 |
|
New nanosensor uses quantum dots to detect DNA
December 06, 2005Quick, highly sensitive method makes genetic material glow
Using tiny semiconductor crystals, biological probes and a laser, Johns Hopkins University engineers have developed a new method of finding specific sequences of DNA by making them light up beneath a microscope.
The researchers, who say the technique will have important uses in medical research, demonstrated its potential in their lab by detecting a sample of DNA containing a mutation linked to ovarian cancer.
The Johns Hopkins team described the new DNA nanosensor in a paper published in the November 2005 issue of the journal Nature Materials.
"Conventional methods of finding and identifying samples of DNA are cumbersome and time-consuming," said Jeff Tza-Huei Wang, senior author of the paper and supervisor of the research team. "This new technique is ultrasensitive, quick and relatively simple. It can be used to look for a particular part of a DNA sequence, as well as for genetic defects and mutations."
The technique involves an unusual blend of organic and inorganic components. "We are the first to demonstrate the use of quantum dots as a DNA sensor," Wang said.
Quantum dots are crystals of semiconductor material, whose sizes are only in the range of a few nanometers across. (A nanometer is one-billionth of a meter.) They are traditionally used in electronic circuitry. In recent years, however, scientists have begun to explore their use in biological projects.
Wang, an assistant professor in the Department of Mechanical Engineering and the Whitaker Biomedical Engineering Institute at Johns Hopkins, led his team in exploiting an important property of quantum dots: They can easily transfer energy. When a laser shines on a quantum dot, it can pass the energy on to a nearby molecule, which in turn emits a fluorescent glow that is visible under a microscope.
But quantum dots alone cannot find and identify DNA strands. For that, the Johns Hopkins team used two biological probes made of synthetic DNA. Each of these probes is a complement to the DNA sequence the researchers are searching for. Therefore, the probes seek out and bind to the target DNA.
Each DNA probe also has an important partner. Attached to one is a Cy5 molecule that glows when it receives energy. Attached to the second probe is a molecule called biotin. Biotin sticks to yet another molecule called streptavidin, which coats the surface of the quantum dot.
To create their nanosensor, the researchers mixed the two DNA probes, plus a quantum dot, in a lab dish containing the DNA they were trying to detect. Then nature took its course. First, the two DNA probes linked up to the target DNA strand, holding it in a sandwich-like embrace. Then the biotin on one of the probes caused the DNA "sandwich" to stick to the surface of the quantum dot.
Finally, when the researchers shined a laser on the mix, the quantum dot passed the energy on to the Cy5 molecule that was attached to the second probe. The Cy5 released this energy as a fluorescent glow. If the target DNA had not been present in the solution, the four components would not have joined together, and the distinctive glow would not have appeared. Each quantum dot can connect to up to about 60 DNA sequences, making the combined glow even brighter and easier to see.
To test the new technique, Wang's team obtained DNA samples from patients with ovarian cancer and detected DNA sequences containing a critical mutation. "This method may help us identify people at risk of developing cancer, so that treatment can begin at a very early stage," Wang said.
Johns Hopkins University
The Johns Hopkins team described the new DNA nanosensor in a paper published in the November 2005 issue of the journal Nature Materials.
"Conventional methods of finding and identifying samples of DNA are cumbersome and time-consuming," said Jeff Tza-Huei Wang, senior author of the paper and supervisor of the research team. "This new technique is ultrasensitive, quick and relatively simple. It can be used to look for a particular part of a DNA sequence, as well as for genetic defects and mutations."
The technique involves an unusual blend of organic and inorganic components. "We are the first to demonstrate the use of quantum dots as a DNA sensor," Wang said.
Quantum dots are crystals of semiconductor material, whose sizes are only in the range of a few nanometers across. (A nanometer is one-billionth of a meter.) They are traditionally used in electronic circuitry. In recent years, however, scientists have begun to explore their use in biological projects.
Wang, an assistant professor in the Department of Mechanical Engineering and the Whitaker Biomedical Engineering Institute at Johns Hopkins, led his team in exploiting an important property of quantum dots: They can easily transfer energy. When a laser shines on a quantum dot, it can pass the energy on to a nearby molecule, which in turn emits a fluorescent glow that is visible under a microscope.
But quantum dots alone cannot find and identify DNA strands. For that, the Johns Hopkins team used two biological probes made of synthetic DNA. Each of these probes is a complement to the DNA sequence the researchers are searching for. Therefore, the probes seek out and bind to the target DNA.
Each DNA probe also has an important partner. Attached to one is a Cy5 molecule that glows when it receives energy. Attached to the second probe is a molecule called biotin. Biotin sticks to yet another molecule called streptavidin, which coats the surface of the quantum dot.
To create their nanosensor, the researchers mixed the two DNA probes, plus a quantum dot, in a lab dish containing the DNA they were trying to detect. Then nature took its course. First, the two DNA probes linked up to the target DNA strand, holding it in a sandwich-like embrace. Then the biotin on one of the probes caused the DNA "sandwich" to stick to the surface of the quantum dot.
Finally, when the researchers shined a laser on the mix, the quantum dot passed the energy on to the Cy5 molecule that was attached to the second probe. The Cy5 released this energy as a fluorescent glow. If the target DNA had not been present in the solution, the four components would not have joined together, and the distinctive glow would not have appeared. Each quantum dot can connect to up to about 60 DNA sequences, making the combined glow even brighter and easier to see.
To test the new technique, Wang's team obtained DNA samples from patients with ovarian cancer and detected DNA sequences containing a critical mutation. "This method may help us identify people at risk of developing cancer, so that treatment can begin at a very early stage," Wang said.
Johns Hopkins University
Quantum Dot Current Events and Quantum Dot News RSSMIT: Better way to harness waste heat
New MIT research points the way to a technology that might make it possible to harvest much of the wasted heat produced by everything from computer processor chips to car engines to electric powerplants, and turn it into usable electricity.
Small nanoparticles bring big improvement to medical imaging
If you're watching the complex processes in a living cell, it is easy to miss something important-especially if you are watching changes that take a long time to unfold and require high-spatial-resolution imaging.
JQI researchers create entangled photons from quantum dots
To exploit the quantum world to the fullest, a key commodity is entanglement-the spooky, distance-defying link that can form between objects such as atoms even when they are completely shielded from one another.
U-M physicists create first atomic-scale map of quantum dots
University of Michigan physicists have created the first atomic-scale maps of quantum dots, a major step toward the goal of producing "designer dots" that can be tailored for specific applications.
New DNA Test Uses Nanotechnology to Find Early Signs of Cancer
Using tiny crystals called quantum dots, Johns Hopkins researchers have developed a highly sensitive test to look for DNA attachments that often are early warning signs of cancer.
2 software tools that improve identification of cancer biomarkers earn certification
The explosive growth of genomic and proteomic data has ushered in a new era of molecular medicine in which cancer detection, diagnosis and treatment are tailored to each individual's molecular profile.
All-in-one nanoparticle: A Swiss Army knife for nanomedicine
Nanoparticles are being developed to perform a wide range of medical uses -- imaging tumors, carrying drugs, delivering pulses of heat. Rather than settling for just one of these, researchers at the University of Washington have combined two nanoparticles in one tiny package.
Singapore scientists synthesize gold to shed light on cells' inner workings
Highly fluorescent gold nanoclusters for sub-cellular imaging have been synthesized by researchers at the Institute of Bioengineering and Nanotechnology (IBN).
McGill researchers squeeze light out of quantum dots
McGill University researchers have successfully amplified light with so-called "colloidal quantum dots," a technology that had been written off by many as a dead-end.
'Strained' quantum dots show new optical properties
Quantum dots, tiny luminescent particles made of semiconductors, hold promise for detecting and treating cancer earlier. However, if doctors were to use them in humans, quantum dots could have limitations related to their size and possible toxicity.
More Quantum Dot Current Events and Quantum Dot News Articles
 |
The Quantum Dot: A Journey into the Future of Microelectronics by Richard Turton (Author) Since first developed in the early sixties, silicon chip technology has made vast leaps forward. From a rudimentary circuit with a mere handful of transistors, the chip has evolved into a technological miracle, packing millions of bits of information on a surface no larger than a human thumbnail. And most experts predict that in the near future, we will see chips with over a billion bits. At the same time, this revolution in microelectronics has sparked a dramatic change in the way we live. An integral part of the computer industry, the microchip is found in everything from lasers, fax machines, and satellites to greeting cards and children's toys. And yet few people have any idea how chips work, or how so much information can be captured in such a miniscule space. Now, in... |
 |
Semiconductor Quantum Dots by Y. Masumoto (Editor), T. Takagahara (Editor) Semiconductor quantum dots represent one of the fields of solid state physics that have experienced the greatest progress in the last decade. Recent years have witnessed the discovery of many striking new aspects of the optical response and electronic transport phenomena. This book surveys this progress in the physics, optical spectroscopy and application-oriented research of semiconductor quantum dots. It focuses especially on excitons, multi-excitons, their dynamical relaxation behaviour and their interactions with the surroundings of a semiconductor quantum dot. Recent developments in fabrication techniques are reviewed and potential applications discussed. This book will serve not only as an introductory textbook for graduate students but also as a concise guide for active researchers. |
 |
Semiconductor Nanocrystal Quantum Dots: Synthesis, Assembly, Spectroscopy and Applications by Andrey Rogach (Editor) This is the first book to specifically focus on semiconductor nanocrystals and address their synthesis and assembly, optical properties and spectroscopy, and potential areas of nanocrystal-based devices including applications in biology and medicine. Nanoscience will transfer into new products and processes in the next two decades. One emerging area where this challenge will be successfully met is the field of semiconductor nanocrystals. Also known as colloidal quantum dots, their unique properties have attracted much attention in the last twenty years. These highly efficient fluorophores have a strong band-gap luminescence tuneable by size as a result of the quantum confinement effect and are particularly interesting for applications in biology as luminescent labels. Control over a... |
 |
Quantum Dots: A Survey of the Properties of Artificial Atoms by T. Chakraborty (Author) This book deals with the electronic and optical properties of two low-dimensional systems: quantum dots and quantum antidots and is divided into two parts. Part one is a self-contained monograph which describes in detail the theoretical and experimental background for exploration of electronic states of the quantum-confined systems. Starting from the single-electron picture of the system, the book describes various experimental methods that provide important information on these systems. Concentrating on many-electron systems, theoretical developments are described in detail and their experimental consequences are also discussed. The field has witnessed an almost explosive growth and some of the future directions of explorations are highlighted towards the end of the monograph. The... |
 |
Quantum Wells, Wires and Dots: Theoretical and Computational Physics of Semiconductor Nanostructures by Paul Harrison (Author) Quantum Wells, Wires and Dots Second Edition: Theoretical and Computational Physics of Semiconductor Nanostructures provides all the essential information, both theoretical and computational, for complete beginners to develop an understanding of how the electronic, optical and transport properties of quantum wells, wires and dots are calculated. Readers are lead through a series of simple theoretical and computational examples giving solid foundations from which they will gain the confidence to initiate theoretical investigations or explanations of their own. Emphasis on combining the analysis and interpretation of experimental data with the development of theoretical ideas Complementary to the more standard texts Aimed at the physics community at large, rather than... |
 |
Quantum Dots: Fundamentals, Applications, and Frontiers: Proceedings of the NATO ARW on Quantum Dots: Fundamentals, Applications and Frontiers, Crete, ... II: Mathematics, Physics and Chemistry) by Bruce A. Joyce (Editor), Pantelis C. Kelires (Editor), Anton G. Naumovets (Editor), Dimitri D. Vvedensky (Editor) This volume contains papers delivered at a NATO Advanced Research Workshop and provides a broad introduction to all major aspects of quantum dot structures. Such structures have been produced for studies of basic physical phenomena, for device fabrication and, on a more speculative level, have been suggested as components of a solid-state realization of a quantum computer. The book is structured so that the reader is introduced to the methods used to produce and control quantum dots, followed by discussions of their structural, electronic, and optical properties. It concludes with examples of how their optical properties can be used in practical devices, including lasers and light-emitting diodes operating at the commercially important wavelengths of 1.3 µm and 1.55 µm. |
 |
Optics of Quantum Dots and Wires (Artech House Solid-State Technology Library) by Garnett W. Bryant (Editor), Glenn S. Solomon (Editor) Quantum technology is the key to next-generation optoelectronics and laser semiconductors, and this new cutting-edge book is an in-depth examination of how quantum dots and wires are fabricated and applied to optics. You find a solid tutorial on the optical properties of nanoscale dots and wires that explains the current state of this technology and why it is so promising. The book presents a detailed survey of techniques based on molecular beam epitaxial growth for fabricating semiconductor quantum dots and wires. You learn how to assess these growth strategies for insertion of dots and wires into devices. Special focus is given to bottom-up growth methods that have the most potential for fabricating atomically precise structures. Each type of these structures is characterized... |
 |
Inventing Reality The Quantum Dots (Performer) The Quantum Dots' impressive new release, "Inventing Reality," is definitely not your average fledgling debut. Having already been compared to everything from Depeche Mode to Tool, the Quantum Dots expertly showcase their diverse talents and defy classification by delving into everything from ambient electronica, to powernoise, to thrash-metal on this CD. Sure to appeal to a broad range of listeners, from metalheads to club kids, "Inventing Reality" also features the guest-talents of a number of respected Pacific Northwest artists, including violinist Jyri Glynn of The Sins and Ned Wahl of Chemlab and Halo-Black. |
 |
Quantum Dots (Selected Topics in Electronics and Systems, Vol. 25) by E. Borovitskaya (Editor), Michael Shur (Editor) Provides comprehensive reviews of all aspects of quantum dot systems. For scientists, engineers and graduate students working in the area of semiconductor materials and devices. |
 |
Inventing Reality The Quantum Dots (Primary Contributor) |
| © 2009 BrightSurf.com |