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Artykuły w czasopismach na temat "Biological Labeling -Semiconductor Nanocrystals"
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Waiskopf, Nir, Rany Rotem, Itzhak Shweky, Lior Yedidya, Hermona Soreq i Uri Banin. "Labeling Acetyl- and Butyrylcholinesterase Using Semiconductor Nanocrystals for Biological Applications". BioNanoScience 3, nr 1 (4.01.2013): 1–11. http://dx.doi.org/10.1007/s12668-012-0072-3.
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Michalet, Xavier, Fabien Pinaud, Thilo D. Lacoste, Maxime Dahan, Marcel P. Bruchez, A. Paul Alivisatos i Shimon Weiss. "Properties of Fluorescent Semiconductor Nanocrystals and their Application to Biological Labeling". Single Molecules 2, nr 4 (grudzień 2001): 261–76. http://dx.doi.org/10.1002/1438-5171(200112)2:4<261::aid-simo261>3.0.co;2-p.
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Sathe, Komal Pramod, Neha Sunil Garud, Vilas Balasaheb Bangar i Namrata Ramesh Gadakh. "A REVIEW ON QUANTUM DOTS (QDS)". Journal of Advanced Scientific Research 13, nr 06 (31.07.2022): 23–27. http://dx.doi.org/10.55218/jasr.202213603.
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Recently, the drugs in nanometer size range have found to increase the performance of various dosage forms. Quantum dots (QDs) have gained attention and interest of scientists due to their targeting and imaging potential in nano based drug delivery, in pharmaceutical and biomedical (cell biology) applications. They are artificial semiconductor nanocrystals that have tunable and efficient photo luminescence with narrow emission spectra and high light stability making them excellent probes for bioimaging applications. QDs absorb white light and can produce different colors determined by the size of the particles and band Gap. Nowadays, quantum dots are used for labeling live biological material in vitro and in vivo in animals (other than humans) for research purposes and also useful for immunoassay studies. In the present article, we have discussed various aspects of QDs, highlighting their pharmaceutical and biomedical applications and current challenges in introducing QDs into clinical practice.
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Luccardini, Camilla, Aleksey Yakovlev, Stéphane Gaillard, Marcel van ‘t Hoff, Alicia Piera Alberola, Jean-Maurice Mallet, Wolfgang J. Parak, Anne Feltz i Martin Oheim. "Getting Across the Plasma Membrane and Beyond: Intracellular Uses of Colloidal Semiconductor Nanocrystals". Journal of Biomedicine and Biotechnology 2007 (2007): 1–9. http://dx.doi.org/10.1155/2007/68963.
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Semiconductor nanocrystals (NCs) are increasingly being used as photoluminescen markers in biological imaging. Their brightness, large Stokes shift, and high photostability compared to organic fluorophores permit the exploration of biological phenomena at the single-molecule scale with superior temporal resolution and spatial precision. NCs have predominantly been used as extracellular markers for tagging and tracking membrane proteins. Successful internalization and intracellular labelling with NCs have been demonstrated for both fixed immunolabelled and live cells. However, the precise localization and subcellular compartment labelled are less clear. Generally, live cell studies are limited by the requirement of fairly invasive protocols for loading NCs and the relatively large size of NCs compared to the cellular machinery, along with the subsequent sequestration of NCs in endosomal/lysosomal compartments. For long-period observation the potential cytotoxicity of cytoplasmically loaded NCs must be evaluated. This review focuses on the challenges of intracellular uses of NCs.
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Azizi, Seyed Naser, Mohammad Javad Chaichi, Parmis Shakeri, Ahmadreza Bekhradnia, Mehdi Taghavi i Mousa Ghaemy. "Chemiluminescence of Mn-Doped ZnS Nanocrystals Induced by Direct Chemical Oxidation and Ionic Liquid-Sensitized Effect as an Efficient and Green Catalyst". Journal of Spectroscopy 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/803592.
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A novel chemiluminescence (CL) method was proposed for doping water-soluble Mn in ZnS quantum dots (QDs) as CL emitter. Water-soluble Mn-doped ZnS QDs were synthesized by using L-cysteine as stabilizer in aqueous solution. These nanoparticles were structurally and optically characterized by X-ray powder diffraction (XRD), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), UV-Vis absorption spectroscopy, and photoluminescence (PL) emission spectroscopy. The CL of ZnS QDs was induced directly by chemical oxidation and its ionic liquid-sensitized effect in aqueous solution was then investigated. It was found that oxidants, especially hydrogen peroxide, could directly oxidize ZnS QDs to produce weak CL emission in basic solutions. In the presence of 1,3-dipropylimidazolium bromide/copper, a drastic light emission enhancement was observed which is related to a strong interaction between Cu2+and the imidazolium ring. In these conditions, an efficient CL light was produced at low pH which is suggested to be beneficial to the biological analysis. The CL properties of QDs not only will be helpful to study physical chemistry properties of semiconductor nanocrystals but also they are expected to find use in many fields such as luminescence devices, bioanalysis, and multicolor labeling probes.
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Camellini, Andrea, Haiguang Zhao, Sergio Brovelli, Ranjani Viswanatha, Alberto Vomiero i Margherita Zavelani-Rossi. "(Invited) Ultrafast Spectroscopy in Semiconductor Nanocrystals: Revealing the Origin of Single Vs Double Emission, of Optical Gain and the Role of Dopants". ECS Meeting Abstracts MA2022-01, nr 20 (7.07.2022): 1104. http://dx.doi.org/10.1149/ma2022-01201104mtgabs.
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A wide variety of materials with nanometre dimensions are increasingly explored for photonic applications. Among them, semiconductor nanocrystals (NCs) are very promising for a variety of uses, including light emission devices (LEDs), lasers, detectors, photovoltaic cells, biological labelling and sensing [1]. Key advantage of NCs is the possibility to tailor their optical response by controlling the electronic structure (“wave function engineering”) through the choice of composition, size and shape. Significant and interesting results have been obtained with heterostructured and doped NCs. Beyond single wavelength tuneable band-edge emission, other regimes have been demonstrated such as intragap emission, simultaneous emission on two different wavelengths, amplified spontaneous emission and laser emission. The luminescent properties are governed by exciton decay, which can proceed through radiative or nonradiative pathways, following different routes. The study of exciton dynamics can allow elucidating the processes connected to single or dual emission and to optical gain. This, in turn, can lead to the identification of the functional and structural characteristics that are responsible for these behaviors. Exciton relaxation occurs on picosecond timescales, so ultrafast optical techniques are required to perform these studies. In this talk, we present studies carried out by ultrafast pump-probe spectroscopy technique, with 100-fs time resolution, on CdSe/CdS and PbS/CdS heterostructured NCs, with different geometries (core/shell, dot-in-rod, dot-in-bulk, with sharp or graded interface) [2-6] and CdSeS and CdZnSe doped NCs [7,8]. These NCs are optically active in the visible and near-infrared spectral region, show single and dual colour photoluminescence emission, optical gain, laser emission and intragap emission [2-9]. The analysis of the experimental data allowed us to unravel the decay processes: the initials take place in a few ps, leading to the ultimate emitting state whose lifetime can extend to hundreds of ps to few ns, allowing for efficient luminescence and optical gain. Our data on heterostructures allowed us to clarify the role of the volume and of the shape of the outer component and the effect of the interface [2-4]. We found that dual emission is possible for both thick and thin quantum-confined shells, and for different interfaces. We studied the decoupling of excitons lying in the two different component of the NC (core exciton and shell exciton) and we revealed the evolution of the exciton barrier known as dynamic hole-blockade effect. We showed that these phenomena are strictly connected to dual emission and optical gain and we identified the condition for their maximum efficiency, in term of band alignment and band transitions. Our results provide a comprehensive understanding of the physical phenomena governing dual-emission mechanisms, suppression of Auger recombination, optical gain and laser emission in heterostructured NCs. Experiments on CdZnSe NCs doped with Mn and on CdSeS NCs engineered with sulfur vacancies, enabled us to disclose donor and acceptor localized states in the band gap. We observed the carrier dynamics responsible for intragap emission which is associated to the emergence of a transient Mn3+ state [7], in the first case, and to a donor state below the conduction band introduced by sulfur vacancies [8], in the latter case. In conclusion, the study of the exciton dynamics in different NCs allowed us to elucidate the relation between structural-morphological characteristics (shape, volume, and interface) and unconventional emission capabilities (dual emission and optical gain) in heterostructures and the photophysics of electronic states introduced by doping. This knowledge is very important to control NC functionalities toward new multilevel electronic or photonic schemes and in applications such as lasers [9], photoelectrochemical (PEC) cell [10], white light emission [11], ratiometric sensing [12]. [1] P. V. Kamat and G. D. Scholes, J. Phys. Chem. Lett. 7, 584 (2016) [2] G. Sirigu et al., Phys. Rev. B 96, 155303 (2017) [3] V. Pinchetti et al., ACS Nano 10, 6877-6887 (2016) [4] H. Zhao et al., Nanoscale 8, 4217-4226 (2016) [5] M. Zavelani-Rossi et al., Nano Lett. 10, 3142-3150 (2010) [6] R. Krahne et al., Appl. Phys. Lett. 98, 063105 (2011) [7] K. Gahlot et al., ACS Energy Lett. 4, 729−735 (2019) [8] F. Carulli et al., Nano Lett. 21, 6211−6219 (2021) [9] M. Zavelani-Rossi et al., Laser & Photonics Reviews 6, 678-683 (2012) [10] L. Jin et al., Nano Energy 30, 531-541 (2016) [11] S. Sapra et al., Adv. Mater. 19, 569 (2007) [12] J. Liu et al., ACS Photonics, 2479 (2019)
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Fu, Aihua, Weiwei Gu, Carolyn Larabell i A. Paul Alivisatos. "Semiconductor nanocrystals for biological imaging". Current Opinion in Neurobiology 15, nr 5 (październik 2005): 568–75. http://dx.doi.org/10.1016/j.conb.2005.08.004.
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Bruchez Jr., M. "Semiconductor Nanocrystals as Fluorescent Biological Labels". Science 281, nr 5385 (25.09.1998): 2013–16. http://dx.doi.org/10.1126/science.281.5385.2013.
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Kang, Bin, Shu-Quan Chang, Hao Sun, Yao-Dong Dai i Da Chen. "γ-Radiation Synthesis and Properties of Superparamagnetic CS-ZnSe:Mn Nanocrystals for Biological Labeling". Journal of Nanoscience and Nanotechnology 8, nr 8 (1.08.2008): 3857–63. http://dx.doi.org/10.1166/jnn.2008.174.
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Chitosan coated ZnSe:Mn (CS-ZnSe:Mn) nanocrystals were successfully synthesized in aqueous system through a γ-radiation route at room temperature under ambient pressure. The structure and properties of nanocrystals were investigated with transmission electron microscope (TEM), fourier transform infrared spectrometer (FT-IR), ultraviolet-visible (UV-vis) spectrometer, photoluminescence emission (PL) spectra, X-ray Diffraction (XRD) and energy dispersion spectrum (EDS). Results showed that the diameter of these nanocrystals was about 4 nm with narrow size distribution. With the increase of doped Mn2+ concentration, strong emission peak at 610 nm was observed besides the weak emission peak at 425 nm since the non-radiative transition of 4T1(4G)–6A1(6S) level, resulting the transfer of fluorescence color from blue to orange. Moreover, analysis of SQUID magnetometer indicated that the nanocrystals were superparamagnetic with a saturation magnetization of 1.7 emu/g and a Curie-Weiss temperature of 14–15 K. Hep G2 cells were incubated in solution of nanocrystals and results showed that the synthesized nanocrystals could stain cytoplasm but could not enter into nucleus.
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Santos, B. S., P. M. A. Farias, A. Fontes, A. G. Brasil, C. N. Jovino, A. G. C. Neto, D. C. N. Silva, F. D. de Menezes i R. Ferreira. "Semiconductor nanocrystals obtained by colloidal chemistry for biological applications". Applied Surface Science 255, nr 3 (listopad 2008): 796–98. http://dx.doi.org/10.1016/j.apsusc.2008.07.026.
Pełny tekst źródłaRozprawy doktorskie na temat "Biological Labeling -Semiconductor Nanocrystals"
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Mikulec, Frederic Victor 1971. "Semiconductor nanocrystal colloids : manganese doped cadmium selenide, (core)shell composites for biological labeling, and highly fluorescent cadmium telluride". Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9358.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1999.Includes bibliographical references.
This thesis describes the characterization and applications of nanometer sized semiconductor (or quantum dot) colloids produced by chemical means. The nanocrystals are synthesized by pyrolysis of organometallic precursors in the coordinating solvent trioctylphosphine oxide (TOPO). The important developments that have contributed to this method are discussed. Manganese doped CdSe nanocrystals are synthesized using a manganese and selenium containing organometallic compound. Chemical etching and electron paramagnetic resonance (EPR) experiments reveal that most of the dopant atoms lie near the surface within the inorganic lattice. Results from fluorescence line narrowing (FLN) and photoluminescence excitation (PLE) spectroscopies show that doped nanocrystals behave as if they were undoped nanocrystals in an external magnetic field. The nanocrystal surface is initially passivated by dative organic ligands. Better passivation and optical properties are achieved by growth of a large band gap semiconductor shell that provides both a physical and an energetic barrier between the exciton and the surface. (CdSe)ZnS (core)shell are prepared with control over both core and shell sizes. The composite nanocrystals are characterized by absorption, emission, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), small angle X-ray scattering (SAXS), and wide angle X-ray scattering (W AXS). The maximum quantum yield is achieved when the core is protected from oxidation by a complete shell; thicker shells show no further increase in quantum yield values, due to defects caused by the large lattice mismatch. Exchange of surface TOPO ligands for mercaptocarboxylic acids produces (core)shell nanocrystals that, when treated with base, are soluble in water and remain fluorescent. Established protocols are used to link these water-soluble nanocrystals to the biomolecules avidin or biotin, producing useful fluorescent labels. Stable phosphine tellurides are prepared using hexapropylphosphorus triamide (HPPT). This precursor is used to prepare CdTe nanocrystals that display room temperature quantum yields up to 70%. The CdTe growth is investigated by absorption and emission spectroscopy. CdTe nanocrystals are characterized by TEM and WAXS.
by Frederic Victor Mikulec.
Ph.D.
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McLaurin, Emily J. (Emily Jane). "Phosphorescent semiconductor nanocrystals and proteins for biological oxygen sensing". Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/62726.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2011.Vita. Cataloged from PDF version of thesis.
Includes bibliographical references.
Oxygen is required for cellular respiration by all complex life making it a key metabolic profiling factor in biological systems. Tumors are defined by hypoxia (low pO2), which has been shown to influence response to radiation therapy and chemotheraphy. However, very little is known about spatio-temporal changes in P0 2 during tumor progression and therapy. To fully characterize and probe the tumor microenvironment, new tools are needed to quantitatively assess the microanatonical and physiological changes occurring during tumor growth and treatment. This thesis explores the design and construction of new oxygen sensors as tools for monitoring the tumor microenvironment in real-time. Semiconductor nanocrystals or quantum dots (QDs) are the basis of these tools. Previously, most imaging applications of QDs have used them as indicators of position; they have lacked a response to their local environment. Tethering a phosphorescent complex to a QD enables fluorescence resonance energy transfer to be exploited as a signal transduction mechanism, sensitizing the QD to oxygen. The mechanism for oxygen sensing involves kinetic quenching of the emission of the energy accepting phosphor in the presence of oxygen, while the emission of the energy donating QD remains stable. This mechanism was chosen owing to the unique ability of oxygen to quench emission from a phosphorescent compound, but not fluorescence from a QD. Phosphors such as osmium polypyridines (Chapter 2), Pd or Pt porphyrins (Chapters 3 and 4), or phosphorescent proteins (Chapters 5 and 6) may all be employed. An additional benefit of FRET excitation includes very large one- and two-photon excitation cross-sections of QDs. Together, these properties make the probes ideal candidates for 02 sensing applications in biological microenvironments, where probe concentrations may vary, and where the use of multiphoton excitation in microscopy presents significant advantages in imaging thick samples and in limiting extraneous tissue damage.
by Emily J. McLaurin.
Ph.D.
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Xu, Yi. "Nona-arginine peptides facilitate cellular entry of semiconductor nanocrystals: mechanisms of uptake". Diss., Rolla, Mo. : Missouri University of Science and Technology, 2009. http://scholarsmine.mst.edu/thesis/pdf/Xu_09007dcc807220a9.pdf.
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Thesis (M.S.)--Missouri University of Science and Technology, 2009.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed December 23, 2009) Includes bibliographical references (p. 39-44).
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Nasilowski, Michel. "Synthesis and optical spectroscopy of thick-shell semiconductor nanoparticles : applications to biological imaging". Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066432/document.
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Les Quantum Dots colloidaux (QDs) sont des nanocristaux colloidaux de semiconducteurs aux propriétés optiques uniques : finesse spectrale d’émission, large gamme spectrale d’excitation, brillance élevée. Cependant, leurs applications sont encore limitées par le clignotement de leur émission de fluorescence à l’échelle de la particule unique.Ce travail se concentre sur l’amélioration des propriétés optiques des QDs de CdSe/CdS, ainsi que sur leurs applications biologiques. Le développement d’une synthèse de nanocristaux de CdSe/CdS à coque épaisse a permis d’obtenir facilement des QDs non-clignotants à partir de cœurs de CdSe de cristallinité différente. Cependant, c’est QDs oscillent entre un état brillant et un état gris. La synthèse de QDs de CdSe/CdS à coque épaisse avec un gradient de composition entre le cœur et la coque produit des nanocristaux dont l’émission de fluorescence est parfaitement stable au cours du temps, et donc les rendements quantiques du mono- et du biexciton sont à 100% à l’air, à température ambiante. Les recombinaisons multiexcitoniques sont également efficaces permettant à un QD unique d’émettre de la lumière blanche à forte excitation. La croissance d’une coque d’or autour d’un QD (QDs-dorés) favorise le couplage entre l’exciton du semiconducteur et les plasmons du métal. Cet effet Purcell a pour conséquence d’accélérer les phénomènes radiatifs, diminuant le temps de vie et supprimant le clignotement du QD. De plus, la couche d’or agit comme une barrière contre la photooxydation et les QDs-dorés présentent une résistance plus élevée aux fortes puissantes d’excitation. Le contrôle de la forme des nanocristaux a permis la synthèse de nanoplaquettes, structures bidimensionnelles dont l’épaisseur est contrôlée à la monocouche atomique près. Une nouvelle synthèse de nanoplaquettes cœur/coque conduit à des propriétés intéressantes tant par la pureté de l’émission des nanocristaux que par leur résistance en température. Enfin, les QDs de CdSe/CdS, de par leur brillance et faible photoblanchiment, sont d’excellentes sondes fluorescentes pour l’imagerie biologique. Leur fluorescence et leur structure inorganique ont permis de réaliser de l’imagerie bimodale optique/électronique pour déterminer le nombre et la localisation précise de récepteurs synaptiques dans C. elegans. La monofonctionnalisation des QDs, nécessaire pour sonder certaines voies d’endocytose dans les cellules, a été réalisée grâce à l’encapsulation des QDs dans une nanocage d’ADN dont la formation est parfaitement contrôlée, à la base près. Ce complexe cage d’ADN – QDs a permis de suivre la dynamique d’endocytose des toxines Shiga dans la voie d’endocytose rétrograde jusqu’à l’appareil de GolgiColloidal Quantum Dots (QDs) are colloidal semiconductor nanocrystals with unique optical properties: narrow emission spectrum, large spectral range of excitation, high brightness. However, their applications are still limited by the blinking of their fluorescence emission at the single particle scale. This work focuses on the improvement of optical properties of CdSe/CdS QDs, as well as on the biological applications. The development of a synthesis of thick-shell CdSe/CdS nanocristals allowed easy obtaining of non-blinking QDs from CdSe cores of different crystallinity. However, these QDs flicker between an on and a grey state. The synthesis of thick-shell CdSe/CdS QDs with a composition gradient between the core and the shell produces nanocrystals whose fluorescence emission is perfectly stable with time. The quantum yields of the mono- and biexciton are 100% in air, at room temperature. Multiexcitonic recombinations are also efficient making a single QD emit white light under strong excitation. The growth of a gold nanoshell around a QD (golden-QDs) allows the coupling of the exciton of the semiconductor and the metal plasmons. This Purcell effect speeds up all the radiative processes, decreasing the lifetime and eliminating the blinking. Besides, the gold shell acts as a barrier against photooxidation and the golden-QDs show increased resistance to high excitation powers. The control of the shape of nanocrystals allowed the synthesis of nanoplatelets, bidimensionnal structures whose thickness is controlled to the atomic monolayer. A new synthesis of core/shell nanoplatelets leads to interesting properties due to the purity of the emission of the nanocrystals and to their resistance with temperature. Finally, Cdse/CdS QDs, because of the low photobleaching and high brightness, are excellent fluorescent probes for biological imaging. Their fluorescence and their inorganic structure were taken advantage of to perform bimodal optical/electron imaging to precisely localize and count synaptic receptors in C. elegans. Monofunctionalization of QDs, required to probe some endocytosis pathways in cells, was performed thanks to encapsulation of QDs in a DNA nanocage whose formation is perfectly controlled. This DNA cage – QD complex was used to study the dynamics of endocytosis of Shiga toxin in the retrograde endocytosis pathway, up to the Golgi apparatus
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Tamang, Sudarsan. "Synthèse et fonctionnalisation des nanocristaux émettant dans le proche infrarouge pour l'imagerie biologique". Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00665109.
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Cette thèse concerne le développement de nanocristaux (NCs) cœur/coquille d'InP/ZnS émettant dans le proche infrarouge pour l'imagerie biologique. Dans la synthèse chimique des NCs cœur d'InP, nous avons utilisé la phosphine générée in situ comme précurseur de phosphore en combinaison avec le myristate d'indium comme précuseur d'indium et l'1-octadécène comme solvant. Les NCs obtenus sont hautement cristallins et présentent une fluorescence dans la gamme 720-750 nm, selon leur taille. La croissance d'une ou deux monocouches (coquille) de ZnS sur la surface des NCs d'InP a considérablement amélioré leur rendement quantique de fluorescence. Nous avons de plus étudié le transfert de phase de ces NCs InP/ZnS du milieu organique au milieu aqueux en utilisant diverses molécules hydrophiles contenant un groupe thiol. En particulier, nous nous sommes intéressés au transfert de phase avec des molécules zwitterioniques tels que la penicillamine et la cystéine afin d'obtenir une taille hydrodynamique compacte, et de réduire les interactions non-spécifiques en milieu biologique. Dans l'étude du transfert de phase, l'accent a été mis sur la stabilité colloïdale des NCs et sur la préservation de leur efficacité de fluorescence en milieu aqueux. La cytotoxicité des NCs InP/ZnS fonctionnalisés avec la pencillamine a été évaluée en culture cellulaire. Puis la bio-distribution de ces NCs a été étudiée dans des souris vivantes par imagerie de fluorescence grâce à leur émission dans le proche infrarouge. Pour finir, les fonctionnalisations de NCs InP/ZnS d'une part avec un peptide de pénétration cellulaire, d'autre part avec des agents de contraste IRM (complexes de gadolinium) et enfin avec un nombre contrôlé de molécules streptavidine ont été explorées, démontrant le grand intérêt de ces NCs pour l'imagerie biologique. Mots clés: phosphure d'indium, boîtes quantiques, nanocristaux, imagerie biologique de fluorescence, infrarouge, transfert de phase, fonctionnalisation de surface
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Wang, Jun. "Synthesis, functionalization, and biological tagging applications of II-VI semiconductor nanocrystals". 2006. http://proquest.umi.com/pqdweb?did=1051282161&sid=9&Fmt=2&clientId=39334&RQT=309&VName=PQD.
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Thesis (Ph.D.)--State University of New York at Buffalo, 2006.Title from PDF title page (viewed on July. 19, 2006) Available through UMI ProQuest Digital Dissertations. Thesis adviser: Mountziaris, Lakis T. J. Includes bibliographical references.
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Sweeney, Rozamond Yvonne Iverson Brent L. "Biological approaches to synthesis and assembly of semiconductor and metallic nanomaterials". 2005. http://repositories.lib.utexas.edu/bitstream/handle/2152/2123/sweeneyd89511.pdf.
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Sweeney, Rozamond Yvonne. "Biological approaches to synthesis and assembly of semiconductor and metallic nanomaterials". Thesis, 2005. http://hdl.handle.net/2152/2123.
Pełny tekst źródłaCzęści książek na temat "Biological Labeling -Semiconductor Nanocrystals"
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Bailey, R. E., i S. Nie. "Core-Shell Semiconductor Nanocrystals for Biological Labeling". W The Chemistry of Nanomaterials, 405–17. Weinheim, FRG: Wiley-VCH Verlag GmbH & Co. KGaA, 2005. http://dx.doi.org/10.1002/352760247x.ch12.
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Fujii, Fumihiko. "Semiconductor Nanocrystals for Biological Imaging and Fluorescence Spectroscopy". W Advances in Experimental Medicine and Biology, 449–73. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-33-6064-8_16.
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C.A. Silva, Anielle, Eliete A. Alvin, Francisco R.A. dos Santos, Samanta L.M. de Matos, Jerusa M. de Oliveira, Alessandra S. Silva, Éder V. Guimarães i in. "Doped Semiconductor Nanocrystals: Development and Applications". W Nanocrystals [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.96753.
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This chapter aims to show significant progress that our group has been developing and the applications of several doped semiconductor nanocrystals (NCs), as nanopowders or embedded in glass systems. Depending on the type of dopant incorporated in the nanocrystals, the physical, chemical, and biological properties can be intensified. However, it can also generate undesired toxic effects that can potentially compromise its use. Here we present the potential of zinc oxide NCs doped with silver (Ag), gold (Au), and magnesium (Mg) ions to control bacterial diseases in agriculture. We have also performed biocompatibility analysis of the pure and Ag-doped sodium titanate (Na2Ti3O7) NCs in Drosophila. The doped nanocrystals embedded in glassy systems are chrome (Cr) or copper (Cu) in ZnTe and Bi2Te3 NCs for spintronic development nanodevices. Therefore, we will show several advantages that doped nanocrystals may present in the technological and biotechnological areas.
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RUPASOV, VALERY I., i SERGEI G. KRIVOSHLYKOV. "LONG-WAVE INFRARED AND TERAHERTZ-FREQUENCY LASING BASED ON SEMICONDUCTOR NANOCRYSTALS". W Spectral Sensing Research for Water Monitoring Applications and Frontier Science and Technology for Chemical, Biological and Radiological Defense, 337–43. WORLD SCIENTIFIC, 2008. http://dx.doi.org/10.1142/9789812833242_0030.
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Jalal, Nahid Rezvani, Fariba Mollarasouli, Mohammad Reza Jalali Sarvestani, Sina Khalili, Sepideh Asadi, Zahra Derakhshan, Tayyebeh Madrakian, Abbas Afkhami i Mazaher Ahmadi. "Quantum Dots in Medical Detection/Diagnosis". W Quantum Dots in Bioanalytical Chemistry and Medicine, 75–106. Royal Society of Chemistry, 2023. http://dx.doi.org/10.1039/9781839169564-00075.
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One area of interest in nanotechnology, particularly in nanobiotechnology, is the study of optical and electrical phenomena related to nanometer-scale semiconductors. Quantum dots (QDs) are semiconductor nanocrystals whose electrons and holes are quantum-confined in all three spatial dimensions. QDs’ unique optical features make them suitable for use as optical probes or as optically trackable biomolecule carriers for in vitro and in vivo research in biological applications. QDs can be used to target specific areas in vitro and in vivo by conjugating relevant functional biomolecules onto their surfaces. This chapter comprehensively describes the different aspects of QDs’ applications in the field of biomedical diagnosis.
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Mohammadpour, Z., i F. Molaabasi. "Application of Quantum Dots to in Vitro and in Vivo pH Detection". W Quantum Dots in Bioanalytical Chemistry and Medicine, 175–96. Royal Society of Chemistry, 2023. http://dx.doi.org/10.1039/9781839169564-00175.
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pH balance in the intra- and extracellular environments is an essential factor in the maintenance of normal cell functions. Intracellular pH significantly affects biological events, including apoptosis, drug resistance, ion transport, growth, and endocytosis. Dysregulation of intracellular pH is the cause of many diseases and life-threatening afflictions, including Alzheimer’s disease, cancer, and stroke. The ability to detect and monitor pH changes in cellular environments is, therefore, crucial to researchers’ understanding of the physiological processes, pathological processes, and biological effects caused by these changes. pH-sensitive optical probes, including fluorescence and surface-enhanced Raman spectroscopy-active materials, are widely used for intra- and extracellular pH measurement. pH-sensitive fluorescent probes are of interest for use in cell labeling. pH can be measured via microscopy by detecting a pH-dependent decrease or increase in the probes’ signals. pH-sensitive dyes and nanomaterials have been studied extensively, and their capacity for sensitive cellular pH detection has been verified. However, fluorescent dyes are subject to photobleaching; conversely, nanomaterials are more photostable. This chapter discusses the applications of quantum-confined particles for in vitro and in vivo pH sensing, including heavy metal-based quantum dots (QDs), carbon dots, Si nanocrystals, polymer dots, and graphene-based QDs.
Streszczenia konferencji na temat "Biological Labeling -Semiconductor Nanocrystals"
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Chen, Kok Hao, i Jong Hyun Choi. "Nanoparticle-Aptamer: An Effective Growth Inhibitor for Human Cancer Cells". W ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-11966.
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Semiconductor nanocrystals have unique optical properties due to quantum confinement effects, and a variety of promising approaches have been devised to interface the nanomaterials with biomolecules for bioimaging and therapeutic applications. Such bio-interface can be facilitated via a DNA template for nanoparticles as oligonucleotides can mediate the aqueous-phase nucleation and capping of semiconductor nanocrystals.[1,2] Here, we report a novel scheme of synthesizing fluorescent nanocrystal quantum dots (NQDs) using DNA aptamers and the use of this biotic/abiotic nanoparticle system for growth inhibition of MCF-7 human breast cancer cells for the first time. Particularly, we used two DNA sequences for this purpose, which have been developed as anti-cancer agents: 5-GGT GGT GGT GGT TGT GGT GGT GGT GG-3 (also called, AGRO) and 5-(GT)15-3.[3–5] This study may ultimately form the basis of unique nanoparticle-based therapeutics with the additional ability to optically report molecular recognition. Figure 1a shows the photoluminescence (PL) spectra of GT- and AGRO-passivated PbS QD that fluoresce in the near IR, centered at approximately 980 nm. A typical synthesis procedure involves rapid addition of sodium sulfide in the mixture solution of DNA and Pb acetate at a molar ratio of 2:4:1. The resulting nanocrystals are washed to remove unreacted DNA and ions by adding mixture solution of NaCl and isopropanol, followed by centrifugation. The precipitated nanocrystals are collected and re-suspended in aqueous solution by mild sonication. Optical absorption measurements reveal that approximately 90 and 77% of GT and AGRO DNA is removed after the washing process. The particle size distribution in Figure 1b suggests that the GT sequence-capped PbS particles are primarily in 3–5 nm diameter range. These nanocrystals can be easily incorporated with mammalian cells and remain highly fluorescent in sub-cellular environments. Figure 1c serially presents an optical image of a MCF-7 cell and a PL image of the AGRO-capped QD incorporated with the cell. Figure 1. (a) Normalized fluorescence spectra of PbS QD synthesized with GT and AGRO sequences, which were previously developed as anti-cancer agents. The DNA-capped QD fluoresce in the near IR centered at ∼980 nm. (b) TEM image of GT-templated nanocrystals ranging 3–5 nm in diameter. (c) Optical image of an MCF-7 human breast cancer cell after a 12-hour exposure to aptamer-capped QD. (d) PL image of AGRO-QD incorporated with the cell, indicating that these nanocrystals remain highly fluorescent in sub-cellular environments. One immediate concern for interfacing inorganic nanocrystals with cells and tissue for labeling or therapeutics is their cytotoxicity. The nanoparticle cytotoxicity is primarily determined by material composition and surface chemistry, and QD are potentially toxic by generating reactive oxygen species or by leaching heavy metal ions when decomposed.[6] We examined the toxicity of aptamer-passivated nanocrystals with NIH-3T3 mouse fibroblast cells. The cells were exposed to PbS nanocrystals for 2 days before a standard MTT assay as shown in Figure 2, where there is no apparent cytotoxicity at these doses. In contrast, Pb acetate exerts statistically significant toxicity. This observation suggests a stable surface passivation by the DNA aptamers and the absence of appreciable Pb2+ leaching. Figure 2. Viability of 3T3 mouse fibroblast cells after a 2-day exposure to DNA aptamer-capped nanocrystals. There is no apparent dose-dependent toxicity, whereas a statistically significant reduction in cell viability is observed with Pb ions. Note that Pb acetate at 133 μM is equivalent to the Pb2+ amount that was used for PbS nanocrystal synthesis at maximum concentration. Error bars are standard deviations of independent experiments. *Statistically different from control (p<0.005). Finally, we examined if these cyto-compatible nanoparticle-aptamers remained therapeutically active for cancer cell growth inhibition. The MTT assay results in Figure 3a show significantly decreased growth of breast cancer cells incorporated with AGRO, GT, and the corresponding templated nanocrystals, as anticipated. In contrast, 5-(GC)15-3 and the QDs synthesized with the same sequence, which were used as negative controls along with zero-dose control cells, did not alter cell viability significantly. Here, we define the growth inhibition efficacy as (100 − cell viability) per DNA of a sample, because the DNA concentration is significantly decreased during the particle washing. The nanoparticle-aptamers demonstrate 3–4 times greater therapeutic activities compared to the corresponding aptamer drugs (Figure 3b). We speculate that when a nanoparticle-aptamer is internalized by the cancer cells, it forms an intracellular complex with nucleolin and nuclear factor-κB (NF-κB) essential modulator, thereby inhibiting NF-κB activation that would cause transcription of proliferation and anti-apoptotic genes.[7] The nanoparticle-aptamers may more effectively block the pathways for creating anti-apoptotic genes or facilitate the cellular delivery of aptamers via nanoparticle uptake. Our additional investigation indicates that the same DNA capping chemistry can be utilized to produce aptamer-mediated Fe3O4 nanocrystals, which may be potentially useful in MRI and therapeutics, considering their magnetic properties and biocompatibility. In summary, the nanoparticle-based therapeutic schemes developed here should be valuable in developing a multifunctional drug delivery and imaging agent for biological systems. Figure 3. Anti-proliferation of MCF-7 human breast cancer cells with aptamer-passivated nanocrystals. (a) Viability of MCF-7 cells exposed to AGRO and GT sequences, and AGRO-/GT-capped QD for 7 days. The DNA concentration was 10 uM, while the particles were incubated with cells at 75 nM. (b) Growth inhibition efficacy is defined as (100 − cell viability) per DNA to correct the DNA concentration after particle washing.
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Chang, Jin, Bingbo Zhang, Dena Li, Guiping Ma, Weicai Wang i Qi Zhang. "Preparation and Characterization of Tricolor CdSe-Tagged Microbeads for Bio-Detection". W 2007 First International Conference on Integration and Commercialization of Micro and Nanosystems. ASMEDC, 2007. http://dx.doi.org/10.1115/mnc2007-21138.
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Tricolor microbeads for biological assay have been prepared by embedding three quantum dots (cadmium selenide semiconductor nanocrystals) of different size into carboxyl-functionalized polystyrene (PS-COOH) microbeads. These efforts can render CdSe nanocrystals water-solubility, chemical stability and good photostability. The results indicate that QDs-tagged microbeads are highly uniform, reproducible and strong in fluorescence emission. Based on the properties it possesses, QDs-tagged microbead may have great potential for bio-detection.
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Chen, Kok Hao, i Jong Hyun Choi. "DNA Oligonucleotide-Templated Nanocrystals: Synthesis and Novel Label-Free Protein Detection". W ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-11958.
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Semiconductor and magnetic nanoparticles hold unique optical and magnetic properties, and great promise for bio-imaging and therapeutic applications. As part of their stable synthesis, the nanocrystal surfaces are usually capped by long chain organic moieties such as trioctylphosphine oxide. This capping serves two purposes: it saturates dangling bonds at the exposed crystalline lattice, and it prevents irreversible aggregation by stabilizing the colloid through entropic repulsion. These nanocrystals can be rendered water-soluble by either ligand exchange or overcoating, which hampers their widespread use in biological imaging and biomedical therapeutics. Here, we report a novel scheme of synthesizing fluorescent PbS and magnetic Fe3O4 nanoparticles using DNA oligonucleotides. Our method of PbS synthesis includes addition of Na2S to the mixture solution of DNA sequence and Pb acetate (at a fixed molar ratio of DNA/S2−/Pb2+ of 1:2:4) in a standard TAE buffer at room temperature in the open air. In the case of Fe3O4 particle synthesis, ferric and ferrous chloride were mixed with DNA in DI water at a molar ratio of DNA/Fe2+/Fe3+ = 1:4:8 and the particles were formed via reductive precipitation, induced by increasing pH to ∼11 with addition of ammonium hydroxide. These nanocrystals are highly stable and water-soluble immediately after the synthesis, due to DNA termination. We examined the surface chemistry between oligonucleotides and nanocrystals using FTIR spectroscopy, and found that the different chemical moieties of nucleobases passivate the particle surface. Strong coordination of primary amine and carbonyl groups provides the chemical and colloidal stabilities, leading to high particle yields (Figure 1). The resulting PbS nanocrystals have a distribution of 3–6 nm in diameter, while a broader size distribution is observed with Fe3O4 nanoparticles as shown in Figure 1b and c, respectively. A similar observation was reported with the pH change-induced Fe3O4 particles of a bimodal size distribution where superparamagnetic and ferrimagnetic magnetites co-exist. In spite of the differences, FTIR measurements suggest that the chemical nature of the oligonucleotide stabilization in this case is identical to the PbS system. As a particular application, we demonstrate that aptamer-capped PbS QD can detect a target protein based on selective charge transfer, since the oligonucleotide-templated synthesis can also serve the additional purpose of providing selective binding to a molecular target. Here, we use thrombin and a thrombin-binding aptamer as a model system. These QD have diameters of 3∼6 nm and fluoresce around 1050 nm. We find that a DNA aptamer can passivate near IR fluorescent PbS nanocrystals, rendering them water-soluble and stable against aggregation, and retain the secondary conformation needed to selectively bind to its target, thrombin, as shown in Figure 2. Importantly, we find that when the aptamer-functionalized nanoparticles binds to its target (only the target), there is a highly systematic and selective quenching of the PL, even in high concentrations of interfering proteins as shown in Figure 3a and b. Thrombin is detected within one minute with a detection limit of ∼1 nM. This PL quenching is attributed to charge transfer from functional groups on the protein to the nanocrystals. A charge transfer can suppress optical transition mechanisms as we observe a significant decrease in QD absorption with target addition (Figure 3c). Here, we rule out other possibilities including Forster resonance energy transfer (FRET) and particle aggregation, because thrombin absorb only in the UV, and we did not observe any significant change in the diffusion coefficient of the particles with the target analyte, respectively. The charge transfer-induced photobleaching of QD and carbon nanotubes was observed with amine groups, Ru-based complexes, and azobenzene compounds. This selective detection of an unlabeled protein is distinct from previously reported schemes utilizing electrochemistry, absorption, and FRET. In this scheme, the target detection by a unique, direct PL transduction is observed even in the presence of high background concentrations of interfering negatively or positively charged proteins. This mechanism is the first to selectively modulate the QD PL directly, enabling new types of label free assays and detection schemes. This direct optical transduction is possible due to oligonucleotidetemplated surface passivation and molecular recognition. This chemistry may lead to more nanoparticle-based optical and magnetic probes that can be activated in a highly chemoselective manner.