Search query: quantum dots

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abstract: Current research into semiconductor clusters is focused on the properties of quantum dots fragments of semiconductor consisting of hundreds to many thousands of atoms with the bulk bonding geometry and with surface states eliminated by enclosure in a material that has a larger band gap. Quantum dots exhibit strongly size dependent optical and electrical properties. The ability to join the dots into complex assemblies creates many opportunities for scientific discovery.
author_names: A Paul Alivisatos
title: Semiconductor Clusters, Nanocrystals, and Quantum Dots
venue: Science
year: 1996

abstract: Research on fluorescent semiconductor nanocrystals (also known as quantum dots or qdots) has evolved over the past two decades from electronic materials science to biological applications. We review current approaches to the synthesis, solubilization, and functionalization of qdots and their applications to cell and animal biology. Recent examples of their experimental use include the observation of diffusion of individual glycine receptors in living neurons and the identification of lymph nodes in live animals by near infrared emission during surgery. The new generations of qdots have far reaching potential for the study of intracellular processes at the single molecule level, high resolution cellular imaging, long term in vivo observation of cell trafficking, tumor targeting, and diagnostics.
author_names: Xavier Michalet

Fabien Pinaud

Laurent A Bentolila

James M Tsay

Soren Doose

Jingyi Jessica Li

Gobalakrishnan Sundaresan

Anna M Wu

Sanjiv Sam Gambhir

Shimon Weiss
title: Quantum Dots for Live Cells, in Vivo Imaging, and Diagnostics
venue: Science
year: 2005

abstract: We propose an implementation of a universal set of one and two quantum bit gates for quantum computation using the spin states of coupled single electron quantum dots. Desired operations are effected by the gating of the tunneling barrier between neighboring dots. Several measures of the gate quality are computed within a recently derived spin master equation incorporating decoherence caused by a prototypical magnetic environment. Dot array experiments that would provide an initial demonstration of the desired nonequilibrium spin dynamics are proposed.
author_names: Daniel Loss

David P DiVincenzo
title: Quantum computation with quantum dots
year: 1998

abstract: We describe the development of multifunctional nanoparticle probes based on semiconductor quantum dots (QDs) for cancer targeting and imaging in living animals. The structural design involves encapsulating luminescent QDs with an ABC triblock copolymer and linking this amphiphilic polymer to tumor targeting ligands and drug delivery functionalities. In vivo targeting studies of human prostate cancer growing in nude mice indicate that the QD probes accumulate at tumors both by the enhanced permeability and retention of tumor sites and by antibody binding to cancer specific cell surface biomarkers. Using both subcutaneous injection of QD tagged cancer cells and systemic injection of multifunctional QD probes, we have achieved sensitive and multicolor fluorescence imaging of cancer cells under in vivo conditions. We have also integrated a whole body macro illumination system with wavelength resolved spectral imaging for efficient background removal and precise delineation of weak spectral signatures. These results raise new possibilities for ultrasensitive and multiplexed imaging of molecular targets in vivo.
author_names: Xiaohu Gao

Yuanyuan Cui

Richard M Levenson

Leland W K Chung

Shuming Nie
title: In vivo cancer targeting and imaging with semiconductor quantum dots
venue: Nature Biotechnology
year: 2004

abstract: The field of nanotechnology holds great promise for the diagnosis and treatment of human disease. However, the size and charge of most nanoparticles preclude their efficient clearance from the body as intact nanoparticles. Without such clearance or their biodegradation into biologically benign components, toxicity is potentially amplified and radiological imaging is hindered. Using intravenously administered quantum dots in rodents as a model system, we have precisely defined the requirements for renal filtration and urinary excretion of inorganic, metal containing nanoparticles. Zwitterionic or neutral organic coatings prevented adsorption of serum proteins, which otherwise increased hydrodynamic diameter by >15 nm and prevented renal excretion. A final hydrodynamic diameter <5.5 nm resulted in rapid and efficient urinary excretion and elimination of quantum dots from the body. This study provides a foundation for the design and development of biologically targeted nanoparticles for biomedical applications.
author_names: Hak Soo Choi

Wenhao Liu

Preeti Misra

Eiichi Tanaka

J Pascal Zimmer

Binil Itty Ipe

Moungi G Bawendi

John V Frangioni
title: Renal clearance of quantum dots
venue: Nature Biotechnology
year: 2007

abstract: We report a synthesis of highly luminescent (CdSe)ZnS composite quantum dots with CdSe cores ranging in diameter from 23 to 55 A. The narrow photoluminescence (fwhm 40 nm) from these composite dots spans most of the visible spectrum from blue through red with quantum yields of 30 50% at room temperature. We characterize these materials using a range of optical and structural techniques. Optical absorption and photoluminescence spectroscopies probe the effect of ZnS passivation on the electronic structure of the dots. We use a combination of wavelength dispersive X ray spectroscopy, X ray photoelectron spectroscopy, small and wide angle X ray scattering, and transmission electron microscopy to analyze the composite dots and determine their chemical composition, average size, size distribution, shape, and internal structure. Using a simple effective mass theory, we model the energy shift for the first excited state for (CdSe)ZnS and (CdSe)CdS dots with varying shell thickness. Finally, we characterize the.
author_names: Bashir O Dabbousi

Javier Rodriguez-Viejo

Frederic Victor Mikulec

J R Heine

Hedi Mattoussi

R Ober

++SS and K F Jensen

Moungi G Bawendi
title: (CdSe)ZnS Core Shell Quantum Dots Synthesis and Characterization of a Size Series of Highly Luminescent Nanocrystallites
year: 1997

abstract: With their bright, photostable fluorescence, semiconductor quantum dots show promise as alternatives to organic dyes for biological labeling. Questions about their potential cytotoxicity, however, remain unanswered. While cytotoxicity of bulk cadmium selenide (CdSe) is well documented, a number of groups have suggested that CdSe QDs are cytocompatible, at least with some immortalized cell lines. Using primary hepatocytes as a liver model, we found that CdSe core QDs were indeed acutely toxic under certain conditions. Specifically, we found that the cytotoxicity of QDs was modulated by processing parameters during synthesis, exposure to ultraviolet light, and surface coatings. Our data further suggests that cytotoxicity correlates with the liberation of free Cd2+ ions due to deterioration of the CdSe lattice. When appropriately coated, CdSe core QDs can be rendered non toxic and used to track cell migration and reorganization in vitro. Our results inform design criteria for the use of QDs in vitro and especially in vivo where deterioration over time may occur.
author_names: Austin M Derfus

Warren C W Chan

Sangeeta N Bhatia
title: Probing the Cytotoxicity Of Semiconductor Quantum Dots.
venue: Nano letters
year: 2004

abstract: Suitable labels are at the core of luminescence and fluorescence imaging and sensing. One of the most exciting, yet also controversial, advances in label technology is the emerging development of quantum dots (QDs) inorganic nanocrystals with unique optical and chemical properties but complicated surface chemistry as in vitro and in vivo fluorophores. Here we compare and evaluate the differences in physicochemical properties of common fluorescent labels, focusing on traditional organic dyes and QDs. Our aim is to provide a better understanding of the advantages and limitations of both classes of chromophores, to facilitate label choice and to address future challenges in the rational design and manipulation of QD labels.
author_names: Ute Resch-Genger

Markus Grabolle

Sara Cavaliere-Jaricot

Roland Nitschke

Thomas Nann
title: Quantum dots versus organic dyes as fluorescent labels
venue: Nature Methods
year: 2008

abstract: We report that nanoscale carbon particles (carbon dots) upon simple surface passivation are strongly photoluminescent in both solution and the solid state. The luminescence emission of the carbon dots is stable against photobleaching, and there is no blinking effect. These strongly emissive carbon dots may find applications similar to or beyond those of their widely pursued silicon counterparts.
author_names: Ya-Ping Sun

Bing Zhou

Yi Lin

Wei Wang

Kurukulasuriya Alexius Shiral Fernando

Pankaj Pathak

Mohammed Meziani

Barbara A Harruff

X P Wang

Haifang Wang

Pengju George Luo

Hua Yang

Muhammet Kose

Baili Chen

Lucia Monica Veca

Su-Yuan Xie
title: Quantum sized carbon dots for bright and colorful photoluminescence.
venue: Journal of the American Chemical Society
year: 2006

abstract: Fluorescent semiconductor nanocrystals (quantum dots) have the potential to revolutionize biological imaging, but their use has been limited by difficulties in obtaining nanocrystals that are biocompatible. To address this problem, we encapsulated individual nanocrystals in phospholipid block copolymer micelles and demonstrated both in vitro and in vivo imaging. When conjugated to DNA, the nanocrystal micelles acted as in vitro fluorescent probes to hybridize to specific complementary sequences. Moreover, when injected into Xenopus embryos, the nanocrystal micelles were stable, nontoxic <5 x 109 nanocrystals per cell) cell autonomous, and slow to photobleach. Nanocrystal fluorescence could be followed to the tadpole stage, allowing lineage tracing experiments in embryogenesis.
author_names: Benoit Dubertret

Paris A Skourides

David J Norris

Vincent Noireaux

Ali H Brivanlou

Albert Libchaber
title: In Vivo Imaging of Quantum Dots Encapsulated in Phospholipid Micelles
venue: Science
year: 2002