Brevets en plasmonique : les tendances depuis 20 ans

La plasmonique fait l’objet d’une attention particulièrement soutenue depuis une vingtaine d’années. Cet intérêt s’explique par son potentiel au niveau des applications qui s’étendent du diagnostic médical aux énergies décarbonées en passant par les communications optiques. Dans cette perspective, une cartographie des brevets focalisée sur ce domaine très actif de la photonique peut apporter un éclairage pertinent

Etude expérimentale des interactions entre luminophores et nanoparticules métalliques

La luminescence se trouve totalement modifiée (inhibée ou exaltée) au voisinage de nanoparticules métalliques. Cette interaction entre luminophores et nanoparticules métalliques met en jeu de nombreux processus et dépend de paramètres dont le rôle est discuté. Dans le cadre de ce travail, nous avons étudié l influence précise de la taille de nanoparticules d or et d argent et de la distance séparant ces nanoparticules des luminophores. Pour atteindre cet objectif, la géométrie des nanoparticules et la distance entre nanoparticules et luminophores ont été maîtrisées à l échelle nanométrique à l aide de la lithographie électronique et des techniques de dépôt moléculaire couche par couche. Au voisinage des nanoparticules d argent, se manifeste une inhibition de luminescence qui tend à disparaître au fur et à mesure que la taille des nanoparticules augmente. S agissant des nanoparticules d or, l inhibition, observée pour des dimensions inférieures à la centaine de nanomètres, cède la place à l exaltation pour des diamètres supérieurs. En réalité, l exaltation apparaît uniquement lorsque les positions des résonances plasmons sont décalées vers les grandes longueurs d onde comparativement à la longueur d onde d émission du luminophore. L exaltation de luminescence semble être corrélée à la désexcitation radiative de l état plasmon excité par la luminescence des nanocristaux. Ce transfert d énergie du luminophore vers les nanoparticules métalliques est également mis en évidence en faisant varier la distance entre les deux objets. L inhibition et l exaltation diminuent lorsque l on s éloigne des nanoparticules et suivent une loi caractéristique d une interaction dipôle-dipôleLuminescence can be modified (enhanced or quenched) by metal nanoparticles. The interplay between fluorescent dyes and metal nanoparticles involves numerous processes and depend on numerous parameters. Their influence on luminescence is still debated. In this study, we focus on nanoparticle size and distance between fluorescent species and nanoparticles. For this purpose, gold and silver nanoparticles are elaborated by electron beam lithography which offers the possibility to control the nanoparticle geometry. The distance between fluorescent dyes and metal nanoparticles is controlled by layer by layer deposition. Quenching is observed near silver nanoparticles but this phenomenon decreases when the nanoparticle size increases. Enhancement is observed near gold nanocylinder for the largest size. Enhancement occurs when the localized surface plasmon resonance of the nanoparticle is redshifted compared with fluorescent specie wavelength emission. Enhancement can be related to the excitation of localized surface plasmon resonance by fluorescence. This energy transfert from fluorescent species to metal nanoparticles is observed by increasing the distance between these objects. The enhancement and quenching phenomena decrease with the distance. This enhancement and quenching decrease can be related to a dipole-dipole couplingTROYES-SCD-UTT (103872102) / SudocSudocFranceF

Enhancement and Quenching Regimes in Metal−Semiconductor Hybrid Optical Nanosources

International audienceWe report on the emission of hybrid nanosources composed of gold nanoparticles coupled with quantum dots. The emission relies on energy transfer from the quantum dots to gold nanoparticles which could be de-excited through radiative plasmon relaxation. The dependence of the emission efficiency is studied systematically as a function of the size of gold nanoparticles and interdistance between gold nanoparticles and quantum dots. We demonstrate a size-dependent transition between quenching and enhancement and a nonradiative energy transfer from the quantum dots to the gold nanoparticles

Control of the optical properties of quantum dots by substrate functionalization: application to active NSOM tip

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Acide tranexamique intra articulaire sans drainage après prothèse totale du genou - Etude prospective, continue, contrôlée de 107 patients

92ème réunion annuelle de la SOFCOT, PARIS, FRANCE, 06-/11/2017 - 09/11/2017L'acide tranexamique diminue le saignement dans la prothèse totale du genou. La procédure d'administration varie et son retentissement fonctionnel est une notion peu évaluée. L'objectif de notre travail est de vérifier qu'une injection intra-articulaire d'Exacyl sans évacuation ni drainage est efficace sur le saignement et garantit un résultat fonctionnel satisfaisant en termes de douleurs et de mobilité, en l'absence de majoration des complications

Self assembly drives quantum dot photoluminescence

International audienceEngineering the spectral properties of quantum dots can be achieved by a control of the quantum dots organization on a substrate. Indeed, many applications of quantum dots as LEDs are based on the realization of a 3D architecture of quantum dots. In this contribution, we present a systematic study of the quantum dot organization obtained on different chemically modified substrates. By varying the chemical affinity between the quantum dots and the substrate, the quantum dot organization is strongly modified from the 2D monolayer to the 3D aggregates. Then the photoluminescence of the different obtained samples has been systematically studied and correlated with the quantum dot film organization. We clearly show that the interaction between the substrate and the quantum dot must be stronger than the quantum dot–quantum dot interaction to avoid 3D aggregation and that these organization strongly modified the photoluminescence of the film rather than intrinsic changes of the quantum dot induced by pure surface chemistry

Couplages radiatifs et non-radiatifs entre nanocristaux semiconducteurs et nanoparticules métalliques

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Plasmonic interaction between quantum dots and metal nanoparticles

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Axial patellar engagement index and patellar tilt after medial patello-femoral ligament reconstruction in children and adolescents

BACKGROUND: The medial patello-femoral ligament (MPFL) is a major patellar stabiliser whose reconstruction in adults involves graft fixation within a femoral tunnel. In skeletally immature patients, in contrast, the graft is fixed to the soft tissues to allow normal growth. The primary objective of this prospective study was to perform computed tomography (CT) and magnetic resonance imaging (MRI) assessments of medium-term correction of patellar tilt and of the axial patellar engagement index (AEI) after a paediatric variant of MPFL reconstruction in skeletally immature patients. HYPOTHESIS: MPFL reconstruction, performed alone or combined with other procedures in skeletally immature patients, decreases patellar tilt and improves the AEI. MATERIAL AND METHODS: Eighteen children and adolescents with a median age of 14.6 years (range, 8-17 years) who underwent MPFL reconstruction on 20 knees were included in this prospective observational study. A double-strand gracilis tendon graft passed through the medial collateral ligament was used. MPFL reconstruction was performed alone in 13 knees and was combined with lateral retinaculum release, tibial tuberosity translation, and/or trochleoplasty in 7 knees. Patellar tilt and AEI values determined on preoperative and post-operative imaging studies with the quadriceps relaxed and contracted were compared. A physical examination was also performed. RESULTS: From baseline to last follow-up after a mean of 43 months (range, 24-63 months), patellar tilt decreased from 20° preoperatively to 9° with the quadriceps relaxed and from 33° to 15.4° with the quadriceps contracted. The AEI increased from 0.78 at baseline to 0.93 at last follow-up. No dislocation or subluxation recurrences were recorded during follow-up. DISCUSSION: The patellar tilt and AEI improvements seen after paediatric MPFL reconstruction confirm the study hypothesis. This is the first prospective study of patellar position in the axial plane as assessed by CT and MRI after paediatric MPFL reconstruction. In everyday clinical practice, 3D assessments of patellar tilt and the AEI should be performed to evaluate correction of the abnormalities. LEVEL OF EVIDENCE: II, non-randomised prospective observational study