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CdSe/ZnS Quantum Dots (cdse/zns + quantum_dot)
Selected AbstractsHybrid Light-Emitting Diodes from Microcontact-Printing Double-Transfer of Colloidal Semiconductor CdSe/ZnS Quantum Dots onto Organic Layers,ADVANCED MATERIALS, Issue 10 2008Aurora Rizzo A novel dry deposition approach is developed to transfer arrays of colloidal quantum dots onto organic thin films, as illustrated in the figure. A red light-emitting device combining inorganic and organic components is fabricated based on this simple transfer protocol. [source] Templated and Hierarchical Assembly of CdSe/ZnS Quantum Dots,ADVANCED MATERIALS, Issue 15 2004Y. Babayan CdSe/ZnS nanocrystals have been assembled into mesoscale structures (see Figure). Templates with dimensions down to 100,nm are generated via phase-shifting photolithography using composite poly(dimethylsiloxane) masks. Upon removal of the template, the CdSe/ZnS structures are found to exhibit hierarchical order over square nanometers (self-assembly of nanocrystals), square micrometers (template shape), and square centimeters (arrays of template pattern). [source] Multiplexed Analysis of Hg2+ and Ag+ Ions by Nucleic Acid Functionalized CdSe/ZnS Quantum Dots and Their Use for Logic Gate Operations,ANGEWANDTE CHEMIE, Issue 42 2009Ronit Freeman Eine logische Analyse: Mit Nucleinsäuren funktionalisierte CdSe/ZnS-Quantenpunkte werden für den optischen selektiven Parallelnachweis von Hg2+ - und Ag+ -Ionen und für die Aktivierung von Logikgattern mithilfe dieser Ionen als Eingabesignale verwendet. [source] Quantitative characterization of quantum dot-labeled lambda phage for Escherichia coli detection ,,§BIOTECHNOLOGY & BIOENGINEERING, Issue 6 2009Peter B. Yim Abstract We characterize CdSe/ZnS quantum dot (QD) binding to genetically modified bacteriophage as a model for bacterial detection. Interactions among QDs, lambda (,) phage, and Escherichia coli are examined by several cross-validated methods. Flow and image-based cytometry clarify fluorescent labeling of bacteria, with image-based cytometry additionally reporting the number of decorated phage bound to cells. Transmission electron microscopy, image-based cytometry, and electrospray differential mobility analysis allow quantization of QDs attached to each phage (4,17 QDs) and show that , phage used in this study exhibits enhanced QD binding to the capsid by nearly a factor of four compared to bacteriophage T7. Additionally, the characterization methodology presented can be applied to the quantitative characterization of other fluorescent nanocrystal-biological conjugates. Biotechnol. Bioeng. 2009;104: 1059,1067. Published 2009 Wiley Periodicals, Inc. [source] Influence of stability on the acute toxicity of CdSe/ZnS nanocrystals to Daphnia magnaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2010Heather E. Pace Abstract The acute toxicity of polymer-coated CdSe/ZnS quantum dots (QDs) to Daphnia magna was investigated using 48-h exposure studies. The principal objective was to relate the toxicity of QDs to specific physical and chemical aspects of the QD. As such, two different CdSe core diameters, 2,nm QDs (green-emitting) and 5,nm QDs (red-emitting), and two different surface coatings, polyethylene oxide (PEO) and 11-mercaptoundecanoic acid (MUA) were studied. The QDs were characterized before and after the 48-h exposure using fluorescence, ultrafiltrations (3 kDa), and inductively coupled plasma-atomic emission spectrometry (ICP-AES) metal analysis. In addition, flow field flow fractionation-inductively coupled plasma-mass spectrometry (Fl FFF-ICP-MS) was used as a more extensive characterization technique to determine particle size and composition as well as identify other potential constituents in the QD solutions. The more stable QDs (PEO) were found to be less acutely toxic than the QDs with accelerated dissolution (MUA), suggesting QD stability has significant impact on the nanoparticles' short-term toxicity. The emergence of dissolved Cd2+ in solution indicates that the toxicity of the MUA QDs is likely due to Cd poisoning, and a mass-based dose response occurred as a consequence of this mode of action. Alternatively, the PEO QDs caused acute toxicity without observed particle dissolution (i.e., no detectable metals were solubilized), suggesting an alternative mode of toxic action for these nanoparticles. Results of the present study suggest that using particle number, instead of mass, as a dose metric for the PEO QDs, produces markedly different conclusions, in that smaller core size does not equate to greater toxicity. Environ. Toxicol. Chem. 2010;29:1338,1344. © 2010 SETAC [source] Organic,Inorganic Sol,Gel Composites Incorporating Semiconductor Nanocrystals for Optical Gain ApplicationsADVANCED MATERIALS, Issue 17 2009Miri Kazes Organic-inorganic sol-gel composite incorporating highly emitting CdSe/ZnS quantum dots and CdSe/CdS/ZnS quantum rods is reported. Optical gain measurements conducted on a quantum rod/sol-gel composite film show stable room temperature amplified spontaneous emission under ambient conditions. [source] Nonradiative resonance energy transfer directed from colloidal CdSe/ZnS quantum dots to epitaxial InGaN/GaN quantum wells for solar cellsPHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 7 2010Sedat Nizamoglu Abstract We report on Förster-type nonradiative resonance energy transfer (NRET) directed from colloidal quantum dots (QDs) to epitaxial quantum wells (QWs) with an efficiency of 69.6% at a rate of 1.527 ns,1 for potential application in III-nitride based photovoltaics. This hybrid exciton generation,collection system consists of chemically-synthesized cyan CdSe/ZnS core/shell QDs (,PL = 490 nm) intimately integrated on epitaxially-grown green InGaN/GaN QWs (,PL = 512 nm). To demonstrate directional NRET from donor QDs to acceptor QWs, we simultaneously show the decreased photoluminescence decay lifetime of dots and increased lifetime of wells in the hybrid dipole,dipole coupled system. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The synthesis of CdSe quantum dots with carboxyl group and study on their optical characteristicsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2009Chen Ye Abstract Quantum dots are nanocrystal semiconductors which attract lots of research interests due to their peculiar optical properties. CdSe/ZnS quantum dots have been synthesized via pyrolysis of organometallic reagents. The color of the quantum dot changes from yellow-green to red as their size increases with reaction time. Photoluminescence quantum efficiency of CdSe quantum dots have been enhanced by passivating the surface of CdSe quantum dots with ZnS layers. Quantum dots are nanocrystal semiconductors which attract lots of research interests due to their peculiar optical properties. CdSe/ZnS quantum dots have been synthesized via pyrolysis of organometallic reagents. The color of the quantum dot changes from yellow-green to red as their size increases with reaction time. Photoluminescence quantum efficiency of CdSe quantum dots have been enhanced by passivating the surface of CdSe quantum dots with ZnS layers. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Anomalous resonant nonlinear absorption of excitons in CdSe/ZnS quantum dotsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2008V. Dneprovskii Abstract We have explained the observed anomalous dependence of colloidal CdSe/ZnS quantum dots' (QDs) absorption upon the intensity of input picosecond laser pulses in the case of one-photon resonant excitation of exciton 1S3/2(h) , 1S (e) transition , the linear absorption at low intensity is replaced by nonlinear decreasing and then increasing of absorption (!) at high intensities , by saturation effect (state filling) of two-level system with variable lifetime of the excited state (variable saturation intensity). The lifetime decreases at high excitation due to nonradiative Auger recombination. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Nonlinear absorption and refraction of CdSe/ZnS quantum dots at two-photon resonant excitation of excitonsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2008V. Dneprovskii Abstract The observed nonlinear absorption, optical limiting and nonlinear refraction of colloidal CdSe/ZnS quantum dots in the case of two-photon resonant excitation of 1S3/2(h) , 1S (e) exciton transition by powerful picosecond laser pulses have been explained by two-photon absorption and self-defocusing effect. The results of experiments have allowed to separate self-defocusing effects arising due to the change of nonlinear refractive index of bound electrons and nonlinear refraction from two-photon generated carriers. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Anomalous resonant nonlinear absorption of excitons in CdSe/ZnS quantum dotsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2008V. Dneprovskii Abstract We have explained the observed anomalous dependence of colloidal CdSe/ZnS quantum dots' (QDs) absorption upon the intensity of input picosecond laser pulses in the case of one-photon resonant excitation of exciton 1S3/2(h) , 1S (e) transition , the linear absorption at low intensity is replaced by nonlinear decreasing and then increasing of absorption (!) at high intensities , by saturation effect (state filling) of two-level system with variable lifetime of the excited state (variable saturation intensity). The lifetime decreases at high excitation due to nonradiative Auger recombination. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||