This work combined two tools, giant unilamellar vesicles (GUVs) and core-shell magnetic nanoparticles (CSMNs), to develop a simplified model for studying interactions between the cell membrane and ...nanoparticles. We focused on charged functionalized CSMNs that can be either cationic or anionic. Using optical, electron, and confocal microscopy, we found that giant vesicle-nanoparticle interactions did not result from a simple electrostatic phenomenon because cationic CSMNs tended to bind to positively charged bilayers, whereas anionic CSMNs remained inert.
The use of emulsions based on vegetable oils as alternative to existing methods for the preparation of iron oxide/silica particles leads to microsized or nanosized magnetic spheres depending on ...shearing rate. Display omitted
► A green alternative to obtain magnetic silica (MS) beads has been designed. ► Polydisperse microspheres or monodisperse nanospheres can be obtained. ► The nanocomposites compare well with MS beads synthesized by conventional methods. ► Hybrid MS microspheres modified by mercaptoporpyl moieties can also be prepared. ► Inorganic and hybrid MS microspheres were tested as adsorbents for heavy metals.
A green and inexpensive alternative to existing methods for the preparation of magnetic iron oxide/silica nanocomposite particles has been investigated. The use of water-in oil emulsions based on vegetable oils instead of usual solvents led to microsized or nanosized magnetic silica spheres exhibiting similar characteristics to those of classical procedures. Furthermore this approach is very general since a large class of porous magnetic colloids differing in size or iron oxide fraction has been obtained. This work emphasizes the importance of the level of the shearing during the emulsification step with regard to the size and monodispersity of the prepared beads. All the materials prepared were fully characterized (SEM and TEM microscopies, SQUID magnetometry, N2 sorption volumetry, etc.). In addition, samples functionalized by thiol groups have been synthesized and successfully tested for the removal of heavy metals in water-treatment.
This article deals with the first covalent grafting of an enzyme on twice functionalized
γ
-Fe
2
O
3
@SiO
2
core–shell magnetic nanoparticles. First, amino-PEG functionalized nanoparticles were ...synthesized in order to comply with non-toxic platforms that would be stable in high concentration and would exhibit chemical groups to allow further coupling with biomolecules. This approach produces a colloidal suspension of covalently grafted enzymes that remains stable for months and mimics the enzyme–substrate interactions in solution. Secondly, nanoparticles synthesis and enzyme coupling process were reported and the catalytic properties of bound enzymes were measured and compared with that of the free one. These new materials appear to be useful tools for enzymatic catalysis research and may be extended to other biomolecules. Furthermore, magnetic properties of these materials open the way to separation, purification, and transport under magnetic field.
A sensor microsystem prototype, using copper phthalocyanine thin film as sensitive layer, and dedicated to ozone evaluation, was developed. The methodology implemented is based on cyclic sensor ...recalibrations by thermal cleaning of the sensitive membrane, and on pollutant concentration quantification according to the kinetics of sensor response. Results of laboratory experiments for various NO
2 and O
3 concentrations, in the range of 10–200 ppb, illustrate the selectivity of CuPc sensors towards ozone, obtained by our methodology. We have shown that ozone selectivity is especially improved for short time of exposure (few minutes) and for phthalocyanine layer maintained at low temperature (80 °C). For optimal conditions, our microsystem exhibits a threshold lower than 10 ppb, a resolution lower than 10 ppb, and good reproducibility of measurements. Performances obtained in real urban atmosphere are satisfying to ensure real time evaluation of ozone during several days. Long-term stability and the detection of NO
2 by associating chemical filters to our microsystem will be also discussed.
Quinones (=cyclohexa‐2,5‐diene‐1,4‐diones) and hydroquinones (=benzene‐1,4‐diols) belong to species that are balanced between their redox character and their ability to build supramolecular ...complexes. Considering the ubiquinol 2,3‐dimethoxy‐5‐methyl‐1,4‐dihydroquinone (=2,3‐dimethoxy‐5‐methylbenzene‐1,4‐diol; 1), the tendency to undergo an oxidation side reaction was overcome by combining this electron‐donating species 1 with a nonreactive partner, benzene‐1,2,4,5‐tetracarbonitrile (TCNB; 3), to yield a 2 : 1 charge‐transfer (CT) complex 4. This work illustrates how very convenient the solvent‐free techniques are to access intermolecular species. X‐Ray diffraction studies revealed that pure ubiquinol 1 (structure included) crystallizes in two enantiomeric conformations, while the triads 4 formed with TCNB (3) exist as meso forms assembled via H‐bonds in zigzag‐chains patterns.
Issue Title: Special Issue: Special focus on Carbon-based Nanostructures This article deals with the first covalent grafting of an enzyme on twice functionalized γ-Fe^sub 2^O3@SiO2 core-shell ...magnetic nanoparticles. First, amino-PEG functionalized nanoparticles were synthesized in order to comply with non-toxic platforms that would be stable in high concentration and would exhibit chemical groups to allow further coupling with biomolecules. This approach produces a colloidal suspension of covalently grafted enzymes that remains stable for months and mimics the enzyme-substrate interactions in solution. Secondly, nanoparticles synthesis and enzyme coupling process were reported and the catalytic properties of bound enzymes were measured and compared with that of the free one. These new materials appear to be useful tools for enzymatic catalysis research and may be extended to other biomolecules. Furthermore, magnetic properties of these materials open the way to separation, purification, and transport under magnetic field.PUBLICATION ABSTRACT
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