Reversible film formation from nano-sized PNIPAM particles below glass transition

Reversible film formation process from nano-sized Poly(N-isopropylacrylamide) (PNIPAM) microgel particles were studied during heating-cooling cycles at various rates. Photon transmission technique was used and transmitted photon intensity I (tr) was monitored during heating-cooling cycles. The increase and decrease in I (tr) during heating and cooling was explained with the void closure and void reconstruction processes, and the corresponding activation energies were measured. It was observed that PNIPAM microgels required less energy during reconstruction of voids than their closure.Publisher's Versio

A Sensitive Micro Conductometric Ethanol Sensor Based on an Alcohol Dehydrogenase-Gold Nanoparticle Chitosan Composite

In this paper, a microconductometric sensor has been designed, based on a chitosan composite including alcohol dehydrogenase—and its cofactor—and gold nanoparticles, and was calibrated by differential measurements in the headspace of aqueous solutions of ethanol. The role of gold nanoparticles (GNPs) was crucial in improving the analytical performance of the ethanol sensor in terms of response time, sensitivity, selectivity, and reproducibility. The response time was reduced to 10 s, compared to 21 s without GNPs. The sensitivity was 416 µS/cm (v/v%)−1 which is 11.3 times higher than without GNPs. The selectivity factor versus methanol was 8.3, three times higher than without GNPs. The relative standard deviation (RSD) obtained with the same sensor was 2%, whereas it was found to be 12% without GNPs. When the air from the operator’s mouth was analyzed just after rinsing with an antiseptic mouthwash, the ethanol content was very high (3.5 v/v%). The background level was reached only after rinsing with water

Development of an ImmunoFET for Analysis of Tumour Necrosis Factor- (alfa) in Artificial Saliva: Application for Heart Failure Monitoring

Assessing tumour necrosis factor-(alfa) (TNF-(alfa)) levels in the human body has become an essential tool to recognize heart failure (HF). In this work, label-free, rapid, easy to use ImmunoFET based on an ion-sensitive field effect transistor (ISFET) was developed for the detection of TNF-(alfa) protein. Monoclonal anti-TNF-(alfa) antibodies (anti-TNF-(alfa) mAb) were immobilized on an ISFET gate made of silicon nitride (Si3N4) after salinization with 11-(triethoxysilyl) undecanal (TESUD). The obtained ISFET functionalized with the mAbs (ImmunoFET) was used to detect TNF-(alfa) protein in both phosphate buffer saline (PBS) and artificial saliva (AS). The change in the threshold voltage of the gate (DVT) showed approximately linear dependency on the concentration of the antigens in the range 5-20 pg/mL for both matrixes. The cross-selectivity study showed that the developed ImmunoFET demonstrated to be selective towards TNF-(alfa), when compared to other HF biomarkers such as N-terminal pro-brain natriuretic peptide (NT-proBNP), interleukin-10 (IL-10), and cortisol, even if further experiments have to be carried out for decreasing possible unspecific absorption phenomena. To the best of our knowledge, this is the first ImmunoFET that has been developed based on Si3N4 for TNF-(alfa) detection in AS by electrical measurement

La nanotecnología en las ciencias biológicas

La nanotecnología ha acompañado al hombre en varias etapas de su evolución, permitiendo el desarrollo de productos innovadores que han mejorado su calidad de vida. Actualmente, ésta es una de las áreas de mayor crecimiento a nivel mundial en lo que a investigación y aplicación tecnológica se refiere. En este contexto, áreas de las Ciencias Biológicas en constante desarrollo, como la agricultura, los alimentos, el medio ambiente y la medicina, han incorporado avances nanotecnológicos de alto impacto en los últimos años. Dentro de los productos desarrollados con mayor aplicación se incluyen nanomateriales, nanosistemas de liberación, nanopelículas, nanorobots, nanodispositivos electrónicos, nanotubos de carbono y nanopartículas metálicas, entre otros. El presente trabajo aborda los principales productos desarrollados a partir de la nanotecnología y su aplicación en las Ciencias Biológicas, destacando la importancia y el avance que otorgan a la vida del hombre

Topical co-delivery of indomethacin and nigella sativa L. essential oil in poly-cappa-caprolactone nanoparticles: in vitro study of anti-inflammatory activity

Indomethacin is a potent, nonselective Non-steroidal Antiinflammatory Drug (NSAID) but its low water-solubility precludes its use as topical dosage form. As with other NSAIDs, the systemic delivery is associated with high risk of serious gastrointestinal adverse events including bleeding, ulceration and perforation of stomach and intestines. Here we demonstrate a safer way of administration i.e via topical demonstrating synergistic effects when co-delivered with Nigella sativa L. seeds essential oil (NSSEO) in the form of coencapsulated particles (~200 nm) of poly--caprolactone. The particles showed penetrability across stratum corneum to dermis layer in ex-vivo human skin. Further study in the xyline-induced ear edema in mice was performed, and co-encapsulated particles demonstrated highest antiinflammatory effect compared to indomethacin particles and indomethacin gels. Despite slower onset compared to indomethacin gels, the inflamed ear continued to show reduction in thickness over 8 hours of observation demonstrating synergistic and pro-longed effect contributed by NSSEO. In immunohistochemistry study of CD45+, the mice ears treated with co-encapsulated particles showed considerable reduction in lesions, epidermal-dermal separation and inflammatory cells (lymphocytes and neutrophils) infiltration as compared to other formulation. Based on microscopic evaluation, the anti-inflammatory inhibition effect of co-encapsulated particles is the highest (90%) followed by indomethacin particles (79%) and indomethacin gel (49%). The findings suggest not only skin permeability of indomethacin significantly improved but also the therapeutic effects, all provided by the presence of NSSEO in the particles. This study paves the way to more co-encapsulation of any other contemporary medicines in combination with this wholesome natural oil, NSSEO

Elaboration de latex magnétiques à partir d'émulsions directes de ferrofluide (forces de surface entre conjugués particules/oligodésoxyribonucléotides)

Ce travail a consisté à élaborer des supports magnétiques particulaires fonctionnalisés à partir d'émulsions directes de ferrofluide pour des applications dans le domaine du diagnostic médical. Cela a d'abord nécessité la préparation d'émulsions magnétiques de type huile-dans-eau obtenues par émulsification d'un ferrofluide organique. Ce ferrofluide a été synthétisé par voie chimique, puis caractérisé à l'aide de nombreuses techniques afin de déterminer sa composition, la nature et la taille des nanoparticules d'oxyde de fer ainsi que ses propriétés magnétiques. Les émulsions magnétiques obtenues ont également été caractérisées afin de mettre en évidence la composition et la morphologie des gouttelettes ainsi que les propriétés colloïdales. Les particules de latex magnétiques ont ensuite été préparées par polymérisation à l'intérieur des gouttelettes d'émulsion gonflées par le styrène. Deux principaux systèmes de polymérisation ont été étudiés, le premier faisant intervenir un amorceur organosoluble (AIBN), le second un amorceur hydrosoluble (KPS). L'utilisation d'un polymère amphiphile, dont l'adsorption à la surface des gouttes d'émulsion a été préalablement étudiée, a permis d'obtenir des particules de latex fonctionnalisées. Différents mécanismes de polymérisation ont également été proposés en fonction de la nature de l'amorceur utilisé. La morphologie des particules de latex magnétiques a été discutée en détail sur la base d'une approche thermodynamique et cinétique du phénomène. Finalement, des conjugués particules/ODN ont été préparés puis étudiés à l'aide de la technique de mesure de forces colloïdales, qui a montré l'évolution de la nature des forces répulsives s'exerçant entre les particules en fonction du pH et de la force ionique du milieu. L'épaisseur de la couche d'ODN immobilisée en surface a également été déterminée par cette méthode.LYON1-BU.Sciences (692662101) / SudocSudocFranceF

Multi-Stimuli Responsive Magnetic Core–Shell Particles: Synthesis, Characterization and Specific RNA Recognition

International audienc

Nucleic acid sample preparation for in vitro molecular diagnosis: from conventional techniques to biotechnology

International audienc

Élaboration de latex fluorescents et de latex magnétiques par polymérisation en miniémulsion en vue d'applications biomédicales

Ce travail a consisté à élaborer deux types de particules de latex submicroniques, l un fluorescent et l autre magnétique, en vue d applications dans le diagnostic biomédical. La synthèse de particules de latex fluorescentes, submicroniques et isodisperses en taille, a été réalisée en incorporant des Quantum dots (QDs ; CdSe/ZnS), par polymérisation en miniémulsion. L étude a montré que l intensité de fluorescence des particules augmente linéairement avec la concentration initiale des QDs. L utilisation de QDs sans la couche de ZnS a conduit à des particules peu fluorescentes. Les particules submicroniques élaborées peuvent être fonctionnalisées par des groupements carboxyliques. Enfin, la taille des particules peut être contrôlée par la concentration initiale de tensioactif (SDS). Parallèlement, des particules magnétiques ont été préparées en utilisant un ferrofluide composé de nanoparticules d oxyde de fer stabilisées dans le styrène par un tensioactif phosphaté polymérisable ou surfmère . Ces ferrofluides organiques stables et superparamagnétiques ont été encapsulés par polymérisation en miniémulsion et donnent lieu à des particules de latex dans lesquelles la répartition des oxydes de fer est homogène au sein de la matrice polymère. Les propriétés magnétiques des particules dépendent des caractéristiques du ferrofluide utiliséThe aim of this work was the elaboration of two kinds of latexes, fluorescent and magnetic, for diagnosis purpose. The synthesis of submicrometer and monodisperse fluorescent particles was carried out via the encapsulation of Quantum Dots (QDs; CdSe/ZnS) by miniemulsion polymerization. The results showed that the fluorescence signal of the particles increased linearly with the initial concentration of QDs. The use of QDs without the ZnS layer led to particules exhibiting a low fluorescent signal. The particles can also be functionalized by carboxylic groups. Finally, particle size can be adjusted by the initial surfactant (SDS) concentration. In parallel, magnetic particles were prepared using a ferrofluid composed of iron oxide nanoparticles stabilized in styrene by a reactive surfactant or surfmer . These stable and superparamagnetic organic ferrofluids were encapsulated by miniemulsion polymerization and led to latex particles in which the distribution of iron oxide was homogeneous within the polymer matrix. Magnetic properties of the particles are directly related with the characteristics of the ferrofluid usedLYON1-BU.Sciences (692662101) / SudocSudocFranceF