There is an effective birth control option for everyone?including those with health conditions like heavy or irregular periods, obesity, diabetes, high blood pressure, or breast cancer. Some methods can actually help treat certain conditions. Let?s look at six fairly common medical conditions and the birth control methods that are best for each.
1. Painful or heavy periods
Good methods:?All hormonal methods, especially the hormonal?IUD, the?implant, and the?shot.
Painful or heavy periods are?unfortunately?pretty common. About one in five U.S. women have?menorrhagia. All types of hormonal birth control will decrease or eliminate monthly bleeding, including the pill, patch, ring, shot, implant and hormonal IUD. For women with conditions that can cause heavy bleeding (endometriosis, adenomyosis, or uterine fibroids), hormonal methods can help make periods shorter, lighter, and less painful. Decreasing or stopping monthly bleeding is also a great treatment to improve anemia (sickle cell anemia or thalassemia) and bleeding disorders (e.g. factor V deficiency).
2. Irregular periods
Good methods:?The?pill, the?patch, and the?ring.
For women with irregular periods who would prefer a more predictable cycle, the pill, patch, and ring can help regulate periods. Medical conditions that can cause an irregular cycle include poly cystic ovary syndrome (PCOS) and thyroid disorders.
3. Obesity
Good methods:?Any and all, except?emergency contraception pills.
Over one in three adult women in the U.S. are considered?obese. We?ve written about?birth control and weight?before. Nearly all forms of birth control are effective for women regardless of weight. The one important exception is emergency contraception (EC). Research shows that levonorgestrel EC (like Plan B and Next Choice) and ella are less effective for obese women. How much less effective? For these women, taking an EC pill is?the same as doing nothing. However, there is an EC that works for women of any weight:?the copper IUD. It?s the most effective form of EC?including for women who aren?t obese.
4. Diabetes
Good methods:?Depends on your health, but nearly always includes progestin-only options like the implant, hormonal IUDs, or?mini pills.
About one in ten adult women in the U.S. have?diabetes, although it?s estimated that half don?t know it. For women who have diabetes without other complications like heart, circulatory system, eye or kidney diseases, the good news is that they can safely use all types of birth control. Diabetic women who do have any of those additional conditions need to talk with their doctors about their options, which will usually include the implant, IUDs, or progestin-only mini pills.
5. High blood pressure
Good methods:?Depending on risk factors, estrogen-free methods might be best.
Relatively few women under age 30 have?high blood pressure?only about one in 50. But of those women who do, many don?t know about their condition. It?s important to get an annual exam and have your blood pressure measured before you choose a method of birth control. High blood pressure can increase the?risk of a blood clot?when using the pill, the patch, or the ring.
Women who know about their high blood pressure can manage it through a variety of tactics, including medication. Women with well-controlled blood pressure should be able to safely use the pill, the patch, or the ring. However, women who have other risk factors for blood clots like smoking or obesity should talk to a doctor about options that do not contain the hormone estrogen.
6. Breast cancer
Good methods:?Non-hormonal options like the copper IUD and?condoms.
Breast cancer is rare in women under age 30, with less than one in 1,500 affected. But current or past breast cancer means that a woman should avoid all hormonal methods of contraception. The non-hormonal IUD is a highly effective and safe option in these cases, and condoms are the most effective of the barrier methods.
Looking for something else?
We couldn?t tackle every health condition here, so if there?s one you?d like to see us cover in the future, let us know below! Whatever it may be, it?s likely that there is a safe and effective birth control for you. And as always, talk to your health care provider about what?s best for you. (Don?t have your own health care provider??Find one here.)
Nerys Benfield, MD MPH, is an obstetrician/gynecologist at Albert Einstein College of Medicine, Montefiore Medical Center in New York City. She is the director of family planning services and specializes in contraception, working to promote contraceptive counseling and distribution locally and internationally.
7 in 10 pregnancies among single women in their 20s are unplanned. Bedsider has set out to reduce that number by making birth control easier. Bedsider.org (Bedsider) is an online birth control support network for women 18-29 operated by?The National Campaign to Prevent Teen and Unplanned Pregnancy, a private non-profit organization. Bedsider serves up authoritative contraception information in a sexy, friendly, and funny way that women? find informative and entertaining.?Bedsider is a HealthyYouNow.com partner.
Candice Glover was announced as the winner on “American Idol” Season 12 last night, beating out Kree Harrison. Glover, who had previously been told by Simon Cowell she’d never be more than a lounge singer, proved him wrong on her third attempt! Candice Glover, 23, an administrative assistant from South Carolina, was shocked to win, ...
Ed Markey is a Democrat with high name recognition running in a blue state, and polls show him leading the GOP's Gabriel Gomez. But another US Senate race, in 2010, showed that Massachusetts voters can mete out some surprises.
By Ryan Lenora Brown,?Correspondent / May 17, 2013
Mass. Gov. Deval Patrick (l.) applauds while joining Democratic US Senate nominee, Rep. Ed Markey of Massachusetts, at a campaign event in Boston, May 8. Markey is running against Republican Gabriel Gomez in the June 25 special election.
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The veteran Democratic congressman has a seven-point lead over Republican Gabriel Gomez in the special election for US Senate in Massachusetts, according to a new poll by the League of Conservation Voters and Public Policy Polling.
The poll is the third in recent days to show Mr. Markey, a four-decade veteran of the House of Representatives, with a healthy margin over Mr. Gomez, a Navy SEAL and businessman who is making his first major foray into politics.?
A poll last week by Boston public radio station WBUR put Markey?s lead at six percentage points, while a Suffolk University/WHDH-TV poll gave him a towering 17-point advantage.
With less than six weeks until Election Day, Markey remains the comfortable favorite, although to understand why you have to read between the polling numbers, says Marc Landy, a political scientist at Boston College.
?Polls vary, and they should be taken with a salt-shaker of salt,? he says, ?but what Markey?s got that?s more substantive is a lot of money, a lot of name recognition, and a very Democratic state.?
To overcome that, Gomez will need both elbow grease and a Markey misstep. He can run a brilliant campaign, Mr. Landy says, but unless Markey makes a major fumble, the Democrat?s advantages may be too significant to overcome.
But the Massachusetts Democratic establishment isn?t resting just yet. That skittish attitude comes courtesy of one man: Scott Brown.
WASHINGTON (Reuters) - Lawmakers in the U.S. House of Representatives trying to write an immigration bill met on Thursday in a last-ditch attempt to resolve their differences over a temporary worker program and healthcare benefits for illegal immigrants.
The group of eight Democratic and Republican lawmakers has been attempting to craft a bill to overhaul the immigration system and deal with the millions of immigrants living illegally in the United States.
But disputes over border security, work visa numbers and healthcare provisions have risen to the point that there are fears some lawmakers might be on the verge of dropping out.
"I am concerned that the bipartisan group has been unable to wrap up their work," House Speaker John Boehner told reporters, adding, "I know there are some very difficult issues that have come up."
Lawmakers have been arguing over the "triggers" that would define when additional border security steps under the legislation would be sufficient to start legalizing some of the 11 million unauthorized foreigners, sources said.
There also continued to be disagreements over several other policy issues central to an immigration bill, including the number of foreign high-tech workers who would be allowed in, as well as low-skilled construction and service industry employees.
Congressional aides were describing the meeting as "one last-ditch effort" to stay together and produce at least an outline of a bill following about four years of private talks.
All of the House's issues were negotiated in a carefully crafted bipartisan bill now being debated in the Senate Judiciary Committee.
That panel is also struggling with the work visa program in the bill and is under intense pressure from technology companies to make it easier to hire foreign workers.
The committee hopes to complete work on the nearly 900-page bill by the end of this month, clearing the way for debate in the full Senate as early as June.
One of the members of the House group, Republican John Carter, repeatedly told reporters that there was no way the Senate bill would pass the Republican-controlled House.
Immediately following the November 6 elections, in which Hispanic voters roundly rejected Republican presidential candidate Mitt Romney, Boehner called on his party to pivot on immigration.
After years of blocking moves to put the 11 million on a pathway to citizenship that many conservatives call "amnesty," Boehner, the top elected U.S. Republican, urged his party to work for a major revamp of immigration laws.
While citing concerns on Thursday about the lack of progress in the House so far, Boehner said: "I continue to believe that the House ... needs to work its will. How we get there, we're still dealing with it."
STRATEGY DEBATE
The chairman of the House Judiciary Committee, Bob Goodlatte of Virginia, has expressed his preference for doing individual bills tackling parts of the immigration policy problems, instead of a comprehensive approach.
But Democrats in both chambers have rejected such a strategy, saying it would indefinitely delay the pathway to citizenship for undocumented residents, many of whom have been in the United States for decades and are raising families here.
Besides policy disagreements, individual members of the House group have differed over whether it would be productive to unveil a House measure while the Senate is in the midst of debating its bill.
Democrats, for example, have been hesitant to embrace a more conservative House immigration bill, which they fear would undercut their fellow Democrats in the Senate.
(Additional reporting by Caren Bohan; Editing by Fred Barbash, Cynthia Osterman and Eric Walsh)
Although capture technologies show promise, pulling CO2 out of the air is unlikely to reduce greenhouse gas concentrations soon
By David Biello
AIR CAPTURE: Could this plastic embedded with resin help draw down atmospheric concentrations of carbon dioxide?Image: ? David Biello
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Carbon dioxide levels in the atmosphere have touched 400 parts per million for the first time in at least 800,000 years. The jagged saw-toothed line of the Keelings' father-and-son measurements climbed above that milestone briefly this month before the budding growth of the Northern Hemisphere's spring began sucking CO2 back out of the sky. But human greenhouse gas pollution looks set to continue to rise?and photosynthetic plants on land or at sea can only do so much. As greenhouse gas levels increase further, could machines help wash the skies of the excess CO2?
On an early spring day touched with the promise of warmth plus the threat of rain, I headed up to Columbia University's Mudd Building and the lab of physicist Klaus Lackner, formerly of Los Alamos National Laboratory. His hearty chuckle belies his formal German diction and physicist's habit of obfuscating with numbers. Girding myself for potentially indecipherable jokes, I'm here to see Lackner?s potentially world-saving technology: a plastic resin that can capture carbon dioxide directly from the air.
The resin rests outside a clear greenhouse bearing basil plants, bamboo, a houseplant and cucumbers that glow an eerie purple-red under ultraviolet light. The plants' leaves rustle in the breeze from a Dyson bladeless fan. Next to the big tank, a computer monitor charts CO2 levels and a tube on one side separates the environment within the greenhouse from the outside world. With the UV light on, the plants are busily sucking in CO2 to make leaves, roots and vegetables. "The cucumber got fat on the CO2," Lackner notes and chuckles.
A pale beige polypropylene plastic embedded with 25-micrometer particles of the resin is inserted into the tube in the form of a long-haired shag carpet sample and, almost immediately, CO2 levels inside the greenhouse begin a steady march downward as the resin binds CO2 to form bicarbonate, a kind of salt produced. This type of salt, more familiar perhaps as baking soda when there's a sodium atom involved, holds the CO2. The resin sucks in CO2 even more powerfully than the plants do, as a function of the relative humidity of the material. That makes the process reversible; just add water to get the CO2 back out again.
This is no joke. A polycarbonate plastic bottle used to store some of the resin ended up scarified. "They broke the plastic," Lacker says of his lab co-conspirators, showing me the streaked, cloudy, hard plastic bottle. The resin pulled CO2 out of the polycarbonate in its vigorous quest for chemical equilibrium.
Lackner calculates that more than 700 kilograms of CO2 passes through an opening the size of the door to this lab over a 24-hour period when the wind is up, courtesy of another Dyson or just a windy building top. That's how much a sheet of this material might pull from the air. Or it could be refashioned into a brushlike or folded checker configuration, exposing more of the resin.
Of course, 700 kilograms of CO2 only equals the breath of 13 people for one day and night. There would need to be a lot of these resin machines to make a significant impact on pulling this trace greenhouse gas out of the atmosphere to lower atmospheric concentrations; Lackner estimates 10 million such artificial ?trees? would be required to drop atmospheric concentrations by 0.5 ppm per year. Each machine would require roughly 1.1 megajoule of electricity for pumping and compressing per kilogram of CO2 captured. That's not to mention all the water required to wet the filters (and evaporate) in order to get the CO2 back out again so the resin can be re-used to capture yet more CO2. The compressed and captured CO2 can then either be used for industrial purposes, like enhanced oil recovery to improve the economics of all this, or buried deep beneath the surface of the planet. In other words, a vast industrial infrastructure of air-capture machines would be required to remedy the effects of our vast, industrial infrastructure for fossil fuels.
Just how the resin operates is the focus of the other experiment in this lab. Hidden inside a Styrofoam cooler?with a dark blue Columbia necktie as de facto latch?the resin is exposed to water and CO2 and precisely weighed while temperature is kept constant. The idea is to keep CO2 steady at 400 ppm with no temperature variation and then change the conditions to determine how well the resin works.
This undated image made available by the Oregon Health & Science University in May 2013 shows developing cloned human embryos. Scientists have finally recovered stem cells from cloned human embryos, a longstanding goal that could lead to new treatments for such illnesses as Parkinson's disease and diabetes. In the Wednesday, May 15, 2013 edition of the journal Cell, scientists at the Oregon Health & Science University report harvesting stem cells from six embryos. Shoukhrat Mitalipov, who led the research, said the success came not from a single technical innovation, but from revising a series of steps in the process. (AP Photo/Oregon Health & Science University)
This undated image made available by the Oregon Health & Science University in May 2013 shows developing cloned human embryos. Scientists have finally recovered stem cells from cloned human embryos, a longstanding goal that could lead to new treatments for such illnesses as Parkinson's disease and diabetes. In the Wednesday, May 15, 2013 edition of the journal Cell, scientists at the Oregon Health & Science University report harvesting stem cells from six embryos. Shoukhrat Mitalipov, who led the research, said the success came not from a single technical innovation, but from revising a series of steps in the process. (AP Photo/Oregon Health & Science University)
This undated image made available by the Oregon Health & Science University in May 2013 shows a stem cell colony developed from cloned human embryos. Scientists have finally recovered stem cells from cloned human embryos, a longstanding goal that could lead to new treatments for such illnesses as Parkinson's disease and diabetes. In the Wednesday, May 15, 2013 edition of the journal Cell, scientists at the Oregon Health & Science University report harvesting stem cells from six embryos. Shoukhrat Mitalipov, who led the research, said the success came not from a single technical innovation, but from revising a series of steps in the process. (AP Photo/Oregon Health & Science University)
NEW YORK (AP) ? Scientists have recovered stem cells from cloned human embryos, a longstanding goal that could lead to new treatments for such illnesses as Parkinson's disease and diabetes.
Experts called the work significant, but noted that a different, simpler technique now under development may prove more useful.
Stem cells can turn into any cell of the body. Scientists are interested in using them to create transplant tissue for treating disease.
But transplants run the risk of rejection. So researchers had proposed creating tissue that used the patient's own DNA through cloning.
But in about a decade of trying, scientists had not been able to produce those stem cells from cloned human embryos.
The success is reported Wednesday in the journal Cell by a team based at Oregon Health & Science University.
Contact: Karen McNulty Walsh kmcnulty@bnl.gov 631-344-8350 DOE/Brookhaven National Laboratory
Approach could be useful in fabricating new kinds of materials with engineered properties
UPTON, NY-Scientists at the U.S. Department of Energy's Brookhaven National Laboratory have discovered that DNA "linker" strands coax nano-sized rods to line up in way unlike any other spontaneous arrangement of rod-shaped objects. The arrangement-with the rods forming "rungs" on ladder-like ribbons linked by multiple DNA strands-results from the collective interactions of the flexible DNA tethers and may be unique to the nanoscale. The research, described in a paper published online in ACS Nano, a journal of the American Chemical Society, could result in the fabrication of new nanostructured materials with desired properties.
"This is a completely new mechanism of self-assembly that does not have direct analogs in the realm of molecular or microscale systems," said Brookhaven physicist Oleg Gang, lead author on the paper, who conducted the bulk of the research at the Lab's Center for Functional Nanomaterials (CFN, http://www.bnl.gov/cfn/).
Broad classes of rod-like objects, ranging from molecules to viruses, often exhibit typical liquid-crystal-like behavior, where the rods align with a directional dependence, sometimes with the aligned crystals forming two-dimensional planes over a given area. Rod shaped objects with strong directionality and attractive forces between their ends-resulting, for example, from polarized charge distribution-may also sometimes line up end-to-end forming linear one-dimensional chains.
Neither typical arrangement is found in the DNA-tethered nanorods.
"Our discovery shows that a qualitatively new regime emerges for nanoscale objects decorated with flexible molecular tethers of comparable sizes-a one-dimensional ladder-like linear arrangement that appears in the absence of end-to-end affinity among the rods," Gang said.
Alexei Tkachenko, the CFN scientist who developed the theory to explain the exceptional arrangement, elaborated: "Remarkably, the system has all three dimensions to live in, yet it chooses to form the linear, almost one-dimensional ribbons. It can be compared to how extra dimensions that are hypothesized by high-energy physicists become 'hidden,' so that we find ourselves in a 3-D world."
Tkachenko explains how the ladder-like alignment results from a fundamental symmetry breaking:
"Once a nanorod connects to another one side-by-side, it loses the cylindrical symmetry it had when it had free tethers all around. Then, the next nanorod will preferentially bind to another side of the first, where there are still DNA linkers available."
DNA as glue
Using synthetic DNA as a form of molecular glue to guide nanoparticle assembly has been a central approach of Gang's research at the CFN. His previous work has shown that strands of this molecule-better known for carrying the genetic code of living things-can pull nanoparticles together when strands bearing complementary sequences of nucleotide bases (known by the letters A, T, G, and C) are used as tethers, or inhibit binding when unmatched strands are used. Carefully controlling those attractive and inhibitory forces can lead to fine-tuned nanoscale engineering.
In the current study, the scientists used gold nanorods and single strands of DNA to explore arrangements made with complementary tethers attached to adjacent rods. They also examined the effects of using linker strands of varying lengths to serve as the tethering glue.
After mixing the various combinations, they studied the resulting arrangements using ultraviolet-visible spectroscopy at the CFN, and also with small-angle x-ray scattering at Brookhaven's National Synchrotron Light Source (NSLS, http://www.bnl.gov/ps/nsls/about-NSLS.asp). They also used techniques to "freeze" the action at various points during assembly and observed those static phases using scanning electron microscopy to get a better understanding of how the process progressed over time.
The various analysis methods confirmed the side-by-side arrangement of the nanorods arrayed like rungs on a ladder-like ribbon during the early stages of assembly, followed later by stacking of the ribbons and finally larger-scale three-dimensional aggregation due to the formation of DNA bridges between the ribbons.
This staged assembly process, called hierarchical, is reminiscent of self-assembly in many biological systems (for example, the linking of amino acids into chains followed by the subsequent folding of these chains to form functional proteins).
The stepwise nature of the assembly suggested to the team that the process could be stopped at the intermediate stages. Using "blocker" strands of DNA to bind up the remaining free tethers on the linear ribbon-like structures, they demonstrated their ability to prevent the later-stage interactions that form aggregate structures.
"Stopping the assembly process at the ladder-like ribbon stage could potentially be applied for the fabrication of linear structures with engineered properties," Gang said. "For example by controlling plasmonic or fluorescent properties-the materials' responses to light-we might be able to make nanoscale light concentrators or light guides, and be able to switch them on demand."
###
Additional authors on this study include: Stephanie Vial of CFN and the International Iberian Nanotechnology Laboratory in Braga, Portugal, and Dmytro Nykypanchuk, and Kevin Yager, all of CFN.
This research was funded by the DOE Office of Science (BES), which also provides operations support for the CFN and NSLS at Brookhaven Lab.
The Center for Functional Nanomaterials is one of the five DOE Nanoscale Science Research Centers, premier national user facilities for interdisciplinary research at the nanoscale supported by the U.S. Department of Energy, Office of Science. Together the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative. The NSRCs are located at DOE's Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge, Sandia and Los Alamos National Laboratories. More information about the DOE NSRCs: http://science.energy.gov/bes/suf/user-facilities/nanoscale-science-research-centers.
One of the world's most widely used scientific research facilities, the National Synchrotron Light Source (NSLS) is host each year to 2,400 researchers from more than 400 universities, laboratories, and companies. Research conducted at the NSLS has yielded advances in biology, physics, chemistry, geophysics, medicine, and materials science. More information about NSLS: http://www.bnl.gov/ps/nsls/About-NSLS.asp.
DOE's Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.
Related Links
Scientific paper:
Linear Mesostructures in DNA-Nanorod Self-Assembly
Online version of this news release with related graphics:
http://www.bnl.gov/newsroom/news.php?a=11540
Press releases on previous related work:
Multi-Component Nano-Structures with Tunable Optical Properties
Switchable Nanostructures Made with DNA
DNA-Based Assembly Line for Precision Nano-Cluster Construction
Media contacts: Karen McNulty Walsh, (631) 344-8350, kmcnulty@bnl.gov, or Peter Genzer, (631) 344-3174, genzer@bnl.gov
One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE's Office of Science by Brookhaven Science Associates, a limited-liability company founded by the Research Foundation for the State University of New York on behalf of Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit applied science and technology organization.
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AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.
Contact: Karen McNulty Walsh kmcnulty@bnl.gov 631-344-8350 DOE/Brookhaven National Laboratory
Approach could be useful in fabricating new kinds of materials with engineered properties
UPTON, NY-Scientists at the U.S. Department of Energy's Brookhaven National Laboratory have discovered that DNA "linker" strands coax nano-sized rods to line up in way unlike any other spontaneous arrangement of rod-shaped objects. The arrangement-with the rods forming "rungs" on ladder-like ribbons linked by multiple DNA strands-results from the collective interactions of the flexible DNA tethers and may be unique to the nanoscale. The research, described in a paper published online in ACS Nano, a journal of the American Chemical Society, could result in the fabrication of new nanostructured materials with desired properties.
"This is a completely new mechanism of self-assembly that does not have direct analogs in the realm of molecular or microscale systems," said Brookhaven physicist Oleg Gang, lead author on the paper, who conducted the bulk of the research at the Lab's Center for Functional Nanomaterials (CFN, http://www.bnl.gov/cfn/).
Broad classes of rod-like objects, ranging from molecules to viruses, often exhibit typical liquid-crystal-like behavior, where the rods align with a directional dependence, sometimes with the aligned crystals forming two-dimensional planes over a given area. Rod shaped objects with strong directionality and attractive forces between their ends-resulting, for example, from polarized charge distribution-may also sometimes line up end-to-end forming linear one-dimensional chains.
Neither typical arrangement is found in the DNA-tethered nanorods.
"Our discovery shows that a qualitatively new regime emerges for nanoscale objects decorated with flexible molecular tethers of comparable sizes-a one-dimensional ladder-like linear arrangement that appears in the absence of end-to-end affinity among the rods," Gang said.
Alexei Tkachenko, the CFN scientist who developed the theory to explain the exceptional arrangement, elaborated: "Remarkably, the system has all three dimensions to live in, yet it chooses to form the linear, almost one-dimensional ribbons. It can be compared to how extra dimensions that are hypothesized by high-energy physicists become 'hidden,' so that we find ourselves in a 3-D world."
Tkachenko explains how the ladder-like alignment results from a fundamental symmetry breaking:
"Once a nanorod connects to another one side-by-side, it loses the cylindrical symmetry it had when it had free tethers all around. Then, the next nanorod will preferentially bind to another side of the first, where there are still DNA linkers available."
DNA as glue
Using synthetic DNA as a form of molecular glue to guide nanoparticle assembly has been a central approach of Gang's research at the CFN. His previous work has shown that strands of this molecule-better known for carrying the genetic code of living things-can pull nanoparticles together when strands bearing complementary sequences of nucleotide bases (known by the letters A, T, G, and C) are used as tethers, or inhibit binding when unmatched strands are used. Carefully controlling those attractive and inhibitory forces can lead to fine-tuned nanoscale engineering.
In the current study, the scientists used gold nanorods and single strands of DNA to explore arrangements made with complementary tethers attached to adjacent rods. They also examined the effects of using linker strands of varying lengths to serve as the tethering glue.
After mixing the various combinations, they studied the resulting arrangements using ultraviolet-visible spectroscopy at the CFN, and also with small-angle x-ray scattering at Brookhaven's National Synchrotron Light Source (NSLS, http://www.bnl.gov/ps/nsls/about-NSLS.asp). They also used techniques to "freeze" the action at various points during assembly and observed those static phases using scanning electron microscopy to get a better understanding of how the process progressed over time.
The various analysis methods confirmed the side-by-side arrangement of the nanorods arrayed like rungs on a ladder-like ribbon during the early stages of assembly, followed later by stacking of the ribbons and finally larger-scale three-dimensional aggregation due to the formation of DNA bridges between the ribbons.
This staged assembly process, called hierarchical, is reminiscent of self-assembly in many biological systems (for example, the linking of amino acids into chains followed by the subsequent folding of these chains to form functional proteins).
The stepwise nature of the assembly suggested to the team that the process could be stopped at the intermediate stages. Using "blocker" strands of DNA to bind up the remaining free tethers on the linear ribbon-like structures, they demonstrated their ability to prevent the later-stage interactions that form aggregate structures.
"Stopping the assembly process at the ladder-like ribbon stage could potentially be applied for the fabrication of linear structures with engineered properties," Gang said. "For example by controlling plasmonic or fluorescent properties-the materials' responses to light-we might be able to make nanoscale light concentrators or light guides, and be able to switch them on demand."
###
Additional authors on this study include: Stephanie Vial of CFN and the International Iberian Nanotechnology Laboratory in Braga, Portugal, and Dmytro Nykypanchuk, and Kevin Yager, all of CFN.
This research was funded by the DOE Office of Science (BES), which also provides operations support for the CFN and NSLS at Brookhaven Lab.
The Center for Functional Nanomaterials is one of the five DOE Nanoscale Science Research Centers, premier national user facilities for interdisciplinary research at the nanoscale supported by the U.S. Department of Energy, Office of Science. Together the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative. The NSRCs are located at DOE's Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge, Sandia and Los Alamos National Laboratories. More information about the DOE NSRCs: http://science.energy.gov/bes/suf/user-facilities/nanoscale-science-research-centers.
One of the world's most widely used scientific research facilities, the National Synchrotron Light Source (NSLS) is host each year to 2,400 researchers from more than 400 universities, laboratories, and companies. Research conducted at the NSLS has yielded advances in biology, physics, chemistry, geophysics, medicine, and materials science. More information about NSLS: http://www.bnl.gov/ps/nsls/About-NSLS.asp.
DOE's Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.
Related Links
Scientific paper:
Linear Mesostructures in DNA-Nanorod Self-Assembly
Online version of this news release with related graphics:
http://www.bnl.gov/newsroom/news.php?a=11540
Press releases on previous related work:
Multi-Component Nano-Structures with Tunable Optical Properties
Switchable Nanostructures Made with DNA
DNA-Based Assembly Line for Precision Nano-Cluster Construction
Media contacts: Karen McNulty Walsh, (631) 344-8350, kmcnulty@bnl.gov, or Peter Genzer, (631) 344-3174, genzer@bnl.gov
One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE's Office of Science by Brookhaven Science Associates, a limited-liability company founded by the Research Foundation for the State University of New York on behalf of Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit applied science and technology organization.
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AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.
Candice Glover was announced as the winner on “American Idol” Season 12 last night, beating out Kree Harrison. Glover, who had previously been told by Simon Cowell she’d never be more than a lounge singer, proved him wrong on her third attempt! Candice Glover, 23, an administrative assistant from South Carolina, was shocked to win, ...
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Public release date: 16-May-2013
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