UGA researcher develops new medicine that attacks HIV before it integrates with human DNA.


Nair, Vasu-h.env dna model 2013

  • Vasu Nair, Georgia Research Alliance Eminent Scholar and director of the UGA Center for Drug Discovery, has developed a drug that blocks HIV from inserting its genome into the DNA of the host cell.

Athens, Ga. – Thirty-four million people are living with human immunodeficiency virus, or HIV, worldwide and each year some 2.5 million more are infected, according to the World Health Organization.

New medicine developed at the University of Georgia attacks the virus before it integrates with human DNA, understood by researchers as the point of no return.

“In our laboratories, we have discovered a highly potent HIV integrase inhibitor, or blocker, aimed at the ‘point of no return’ in HIV infectivity,” said Nair, who is the Georgia Research Alliance Eminent Scholar in Drug Discovery in the UGA College of Pharmacy. “This inhibitor is highly effective against many variations of HIV.”

According to Nair, HIV integrase is an ideal target for drug therapy because it is essential for viral replication, and there is no human counterpart, which means there is a low risk of side effects.

Cell signaling, the transmission of information by molecules that coordinate and direct cellular actions, plays a key role in HIV cell invasion and the hijacking of cellular biochemistry, allowing the virus to replicate itself.

In the initial stage of HIV infection, the body’s immune system releases antibodies to attack the virus. Helper T-cells, called CD4+ cells, play a central role in the body’s immune response, orchestrating other cells in the immune system to carry out their specific protective functions. In its invasion of CD4+ cells, HIV recognizes and attaches itself to the outer surface of the cell, penetrates it, sheds its outer coat, releases its 15 viral proteins and a ribonucleic acid and proceeds with exploiting the human cellular biochemical machinery to reproduce itself in massive numbers.

“Of all of the steps involved in the replication or reproduction of HIV in its infectivity of the human system, the single most devastating point is the incorporation or integration of viral DNA into human chromosomal DNA,” said Nair.

This insertion of viral DNA into human DNA occurs through a complex biochemical process that is facilitated by HIV integrase, a viral enzyme. Only after this crucial step is the viral invader in a position to exploit human cellular biochemistry to reproduce itself in astonishing numbers to ultimately bring about the destruction of CD4 lymphocytes, the coordinators of the immune response system of the human body.

As the infected T-cells die, the immune system of the infected body is unable to defend itself; opportunistic infections such as pneumonia, meningitis, antibiotic-resistant TB and other bacterial and viral infections become deadly. HIV and, eventually, AIDS and drug-resistant tuberculosis are a particularly deadly liaison, which kill a quarter of a million people a year, according to the WHO.

“A devastating consequence of the integration step is that once viral integration has occurred, it cannot be reversed,” Nair said. “That’s why integration is viewed as the ‘point of no return’ in HIV infection.”
The drug developed in Nair’s lab blocks the viral enzyme from inserting its genome into the DNA of the host cell.

While Nair acknowledges an HIV vaccine that eliminates the virus altogether may not be doable, therapies that allow people to live longer lives while infected are attainable.

“I don’t really think that a single vaccine would be truly effective in providing total immunity against HIV because the virus has multiple forms or subtypes,” he said. “By inhibiting replication while viral counts are still low, however, a drug can render HIV almost entirely impotent.”

Research efforts worldwide on HIV integrase inhibitors have resulted in two Federal Drug Administration-approved drugs. However, co-infection of HIV with Mycobacterium tuberculosis and other microbial and viral agents has introduced added complications to the HIV pandemic, requiring drugs that work well together for antiviral combination therapeutics targeting HIV. Targeting the virus, rather than the human mechanism that allows it to reproduce, prevents interference with enzymes that are key to the natural and required biochemical metabolic processes in the human system.

“The compound displays low toxicity, which is very important,” Nair said. “Its resistance and related drug susceptibility profiles against resistant HIV-1 isolates are favorable. When taken together, the antiviral activity profile and the drug interaction profile of our integrase inhibitor present a compelling case for its further development as an anti-HIV/AIDS therapeutic agent.”

The therapy is now in the pre-clinical testing phase.

“There are potential ramifications of this invention in other therapeutic areas, as well as in co-infection therapeutics,” said Nair. “This is perhaps the most exciting aspect of our discovery.”

The research was funded through the Division of AIDS in the National Institutes of Health’s National Institute of Allergy and Infectious Diseases. Results were recently published in the journal Antiviral Research.

Dyson registers patent of plans for soundless model.


  • Dyson puts in patent for ‘hand-held blower with an insulating chamber’
  • New designs usually closely guarded
  • Dyson spends nearly £1.5 million a week on research and development

Hairdryers will be the next household gadget to be given the silent treatment by Sir James Dyson as he puts in a patent for a soundless model.

The inventor of the bagless vacuum cleaner has registered plans for the gadget which shows diagrams of the ‘hand-held blower with an insulating chamber’.

Sir James is widely known for his vacuum cleaners but he has more recently branched out into bladeless fans and the ‘airblade’ fast-drying hand dryer, The Guardian has reported.

Design: The 'hairblade' hairdryerDesign: The ‘hairblade’ hairdryer

DYSON’S INVENTIONS

Ballbarrow A wheelbarrow with a ball replacing the wheel

Trolleyball A trolley that launched boats

Bagless vacuum cleaner The Dyson cleaner was the first bagless vacuum

Dyson Ball Vacuum cleaner using the ball from the Ballbarrow

Dyson Airblade Fast-working hand dryer

Air Multiplier Bladeless fan

The blueprint for the new hairdryer goes into detail about how it will work. The patent application shows air will flow through two chambers and out the front of the handheld device.

The bladeless fan was another ‘noiseless’ device and hairdressers will surely be first in line as standard hairdryers can be as loud as 75 decibels.

Sir James usually keeps his new designs under wraps and his patents closely guarded. He recently begun a legal battle with Samsung, claiming that the electronics giant ‘ripped off’ one of its inventions.

Inventor: Sir James Dyson closely guards his patents and his company now holds 3,000 for 500 inventions Inventor: Sir James Dyson closely guards his patents and his company now holds 3,000 for 500 inventions

The 66-year-old engineer said the South Korean company’s new MotionSync range ‘directly copied’ the steering mechanics of Dyson’s DC37 and DC39 models.

Dyson said it patented the central ball system – which allows a vacuum to move more easily around corners, table legs and over carpets – in 2009, and spent three years developing the design.

In 2009 a British judge ordered Samsung to pay Dyson about £600,000 after it tried to patent the UK firm’s ‘triple-cyclone’ suction technology.

A champion of British industry, Dyson spends nearly £1.5 million every week on research and development. The company now holds more than 3,000 patents for over 500 inventions.

He also supports up and coming inventors with The James Dyson Award that celebrates and encourages the next generation of design engineers.

It is run by the James Dyson Foundation, Sir James Dyson’s charitable trust, as part of its mission to inspire young people about design engineering.

Super-vaccine could eliminate need for annual flu jabs within five years after successful trials.


  • New universal vaccine being developed by British and European scientists
  • Job would provide lifetime immunity against all flu viruses
  • First ever successful human trials have taken place
  • Larger trails involving thousands of people now planned
  • Researchers believe the new vaccine could be available in 2018
A new ‘Holy Grail‘ flu vaccine which gives lifelong protection against all strains of the virus could be available within five years.
A new universal vaccine which could provide lifetime protection against every type of flu has shown successful results for the first time in small trials

Scientists from Britain and Europe are getting ready to start large-scale trials of a universal vaccine after early tests on humans proved successful.

If all goes to plan the new injection would stop the need for annual flu jabs and could save thousands of lives every year.

It could also be effective against highly dangerous forms of the disease, such as Spanish flu, even if they mutate, preventing global pandemics like the one which killed 100million people in 1918.

Despite carrying out human trials on almost 100 patients over many years, this is the first positive news.

Professor John Oxford, British flu expert and a key researcher of the study, said that his team are ‘wildly enthusiastic’ about the vaccine’s prospects.

The programme has recently received a multi-million pound EU grant to fund its research.

At the moment vaccines work by identifying viruses by their ‘coats’, however as viruses mutate these change, making old vaccines ineffective.

The universal vaccine works by attacking proteins hidden within the virus which are common throughout harmful strains.

If it works, the 'Holy Grail' vaccine would eliminate the need for annual flu jabs and could save thousands of lives every year and prevent global flu pandemics If it works, the ‘Holy Grail’ vaccine would eliminate the need for annual flu jabs and could save thousands of lives every year and prevent global flu pandemics

The news comes at the end of a week which has seen a new strain of bird flu re-emerge in China and after it was reported to have passed between humans in August.

A 32-year-old woman was said to have died after caring for her father who was infected by the H7N9 strain of bird flu.

A new strain of bird flu, H7N9, has begun spreading in China after killing 45 people earlier in the yearA new strain of bird flu, H7N9, has begun spreading in China after killing 45 people earlier in the year

Reports of human infection began in March this year but have trailed off in the last few months having killed at least 45 people out of 136 cases.

However as poultry stocks swell ahead of Chinese new year a 35-year-old man in the eastern province of Zhejiang has been hospitalised and the World Health Organisation confirms two more people are in hospital with another 88 being sent home.

A nasal flu spray has also been made available for all children aged between two and three years old, and will eventually be extended into a national programme for all under-16s.

While children are less likely to die from flu compared with the elderly, they are key spreaders of flu, and can become very ill if they have asthma, heart or lung conditions.

While specialists agree that the vaccine could help protect elderly relatives of younger children, Dr Richard Halvorsen disagrees.

Speaking to the Sunday Express, he said: ‘It is rare for children to die from flu and giving extra vaccines a year is a lot of extra vaccinations.’

If trials of the new flu super-jab are successful it could be available for use by 2018.

CATCHING A CHANGING KILLER – THE SCIENCE BEHIND THE VACCINE

Bird Flu Virus. January 2004

Traditional vaccines work by training an immune system to identify a disease and increasing the body’s defences, usually by injecting weak or dead parts of a disease into the patient.

Flu vaccines work by attacking the ‘coat’ of a virus, the H and N protein shell which surrounds the disease.

However this is problematic as this coat changes every time the virus mutates, meaning flu vaccines are only truly effective for a year as the virus will change rapidly, meaning vulnerable patients, such as elderly people, have to have injections every year.

But, hidden within every dangerous strain of influenza, are two proteins known as M and NP proteins which do not change with mutations.

Researches have tried for years to develop a vaccine which could target and attack these parts of the virus, and now think they may have found the solution.

In small human trials they have shown the first successful results ever for a universal vaccine and are now rolling out wider trials of the new medicine.

If these are successful then the new jab could be on the market by 2018, saving thousands of lives each year.

Modular Robotics.


Fifteen years ago, Lego released the Mindstorms Robotics Invention System, and amateur roboticists went wild. With it, they could snap together motorized creations that they could program with an intelligent brick. Since then, the Mindstorms online community has shared more than 17,000 designs—as varied as automatic toilet flushers and bumper cars—and started robotics leagues and engineering curriculums. This summer, Lego will release the EV3, the first Mindstorms update in seven years. The kit will allow builders to create tens of thousands of new robots, all of which will be smarter, faster, and more responsive than before.

1) INTELLIGENCE UPGRADE

The heart of the EV3 is an upgraded processing brick. A 300-megahertz processor runs up to 10 times faster than its predecessor, so the brick can control more appendages and monitor more sensors at once. The system also has 64 megabytes of RAM to boost response time and 16 megabytes of storage.

2) SENSOR SUITE

EV3 robots can navigate autonomously. Designers embedded an infrared proximity sensor in the eyes, so robots can follow, attack, or run from what they encounter. Users will be able to buy additional bricks with gyroscopes, which will enable the robot to balance itself.

3) FASTER MOTORS

Each kit comes with three motors. Two large ones transfer their 170 rpms to double-sided output drives; each motor can move pairs of legs, arms, or tentacles independently of one another. The third, smaller motor spins at 250 rpm and handles minute actions, such as firing ammo or flicking fingers.

4) WIRELESS CONTROL

A Bluetooth radio on the processing brick’s circuit board lets builders control and program their robots through an iOS or Android app. They can also connect a Wi-Fi radio via a USB port on the processing brick; with a robot linked to a router, it’s accessible from anywhere.

5) EXPANSION-READY

For massive, complicated creations, builders can daisy-chain up to four processing bricks together. A “master” brick sends commands to the other three bricks that rely on it and relays instructions to extremities, such as a command to pinch together a thumb and forefinger.

The Fastest DNA Sequencer.


DNA sequencing has revolutionized medicine and biomedical research. For example, DNA analysis can tell doctors which drug might work best against a particular cancer. But current technology usually sequences only short stretches of DNA and can take hours or days.

To sequence anything longer than a few hundred base pairs, scientists mince up thousands of copies of the target DNA, sequence all the fragments, and use software to painstakingly reconstruct the order of the DNA bases by matching overlap within fragments. A new approach, called nanopore sequencing, can handle long strands of DNA at once, eliminating the need for overlap analysis. As a result, nanopore sequencers could be cheaper, faster, and more compact than other DNA sequencers. They can also accurately sequence stretches with many repeating base pairs. The MinION from Oxford Nanopore Technologies connects to a USB port. Soon, anyone with $1,000 and a computer will be able to sequence DNA.

Fastest DNA Sequencer Diagram
Davvi

1) Drop the DNA sample on a chip.
Researchers place pretreated samples—blood from a patient or purified DNA, for example—into a small port. Within the device is a silicon chip with many thin membranes studded with tiny pores.

2) Unzip the DNA.
An enzyme shuttles the DNA to the membrane’s nanopore. It then unzips the twin strands of DNA and feeds one end into the pore. The pore is a set of proteins arranged in a ring and derived from bacteria. The inner diameter of the pore is a couple of nanometers wide: 100,000 times thinner than a human hair.

3) Block the ion current.
Electrodes send an ionic current, a flow of ions, through the open nanopore. As a group of a few DNA bases—the As, Ts, Cs, and Gs—threads through the neck of the pore, it blocks the ions and interrupts the current. A sensor records the electrical disturbance.

4) Determine the sequence.
Software in an attached computer analyzes the electrical signal recorded for every group of bases. Because each combination of bases blocks the current in a distinctive fashion, the software can deduce the identity and sequence of the individual bases in the group. As the DNA strand feeds through the pore, the software stitches together the sequence of bases on the entire strand.

5) Check for errors.
The device can determine the sequence of a single strand of DNA, but for greater precision, it can also read the complementary strand. Once the first strand of the DNA ratchets through the pore, a small stretch of DNA called a hairpin structure acts as a tether to draw the matching half into the pore as well.

Stroke Warning Signs and Symptoms.


http://strokeassociation.org/STROKEORG/WarningSigns/Stroke-Warning-Signs-and-Symptoms_UCM_308528_SubHomePage.jsp#mainContent

More children are suffering from fatty liver disease.


DEAR MAYO CLINIC: I recently read that fatty liver disease is becoming common in young children. What’s the cause of this condition? How is it diagnosed, and can it be reversed?

ANSWER: The number of children who have fatty liver disease is rising. Currently, about 10 percent of children in the U.S. have this disease. It is the most common cause of childhood chronic liver disease in this country. The increase is linked to the childhood obesity epidemic, as fatty liver disease is often caused by excessive weight gain. If it is caught and treated early, the disease typically can be reversed through lifestyle changes, including diet and exercise.

The liver is one of the largest organs in the body. About the size of a football, it is located on the right side of the abdomen, behind the lower ribs. Fatty liver disease (also called nonalcoholic fatty liver disease) occurs when fat builds up in the liver of people who drink little or no alcohol.
Typically the disease causes few, if any, symptoms. Many people with fatty liver disease have it for years and don’t know it. It is important for the disease to be diagnosed, however. If left unchecked, it could eventually lead to liver function problems, especially in children.

The most common cause of fatty liver disease in children is obesity. In children who are at a healthy body weight, fatty liver disease can also be the result of rare metabolic disorders, such as Wilson’s disease or cystic fibrosis, among others.

A doctor may suspect fatty liver disease if a blood test shows that a child’s level of liver enzymes is higher than normal, especially if the child is overweight. The disease also may be discovered through an imaging exam, such as an ultrasound. A diagnosis of fatty liver disease can be confirmed by microscopic examination of a small sample of tissue removed from the liver, a procedure known as a liver biopsy.

If caught while still in the early stages, fatty liver disease may be reversible. In children who are overweight, weight loss often is key to treating the disease. Weight loss usually is best accomplished with a combination of a healthy diet and regular physical activity.

In general, there are some strategies all families can use to help children reach and maintain a healthy weight. For example, make sure you have lots of healthy food choices available in your home. Buy plenty of fruits and vegetables. Cut down on convenience foods, such as cookies, crackers and prepared meals that are high in sugar and fat. Limit sweetened beverages, including fruit juices. These drinks are high in calories and low in nutritional value. They also can make a child feel too full to eat healthier foods.

Encourage your child to be physically active. This not only helps with weight loss, but also builds strong bones and muscles and helps a child sleep better at night. Keep in mind that activity does not have to be structured exercise to burn calories and improve fitness. Playing outdoors, jumping rope and going for hikes can all be good ways for a child to be active.

It is very important that children and teens avoid using supplements to help with weight loss or building muscle. Some of these supplements have recently been associated with acute liver failure and other dangerous health outcomes.

Don’t start a child on a specific weight-loss program before talking with his or her health care provider. It’s important that a weight-loss approach be tailored to a child’s individual situation and needs, including the child’s age and if he or she has any other health problems. — Samar Ibrahim, M.B., Ch.B., Pediatric Gastroenterology, Mayo Clinic, Rochester, Minn.

Blood test ‘detects sepsis in hours’


Sepsis kills more people than breast and bowel cancer combined
Sepsis kills more people than breast and bowel cancer combined

A rapid blood test to diagnose blood poisoning, or sepsis, at the hospital bedside could potentially save thousands of lives, say researchers.

Early studies at King’s College London suggest the condition can be diagnosed in two hours using a simple blood test.

Current diagnostic methods take up to two days, which may delay treatment with life-saving antibiotics.

The condition – caused when the body’s immune system overreacts to infection – causes 37,000 UK deaths each year.

In the study, published in the journal PLOS ONE, researchers identified a biomarker for diagnosing sepsis rapidly in blood samples.

It is based on detecting nucleotides specific to sepsis to rule out similar conditions that can mimic its symptoms.

A small study at a London hospital and a larger study in Sweden demonstrated that sepsis could be diagnosed within two hours, with an accuracy of 86%.

Facts about sepsis

  • Sepsis is a more common reason for hospital admission than heart attack – and has a higher mortality.
  • The most common causes of severe sepsis are pneumonia, bowel perforation, urinary infection, and severe skin infections.
  • The most common signs of sepsis are a high fever, violent shivering, fainting, cold and pale hands, rapid breathing, confusion or delirium.
  • In the UK, 37,000 people are estimated to die of sepsis each year.
  • From the time sepsis first takes hold, healthcare workers have just hours to deliver the right care.

Lead researcher Prof Graham Lord, director of the NIHR biomedical research centre at Guy’s and St Thomas’ NHS Foundation Trust and King’s College London, told BBC News: “If our early phase result holds up in a large trial, it could have significant effects in saving thousands of lives and reducing the use of unnecessary antibiotics.

“If we can prove its value in prospective trials, we can quite rapidly translate it into NHS clinical care.”

He said more research was needed to be done, but if successful, the test could be available for use in the NHS in about two years.

UK Sepsis Trust chairman Dr Ron Daniels said the work paved the way for earlier detection of sepsis.

“If we had a simple test that would reliably detect sepsis – particularly in vulnerable groups – it would significantly improve the reliability of the delivery of care,” he said.

He added: “We still need the suspicion of sepsis to be present for someone to give the test.”

In September, a report from the health service ombudsman found significant failings in treatment of sepsis and said more had to be done to save the lives of patients.

The National Institute for Health and Care Excellence will produce guidance for GPs and clinicians to help them recognise sepsis at an early stage.

Talking therapy ‘eases hypochondria’


An anxious patient
Health anxiety can cause terrible suffering

Cognitive behavioural therapy is more effective than standard care for people with hypochondria or health anxiety, say researchers writing in The Lancet.

In their study, 14% of patients given CBT regained normal anxiety levels against 7% given the usual care of basic reassurance.

It said nurses could easily be trained to offer the psychological therapy.

Between 10% and 20% of hospital patients are thought to worry obsessively about their health.

“Start Quote

Health anxiety is costly for healthcare providers and an effective treatment could potentially save money”

Prof Peter Tyrer Imperial College London

Previous studies have shown that CBT, which aims to change thought patterns and behaviour, is an effective treatment for other anxiety disorders.

But there is a shortage of specialists trained to deliver CBT, and as a result waiting lists can be long.

In this study, 219 people with health anxiety received an average of six sessions of cognitive behavioural therapy while 225 received reassurance and support, which is standard.

After periods of six months and 12 months, patients in the CBT group showed “significantly greater improvement in self-rated anxiety and depression symptoms” compared with standard care, the study showed.

There was also a particularly noticeable reduction in health anxiety in the CBT group straight after treatment began.

The therapy was delivered by non-CBT experts who had been trained in only two workshops.

Study author Prof Peter Tyrer, head of the Centre for Mental Health at Imperial College London, said the results showed that hypochondria could be successfully treated, in a “relatively cheap” way, by general nurses with minimal training in a hospital setting.

WHAT IS CBT?

Cognitive behavioural therapy is:

  • a way of talking about how you think about yourself, the world and other people
  • how what you do affects your thoughts and feelings

CBT can help you to change how you think (cognitive) and what you do (behaviour).

Unlike some other talking treatments, it focuses on the “here and now” instead of the causes of distress or past symptoms.

Reducing the anxiety levels of 14% of the CBT group might not seem a high figure, he said, but these were often people with serious problems who had sometimes spent thousands of pounds on private health assessments because of fears about their health.

“Health anxiety is costly for healthcare providers and an effective treatment could potentially save money by reducing the need for unnecessary tests and emergency hospital admissions,” Prof Tyrer said.

Writing about the study in The Lancet, Chris Williams from the University of Glasgow and Allan House from the University of Leeds, said the findings were “intriguing” but translating them into services was “problematic”.

They also questioned the cost-effectiveness of screening patients for health anxiety and CBT.

They wrote: “Health anxiety is only one of the problems noted in medical outpatients – depression, hazardous alcohol use, poor treatment adherence, and other forms of medically unexplained presentation all press for recognition and intervention.

“To develop multiple parallel services makes no sense, especially since the common emotional disorders overlap substantially.”

But Prof Tyrer said health anxiety was a hidden epidemic that required the correct treatment, not just reassurance.

Mixing nanoparticles to make multifunctional materials.


Scientists at the U.S. Department of Energy‘s Brookhaven National Laboratory have developed a general approach for combining different types of nanoparticles to produce large-scale composite materials. The technique, described in a paper published online by Nature Nanotechnology on October 20, 2013, opens many opportunities for mixing and matching particles with different magnetic, optical, or chemical properties to form new, multifunctional materials or materials with enhanced performance for a wide range of potential applications.

Mixing nanoparticles to make multifunctional materials

The approach takes advantage of the attractive pairing of complementary strands of synthetic DNA-based on the molecule that carries the genetic code in its sequence of matched bases known by the letters A, T, G, and C. After coating the  with a chemically standardized “construction platform” and adding extender molecules to which DNA can easily bind, the scientists attach complementary lab-designed DNA strands to the two different kinds of nanoparticles they want to link up. The natural pairing of the matching strands then “self-assembles” the particles into a three-dimensional array consisting of billions of particles. Varying the length of the DNA linkers, their surface density on particles, and other factors gives scientists the ability to control and optimize different types of newly formed  and their properties.

“Our study demonstrates that DNA-driven assembly methods enable the by-design creation of large-scale ‘superlattice’ nanocomposites from a broad range of nanocomponents now available-including magnetic, catalytic, and fluorescent nanoparticles,” said Brookhaven physicist Oleg Gang, who led the research at the Lab’s Center for Functional Nanomaterials (CFN). “This advance builds on our previous work with simpler systems, where we demonstrated that pairing nanoparticles with different functions can affect the individual particles’ performance, and it offers routes for the fabrication of new materials with combined, enhanced, or even brand new functions.”

Future applications could include quantum dots whose glowing fluorescence can be controlled by an external magnetic field for new kinds of switches or sensors; gold nanoparticles that synergistically enhance the brightness of quantum dots’ fluorescent glow; or catalytic nanomaterials that absorb the “poisons” that normally degrade their performance, Gang said.

“Modern nano-synthesis methods provide scientists with diverse types of nanoparticles from a wide range of atomic elements,” said Yugang Zhang, first author of the paper. “With our approach, scientists can explore pairings of these particles in a rational way.”

Pairing up dissimilar particles presents many challenges the scientists investigated in the work leading to this paper. To understand the fundamental aspects of various newly formed materials they used a wide range of techniques, including x-ray scattering studies at Brookhaven’s National Synchrotron Light Source (NSLS) and spectroscopy and electron microcopy at the CFN.

For example, the scientists explored the effect of particle shape. “In principle, differently shaped particles don’t want to coexist in one lattice,” said Gang. “They either tend to separate into different phases like oil and water refusing to mix or form disordered structures.” The scientists discovered that DNA not only helps the particles mix, but it can also improve order for such systems when a thicker DNA shell around the particles is used.

They also investigated how the DNA-pairing mechanism and other intrinsic physical forces, such as magnetic attraction among particles, might compete during the assembly process. For example, magnetic particles tend to clump to form aggregates that can hinder the binding of DNA from another type of particle. “We show that shorter DNA strands are more effective at competing against magnetic attraction,” Gang said.

For the particular composite of gold and magnetic nanoparticles they created, the scientists discovered that applying an  could “switch” the material’s phase and affect the ordering of the particles. “This was just a demonstration that it can be done, but it could have an application-perhaps magnetic switches, or materials that might be able to change shape on demand,” said Zhang.

The third fundamental factor the scientists explored was how the particles were ordered in the superlattice arrays: Does one type of particle always occupy the same position relative to the other type-like boys and girls sitting in alternating seats in a movie theater-or are they interspersed more randomly? “This is what we call a compositional order, which is important for example for  because their optical properties-e.g., their ability to glow-depend on how many  are in the surrounding environment,” said Gang. “If you have compositional disorder, the optical properties would be different.” In the experiments, increasing the thickness of the soft DNA shells around the particles increased compositional disorder.

These fundamental principles give scientists a framework for designing . The specific conditions required for a particular application will be dependent on the particles being used, Zhang emphasized, but the general assembly approach would be the same.

Said Gang, “We can vary the lengths of the DNA strands to change the distance between  from about 10 nanometers to under 100 nanometers-which is important for applications because many optical, magnetic, and other properties of nanoparticles depend on the positioning at this scale. We are excited by the avenues this research opens up in terms of future directions for engineering novel classes of materials that exploit collective effects and multifunctionality.”