage by reacting those with isocyanate groups on the wafer surface. Both steps can be monitored by ATR FTIR showing the appearance/disappearance of the isocyanate band. Measuring the contact angles along with the AFM imaging of the surfaces indicated the formation of the monolayers.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Polycarbonate (PC) is a useful substrate for the preparation of microfluidic devices. Recently, its utility in bioanalysis has attracted much attention owing to the possibility of using compact discs as platforms for the high-throughput analysis of biomolecular interactions. In this article we report a novel method for the chemical micropatterning of polycarbonate based on the printing of functionalized silica nanoparticles. The semicarbazide groups present on the surface of the nanoparticles were used for the site-specific semicarbazone ligation of unprotected peptides derivatized by an alpha-oxoaldehyde group. The peptide micropatterns permitted the specific capture of antibodies. We report also the characterization of micropatterns on PC by using a wide-field optical imaging technique called Sarfus; this allows the detection of nm-thick films by using nonreflecting PC substrates and an optical microscope working with reflected differential interference contrast. The method described here is an easy way to modify polycarbonate surfaces for biomolecular interaction studies and should stimulate the use of PC for developing plastic biosensors.

The synthesis and characterisation of α-oxo aldehyde-supported silicas by the sol-gel procedure is described. The glyoxylyl group was generated after gelation, either by periodic oxidation of gluconamide chains or by deprotection of a diisopropylthioacetal-protected derivative. The accessibility and reactivity of the supported α-oxo aldehyde function was investigated in model reactions with hydroxylamine and hydrazine derivatives. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

The modification of metal oxide surfaces by π-conjugated ferrocene units has been performed. A phosphonic acid functionality was used to covalently anchor the π-conjugated ferrocene moiety to SnO2 and TiO2 particles. The covalent attachment and the monolayer coverage at the surface of the particles were confirmed by solid-state MAS 31P NMR spectroscopy, microanalysis and electronic microscopy (EDX). The properties of the ferrocene-modified oxides were analysed by cyclic voltammetry, which confirmed the electroactivity of the material, and 57Fe Mossbauer spectrometry, which provided information about the oxidation state and environment of the iron atoms. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

With the description of more and more complex one- and two-dimensional NMR experiments comes the need to develop methods to make a comprehensive interpretation of the various different experiments that can be carried out on the same sample or series of related samples. We present some examples of modelling one- and two-dimensional solid-state NMR spectra of I = ½ spin and quadrupolar nuclei, using laboratory-developed software that is made available to the NMR community. Copyright © 2001 John Wiley & Sons, Ltd.

An easy access to the 3-fluoroazetidinone 4a based on electrophilic fluorination, is reported. The fluorination of the β-lactam 7 with Differding's N-fluorosulfonimide proceeds stereoselectively, under mild conditions and in good yield.

A short stereoselective synthesis of (−)-(2 S ,3 S )-3-hydroxyproline has been realized from L-malic acid as the source of chirality. The key step was the reductive cyanation of the intermediate 1a , in high stereoselectivity and yield.