Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2006. / Includes bibliographical references (leaves 100-110). Also available in electronic version.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Submitted by Milena Dias (milena.dias@ufpe.br) on 2015-03-12T18:06:42Z No. of bitstreams: 2 Dissertaçao Renata Raele.pdf: 3359515 bytes, checksum: 46b18a28bc6517d1fd8e4e64d2c2680f (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) / Made available in DSpace on 2015-03-12T18:06:42Z (GMT). No. of bitstreams: 2 Dissertaçao Renata Raele.pdf: 3359515 bytes, checksum: 46b18a28bc6517d1fd8e4e64d2c2680f (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Previous issue date: 2013 / Quantum Dots (QDs) são nanocristais fluorescentes de semicondutores que vêm ganhando espaço em Ciências da Saúde como sondas fluorescentes para estudos de sistemas biológicos tanto in vitro como in vivo. Entretanto, para assegurar sua aplicabilidade em organismos vivos, são necessários testes de avaliação de toxicidade. Tendo em vista estes aspectos, o objetivo deste trabalho foi avaliar e comparar o efeito de diferentes concentrações de QDs de CdTe e ZnSe funcionalizados com Ácido Mercaptopropiônico (AMP) e/ou Ácido Mercaptosuccínico (AMS) sobre cultura de macrófagos da linhagem RAW 264.7, células imuno efetoras que desempenham papel relevante na defesa do organismo frente a patógenos. Para tanto, foram realizados testes de: (1) viabilidade celular através de MTT para definição de IC50 em 24 horas de exposição aos QDs, (2) viabilidade por exclusão de Iodeto de Propídio (PI) e análise de ciclo celular por PI na IC50 por 24 horas, e por fim (3) avaliação dos níveis de Ca2+ citoplasmático utilizando o Fluo-3. O teste estatístico utilizado foi One-Way ANOVA com nível de significância p ≤ 0,05. O teste MTT mostrou que após um período de 24 h de exposição aos QDs de CdTe houve redução da viabilidade para ~35 e 70% nas concentrações máximas e mínimas utilizadas (35,3+2% e 71+3,5% respectivamente) sendo a IC50 obtida para em ~76 nM (AMP=51,7+3,5% e AMS=56,3+8,6%). Essa toxicidade se apresentou de forma dose-dependente. Já o ZnSe se mostrou menos tóxico com IC50 em ~380 nM (48,7+11,3%). A análise da viabilidade com PI em 76 nM para todas as nanopartículas, indicou que não há lesão significativa da membrana plasmática após 24 h de incubação. O teste de ciclo celular, também em 76 nM, indicou que as amostras expostas aos QDs de CdTe apresentaram mais debris (AMP=27,4+3,8;%; AMS=28,4+3,9% e C=4,4+1,3) e menos células em S e G2 (AMP=7,3+0,3 e 4,7+0,5%; AMS=7,6+0,6 e 3,9+0,5% e C=16,1+2,3 e 13+1,7 % respectivamente). Já os resultados de ZnSe não diferiram do controle. As análises com Fluo-3 mostraram, para os QDs de CdTe, um aumento significativo de cálcio citoplasmático a partir da concentração de 76 nM (AMP=263,1+17,8; AMS=255,1+16,2 e C=102,5+6,5). Entretanto para o ZnSe só foi observado aumento significativo desse íon para concentrações a partir de 260 nM (ZnSe=188+15,8 e C=107,2+4,6). Concluímos que QDs de CdTe apresentam toxicidade consideravelmente maior que de ZnSe para as células RAW 264.7, independente do agente estabilizante/funcionalizante ou tamanho do QD. Isso indica que a toxicidade está provavelmente ligada à liberação do Cádmio. Com relação ao CdTe, acredita-se que danos posteriores à membrana plasmática nessas células podem ser reflexo dos eventos precoces ocorridos na mitocôndria e nos níveis de Ca2+. Por fim, de acordo com os resultados apresentados, observamos que a morte celular de RAW 264.7 devido à exposição aos QDs é um evento crescente e contínuo diretamente relacionado com o tempo de exposição e com a concentração de QDs ministrada.

Submitted by Isaac Francisco de Souza Dias (isaac.souzadias@ufpe.br) on 2016-02-16T16:55:59Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação Anna LíviaFINALIZADA E COM FICHA.pdf: 4755413 bytes, checksum: 4691e65d161267ed8769212d59e3b396 (MD5) / Made available in DSpace on 2016-02-16T16:55:59Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação Anna LíviaFINALIZADA E COM FICHA.pdf: 4755413 bytes, checksum: 4691e65d161267ed8769212d59e3b396 (MD5) Previous issue date: 2015-02-26 / FACEPE / Ensaios baseados em fluorescência possuem alta sensibilidade, o que pode proporcionar a identificação e quantificação de biomoléculas e ajudar a elucidar diversos eventos celulares. O desenvolvimento de novas sondas fluorescentes, tais como os Quantum Dots (QDs), tem permitido aos pesquisadores usufruir de todo o potencial de fluorescência. QDs são nanopartículas de materiais semicondutores, de 2 a 10 nm, que possuem características ópticas únicas, tais como fotoestabilidade. Todavia sua utilização no estudo intracelular ainda é limitada, pois sua passagem através da membrana celular não se dá passivamente, ficando preso em vesículas endocíticas, necessitando assim de um método que realize a sua entrega livre no citosol. Dentre algumas metodologias já descritas para entrega intracelular de QDs destacam-se a eletroporação, microinjeção e a fixação celular. Todavia, essas apresentam algumas desvantagens, sendo metodologias laboriosas ou danosas às células. Dentro dessa realidade os lipossomas fusogênicos aparecem como uma ferramenta capaz de sanar essas desvantagens, por serem vesículas de bicamadas lipídicas que podem se fundir às células liberando seu conteúdo no citosol. Assim, neste trabalho teve-se como objetivo desenvolver dois métodos utilizando lipossomas para carrear QDs hidrofílicos ao interior de células vivas. Primeiramente QDs de CdTe aniônicos foram encapsulados em lipossomas de fosfatidilcolina, catiônicos (contendo DOTAP) e fusogênicos (contendo DOPE, DOTAP e DPPE-Rh). A análise por microscopia de fluorescência de hemácias e células tronco incubadas com os lipossomas fusogênicos contendo os QDs negativos, evidenciou que os QDs ficaram ligados à membrana celular devido à diferença de cargas negativas dos QDs e positivas dos lipídeos. Portanto, na continuidade deste trabalho uma segunda abordagem, baseada na método de injeção em etanol, foi desenvolvida para a encapsulação de QDs e aplicada para os mesmos tipos de lipossomas anteriormente descritos. Nessa segunda metodologia, os QDs de CdTe positivos foram também utilizados, de forma a evitar a interação eletrostática entre os QDs e os lipídeos. Para ambos os métodos desenvolvidos, os lipossomas foram caracterizados por medidas de potencial zeta, de raio hidrodinâmico, microscopia de fluorescência e eletrônica de transmissão, confirmando que houve a encapsulação de QDs para todos os sistemas lipossomais utilizados. Ao longo de todo o estudo as hemácias foram células modelo importantes para avaliar a fusão dos lipossomas com a membrana celular, pois estas não apresentam atividade endocítica. Os lipossomas de fosfatidilcolina e catiônicos serviram de modelo para desenvolver as duas metodologias de encapsulação que posteriormente foram aplicadas aos fusogênicos. Os estudos feitos com hemácias e células HeLa, utilizando a segunda metodologia de encapsulação e lipossomas fusogênicos, sugerem a entrega dos QDs positivos nas células vivas. No entanto, estudos adicionais precisam ser desenvolvidos para comprovar se os QDs positivos se encontram livres ou não no citosol. Este novo método apresenta ainda potencialidade para a encapsulação de QDs bioconjugados, pois o processo de congelamento do anterior poderia desnaturar as proteínas. Esperamos que este estudo possa ajudar no desenvolvimento de métodos efetivos de liberação de QDs no citosol, de forma que seja possível se utilizar as vantagens dessas sondas fluorescentes para melhor compreender vários processos intracelulares. / Fluorescence-based assays have high sensitivity, which can provide the identification and quantification of biomolecules and help elucidate cellular events. The development of new fluorescent probes such as Quantum Dots (QD) has enabled researchers to take advantage of the full fluorescence potential. QDs are semiconductor nanoparticle materials from 2 to 10 nm which have unique optical properties such as photostability. However, their use in intracellular study is limited because its passage through the cell membrane does not occur passively, getting stuck in endocytic vesicles, thus requiring a method to conduct their free delivery in the cytosol. Among some methods already described for the intracellular delivery of the QDs include electroporation, microinjection and cell attachment. However, these have disadvantages, like being laborious methods or damaging the cells. Within this reality, the fusogenic liposomes appear as a tool to solve these drawbacks, being vesicles of lipid bilayers that can merge the cells releasing its contents into the cytosol. Thus, this study was aimed to develop two methods using liposomes to adduce hydrophilic QDs inside living cells. First of anionic CdTe QDs were encapsulated in phosphatidylcholine liposomes, cationic (containing DOTAP) and fusogenic (containing DOPE, DOTAP and DPPE-Rh). Analysis by fluorescence microscopy of stem cells and red blood cells incubated with the fusogenic liposomes containing the negative QDs, the QDs showed that they were bound to the cell membrane due to the difference of negative and positive charges of QDs and lipids, respectively. Therefore, the continuation of this work a second approach based on the ethanol injection method has been developed for encapsulating and implemented QDs for the same types of liposomes described above. In this second method, the positive CdTe QDs were also used in order to prevent electrostatic interaction between the lipid and the QDs. For both developed methods, the liposomes were characterized by zeta potential measurements, hydrodynamic radius, fluorescence microscopy and transmission electron confirming that there was encapsulating QDs for all liposomal systems used. The study with red blood cells were important to assess the fusion of the liposomes with the cell membrane, because they do not have the endocytic activity. The cationic and the phosphatidylcholine liposomes served as a model to develop methods for encapsulation, and subsequently applied to the fusogenic. Studies done with red blood cells and HeLa cells using the second method of encapsulation and fusogenic liposomes, suggest delivery of positive QDs in living cells. However, additional studies are needed to see if the positive QDs are free or not in the cytosol. This new method also has potential for encapsulating QDs bioconjugates because the freezing process, used before, may denature proteins. We hope that this study may help in the development of effective methods of QDs release in the cytosol, so being possible to use the full advantages of these fluorescent probes to better understand several intracellular processes.

Indiana University-Purdue University Indianapolis (IUPUI) / Optical refrigeration in quantum dots was carried out in this research. Zinc-blende crystalline CdSe/CdS (core/shell structure) QDs with complete surface passivation were synthesized and been used as the cooling substance. Phonon-assisted up-conversion photoluminescence driven by sub-band gap laser excitation was utilized as the cooling mechanism in the QD samples. A net cooling efficiency was predicted by a semi-empirical model developed during the research, within a range of the laser excitation energy, even after taking into account possible parasitic heating processes. To observe the cooling effect, the experiment was carried out in a thermally isolated environment, which temperature was also monitored. By using an optical thermometry technique developed for this research, a maximum temperature drop around 0.68 K was observed in the experiment. This development paves the way to use QDs' cooling in new industrial and fundamental research approaches.

Quantum dots (QDs) are semiconductor nanoparticle fluorophores with size tunable emission wavelengths and large absorption cross sections, making QDs ideal optical imaging agents. Optical imaging has seen considerable academic and commercial interest, particularly for preclinical imaging. This interest stems from the capacity to multiplex, i.e., the detection of multiple independent imaging probes simultaneously, the accessibility of optical imaging equipment, and the absence of ionizing radiation. Since multiple in vivo targets can be imaged simultaneously, multiplexing is particularly appealing for targeted molecular imaging. In oncology, where a myriad of receptors can be used as targets for personalized medicine, multiplexed imaging would improve rapid receptor status profiling. Given their flexible design, QDs can be engineered for use as targeted contrast agents. To meet the needs of this application, the QDs must 1) emit in the near or short wavelength infrared (NIR/SWIR) wavelength regime to mitigate absorption of light by tissues, 2) be biocompatible, and 3) enable functionalization with targeting agents, such as antibodies or small molecules. In this thesis, the first requirement was addressed by synthesizing an inverted Type-I ZnSe/InP/ZnS system, which is the first InP based system with tunable emission past 750 nm. Biocompatibility of the InP system was confirmed with in vivo toxicity studies of the ZnSe/InP/ZnS QDs. The third requirement was addressed by the development of bioconjugation and functionalization schemes resulting in active QD targeting to the biologically interesting cellular targets human epidermal growth factor receptor 2 (HER2) and folic acid receptor alpha. In addition to developing the new contrast agent, the imaging approach was also refined to address concerns of non-specific labeling of the tumor. To discern between targeted and untargeted binding in vivo, a dual tracer approach using both an untargeted and targeted imaging probe, paired with a corresponding image processing algorithm, was implemented and validated. Identifying the limitations of this approach in NIR-I imaging, resulting from tissue auto fluorescence and light attenuation, laid the groundwork for future imaging work in the SWIR. In order to explore the utility of SWIR for dual tracer approaches, PbS/CdS QDs emitting throughout the SWIR wavelength regime were synthesized. The PbS/CdS QDs were used to generate pilot in vivo SWIR imaging data in collaboration with the National Research Council of Canada. The pilot data demonstrate that tissue attenuation and autofluorescence will not be an issue in the SWIR wavelength regime. By pairing SWIR emitting QDs with dual tracer imaging principles, future studies may be able to discern tumor biomarker status at tissue depth. Such an approach would allow researchers to determine how tumors respond to targeted therapies, furthering the development of personalized medicine. / 2022-09-27T00:00:00Z

No description available.

Les amines biogènes (AB) sont des substances physiologiquement actives résultant de la décarboxylation enzymatique des acides aminés libres. Elles participent, dans le corps, aux processus de transmissions d'informations et de régulation de fonctions physiologiques mais peuvent aussi, à doses élevées, avoir des effets néfastes pour la santé. De nombreuses AB sont répertoriées dans la littérature, telles que l'histamine, la cadavérine et la putrescine. Mais, seul le contrôle d'histamine dans la chair de certains poissons de la famille des scombridés est actuellement réglementée (CE n° 2073/2005). Du fait de cette réglementation, les techniques d'analyses chimiques de l'histamine sont largement documentées. Elles peuvent être semi-quantitatives (chromatographie sur couche mince) ou encore quantitatives (fluorescence moléculaire) mais, la chromatographie liquide haute-performance reste, à ce jour, l'unique méthode homologuée au niveau des instances de santé européenne. En marge de ces méthodes traditionnelles, l'enjeu d'un dispositif rapide, peu onéreux et permettant un contrôle plus systématique des aliments anime à la fois la communauté scientifique et le monde économique. Dans ce contexte, la pertinence à recourir à des Quantum Dots (QD) fonctionnalisés par un dérivé d'ortho-phthalaldéhyde (OPA) (utilisé en tant qu'agent de dérivation en fluorescence moléculaire pour les AB) a été posée. Lors de ce projet, deux éléments clés d'un tel dispositif ont été réalisés et caractérisés. Les premiers correspondent aux dérivés fonctionnalisés de l'OPA (4-Me-OPA et 4-HO-OPA). Ils ont été obtenus avec succès selon trois voies de synthèse. Les premières correspondent à des optimisations de synthèses référencées du 4-HO-OPA à partir d'alcool furfurylique ou du 3,4-diméthylphénol. Enfin, celle issue de l'acide 3-méthoxybenzoïque est une adaptation d'une synthèse référencée du 4-MeO-OPA. Dans un second temps, les propriétés du 4-MeO-OPA en tant qu'agent de dérivation vis-à-vis de l'histamine ont été évaluées et comparées à celles de l'OPA. Pour cela, les conditions optimales de complexation ont été étudiées par spectroscopies Ultra-Violet (UV) et de fluorescence moléculaire. Les seconds composants du dispositif sont des nanostructures fluorescentes (QD) dont les propriétés d'émission de fluorescence sont modulables. Notre choix s'est porté sur les QD hydrosolubles de cadmium et sélénium stabilisés par de l'acide mercaptosuccinique. Ces derniers ont été synthétisés par trois modes d'activation (thermique, micro-ondes, ultrasons) et caractérisés par diffractométrie de rayons X, spectrométrie à plasma à couplage inductif, spectroscopies UV et de fluorescence moléculaire. En conclusion, deux entités, le 4-HO-OPA et des QD possédant des ligants de type mercaptosuccinique, ont été réalisées en vue de la mise en place d'un dispositif innovant d'analyse d'histamine. / The biogenic amines (BA) are physiologically active substances resulting from the enzymatic decarboxylation of free amino acids. In the body, they are involved in the transmission of informations and in regulating physiological functions but, at high levels, they can also have damaging health effects. Many BA are recorded in literature, such as histamine, cadaverine and putrescine. Currently, the control of histamine in fish flesh is only regulated in the case of some Scombridae species (CE N° 2073/2005). As a consequence, histamine chemical analysis techniques are widely documented. They can be semi-quantitative (thin layer chromatography) or quantitative (molecular fluorescence). At present, high-performance liquid chromatography remains the only approved method by public heath authorities. Next to the commonly used methods, the challenge of a fast inexpensive system that allows a more systematic control of food animates both the scientific community and the economic world. In this context, a study of the relevance of using Quantum Dots (QD) functionalized by an ortho-phtalaldehyde (OPA) derivative (OPA), used as molecular fluorescence derivation agent for BA, was undertaken. During this project, two key elements of the system were realized and characterized. The first corresponds to OPA functionalized derivates (4-MeO-OPA and 4-HO-OPA). They have been successfully achieved through three synthesis ways. The first two are optimizations of 4-HO-OPA referenced syntheses from furfuryl alcohol or 3,4-dimethylphenol. Finally, the last one uses 3-methoxybenzoic acid and is a 4-Me-OPA reference synthesis adaptation. In a second part, the 4-MeO-OPA properties as a bypass agent for histamine analysis were evaluated and compared with OPA ones. In this case, optimal complexation conditions were analyzed by ultra-violet (UV) and molecular fluorescence spectroscopies. The second components are QD, which are fluorescent nanostructures with molecular properties. We selected water soluble cadmium and selenium QD which were stabilized by mercaptosuccinic acid. They were synthesized by three activation modes (thermal, microwave, ultrasound) and characterized by X-ray diffractometry, inductively coupled plasma spectrometry, UV spectroscopy and molecular fluorescence. In conclusion, two entities, 4-HO-OPA and QD, both having a mercaptosuccinic-type shell, were created as the innovative set up for histamine analysis.

Nous utilisons un microscope à effet tunnel (STM) associé à un microscope optique inversé pour l’excitation et la détection des plasmons de surface propagatifs et/ou localisés. L’excitation de ces plasmons est assurée par passage d’un courant tunnel inélastique entre la pointe du STM et la surface d’un film métallique mince (épaisseur de 50 nm) d’or ou d’argent déposé sur une lamelle de verre. Les fuites radiatives des plasmons de surface propagatifs et la lumière émise par les plasmons localisés dans le substrat de verre sont collectées par un microscope optique via un objectif à immersion. Il est alors possible de déterminer à la distribution spatiale et angulaire des émissions issues de ces plasmons de surface excités par STM, ainsi qu’à leur distribution en longueurs d’onde. Dans cette thèse, nous nous sommes intéressés au fonctionnement et à l’émission de lumière sous la pointe d’un microscope à effet tunnel fonctionnant à l’air. Nous montrons que la présence d’eau adsorbée au sein de la jonction tunnel, associée à la boucle d’asservissement du STM induit un mode de fonctionnement oscillant et périodique du STM sans lequel il serait difficile d’exciter les plasmons de surface. Ensuite, nous avons montré qu’il est possible de contrôler la directivité des plasmons de surface propagatifs excités par STM en excitant localement un nanofil d’or déposé sur le film d’or. L’étude détaillée de cette directivité nous a permis de démontrer que, contrairement au cas du nanofil d’or déposé sur verre, un nanofil d’or déposé sur film d’or ne se comporte pas comme un résonateur Fabry Pérot. Nous avons proposé un modèle simple dans lequel le nanofil est assimilé à un réseau linéaire d’antennes. Ce modèle permet de rendre compte des structurations spectrales et spatiales des plasmons de surface sur le film d’or résultant de l’ajout du nanofil d’or. Puis, nous avons étudié le couplage entre des nanofibres organiques fluorescentes (structures excitoniques) et les plasmons de surface propagatifs d’un film métallique d’or ou d’argent sur lequel ces nanofibres sont déposées. Nous avons ainsi montré que (i) la fluorescence de la nanofibre peut exciter des plasmons de surface à la surface du film d’or, (ii) la nanofibre organique agit comme un guide d’onde plasmonique et (iii) qu’il est possible d’injecter des plasmons de surface propagatifs du film excités par STM dans ces modes guidés par la nanofibre. D’autre part, en étudiant la figure d’interférences dans le plan de Fourier, nous avons pu confirmer que l’émission du dipôle sous la pointe STM et les plasmons de surface propagatifs excités par STM sont cohérents, donc issus du même événement tunnel. Enfin, nous discutons les effets du couplage entre des nanocristaux semiconducteurs (quantum dots) individuels et un monofeuillet de graphène. Nous montrons que la présence du graphène réduit d’un facteur ~10 la durée de vie de l’état excité des quantum dots déposés sur graphène par rapport aux quantum dots déposés sur verre. Pour les quantum dots déposés sur graphène, il résulte de cette réduction de la durée de vie de l’état excité, une baisse de l’intensité de fluorescence et une réduction du phénomène de scintillement avec un temps de résidence dans un état brillant globalement plus long que pour les quantum dots déposés sur verre. Les différents résultats obtenus au cours de cette thèse permettent de mieux comprendre l’excitation de plasmons de surface avec un microscope à effet tunnel, le couplage entre nanostructures plasmoniques et le couplage entre une structure plasmonique et une nanostructure excitonique. Ils ouvrent des perspectives intéressantes pour le développement de nanodispositifs hybrides plus complexes liants plasmons et excitons et contrôlés électriquement / We use a scanning tunnelling microscope (STM) to excite propagating and/or localised surface plasmons on a thin metallic film (50 nm thick) made of gold or silver deposited on a glass substrate. The leakage radiation of these STM-excited propagating surface plasmons, and the light emitted by localized plasmons into the glass substrate are collected by an inverted optical microscope equipped with an oil immersion objective. Using this setup, it is possible to image both the spatial and angular distribution of the light emitted into the glass substrate on a cooled-CCD. Sending this light to a spectrometer, it is also possible to obtain the wavelength distribution of these STM-excited plasmons. In this manuscript, we discuss the different operation modes of an STM in air. We show that the thin water layers adsorbed on both the STM tip and sample, along with the STM feedback loop, may give rise to an oscillatory mode of operation. Moreover, this mode turns out to be the most efficient one for plasmon excitation with a STM in air. We then show that, when the STM tip is used to locally excite plasmons on a gold nanowire deposited on a gold film, propagating surface plasmons may be preferentially launched along the nanowire axis. Precise understanding of this directivity allows us to demonstrate that, when deposited on a gold film, gold nanowires do not behave as Fabry-Perot resonators, but may be described quite accurately with a one dimensional antenna array model. With this model, it is thereby possible to explain the complex spatial and spectral characteristics of the STM-excited plasmons on the gold film after the addition of the nanowire. Next, we focus on the coupling between fluorescent organic nanofibres (excitonic nanostructures) and propagating surface plasmons on a metallic film (either gold or silver). We show that when the nanofibres are deposited on the metallic film, (i) their fluorescence can excite propagating surface plasmon, (ii) the nanofibre can act as a plasmonic waveguide, and (iii) it is possible to inject surface plasmons propagating onto the metallic film into the guided plasmonic modes of the nanofibre. Moreover, by studying Fourier space images, we confirmed that the vertical dipole localised under the STM tip and the STM-excited propagating surface plasmons are coherent. We finally study the coupling between individual semiconducting nanocrystals (quantum dots) and a graphene monolayer deposited on a glass substrate. We show that, when deposited on graphene, the fluorescence lifetime of the quantum dots is about 10 times shorter than for the quantum dots deposited on bare glass. This leads to a weaker fluorescence signal and reduced blinking behaviour with longer time spent into a bright state. These results improve our understanding of the STM excitation of surface plasmons. They also provide information on the coupling between plasmonic nanostructures and between plasmonic and excitonic entities. in particular, these results are a promising step toward the conception and the realisation of complex electrically driven hybrid plasmonic/excitonic nanodevices