Strong Purcell effect observed in single thick shell CdSe/CdS nanocrystals coupled to localized surface plasmons

High quality factor dielectric cavities designed to a nanoscale accuracy are mostly used to increase the spontaneous emission rate of a single emitter. Here we show that the coupling, at room temperature, between thick shell CdSe/CdS nanocrystals and random metallic films offers a very promising alternative approach. Optical modes confined at the nanoscale induce strong Purcell factors reaching values as high as 60. Moreover the quantum emission properties can be tailored: strong antibunching or radiative biexcitonic cascades can be obtained with high photon collection efficiency and extremely reduced blinking.Comment: 16 pages, 7 figure

A Solve-RD ClinVar-based reanalysis of 1522 index cases from ERN-ITHACA reveals common pitfalls and misinterpretations in exome sequencing

Purpose Within the Solve-RD project (https://solve-rd.eu/), the European Reference Network for Intellectual disability, TeleHealth, Autism and Congenital Anomalies aimed to investigate whether a reanalysis of exomes from unsolved cases based on ClinVar annotations could establish additional diagnoses. We present the results of the “ClinVar low-hanging fruit” reanalysis, reasons for the failure of previous analyses, and lessons learned. Methods Data from the first 3576 exomes (1522 probands and 2054 relatives) collected from European Reference Network for Intellectual disability, TeleHealth, Autism and Congenital Anomalies was reanalyzed by the Solve-RD consortium by evaluating for the presence of single-nucleotide variant, and small insertions and deletions already reported as (likely) pathogenic in ClinVar. Variants were filtered according to frequency, genotype, and mode of inheritance and reinterpreted. Results We identified causal variants in 59 cases (3.9%), 50 of them also raised by other approaches and 9 leading to new diagnoses, highlighting interpretation challenges: variants in genes not known to be involved in human disease at the time of the first analysis, misleading genotypes, or variants undetected by local pipelines (variants in off-target regions, low quality filters, low allelic balance, or high frequency). Conclusion The “ClinVar low-hanging fruit” analysis represents an effective, fast, and easy approach to recover causal variants from exome sequencing data, herewith contributing to the reduction of the diagnostic deadlock

Blinking suppression and biexcitonic emission in thick-shell CdSe/CdS nanocrystals at cryogenic temperature

International audienceThe fluorescence of single colloidal thick-shell CdSe/CdS nanocrystals (NCs), at cryogenic temperature (4 K) and room temperature (RT), is studied using the intensity autocorrelation function (ACF) and lifetime measurements. The radiative and Auger decay rates corresponding to the desexcitation of the charged biexcitonic state are determined through an original method of photon postselection. Especially, the charged biexciton quantum yield increases from about 15% at RT to 60% at 4 K. The high inhibition of Auger recombination already observed for the trion state of CdSe/CdS NCs at low temperature is also demonstrated for the charged biexcitonic state. At 4 K, the ACF is equal to 1 for time scales ranging from 50 ns to 200 ms. In contrast with RT operation, the intensity of the trion emission is then perfectly stable and no blinking is observed. All the results highlight the strong confinement of the charge carriers in the CdSe core

Fetal costello syndrome with neuromuscular spindle excess and p.Gly12Val HRAS mutation

International audienc

Photon-correlation Fourier spectroscopy of the trion fluorescence in thick-shell CdSe/CdS nanocrystals

International audienceThe emission spectrum of the trion state in very thick shell CdSe/CdS nanocrystals is characterized at 4 K by photon correlation Fourier spectroscopy. A value of 50 μeV for the width of the zero phonon line is measured. The absence of blinking and the high photostability of these emitters offer the possibility to investigate the dynamics of the emission spectrum at a time scale as short as 250 ns. We show that the high value of the linewidth (50 μeV) is not due to spectral diffusion induced by the close environment of the emitter at time scales larger than 250 ns. The broadening is attributed to the additional third carrier when compared to the monoexcitonic state

Single-molecule controlled emission in planar plasmonic cavities

International audienceWe study the fluorescence emission from single dye molecules in coplanar plasmonic cavities composed of a thin gold film surrounded by two in-plane surface plasmon Bragg mirrors. We first discuss the effect of the presence of Bragg mirrors on the radiation diagram of surface plasmon coupled emission. Then, we investigate the role of the planar cavity size by single-molecule fluorescence lifetime imaging. Experimental data are compared to numerical simulations of the decay rates calculated as a function of the molecule orientation and position within the cavity. The creation of new decay channels by coupling to the cavity modes is also discussed. We measure a plasmonic Purcell factor up to five, attributed to the enhancement of the radiative rate

Aide médicale à la procréation, malformations congénitales et santé postnatale

International audienceInfertility is considered as a major public health issue and the use of infertility treatments is increasing. Each year, 200,000 children worldwide and approximately 1 in 30 in France are born using assisted reproductive technologies (ART). The overall incidence of congenital malformations, including major features, is increasing in these children compared to the data observed in spontaneous pregnancies. The specific risk for congenital malformation is also increased and concerns mainly congenital heart defects, urogenital, nervous system, and musculoskeletal malformations. Risk of imprinting-related diseases appears also increased in children conceived by ART. ART itself may be implicated; nevertheless, other factors must be considered such as advanced age, factors leading to infertility, and way of life. The impact of ART on individual health is a major concern, particularly with the new French Bioethics law, which offers wider access to this procedure, and will inevitably result in an increased number of pregnancies conceived by ART. The pursuit of research on ART and their consequences on the health of children seems essential, and the data arising from the regional registers of congenital malformations could bring some help in this direction.L’infertilité est considérée comme un problème de santé publique majeur, et le recours aux traitements de l’infertilité est en augmentation. Chaque année, 200 000 enfants naissent dans le monde et 1 enfant sur 30 en France grâce aux techniques d’assistance médicale à la procréation (AMP). L’incidence globale des malformations congénitales (MC), y compris les formes majeures, semble augmentée chez ces enfants par rapport à celle observée chez les enfants conçus spontanément. Le risque malformatif spécifique est également augmenté avec notamment l’implication des systèmes cardiovasculaire, urogénital, nerveux et musculosquelettique. Le risque de maladies liées à l’empreinte parentale apparaît également plus élevé chez les enfants conçus par AMP. Les techniques d’AMP pourraient avoir un impact délétère. Néanmoins, d’autres facteurs sont à prendre en compte tels que l’âge parental avancé, les facteurs à l’origine de l’infertilité et le mode de vie. L’impact de l’AMP sur la santé des individus qui en sont issus est une préoccupation majeure, notamment avec l’arrivée de la nouvelle loi de bioéthique qui ouvre un accès élargi à cette procédure et qui se traduira inévitablement par une augmentation du nombre de grossesses conçues par AMP. La poursuite des recherches sur les différentes techniques d’AMP et leurs conséquences sur la santé des enfants paraît indispensable, les données issues des registres régionaux des MC pourraient apporter une aide en ce sens

Significant decrease of the optical losses in the coupling between colloidal CdSe/CdS nanocrystals and a flat gold film at cryogenic temperature

International audienc

Enhanced and polarized emission from single colloidal CdSe/CdS nanocrystals coupled to a one-dimensional gold grating

International audienceWe present in detail the fluorescence properties of single thick-shell CdSe/CdS colloidal nanocrystals coupled to a linear one-dimensional gold grating. In addition to the photoluminescence decay rate increase, we point out that the polarization ratio of the emission is dramatically enhanced. It overcomes 80% and can reach values close to unity. Experimental results are successfully compared to theoretical predictions. Blinking suppression is also reported