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Monoliths functionalized with ethylene diamine-derived ligands were synthetized within micro-sized channels as highly permeable catalytic supports for the immobilization of in-situ generated gold nanoparticles. The as-obtained hybrids, essentially differing on the grafted amine-containing ligands were compared, notably regarding the immobilized nanoparticles morphology and their dispersion at the monolith pore surface. Further, such in-capillary hybrid monoliths were successfully applied as flow-through microreactors for the catalytic reduction of nitroaromatic compounds. The general synthetic route for preparing these composite materials consisted in a three-step procedure involving (i) UV-induced polymerization of N-acryloxysuccinimide and ethylene glycol dimethacrylate in toluene, (ii) surface grafting of a series of ethylene diamine derivatives through nucleophilic substitution of N-hydroxysuccinimide leaving groups, and (iii) successive in situ reduction of tetrachloroauric acid to generate monolith-adsorbed gold nanoparticles. The successful synthesis of such hybrid monoliths was ascertained by in-situ Raman spectroscopy, EDX analysis and SEM observations. Microscopy demonstrated the key role of the grafted amine-bearing ligand regarding the morphology, size and surface coverage of the immobilized gold nanoparticles at the monolith pore surface. Monolith-adsorbed gold nanoparticles exhibited good catalytic activities towards the conversion of nitroaromatic compounds into the corresponding amino derivatives in a flow-through process. This study clearly demonstrates the key role of the nature, primary vs. secondary, of the chelating amine in the morphology (shape, size, dispersion) of the supported gold nanoparticles.

This work reports the non-covalent functionalization of SWNTs with Fe-porphyrin, Co-porphyrin and Co-phthalocyanine molecules. The functionalized SWNTs were first characterized using Raman and X-ray photoelectron spectroscopies. Observations down to nanoscale resolution were also performed by atomic force microscopy, as well as scanning and transmission electron microscopies. The spectroscopic methods evidenced an electronic interaction between the metal-centered molecules and the SWNTs, ensuring the robustness of the functionalization. High resolution microscopy characterizations reveal that the porphyrin and phthalocyanine molecules are adsorbed on the surface of SWNTs. The electrical characterizations show a weak charge transfer between those grafted molecules and the SWNTs, confirming the electronic interaction between the molecules and the SWNTs. Density functional theory (DFT) supports experimental data and helps understanding the experimental results of selective interaction of metal complexes with one type of semiconducting SWNTs.

Creating an appropriate antibacterial disinfection system without forming any harmful compounds is still a major challenge and calls for new technologies for efficient disinfection and microbial control. Towards this aim, we report on the elaboration of biodegradable and biocompatible polymeric nanocapsules, also called hollow nanoparticles, for potential applications in antibiotic therapy. These nanomaterials are based on the self-assembly of charged polysaccharides, namely chitosan and alginate, onto gold nanoparticles as a sacrificial matrix (60 nm). Electrostatic interactions between the protonated amine groups of chitosan (+35 mV) and the carboxylate groups of alginate (- 20 mV) are the driving attraction force enabling the elaboration of well-ordered multilayer films onto the spherical substrate. The removal of the colloidal gold, via cyanide-assisted hydrolysis, is evidenced by time-dependent variation of the gold spectroscopic signature (30 min is required). TEM shows the obtention of nanocapsules. An inhibitory effect of these particles has been demonstrated during the growth of two representative bacteria in a liquid medium: Staphylococcus aureus (Gram-positive) (from 4.6% to 16.3% for gold nanomaterials + and from 18.6% to 34.9% for (chi+/alg−)n-chi+ nanocapsules) and Escherichia coli (Gram-negative) (from 5.4% to 20% for gold nanomaterials and from 23.7% to 40% for (chi+/alg−)n-chi+ nanocapsules). Acridine orange staining demonstrated the bactericidal effect of chitosan-based capsules. These findings demonstrate that (chitosan/alginate)n capsules can be exploited as new antibacterial material. Thus, we present a complementary approach to classical nanoparticles prepared by complexation between alginate and chitosan or other materials.

International audience; Most of the drug molecules are partially insoluble in aqueous solution and then may accumulate in fat tissues hampering efficient therapy. Innovative drug delivery strategies have emerged in industry or academia over the last decades, however preserving the activity of the encapsulated drug, having high drug loading capacity and controlling drug release kinetics, are still challenging. In this context, we explored the preparation of new nanocarriers, namely nanocapsules, via a templating method, and using polysaccharides exhibiting biological functions. Cationic poly(cyclodextrin) (P(CD+)) and alginate (alg−) were initially self-assembled layer-by-layer on colloidal gold nanoparticles. Removal of gold nanoparticles was then induced thorough cyanide-assisted hydrolysis, enabling the recovery of nanocapsules. A hydrophobic drug known to allow the mutation of genes inside cells, namely 4-hydroxy-tamoxifen, was loaded within the nanocapsules’ shell via inclusion with the cyclodextrin cavities. The so-designed nanomaterials were incubated with immortalized podocytes to investigate i) their incorporation inside cells and ii) their efficiency for in vitro 4-hydroxy-tamoxifen-induced CreERT2 recombination. This work undoubtedly highlights a proof-of-concept for drug delivery using polysaccharides-based capsules with host properties.

The in situ detection of organic molecules in space is key to understanding the variety and the distribution of the building blocks of life, and possibly the detection of extraterrestrial life itself. Gas chromatography mass spectrometry (GC-MS) has been the most sensitive analytical strategy for organic analyses in flight, and was used on missions from NASA's Viking, Phoenix, Curiosity missions to ESA's Rosetta space probe. While pyrolysis GC-MS revealed the first organics on Mars, this step alters or degrades certain fragile molecules that are excellent biosignatures including polypeptides, oligonucleotides and polysaccharides, rendering the intact precursors undetectable. We have identified a solution tailored to the detection of biopolymers and other biomarkers by the use of liquid-based capillary electrophoresis and electrochromatography. In this study, we show that a capillary electrochromatography approach using monolithic stationary phases with tailor-made surface chemistry can separate and identify various polycyclic aromatic hydrocarbons, nucleobases and aromatic acids that could be formed under astrophysically relevant conditions. In order to simulate flyby organic sample capture, we conducted hypervelocity impact experiments which consisted of accelerating peptide-soaked montmorillonite particles to a speed of 5.6 km s−1, and capturing them in an amorphous silica aerogel of 10 mg cm−3 bulk density. Bulk peptide extraction from aerogel followed by capillary zone electrophoresis led to the detection of only two stereoisomeric peptide peaks. The recovery rates of each step of the extraction procedure after the hypervelocity impact suggest that major peptide loss occurred during the impact. Our study provides initial exploration of feasibility of this approach for capturing intact peptides, and subsequently detecting candidate biomolecules during flight missions that would be missed by GC-MS alone. As the monolith-based electrochromatography technology could be customized to detect specific classes of compounds as well as miniaturized, these results demonstrate the potential of the instrumentation for future astrobiology-related spaceflight missions.

Polyelectrolytes (PEs) bearing easily derivatizable functions for possible post-modification under mild conditions can find a broad range of applications in various fields. The present paper describes the successful controlled side-chain allylation of two types of PEs: polyamine-based polycations, i.e. poly(allylamine hydrochloride) (PAH) and branched polyethyleneimine (PEI), and strong polyanions, i.e. poly(sodium vinyl sulfonate) (PVS) and poly(sodium 4-styrene sulfonate) (PSS). PSS has been largely investigated in the literature, while PVS is much less commonly explored. The allylation of each type presents its own drawback, i.e. heterogeneous reaction in the case of strong polyanions and instability of partially protonated allylated polyamine products. Nevertheless, all encountered difficulties could be solved and thoroughly elucidated by different experimental tests. This partial allyl-functionalization does not affect the electrolytic properties of the newly allylated PEs, as evidenced by the effective construction of two series of polyelectrolyte multilayer (PEM) films, namely PEI-ene (PSS-ene/PAH-ene)4 and PEI-ene (PVS-ene/PAH-ene)4, the latter being one of the rare examples developed in the literature. The presence of allyl groups on the PE side-chains allows for the stabilization of the resulting PEM films via thiol-ene photo-crosslinking in the presence of a water-soluble dithiol crosslinker. In order to fix permanently the resulting crosslinked PEM films on substrates, the covalent crosslinking occurs not only between different C=C bonds on PE layers but also with those present on substrates preliminarily functionalized with allyl groups via sulfur–gold chemistry. The robustness of both resulting crosslinked PEM films under strongly basic solution (pH 14) is validated by Quartz Crystal Microbalance (QCM) measurements. The versatility and effectiveness of the present approach is expected to find potential applications in different scientific and technological fields.

Selective extraction of hydrophilic compounds is a challenging task for analytical laboratories. In an attempt to address this issue, application of titanium dioxide nanoparticles as a dispersive solid phase extraction sorbent was investigated. In the study, three model analytes were used for method optimization: flavin mononucleotide, thiamine monophosphate and thiamine pyrophosphate. The influence of various parameters on sorption and desorption process was evaluated. Under optimized conditions, the sorption was performed in a presence of 1 M formic acid (pH 1.9) for 10 min under vortex stirring providing efficiency up to 94%. The influence of salt content in sample matrix was found to be negligible while the organic solvent presence slightly improved the sorption efficiency. Elution of analytes from TiO2 sorbent was obtained with both aqueous ammonia and phosphate buffer (pH 11.8) solutions. Under optimized conditions dispersive solid phase extraction method was shown to provide high selectivity with extraction recoveries >89.0% for studied compounds. The susceptibility of the method on various matrices was assayed for extraction of model analytes from enriched tap water, milk, apple juice and human urine samples. Moreover, the methodology was applied for phospholipids removal from pharmaceutical formulation (lecithin microemulsion) of propofol. Due to the utilization of titanium dioxide nanoparticles, the cost of sample preparation step was estimated to be about 0.1 Euro per sample, providing >100-fold reduction of the price for typical analysis using titanium dioxide microspheres.

This paper highlights the straightforward and versatile functionalization of biporous poly(2-hydroxyethyl methacrylate) (PHEMA)-based networks obtained from the double porogen templating approach, and their subsequent utilization as efficient catalytic supports in heterogeneous supported catalysis. Advantage of the availability of hydroxyl groups within the PHEMA-based frameworks was taken through chemical modification with carbonyl diimidazole. This key activation led to miscellaneous functionalization reactions of the materials via nucleophilic substitution or thiol-ene/thiol-yne “click” additions of functional organic molecules mainly containing amino or thiol groups. Further, in-situ generation and immobilization of gold nanoparticles (GNPs) on selected thiol- or amine-functionalized biporous frameworks allowed for the preparation of innovative GNP@PHEMA materials. The as-obtained hybrid frameworks could efficiently be used as supported catalysts in NaBH4-mediated reduction of 4-nitrophenol. The reusability of amine-bearing hybrid catalysts is proved over 5 successive 1 h-cycles with stable yields around 90%.

Herein, polystyrene (PS) bearing di(2-aminothiazole)-substituted triazine as chelation unit for both Au(III) ions and Au(0) nanoclusters was prepared through successive chemical modification of native polystyrene including nitration (treatment with HNO3/H2SO4), reductive amination (treatment with SnCl2/HCl), and successive grafting of 2,4,6-trichloro-1,3,5-triazine and 2-aminothiazole. The derived gold nanoparticles- (AuNPs-) containing composite material was obtained through chelation of the nanogold precursor, namely hydrogen tetrachloroaurate, and subsequent in situ hydride-assisted reduction providing gold nanoparticles with low size (about 14 nm) and spherical shape. It is shown that the presence of 2-aminothiazole-grafted triazine units on the phenyl side groups of PS enables the stable anchoring of the AuNPs while preventing agglomeration. Chemical structure of the PS derivatives was confirmed after each synthesis step by a combination of experimental methods such as infrared and energy dispersive X-ray spectroscopies, elemental analysis, X-ray diffraction and scanning electron microscopy. To highlight the catalytic potential of the so-designed nanostructured catalyst, the reduction of 4-nitrophenol was considered in the presence of a large excess of sodium borohydride as reductant specie. UV–visible spectroscopic monitoring of the progress of the reaction confirmed the pseudo-first order kinetic profile associated with a rate constant as high as 3.07 × 10− 2 s− 1.

This study describes the synthesis and evaluation of different imprinted hydrogels using ribavirin as template molecule. Ribavirin serves as a model molecule because it possesses a broad-spectrum antiviral effect against RNA viruses, which are expected as emerging viruses. The choice of monomers enables to stabilize the pre-polymerization complex and to synthesize biocompatible polymers. Predictive studies as well as experimental works conclude similar results on best ribavirin:monomers ratios. Thus, materials exhibit high selective cavities toward ribavirin. These affinities allow to show release profiles drastically different from the non-imprinted ones at two temperatures. The imprinted materials show a sustained profile able to release antiviral for more than 24 h. The hydrogels obtained are biocompatible with model cells retained, human lung epithelial BEAS-2B cells. Cell viability is excellent and pro-inflammatory response is insignificant when imprinted polymers are incubated with cells. Finally, viral tests carried out on Influenza A infected lung cells show that imprinted delivery systems delivering 1 to 3 µg of antiviral have the same efficiency as a medium containing 30 µg mL-1 of active agent. As a very interesting result, the molecularly imprinted polymers as drug delivery systems allow to increase the local concentration of antiviral, to improve their delivery when its bioavailability is low.

The development of new membranes with improved separation properties, high mechanical and thermal stability using inexpensive and naturally abundant materials is of utmost importance for sustainable development and environmental applications. Ceramic materials due to their high chemical, mechanical and thermal stability in combination to their facile surface functionalization have inspired material scientists to design innovative low-cost ceramic-based membrane supports. This study focuses on the preparation and characterization of novel asymmetric ultrafiltration ceramic membrane coated with single separation layer made of TiO2 nanoparticles, and its application to removal of alizarin dye from aqueous solutions. The membrane was prepared by a simple and one-step deposition of micrometer-thick titania layer on the internal surface of the tubular-shape porous clay-alumina membrane support from an aqueous colloidal suspension of titanium oxide (TiO2) nanoparticles with size of 10 nm. The colloidal suspension was prepared in the presence of 0.2 wt.% of Dolapix, and 30 g of an aqueous solution of polyvinyl alcohol at 12 wt.% and 66 mL of H2O. Microfiltration tubular supports of 10 mm/7 mm (outer/inner diameter) were prepared through an extrusion method followed by a sintering process using China Clay Rajmahal grade and alumina, as mineral precursors. The composition of 25% of clay and 75% of alumina was selected in this work as it showed a lower sintering temperature (Tf = 1350 °C) which could ensure low cost elaboration process, an average water flux of 850 L h−1 m−2 bar−1 as well as enhanced mechanical performance (≈37 MPa) and large porosity (48%) with an average pore diameter of 0.75 µm. SEM characterization showed that at the sintering temperature of 800 °C, the TiO2 nanoparticles coated densely and homogeneously the ceramic support forming a thin layer of about 4.2 µm in thickness and leading to a clear reduction of the mean pore size (50 nm approximatively) while providing a water permeability of 117 L h−1 m−2 bar−1. The so-designed ultrafiltration (UF) tubular ceramic membrane has proved efficient for alizarin red dye removal with a retention rate of 99% and a permeate flux of 70 L h−1 m−2 at pH 9 and a transmembrane pressure of 5 bar.

There is a world demand for biobased materials in many areas of (nano)science and (nano)technology. In particular, one can benefit from the abundant agricultural waste residues to design high performance materials provided this is achieved through smart surface chemical processes. In this context, olive pit particles were modified with in situ generated aryl diazonium salts in organic medium to provide new functional materials. Various chemical functionalities were successfully anchored onto the olive pit surfaces, namely thiol ( SH), amine ( NH2) and carboxylic acid ( COOH) moities. The as-modified olive pits served for the immobilization of gold and silver metal nanoparticles (Au and Ag NPs) and selected olive pit/NP hybrids were evaluated as catalysts. Surface composition and morphology of the pristine, grafted and nanoparticle-decorated olive pit particles were characterized by X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The hybrid materials were found to catalyse remarkably well the reduction of 4-nitrophenol to 4-aminophenol, taken as an example.

In this work, we report on the design and synthesis of an original methacrylic monolith bearing selectively cleavable disulfide bridges. One such monolith was prepared by thermally-induced free-radical copolymerization using a disulfide-based labile dimethacrylate, i.e. bis(2-methacryloyl)oxyethyl disulfide, and ethylene glycol dimethacrylate as comonomers, as well as toluene as a porogenic solvent. Upon dithiothreitol-mediated reduction of the disulfide moieties within the as-obtained disulfide-bearing monolith, thiol functions were formed at the pore surface of the resulting monolith, which was confirmed by means of in-situ Raman spectroscopy, while the pore size distribution was analyzed by mercury intrusion porosimetry. Immersion of the thiol-functionalized porous material in a chloroauric acid solution allowed for successful chelation of Au 3+ ions. Subsequent hydride-mediated reduction of the latters in the presence of NaBH 4 gave rise to the generation of gold nanoparticles (AuNPs) that were immobilized at the monolithic pore surface. The efficiency of this hybrid material based on AuNPs@porous monolith as a heterogeneous supported catalyst was further demonstrated through the reduction of a relatively toxic dye commonly used in textile and dye industries, i.e. Eosin Y. Notably, no loss of catalytic activity was observed by using this hybrid supported catalyst after 6 consecutive runs.

The emerging field of bionanotechnology aims at advancing colloidal through the development of multifunctional nanoparticle-based containers for drug delivery systems. The primary focus is to enhance the loading/release of therapeutic agents. Herein, nanocarriers with a synthetic polymer core and multilayers of polysaccharides were elaborated by combining two techniques to load all at once two different drugs. The present strategy is advantageous in comparison with other synthetic routes because at all steps, only water is used as a solvent and not organic one. Poly(vinyl acetate) (PVac) latex particles, loaded with tocopherol acetate (vitamin E) through hydrophobic interaction, were prepared via miniemulsion polymerization of vinyl acetate in the presence of sodium dodecyl sulfate (SDS) as an emulsifier. This latter leads to a negatively charged surface of latex nanoparticles and was advantageously used as a core to be coated with natural polyelectrolytes (alginate and chitosan) via the layer-by-layer deposition. Entrapment of amoxicillin (an antibiotic) into the multilayer shell was then induced through a simple diffusion process / electrostatic interaction. The loaded nanocarriers covered by (chitosan/alginate) n - chitosan layers showed high zeta-potential value (about +35 mV provided by zeta potential measurement). Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM) highlighted a spherical shape and a size lower than 200 nm. Finally, we evidence the pH-triggered drugs release (tocopherol acetate and amoxicillin) and the impact of the parameter constituting the multilayer, i.e. (i) number and (ii) crosslinking. Our results demonstrate that the elaborated latex-core polysaccharide-coated nanoparticles are promising as multifunctional nanocarrier.

Determination of proteins and peptides is among the main challenges of today's bioanalytical chemistry. The application of microchip technology in this field is an exhaustively developed concept that aims to create integrated and fully automated analytical devices able to quantify or detect one or several proteins from a complex matrix. Selective extraction and preconcentration of targeted proteins and peptides especially from biological fluids is of the highest importance for a successful realization of these microsystems. Incorporation of solid structures or supports is a convenient solution employed to face these demands. This review presents a critical view on the latest achievements in sample processing techniques for protein determination using solid supports in microfluidics. The study covers the period from 2006 to 2015 and focuses mainly on the strategies based on microbeads, monolithic materials and membranes. Less common approaches are also briefly discussed. The reviewed literature suggests future trends which are discussed in the concluding remarks.

A general approach to side-chain allyl-functionalization of three different polyelectrolytes (PEs), namely poly(allylamine hydrochloride) (PAH·HCl), branched polyethyleneimine (PEI) and poly(sodium 4-styrenesulfonate) (PSS), is reported for the first time. This functionalization does not affect the electrolytic properties of the newly functionalized PEs (named PEs-ene), as confirmed by the effective formation of PE-ene multilayer (PEM) films. The stepwise construction of these films is monitored using different techniques, including QCM, SEM, XPS, and WCA measurements. The incorporation of allyl functional groups into the PE side-chains allows for the stabilization of the resulting PEM films via thiol–ene UV photo-crosslinking in the presence of a water-soluble dithiol crosslinker. To overcome the problem of film delamination, the covalent crosslinking occurs not only between different layers of PEM films but also with the substrates preliminarily functionalized with allyl functional groups either via sulfur–gold chemistry or via chemical reduction of aryldiazonium salts using two newly synthesized anilinium derivatives. The stability of the resulting crosslinked PEM films in a strongly alkaline solution (pH = 14) is validated on gold substrates under QCM conditions (from 30 min to 3 h), while XPS and WCA measurements are used for evidencing such a stability under strongly acidic conditions (pH = 1) or at high salt concentration (saturated NaCl solution) on a modified anion-exchange membrane during a longer study time, i.e. 10 days. Finally, this stability study also gives evidence for a greater crosslinking efficiency of PEG-diSH, namely a macromolecular crosslinker, over dithiothreitol (DTT), a small molecule. The versatility and effectiveness of the approach presented here are expected to find widespread interest in different fields of emerging applications.

Herein, highly defined monolithic beds were prepared in glass microchips by photopolymerization of ethylene glycol methacrylate phosphate (EGMP), acrylamide, and N,N'-methylenebisacrylamide (BAA) using an epifluorescence microscope as UV-irradiation source. Such a fast and easy method allowed precise control of (i) the edge shape, (ii) the location along the microchannel, and (iii) the length of the monolithic plugs within glass microchips. The addition of hydroquinone, a polymerization inhibitor, to the prepolymerization mixture was beneficial for achieving local and robust incorporation of monoliths with sharp edges within microchannels. The monolith length was easily tuned from 160 to 400 μm through simple change in the magnification of the objective and was found to be repeatable (relative standard deviation7.5%). Further application for on-chip monolith-assisted solid - phase extraction is demonstrated for fluorescently labeled peptide. Both binding and subsequent elution behaviors were found to fully agree with a cation-exchange mechanism in concordance with the presence of phosphate groups at the monolith surface. Graphical abstract In-chip microscope-UV-synthesis of monolithic plugs with sharp edges.

International audience; Pathogenic bacteria resistance to antimicrobial agents has emerged as a major health issue. Developing new systems enabling inhibitory and bactericidal effects is crucial. Herein, layer-by-layer technique (LbL) was used to fabricate microcapsules composed of biopolymers, cationic polycyclodextrin (P(CD+)) and anionic alginate (alg−). This was achieved through successive adsorption of these polyelectrolytes onto calcium carbonate microparticles (CaCO3) used as template. Then, a chelating agent was added for removing the CaCO3 core, leading to microcapsules. Quartz crystal microbalance and zeta potential measurements evidenced the successful alternate adsorption of polyelectrolytes and related charge reversal, respectively, upon the LbL deposition. The shape of the capsules was characterized by Scanning Electron Microscopy (SEM) and fluorescence microscopy. The antibacterial activity of P(CD+) was first evidenced on two well-known bacteria: Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) using well diffusion method on Plate Count Agar (PCA) medium. Then, an inhibitory effect on the bacteria growth has been observed for the P(CD+)-based microcapsules during bacterial culture in Luria-Bertani (LB) broth medium. Our results pointed out towards a strong dependence of the extent of inhibition on the number of self-assembled polyelectrolytes' layers and capsules’ concentration. The effect increased with both concentration and number of layers. Acridine orange staining evidenced the bactericidal effect of P(CD+)-based microcapsules. This contribution demonstrates unambiguously that: i) aqueous solutions of P(CD+) exhibit antibacterial activity at physiological pH suggesting that P(CD+) can act as a versatile alternative to the widely studied chitosan whose antimicrobial activity is limited to acidic pH and ii) (P(CD+)/alg−)n hollow capsules can be exploited as an antibacterial agents with additional host properties.

Despite the unique mechanical strength and adhesion properties of epoxy resins, they still suffer from poor toughness and brittleness inducing poor resistance to cracks. Herein, we report an efficient method of synthesis of bioepoxy resin nanocomposites filled with highly exfoliated epoxy-grafted montmorillonite. The filled resin network was produced by covalent incorporation of a binary nanocomposite (MMT-PGMA) synthesized via in situ photoinduced polymerization of glycidyl methacrylate, into a Bioepoxy resin matrix to design a ternary nanocomposite (MMT-PGMA/Bioepoxy) and this in the presence of a green polyamine used as curing agent. The materials structure and morphology were characterized by FTIR, TGA, XRD, SEM, and TEM which show the key role of the MMT surface modification on its interfacial adhesion with the epoxy resin. The results showed that the clay interlayer d-spacing increases from 1.23 nm to more than 2.2 nm upon grafting of the polymer. The homogeneous solvent-free dispersion of hybrid cl...

International audience; Herein, we propose the synthesis of a microspherical imprinted hydrogel meant for the controlled release of a nucleotide, adenosine 5'-monophosphate (5'-AMP). Indeed, molecularly imprinted polymers-based (MIPs) materials possess remarkable selective molecular recognition ability that mimicks biological systems. MIPs have been used in numerous applications and hold great promise for the vectorization and/or controlled release of therapeutics and cosmetics. But, the conception of imprinted hydrogels-based drug delivery systems that are able to release polar bioactive compounds is explored weakly. Herein, the synthesis of imprinted hydrogel microbeads by inverse Pickering emulsion is detailed. Microspheres showed a large 5'-AMP loading capacity, around 300 mg·g-1, and a high binding capacity comparatively to the non-imprinted counterpart. The MIP had a thermo-responsive release behavior providing sustained release of adenosine 5'-monophosphate in an aqueous buffer simulating both human skin pH and temperature.

The surface chemistry of aryl diazonium salts has progressed at a remarkable pace in the last two decades, and opened many avenues in materials science. These compounds are excellent coupling agents for polymers to surfaces via several surface-confined polymerization methods. For the first time, we demonstrate that diazonium salts are efficient for surface initiating radical photopolymerization in the visible light of methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA) taken as model monomers. To do so, 4-(dimethylamino)benzenediazonium salt was electroreduced on gold plates or flexible ITO sheets to provide 4-(dimethylamino)phenyl (DMA) hydrogen donor layers; while excited state camphorquinone acted as the free hydrogen abstractor. In the same way, we co-polymerized HEMA and MMA with ethylene glycol dimethacrylate in order to obtain crosslinked polymer grafts. We demonstrate by XPS that gold was efficiently screened by the polymer layers and that the wettability of the surfaces accounts for the hydrophilic or hydrophobic characters of the tethered polymers. Homo- and crosslinked PMMA grafts were found to resist removal by the paint stripper methyl ethyl ketone. The grafted DMA/camphorquinone system operating in the visible light holds great promises in terms of adhesion of in situ designed continuous or patterned polymer coatings on various substrates. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 3506–3515

A triphenylmethylamine-functionalized monolithic capillary column was newly designed for reversed-phase capillary electrochromatographic applications. Incorporation of the three phenyl rings-containing selector (also referred to as trityl selector) was achieved through post-polymerization functionalization of a generic monolithic matrix bearing nucleophilic-sensitive hydroxysuccinimide moieties. Such a 3D polymer matrix was obtained through UV-induced in situ free radical copolymerization of N-acryloxysuccinimide and ethylene dimethacrylate. The separation properties of the trityl monolithic capillary column were initially evaluated vis-a-vis polycyclic aromatic hydrocarbons, as model hydrophobic compounds, and compared to the separation ability of a benzylamine-functionalized monolithic capillary column prepared using the same generic monolithic matrix. Electrochromatographic separation of phenols and anilines was also considered, and our preliminary results suggest the occurrence of hydrophobic interactions due to the aromatic and non-polar nature of the surface-grafted trityl selector. The triphenyl monolithic capillary column exhibited relative standard deviation values (% RSD) below 4.1 % for the here-studied chromatographic parameters, namely, retention factor, selectivity, resolution, and efficiency.

A new and efficient approach based on the thiol–maleimide Michael addition click reaction is presented for the post-polymerization modification of porous monoliths. To establish the method, a generic matrix containing N-hydroxysuccinimide esters (NHS) as surface reactive units is synthesized inside a capillary column through photoinduced polymerization of N-acryloxysuccininimide and ethylene glycol dimethylacrylate. The as-obtained reactive monolith is further surface-functionalized through nucleophilic substitution of the NHS units with 2-aminoethanethiol. Following such an approach, free thiols are available for reacting with functional maleimides through Michael addition. Success of the successive molecular level surface functionalization steps is ascertained by Raman spectroscopy measurements. Of utmost importance, it is undoubtedly demonstrated that the chemical nature, i.e., hydrophilic versus hydrophobic, of the surface-grafted maleimide governs the surface properties of the corresponding monoliths. More precisely, the electrochromatographic separation mode is found to be intimately correlated to the chemical nature—C8-like versus COOH-like—of the maleimide-functionalized monolith allowing separation upon either reversed-phase or hydrophilic interaction modes, respectively. Furthermore, the strategy is extended to enhancement of surface NHS reactivity enabling the efficient grafting of model biomacromolecule via a spacer arm-driven effect.

Clay–polymer nanocomposites were prepared by living free radical photopolymerization initiated from a lamellar clay-anchored photoiniferter resulting from a cation exchange reaction of sodium by diethyldithiocarbamate benzyldiazonium tetra-fluoroborate salt. The success of the cation exchange process, followed by iniferter graft polymerization of glycidyl methacrylate (GMA) on clay nanoplatelets was confirmed by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). Thereby, the original cation exchange method induced by diazonium salt produces intercalated nanocomposite materials with an important organic mass loading around 41 wt%. More importantly, the content of the organic component included in the final nanocomposite material could be controlled by the diazonium salt concentration used during the synthesis.

A monolithic material with dual functionality was successfully synthesized through the combination of UV-initiated free radical copolymerization, nucleophilic substitution reaction and thiol–ene radical photoaddition. Firstly, poly(N-acryloxysuccinimide-co-ethylene dimethacrylate) was prepared by non-solvent induced phase separation occurring within the course of the polymerization of the respective monomers. Toluene was selected as a porogen providing percolating pores in the micrometer range. Secondly, N-hydroxysuccinimide units on the monolith surface were converted into ene functionality through covalent immobilization of allylamine. Finally, thioglycerol served as a hydrophilizing agent of the pore surface via surface confined thiol–ene click grafting. All the preparation steps were performed, in situ, i.e. within the confines of UV-transparent capillary channels, affording a micro-column with electro-osmotic flow generation and hydrogen bond forming abilities. Raman microspectrocopy confirmed that all the synthetic steps were accomplished successfully. Investigation of the electrochromatographic retention behavior of hydrophobic and hydrophilic solutes revealed the possibility of tuning the interfacial character of the diol-functionalized monolithic stationary phases with respect to the water content in the surrounding liquid phase. For the acetonitrile-rich mobile phase, the diol-monolith interface exhibited highly hydrophilic character allowing fast and efficient separation of phenol and aniline derivatives, as well as methylxanthines and pyrimidic bases. Moreover, the relative standard deviation of the retention factor values was less than 3.3%.

In-capillary reactive polymer monoliths have been prepared from glycerol carbonate methacrylate functional monomers. Following functionalization with suitable ligands and eventually after immobilization of metallic nanoparticles, these materials can be successfully employed as supports for chromatographic applications or microreactors for flow-through catalysis.

In this work, a 3D finite element model has been developed to compute the macroscopic elastic properties of polymer/clay nanocomposites (PCNs) from the microstructure morphologies and the elastic behaviour of each phase. Microstructural parameters of clay or clay stacks such as elastic properties, aspect ratio, interlayer spacing and clay volume fraction have been taken into account in the proposed models. A parametric study of the effect of these parameters on the macroscopic elastic properties of PCNs has been carefully investigated. The results show that the macroscopic rigidity of PCNs materials depends not only on the clay volume fraction but also on the dispersion state of clay platelets in the polymer matrix. An exfoliated structure may improve the macroscopic rigidity of PCNs much more efficiently than intercalated ones, particularly at high volume fraction of clays. The key role of interphase on the mechanical properties enhancement of PCNs has also been demonstrated. In addition, the partially exfoliated morphology, in which individual clay layers and intercalated blocks are simultaneously present in the polymer matrix, has been studied. The last morphology is commonly encountered in PCN processing, especially when high clay content is used. The comparison with the experimental and theoretical results extracted from the literature has been performed.

We report here a one-pot approach to achieve, for the first time, the simultaneous synthesis/anchorage of polymer monoliths in native PDMS channels. Monoliths consisting of ethylene glycol methacrylate phosphate (EGMP) and N,N′-methylene-bis-acrylamide (BAA) were synthesized within PDMS microchips through a photo-driven process. The EGMP monomer has never been employed for this purpose. To achieve this method, both the chemical nature of the photoinitiator and irradiation conditions were investigated. The main result was that the use of 2-methyl-4′-(methylthio)-2-morpholino-propiophenone, as photoinitiator, allowed simultaneous polymerization and anchorage of the resulting monolithic structure onto the PDMS channel. Morphology of the monolith revealed a compact structure composed of uniform nodules (135 ± 30 nm) and small pores (10–200 nm). The high specific surface area (66 m2/g) and the sufficient permeability (14.35 × 10−14 m2) obtained make the monolith particularly interesting for preconcentration. Such free radical-mediated method open new perspectives for preconcentration and electrophoretic separation in PDMS microsystems.

International audience; Non-covalent chiral stationary phases for open-tubular capillary electrochromatography (OT-CEC) were developed using polyelectrolyte multilayer (PEM) coatings. These chiral coatings were made by alternately flushing the separation capillary with cationic and anionic polymers using a polymer of trimethylammonium-β-CD (pCD+) as a chiral selector. The layer-by-layer construction was monitored by EOF measurements. To our knowledge, it is the first OT-CEC chiral stationary phase based on a layer-by-layer assembly including an ionic cyclodextrin polymer. The composition of PEM coating was optimized as regards chiral separation. Thus, the influence of the nature of the first adsorbed cationic polymer (pCD+, polyethyleneimine or poly(diallyldimethyl ammonium chloride)) and the influence of the anionic polymer (poly(sodium 4-styrenesulfonate), polycarboxymethyl-β-CD or chondroitin sulfate) were studied with regard to the apparent surface charge and the enantioselective properties of the coatings. Interactions between the studied enantiomers and the internal layers of the stationary phase were pointed out. We found that the optimal stationary phase was based on a pCD+/poly(sodium 4-styrenesulfonate)/pCD+ three-layer coating. This optimal coating was found to be stable as evidenced by the RSD of 2.2 % for the EOF values calculated from five independent analyses. It was effective for the chiral separation of both neutral and anionic solutes.

Novel chemical stimulus-responsive multilayer assemblies have been elaborated through the layer-by-layer deposition of oppositely charged polysaccharides on either flat or spherical surfaces. Concentration-dependent glucose responsiveness was obtained through chemical modification of alginate, selected as polyanion, with phenylboronic acid moieties. QCM measurements showed that the alginate derivate still self-assembles though electrostatically-driven interactions with chitosan at pH 4, and that the polysaccharides multilayer assemblies, as obtained after crosslinking, exhibit improved stability versus pH (in the range 4-9) as well as swelling ability in the presence of glucose-containing solution. Glutaraldehyde-mediated crosslinking was achieved through reaction with free primary amines of chitosan. This approach was further extended to the preparation of smart capsules using CaCO3 microparticles as dissolvable core templates. Success of the LbL deposition process, stability (pH range 4-9) of the multilayer assemblies and glucose-induced swelling were fully confirmed for the microcapsules. One of the major result of this study is that crosslinking prevents total dissolution of the capsules and enables modulating the permeability of the polysaccharide shell yielding controlled release on in-capsule entrapped low molecular weight molecules.

A microdevice combining online preconcentration and separation of phosphopeptides was developed in a glass microchip. An ethylene glycol methacrylate phosphate (EGMP), acrylamide (AM) and bisacrylamide (BAA) based monolith was synthesized within microchannels through a photo-driven process. Morphological investigations revealed a homogeneous monolithic structure composed of uniform nodules (∼0.8 μm), with a large pore volume (0.62 cm3 g-1) and sufficiently high specific surface area (34.1 m2 g-1). These features make the monolith particularly interesting for preconcentration purposes. Immobilization of Zr4+ ions on the phosphate groups present at the poly(EGMP-co-AM-co-BAA) monolith surface leads to immobilized metal affinity chromatography support. This monolith-Zr4+ showed a great capacity to capture phosphopeptides. Successful preconcentration and separation of a mixture of ERK2 derived peptides differing only by their phosphorylation degree and sites could be achieved with signal enhancement factors between 340 and 910 after only 7 min of preconcentration. This integrated microdevice represents a novel approach for phosphoproteomic applications.

In this chapter, methods of preparation of polymer–clay nanocomposites are discussed and special attention is paid to advanced synthetic methods including surface-initiated polymerization, controlled radical polymerization, click coupling chemistry, photodriven grafting, and polymerization. These strategies have been successfully used for both the chemical modification of clay surface and the covalent grafting of clay to polymer matrices serving as dispersion media. As such, this contribution should not be considered as an exhaustive review of the field but rather as a focused discussion on selected methods that caught our attention. Beyond synthetic strategies, properties improvement, morphological characterization, and applications of the as-prepared polymer nanocomposites are also covered and rationalized in terms of chemical nature of the nanocomposites. The discussion encompasses all types of clay nanoparticles, although myriad examples are devoted to montmorillonite.

International audience; Polymer/clay nanocomposites (PCNs) are multi-functional materials that have superior mechanical and thermal properties than polymer-based materials while maintaining their characteristic properties of lightweight and optical clarity. These materials are obtained by adding small amounts of clay nanofillers to a polymer matrix. In this work, we proposed a molecular model to investigate the morphology and thermomechanical properties of thermosetting clay nanocomposites. The epoxy matrix was composed of several representative cross-linked epoxy units, and different structures of PCNs, which correspond to intercalated or exfoliated status, were considered by varying the amount of polymer phase in the interlayer space. Molecular dynamics simulations of different nanocomposite structures were used to provide atomistic insights into the arrangement of the constitutive components of PCNs, the molecular interactions occurring in the interphase zone, and the influence of silicate layer on the thermodynamic and elastic properties of these multi-functional materials

Ultrathin films of molecularly imprinted polymer (MIP) were prepared by photoiniferter on PVC beads for the selective uptake of lysozyme, taken as a model protein. Acrylamide was selected as the functional monomer and N,N-methylenebisacrylamide as the crosslinking agent. The copolymerization process was confined to the surface of the PVC beads grafted with diethyldithiocarbamate iniferter initiator in the presence of lysozyme. After extraction of lysozyme from the shell of the PVC-MIP beads, the latter were then used as artificial receptors for the rebinding of lysozyme. The sequential steps of the modification of PVC beads were monitored by XPS, infrared and Raman spectroscopies. The imprinting step was found to be essential as the PVC-MIP beads could recognize lysozyme but not the non-imprinted beads (PVC-NIP). The binding properties of PVC-MIP beads were determined using UV spectroscopy from adsorption isotherms of lysozyme, cytochrome, and myoglobin. The imprinted beads were found to be highly selective toward lysozyme over the competitive proteins. This work shows the interest of photoiniferter as an efficient mean for the design of molecularly imprinted polymer beads for rapid, selective removal of proteins. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43694.

In situ photoinduced SI-ATRP is reported as a novel and efficient route for preparing intercalated nano-clay fillers bearing clickable functions. Poly(propargyl methacrylate) chains are grown inside the clay interlayer after silanisation and grafting of bromine ATRP initiator. The generic clickable character is demonstrated through grafting with azidomethyl benzene and mercaptosuccinic acid via photodriven 1,3-dipolar cycloaddition and thiol-yne click reactions, respectively.

Nanometer-scale multilayered coatings were prepared by sequential surface reactions on gold plates. First 4-ethynylphenyl organic layer was electrografted from the parent diazonium tetrafluoroborate salt providing reactive alkynylated gold plate (Au-Y). The latter served for clicking mercaptosilane via a thiol-yne photo-triggered reaction to obtain alkoxysilane-functionalized surface. The trialkoxysilane top groups in turn served as anchor sites for the final sol-gel coating resulting from the surface reaction between aminopropylsilane and tetraethoxysilane (TEOS). It is demonstrated that two coupling agents, namely, aryl diazonium salt and silane, can be coupled using photo-triggered thiol-yne click reaction, resulting in robust multilayered coatings. In addition, the process is versatile in that it offers the possibility to design patterned surfaces. The top sol-gel layer can in turn be reacted with aminosilane, therefore providing a reactive and functional surface that can be used for different applications given the reactivity of amine groups. This approach opens new avenues for photo-triggered click reactions of aryl layers from diazonium salts. It shows that the new class of surface modifiers and coupling agents has much to offer and continues to be renewed for achieving tightly bound, reactive top coatings.

International audience; Homopolymer grafts from α-tert-butoxy-ω-vinylbenzyl-polyglycidol (PGL) were prepared on gold and stainless steel (SS) substrates modified by 4-benzoyl-phenyl (BP) moieties derived from the electroreduction of the parent salt 4-benzoyl benzene diazonium tetrafluoroborate. The grafted BP aryl groups efficiently served to surface-initiate photopolymerization (SIPP) of PGL. In similar conditions, SIPP of hydroxyethyl methacrylate (HEMA) permitted the production of PHEMA grafts as model surfaces. Water contact angles were found to be 66°, 15°, and 0° for SS-BP, SS-PHEMA, and SS-PPGL, respectively. The spontaneous spreading of water drops on SS-PPGL was invariably observed with 1.5 μL water drops. PPGL thus appears as a superhydrophilic polymer. Resistance to nonspecific adsorption of proteins of PPGL and PHEMA grafts on gold was evaluated by surface plasmon resonance (SPR) using antibovine serum albumin (anti-BSA). The results conclusively show that PPGL-grafts exhibit enhanced resistance to anti-BSA adsorption compared to the well-known hydrophilic PHEMA. PPGL grafts were further modified with BSA through the carbonyldiimidazole activation of the OH groups providing immunosensing surfaces. The so-prepared PPGL-grafted BSA hybrids specifically interacted with anti-BSA in PBS as compared to antimyoglobin. It is clear that the superhydrophilic character of PPGL grafts opens new avenues for biomedical applications where surfaces with dual functionality, namely, specific protein grafting together with resistance to biofouling, are required.

6 pages; International audience; This paper reports the preparation of a molecularly imprinted inverse opal hydrogel containing a 2D defect layer, by combining the Langmuir-Blodgett technique and the photonic crystal template method. By coupling the exceptional characteristics of molecularly imprinted polymers, sensitive to the presence of a target molecule, and those of photonic crystals in a single device, we could obtain a defect-embedded imprinted photonic polymer consisting in a three-dimensional, highly-ordered and interconnected macroporous array, where nanocavities complementary to analytes in shape and binding sites are distributed. As a proof of concept, we prepared a three-dimensional macroporous array of poly(methacrylic acid) (PMAA) containing molecular imprints of bisphenol A (BPA) and a planar defect layer consisting in macropores of different size. The optical properties of the resulting inverse opal were investigated using reflection spectroscopy. The defect layer was shown to enhance the sensitivity of the photonic crystal material, opening new possibilities towards the development smart optical sensing devices.

The free radical copolymerization of vinylpyrrolidone (VP) with 2-hydroxy-3-methacryloyloxypropyl β-cyclodextrin (βW7 MAHP), a derivative of hydroxypropyl β-cyclodextrin (CD) substituted by polymerizable methacryloyl groups, is carried out in water by varying the molar ratio of the comonomers. It is found that the higher the molar ratio of βW7 MAHP to VP, the larger the molar mass of the water-soluble copolymer. A size exclusion chromatography analysis coupled with multiangle laser light scattering detection (SEC–MALLS) suggests that VP-rich copolymers with a mass-average molar mass (MM) of about 2.5 × 104 g mol−1 may consist of βW7 MAHP dimers, trimers, and oligomers containing few CD units whereas βW7 MAHP rich copolymers with an MM of about 5.5 × 106 g mol−1 are likely to be dominated by crosslinked polymer materials. βW7 MAHP-co-VP copolymers coated on porous silica are used as high-performance liquid chromatography chiral selectors. The effects of the structural features of the guest molecule and the characteristics of the chiral stationary phases on the retention and resolution are evaluated. SEC–MALLS detection shows that, by varying the comonomer feed, copolymers with different molar masses and macromolecular structures are formed. The chiral separation ability of Copo VP is evaluated toward enantiomers having one or more aromatic rings as a function of the amount of copolymer adsorbed onto the silica surface, the βW7 MAHP content, and the concentration of solute. It is clear that the column combining the greater amounts of adsorbed copolymer and βW7 MAHP exhibits better resolving power. Moreover, the size, geometry, and functionality of the guest molecule are important factors that strongly affect the enantioselectivity. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2364–2374, 2005

The characterization of a new cyclodextrin (CD) derivative, developed by Wacker Chemie GmbH under the name βW7-MAHP and consisting of methacrylic moieties attached to hydroxypropyl-β-CD units, was investigated in terms of molecular structure and reactivity. The structural study was performed using a matrix-assisted laser-desorption ionization time-of-flight (MALDI-TOF) mass spectrometry analysis, which revealed that βW7-MAHP is a mixture of at least 60 identified compounds. The substituent natue was determined from the two successive chemical modifications performated on β-CD (hydroxypropylation with propylene oxide followed by the reaction with glycidyl methacrylate). Furthermore, each reaction resulted in a mixture of compounds haveing different numbers of substituents because of the polyfunctionality of the β-CD molecule (14 secondary and 7 primary OH group). Only 50 wt.% of the mixture consisted of polymerizable components among which a small proportion contained two or more methacrylic residues. The polymerizability of βW7-MAHP was studied, and the reactivity ratios in the copolymerization with 1-vinyl-2-pyrrolidinone were estimated. Soluble copolymers were obtained for monomer compositions having a βW7-MAHP fraction less than 60 mol-% whereas for higher amounts cross-liked gels were produced.

New silica based supports for use in HPLC separations have been prepared by the coating of a series of copolymers containing various molar fractions of vinylpyrrolidone (VP) and methacryloyloxypropyl beta cyclodextrin (βW7 MAHP) units on LiChrospher Si100. These chromatographic supports were fully characterised using the following techniques: thermogravimetric analysis, specific area and porous volume measurements, scanning electron micrography, NMR, EDAX and RAMAN spectroscopy. It was demonstrated that the interactions of the copolymer with the silica surface imply the VP units through H-bonding between the amide groups and the silanol functions explaining the increase of the polymer adsorption with the VP residue content. The analysis of the surface area, porous volume and pore size distribution showed that the coating process involved first the largest pores of silica and in a second step the smallest ones. From the 29Si NMR spectroscopy and scanning electron microscopy analysis, it appears that only the supports with high amounts of polymer adsorbed ensured a complete passivation of the silanol groups.

This paper describes the preparation of a chiral stationary phase based on a 2-hydroxypropyl-β-cyclodextrin polymer coated on porous silica. This method requires first the synthesis of a water-soluble cyclodextrin polymer carried out by the polycondensation of 2-hydroxypropyl-β-cyclodextrin with epichlorohydrin under controlled conditions. In the second step, the obtained copolymer was immobilised onto the porous silica surface by physisorption. The macromolecular features of the copolymer were investigated by size exclusion chromatography coupled with a multiple angle laser-light scattering detector. The evolution of the structural parameters of the modified silica beads (specific surface area and pore size distribution) was determined using a nitrogen adsorption method. The enantio-separation capability of the coated silica phase was evaluated for different polycyclic molecules. It was found that the enantioselectivity was strongly influenced by the geometry and shape of the solutes under study and the presence of an acidic modifier in the mobile phase.