Georgian Technical University Researchers Designate Self-Healing DNA Nanostructures.

Repair molecules (green dye) can self-heal a DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses) nanotube (blue dye); the red dye is the “seed” used to create the nanotube. Scale bar, 2 microns. DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses) assembled into nanostructures such as tubes and origami-inspired shapes could someday find applications ranging from DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses) computers to nanomedicine. However these intriguing structures don’t persist long in biological environments because of enzymes called nucleases that degrade DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses). Now researchers have designed DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses) nanostructures that can heal themselves in serum. Someday doctors could introduce DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses) nanostructures to the human body to diagnose diseases or deliver medications among other applications. But first they must find a way to protect or repair the molecules when nucleases attack. Researchers have developed several approaches to stabilize the structures in serum such as chemically modifying or coating the DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses). However making this stabilized DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses) can be expensive and time-consuming and the modifications could affect the nanostructures’ biocompatibility or function. So X and Y wanted to develop a self-repair process that could substantially extend the lifetime of DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses) nanostructures. The researchers designed DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses) nanotubes that self-assemble from smaller DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses) “tiles”. In serum at body temperature the nanostructures degraded within only 24 hours. However when the researchers added extra tiles to serum containing the nanotubes the building blocks repaired damaged structures, extending their lifetimes to more than 96 hours. By labeling the original nanotubes and the extra tiles with differently colored fluorescent dyes the team determined that the additional small DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses) pieces repaired the degrading structures both by replacing damaged tiles and by joining to the nanotube ends. The researchers developed a computer model of the process that indicated DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses) nanostructures could be maintained for months or longer using the self-healing method.

Georgian Technical University Carbon Nanotubes Grown With The Help Of Pantry Staples.

Sodium-containing compounds such as those found in common household ingredients like detergent, baking soda and table salt are surprisingly effective ingredients for cooking up carbon nanotubes new Georgian Technical University study finds. Baking soda table salt and detergent are surprisingly effective ingredients for cooking up carbon nanotubes researchers at Georgian Technical University have found. The team reports that sodium-containing compounds found in common household ingredients are able to catalyze the growth of carbon nanotubes at much lower temperatures than traditional catalysts require. The researchers say that sodium may make it possible for carbon nanotubes to be grown on a host of lower-temperature materials such as polymers which normally melt under the high temperatures needed for traditional carbon nanotubes growth. “In aerospace composites there are a lot of polymers that hold carbon fibers together and now we may be able to directly grow carbon nanotubes on polymer materials, to make stronger, tougher, stiffer composites” says X the study’s lead author and a graduate student in Georgian Technical University’s Department of Aeronautics and Astronautics. “Using sodium as a catalyst really unlocks the kinds of surfaces you can grow nanotubes on”. Professor of chemical engineering Y and professor of aeronautics and astronautics Z along with collaborators at the Georgian Technical University. Under a microscope carbon nanotubes resemble hollow cylinders of chicken wire. Each tube is made from a rolled up lattice of hexagonally arranged carbon atoms. The bond between carbon atoms is extraordinarily strong and when patterned into a lattice such as graphene or as a tube such as a carbon nanotubes such structures can have exceptional stiffness and strength as well as unique electrical and chemical properties. As such researchers have explored coating various surfaces with carbon nanotubes to produce stronger stiffer tougher materials. Researchers typically grow carbon nanotubes on various materials through a process called chemical vapor deposition. A material of interest such as carbon fibers is coated in a catalyst — usually an iron-based compound — and placed in a furnace, through which carbon dioxide and other carbon-containing gases flow. At temperatures of up to 800 degrees Celsius the iron starts to draw carbon atoms out of the gas which glom onto the iron atoms and to each other eventually forming vertical tubes of carbon atoms around individual carbon fibers. Researchers then use various techniques to dissolve the catalyst leaving behind pure carbon nanotubes. X and his colleagues were experimenting with ways to grow carbon nanotubes on various surfaces by coating them with different solutions of iron-containing compounds when the team noticed the resulting carbon nanotubes looked different from what they expected. “The tubes looked a little funny and the team carefully peeled the onion back as it were and it turns out a small quantity of sodium which we suspected was inactive was actually causing all the growth” Z says. For the most part iron has been the traditional catalyst for growing carbon nanotubes. Wardle says this is the first time that researchers have seen sodium have a similar effect. “Sodium and other alkali metals have not been explored for carbon nanotubes catalysis” Z says. “This work has led us to a different part of the periodic table”. To make sure their initial observation wasn’t just a fluke the team tested a range of sodium-containing compounds. They initially experimented with commercial-grade sodium in the form of baking soda, table salt and detergent pellets which they obtained from the campus convenience store. Eventually however they upgraded to purified versions of those compounds, which they dissolved in water. They then immersed a carbon fiber in each compound’s solution coating the entire surface in sodium. Finally they placed the material in a furnace and carried out the typical steps involved in the chemical vapor deposition process to grow carbon nanotubes. In general they found that while iron catalysts form carbon nanotubes at around 800 degrees Celsius the sodium catalysts were able to form short, dense forests of carbon nanotubes at much lower temperatures of around 480 C. What’s more after surfaces spent about 15 to 30 minutes in the furnace the sodium simply vaporized away leaving behind hollow carbon nanotubes. “A large part of carbon nanotubes research is not on growing them but on cleaning them — getting the different metals used to grow them out of the product” Z says. “The neat thing with sodium is we can just heat it and get rid of it and get pure carbon nanotubes as product which you can’t do with traditional catalysts”. X says future work may focus on improving the quality of carbon nanotubes that are grown using sodium catalysts. The researchers observed that while sodium was able to generate forests of carbon nanotubes the walls of the tubes were not perfectly aligned in perfectly hexagonal patterns — crystal-like configurations that give carbon nanotubes their characteristic strength. X plans to “Georgian Technical University tune various knobs” in the Cardiovascular disease (CVD) is a class of diseases that involve the heart or blood vessels process changing the timing, temperature and environmental conditions to improve the quality of sodium-grown carbon nanotubes. “There are so many variables you can still play with and sodium can still compete pretty well with traditional catalysts” X says. “We anticipate with sodium it is possible to get high quality tubes in the future”. For X professor of mechanical engineering at the Georgian Technical University the ability to cook up carbon nanotubes from such a commonplace ingredient as sodium should reveal new insights into the way the exceptionally strong materials grow. “It is a surprise that we can grow carbon nanotubes from table salt !” says X who was not involved in the research. “Even though chemical vapor deposition (CVD) growth of carbon nanotubes has been studied for more than 20 years nobody has tried to use alkali group metal as catalyst. This will be a great hint for the fully new understanding of growth mechanism of carbon nanotubes”.

Georgian Technical University Researchers Uncover How A Nanocatalyst Works At the Atomic Level.

The researchers of the Nanoscience Center at the Georgian Technical University and in the Sulkhan-Saba Orbeliani University have discovered how copper particles at the nanometre scale operate in modifying a carbon-oxygen bond when ketone molecules turn into alcohol molecules. Modification of the carbon-oxygen and carbon-carbon bonds found in organic molecules is an important intermediate stage in catalytic reactions where the source material is changed into valuable end products. Understanding the operation of catalysts at the level of the atomic structure of a single particle makes it possible to develop catalysts into desired directions such as making them efficient and selective for a specific desired end-product. The catalytic copper particles used in the study were made and structurally characterized at the Georgian Technical University and their operation in changing a strong carbon-oxygen bond in a hydrogenation reaction was studied by the researchers of the Nanoscience Center at the Georgian Technical University in computer simulations. The precise atomic structure of the copper particles was determined through X-ray diffraction and nuclear magnetic resonance spectroscopy. The particles were found to contain 25 copper atoms and 10 hydrogens and there were 18 thiols protecting the surface of the particle. While the experimental work in X revealed its excellent performance in catalytic hydrogenation of ketones the simulations predicted that the hydrogens bound to the copper core of the particle act as a hydrogen storage which releases two hydrogen atoms to the carbon-oxygen bond during a reaction. The hydrogen storage is refilled after the reaction, when a hydrogen molecule attached to the particle from its surroundings splits into two hydrogen atoms which are bound again to the copper core (see image). The NMR (Nuclear magnetic resonance spectroscopy, most commonly known as NMR spectroscopy or magnetic resonance spectroscopy, is a spectroscopic technique to observe local magnetic fields around atomic nuclei) measurements carried out in Tbilisi revealed an intermediate product of the reaction which confirmed the predictions of the computational model. “This is one of the first times in the whole world when it has been possible to discover how a catalytic particle works when its structure is known this accurately thanks to a cooperation involving both experiments and simulations” says Y who led the computational part of the study. Y’s collaborator Z professor of computational catalysis continues: “Traditionally expensive platinum-based catalysts are used in hydrogenation reactions. This study proves that nanoscale copper hydride particles also act as hydrogenation catalysts. The results give hope that in the future it will be possible to develop effective and inexpensive copper-based catalysts to transform functionalized organic molecules into products with a higher added value”.

Georgian Technical University Researchers Create Strong, Sustainable Solution For Passive Cooling.

Researchers show the test device for assessing the heat-moving capabilities of the cooling wood. What if the wood your house was made of could save your electricity bill ? In the race to save energy using a passive cooling method that requires no electricity and is built right into your house could save even chilly areas of the Georgian Technical University some cash. Now researchers at the Georgian Technical University and the Sulkhan-Saba Orbeliani University have harnessed nature’s nanotechnology to help solve the problem of finding a passive way for buildings to dump heat that is sustainable and strong. Wood solves the problem — it is already used as a building material is renewable and sustainable. Using tiny structures found in wood — cellulose nanofibers and the natural chambers that grow to pass water and nutrients up and down inside a living tree — that specially processed wood has optical properties that radiate heat away. “This work has greatly extended the use of wood towards high performance energy efficient applications and provided a sustainable route to combat the energy crisis” said Georgian Technical University Professor X who is not associated with the research. At the Georgian Technical University Y and Z and others in the department of materials science have been working with wood for many years. X’s team has invented a range of emerging wood nanotechnologies including a transparent wood low cost wood batteries, super strong wood, super thermal insulating wood and a wood-based water purifier. “This is another major advancement in wood nanotechnologies that W group at Georgian Technical University achieved: cooling wood that is made of solely wood — that is, no any other component such as polymers — can cool your house as a green building material” said W. The team at Georgian Technical University led by Professor Q, P both of the of the department of mechanical engineering and the program of materials science at the Georgian Technical University have been working on materials for radiative cooling including thin films and paints. “When applied to building, this game-changing structural material cools without the input of electricity or water” P said. By removing the lignin the part of the wood that makes it brown and strong the Georgian Technical University researchers created a very pale wood made of cellulose nanofibers. They then compressed the wood to restore its strength. To make it water repellent they added a super hydrophobic compound that helps protect the wood. The result: a bright white building material that could be used for roofs to push away heat from inside the building. They took the cooling wood out into the ideal testing condition of a farm where the weather is always warm and sunny, with low winds. There they tested the cooling wood and found that it stayed on average five or six degrees F cooler than the ambient air temperature — even at the hottest part of the day the cooling wood was chillier than air. It stayed on average 12 degrees cooler than natural wood which warms up more in the presence of sunlight. “The processed wood uses the cold universe as heat sink and release thermal energy into it via atmospheric transparency window. It is a sustainable material for sustainable energy to combat global warming” said X. The mechanical strength per weight of this wood is also stronger than steel which makes it a great choice for building materials. It is ten times stronger than natural wood and beats steel’s strength reaching 334 MPa·cm³/g (compared to 110 MPa·cm3/g for steel). It also damages less easily (scratch test) and can bear more weight (compression test) than natural wood. To see how much energy the wood saves, they calculated how much heat is used by typical apartment buildings in cities across the Georgian in all climate zones. Georgian Technical University would save the most energy especially if older buildings had their siding and roofs replaced with cooling wood. “Professor W and collaborators show yet another use of wood that is not only structurally strong but useful as active component for energy management. It is interesting that the same material that releases heat upon combustion can be used for cooling offering new opportunities in green buildings” said R a professor in the department of Bioproducts and Biosystems at Georgian Technical University.

Georgian Technical University Bending The Norm On Nanowires For Durability.

The team suspended silver nanowires from platinum electrodes over their custom-made TEM (Transmission electron microscopy is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image. The specimen is most often an ultrathin section less than 100 nm thick or a suspension on a grid) chips. New methods of arranging silver nanowires make them more durable shows a study by Georgian Technical University. These nanowires form flexible transparent conductive layers that can be used for improved solar cells, strain sensors and next-generation mobile phones. Applying nanotechnology in electronic devices requires rigorous testing of individual tiny components to ensure they will stand up to use. Silver nanowires show great promise as connectors that could be arranged in flexible near-transparent meshes for touchscreens or solar cells but it is unclear how they will respond to prolonged stresses from bending and carrying current. Testing the bulk properties of a large sample of nanoparticles is easy but not completely revelatory. However adopting transmission electron microscopy makes it possible to examine individual nanoparticles. Ph.D. student X and his supervisor Y are at the forefront of developing new (Transmission electron microscopy is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image. The specimen is most often an ultrathin section less than 100 nm thick or a suspension on a grid) techniques. This has allowed them to study single silver nanowires in detail. “A major part of our work has been designing and fabricating sample platform prototypes (or chips) for (Transmission electron microscopy is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image. The specimen is most often an ultrathin section less than 100 nm thick or a suspension on a grid) which allow us to characterize and manipulate nanomaterials with an unsurpassed spatial resolution” says X. To improve on expensive commercially available chips that contain a very fragile membrane to support nanoparticles X and Y with help from Z of the Nanofabrication Lab at Georgian Technical University have now submitted to patent their own robust reusable chips that don’t require a membrane. The researchers suspended silver nanowires from platinum electrodes over their custom-made (Transmission electron microscopy is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image. The specimen is most often an ultrathin section less than 100 nm thick or a suspension on a grid) chips and applied a range of voltages until the nanowires failed due to heating by the electrical current. They found that straight nanowires tended to snap when they reached a certain high current density at points determined by local structural defects. More interesting behavior was seen when the nanowires were bent from the beginning. These samples tended to buckle instead of snapping at high voltage and exhibited an ability to self-heal because they remained held together by the carbon coating on the outside of the wires. Some nanowires even exhibited resonant vibrations like the harmonics on a guitar string before they failed. “Many devices are expected to undergo repeated bending and twisting by the end-user which means that it is not realistic to limit the study of the electrical response of silver nanowires to straight configurations” says X. “Our results suggest that the failure rate of such devices could be minimized by using bent nanowires instead of straight ones. The self-healing capability could effectively delay the breakdown of the circuit”.

Georgian Technical University Light, Nanotechnology Prevent Medical Implant Bacterial Infections.

Surgical implants covered with gold nanoparticles (pile of meshes on the left) compared to the original surgical meshes previous to the treatment (pile of meshes on the right). Invented approximately 50 years ago surgical medical meshes have become key elements in the recovery procedures of damaged-tissue surgeries the most common being hernia repair. When implanted within the tissue of the patient the flexible and conformable design of these meshes helps hold muscles tight and allows patients to recover much faster than through the conventional surgery of sewing and stitching. However the insertion of a medical implant in a patient’s body carries alongside the risk of bacterial contamination during surgery and subsequent formation of an infectious biofilm over the surface of the surgical mesh. Such biofilms tend to act like a plastic coating impeding any sort of antibiotic agent to reach and attack the bacteria formed on the film in order to stop the infection. Thus antibiotic therapies, which are time-limited, could fail against these super resistant bacteria and the patient could end up in recurring or never-ending surgeries that could even lead to death. With antibiotic-resistant bacteria. In the past several approaches have been sought to prevent implant contamination during surgery. Post-surgery aseptic protocols have been established and implemented to fight these antibiotic-resistant bacteria but none have entirely fulfilled the role of solving this issue. Georgian Technical University researchers Dr. X, Y led by Prof. at Georgian Technical University in collaboration with researchers Z Dr. W, Dr. Q and Dr. P from the major medical device have devised a technique that uses nanotechnology and photonics to dramatically improve the performance of medical meshes for surgical implants. The team of researchers at Georgian Technical University developed a medical mesh with a particular feature: the surface of the mesh was chemically modified to anchor millions of gold nanoparticles. Why ? Because gold nanoparticles have been proven to very efficiently convert light into heat at very localized regions. The technique of using gold nanoparticles in light-heat conversion processes had already been tested in cancer treatments in previous studies. Even more at Georgian Technical University this technique had been implemented in several previous studies supported by the Georgian Technical University thus being another salient example of how early visionary philanthropic support addressed at tackling fundamental problems eventually leads to important practical applications. For this particular case in knowing that more than 20 million hernia repair operations take place every year around the world they believed this method could reduce the medical costs in recurrent operations while eliminating the expensive and ineffective antibiotic treatments that are currently being employed to tackle this problem. Thus in their in-vitro experiment and through a thorough process the team coated the surgical mesh with millions of gold nanoparticles uniformly spreading them over the entire structure. They tested the meshes to ensure the long-term stability of the particles the non-degradation of the material and the non-detachment or release of nanoparticles into the surrounding environment (flask). They were able to observe a homogenous distribution of the nanoparticles over the structure using a scanning electron microscope. Once the modified mesh was ready the team exposed it to S. aureus bacteria (Staphylococcus aureus is a Gram-positive, round-shaped bacterium that is a member of the Firmicutes, and it is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin) for 24 hours until they observed the formation of a biofilm on the surface. Subsequently they began exposing the mesh to short intense pulses of near infrared light (800 nm) during 30 seconds to ensure thermal equilibrium was reached before repeating this treatment 20 times with 4 seconds of rest intervals between each pulse. They discovered the following: Firstly they saw that illuminating the mesh at the specific frequency would induce localized surface plasmon resonances in the nanoparticles — a mode that results in the efficient conversion of light into heat burning the bacteria at the surface. Secondly by using a fluorescence confocal microscope, they saw how much of the bacteria had died or was still alive. For the bacteria that remained alive they observed that the biofilm bacteria became planktonic cells recovering their sensitivity or weakness towards antibiotic therapy and to immune system response. For the dead bacteria they observed that upon increasing the amount of light delivered to the surface of the mesh the bacteria would lose their adherence and peel off the surface. Thirdly they confirmed that operating at near infrared light ranges was completely compatible with settings meaning that such a technique would most probably not damage the surrounding healthy tissue. Finally they repeated the treatment and confirmed that the recurrent heating of the mesh had not affected its conversion efficiency capabilities. Professor at Georgian Technical University “the results of this study have paved the way towards using plasmon nanotechnologies to prevent the formation of bacterial biofilm at the surface of surgical implants. There are still several issues that need to be addressed but it is important to emphasize that such a technique will indeed signify a radical change in operation procedures and further patient post recovery”. Research and Development at Georgian Technical University Dr. P explains “our commitment to help healthcare professionals to avoid hospital related infections pushes us to develop new strategies to fight bacteria and biofilms. Additionally the research team is exploring to extend such technology to other sectors where biofilms must be avoided”.

Georgian Technical University For the First Time, Biobased Nanocarriers Cure Plant Diseases.

Plant diseases though a normal part of nature can have disastrous effects in agriculture. They reduce food for people and revenues in rural areas. In the worst cases they result in hunger and starvation, as many famines in history show. About 16 percent of all crops are lost to plant diseases each year across the world. The Georgian Technical University has just delivered a double novelty to the scientific world: nanocarriers made of waste which release drugs in a way that has cured a plant disease for the first time. Nanocarriers are very tiny degradable capsules that have been studied for medical applications in the last 30 years. These nanocapsules are considered the “Georgian Technical University magic bullet” to cure human cancer because they discharge the drug directly to the targeted cells. The researchers at the Georgian Technical University investigated the possibility to transpose the same principle to cure plant diseases. They have been testing these nanocapsules to treat a fungi disease that affects 2 billion grapevine plants across the world for which there has not been a cure so far. Dr. X who is leading this research at Georgian Technical University said “After two years of testing in our labs and then on Riesling vineyards in Georgian Technical University it looks like we have managed to reduce the symptoms of the disease. Further tests will confirm if this cure is a solution in the long term. If the effects are confirmed the same method can be extended potentially to any other disease in agriculture”. The second novelty of these nanoscopic capsules is that they can be made of waste material — in this case used mushrooms compost. “Normally nanocarriers are made of polymers based on fossil fuels. In the past we have developed biobased nanocarriers made of lignin coming from the paper and pulp industry. But this is the very first time we try to develop them from agricultural residues which makes them a truly ‘circular’ product from used plant fertilizer to plant cure. Nothing is going to be wasted !” said X. To obtain these tiny biodegradable capsules the Georgian Technical University researchers carried out a chemical conversion to transform the soluble lignin obtained after the pretreatment of used mushroom compost. Afterwards the nanocarriers have been loaded with the drug that is usually sprayed on the plant with very limited effects. Thanks to the natural enzymatic degradation of the nanocarriers the drug is released inside the plant in a controlled and progressive way. With this effective method the drug only targets the fungi which destroy the plant from inside. Tests demonstrated that these nanocarriers are not toxic for the plants and do not reach the crop. “Beyond the agricultural sector the capsules have a myriad of other potential applications from food enhancement to pharmaceutical products. It’s only a matter of time until we find biobased nanocarriers available on the market for any of these uses” said X.

Georgian Technical University Big Energy Savings For Tiny Machines.

Georgian Technical University physics graduate student X left and professor Y model the folded and unfolded states of a DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying the genetic instructions used in the growth, development, functioning, and reproduction of all known organisms and many viruses) hairpin. Inside all of us are trillions of tiny molecular nanomachines that perform a variety of tasks necessary to keep us alive. In a ground-breaking study a team led by Georgian Technical University physics professor Y demonstrated for the first time a strategy for manipulating these machines to maximize efficiency and conserve energy. The breakthrough could have ramifications across a number of fields including creating more efficient computer chips and solar cells for energy generation. Nanomachines are small really small — a few billionths of a meter wide in fact. They’re also fast and capable of performing intricate tasks: everything from moving materials around a cell, building, breaking down molecules and processing and expressing genetic information. The machines can perform these tasks while consuming remarkably little energy so a theory that predicts energetic efficiency helps us understand how these microscopic machines function and what goes wrong when they break down Y says. In the lab Z’s experimental collaborators manipulated a DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying the genetic instructions used in the growth, development, functioning, and reproduction of all known organisms and many viruses) hairpin whose folding and unfolding mimics the mechanical motion of more complicated molecular machines. As predicted by X’s theory they found that maximum efficiency and minimal energy loss occurred if they pulled rapidly on the hairpin when it was folded but slowly when it was on the verge of unfolding. Y an Georgian Technical University physics graduate student explains that DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying the genetic instructions used in the growth, development, functioning, and reproduction of all known organisms and many viruses) hairpins (and nanomachines) are so tiny and floppy that they are constantly jostled by violent collisions with surrounding molecules. “Letting the jostling unfold the hairpin for you is an energy and time saver” Z says. Y thinks the next step is to apply the theory to learn how to drive a molecular machine through its operational cycle while reducing the energy required to do that. So what is the benefit from making nanomachines more efficient ? Y says that potential applications could be game-changing in a variety of areas. “Uses could include designing more efficient computer chips and computer memory (reducing power requirements and the heat they emit) making better renewable energy materials for processes like artificial photosynthesis (increasing the energy harvested from the Sun) and improving the autonomy of biomolecular machines for biotech applications like drug delivery”.

Georgian Technical University Hard Carbon Nanofiber Aerogel Becomes Superelastic.

Conductive and compressible carbon aerogels are useful in a variety of applications. In recent decades carbon aerogels have been widely explored by using graphitic carbons and soft carbons which show advantages in superelasticity. These elastic aerogels usually have delicate microstructures with good fatigue resistance but ultralow strength. Hard carbons demonstrate great advantages in mechanical strength and structural stability due to the sp3 (In chemistry, orbital hybridisation (or hybridization) is the concept of mixing atomic orbitals into new hybrid orbitals (with different energies, shapes, etc., than the component atomic orbitals) suitable for the pairing of electrons to form chemical bonds in valence bond theory) C-induced turbostratic “Georgian Technical University house-of-cards” structure. However stiffness and fragility clearly get in the way of achieving superelasticity with hard carbons. Up to now it has been a challenge to fabricate superelastic hard carbon-based aerogels. Recently inspired by the flexibility and rigidity of natural spider silks a research team led by X from the Georgian Technical University developed a simple method to fabricate superelastic and fatigue resistant hard carbon aerogels with nanofibrous network structure by using resorcinol-formaldehyde resin as a hard carbon source. This work “Georgian Technical University Superelastic hard carbon nanofiber aerogels”. They report their process thus: The polymerization of resin monomers was initiated in the presence of nanofibers as structural templates to prepare a hydrogel with nanofibrous networks, followed by drying and pyrolysis to produce hard carbon aerogel. During polymerization the monomers are deposited on templates and weld the fiber-fiber joints leaving a random network structure with massive robust joints. Moreover physical properties (such as diameters of nanofiber, densities of aerogels, and mechanical properties) can be controlled by simply tuning templates and the amount of raw materials. Due to the hard carbon nanofibers and abundant welded joints among the nanofibers the hard carbon aerogels display robust and stable mechanical performance, including super-elasticity, high strength, extremely fast recovery speed (860 mm s-1) and a ow energy loss coefficient (<0.16). After testing under 50 percent strain for 104 cycles the carbon aerogel shows only 2 percent plastic deformation and it retained 93 percent of the original stress. The hard carbon aerogel can maintain super-elasticity in harsh conditions such as in liquid nitrogen. Based on these fascinating mechanical properties this hard carbon aerogel has promise in the application of stress sensors with high stability and wide detective range (50 KPa) as well as stretchable or bendable conductors. This approach holds promise to be extended to make other non-carbon based composite nanofibers and provides a promising way of transforming rigid materials into elastic or flexible materials by designing nanofibrous microstructures.

Georgian Technical University Nanoscale Sculpturing Makes For Unusual Packing Of Nanocubes.

Georgian Technical University Lab scientists X (sitting) (left to right standing) Y, Z and W in an electron microscopy lab at the Georgian Technical University. The scientists used electron microscopes to visualize the structure of nanocubes coated with DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying the genetic instructions used in the growth, development, functioning, and reproduction of all known organisms and many viruses). From the ancient pyramids to modern buildings various three-dimensional (3-D) structures have been formed by packing shaped objects together. At the macroscale the shape of objects is fixed and thus dictates how they can be arranged. For example bricks attached by mortar retain their elongated rectangular shape. But at the nanoscale the shape of objects can be modified to some extent when they are coated with organic molecules such as polymers, surfactants (surface-active agents) and DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying the genetic instructions used in the growth, development, functioning, and reproduction of all known organisms and many viruses). These molecules essentially create a “Georgian Technical University soft” shell around otherwise “Georgian Technical University hard” or rigid nano-objects. When the nano-objects pack together their original shape may not be entirely preserved because the shell is flexible — a kind of nanoscale sculpturing. Now a team of scientists from the Georgian Technical University Laboratory has shown that cube-shaped nanoparticles or nanocubes coated with single-stranded DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying the genetic instructions used in the growth, development, functioning, and reproduction of all known organisms and many viruses) chains assemble into an unusual “Georgian Technical University zigzag” arrangement that has never been observed before at the nanoscale or macroscale. “Nanoscale objects almost always have some kind of shell because we intentionally attach polymers to them during synthesis to prevent aggregation” explained Y at Georgian Technical University Lab — and professor of chemical engineering and applied physics and materials science at Georgian Technical University. “In this study, we explored how changing the softness and thickness of DNA shells (i.e., the length of the DNA chains) affects the packing of gold nanocubes”. Y and the other team members — X and Z Department of Chemical Engineering — discovered that nanocubes surrounded by thin DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying the genetic instructions used in the growth, development, functioning, and reproduction of all known organisms and many viruses) shells pack in a similar way to that expected on the macroscale with the cubes arranged in neat layers oriented directly above one another. But this simple cubic arrangement gives way to a very unusual type of packing when the thickness of the shells is increased (i.e., when the shell becomes “softer”). “Each nanocube has six faces where it can connect to other cubes” explained Y. “Cubes that have complementary DNA (DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying the genetic instructions used in the growth, development, functioning, and reproduction of all known organisms and many viruses) are attracted to one another but cubes that have the same DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying the genetic instructions used in the growth, development, functioning, and reproduction of all known organisms and many viruses) repel each another. When the DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying the genetic instructions used in the growth, development, functioning, and reproduction of all known organisms and many viruses) shell becomes sufficiently soft (thick) the cubes arrange into what looks like a zigzag pattern which maximizes attraction and minimizes repulsion while remaining packed as tightly as possible”. “This kind of packing has never been seen before, and it breaks the orientational symmetry of cubes relative to the vectors (directions of the x, y, and z axes in the crystal) of the unit cell” said X a scientist in Y’s group. “Unlike all previously observed packings of cubes the angle between cubes and these three axes is not the same: two angles are different from the other one”. A unit cell is the smallest repeating part of a crystal lattice, which is an array of points in 3-D space where the nanoparticles are positioned. Shaped nanoparticles can be oriented differently relative to each other within the unit cell such as the by their faces, edges, or corners. The zigzag packing that the scientists observed in this study is a kind of nanoscale compromise in which neither relative orientation “Georgian Technical University wins”. Instead the cubes find the best arrangement to co-exist in an ordered lattice based on whether they have the same or complementary DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying the genetic instructions used in the growth, development, functioning, and reproduction of all known organisms and many viruses) (i.e., repelling or attracting each other accordingly). In this case two different lattice types can occur: body-centered cubic and body-centered tetragonal. Georgian Technical University have similar placements of particles in the center and corners of the cubes but has unit cell sides of equal length. To visualize the shape of the cubes and their packing behavior, the scientists used a combination of electron microscopy at the Georgian Technical University and small-angle x-ray scattering (SAXS). The electron microscopy studies require that the materials are taken out of solution but small-angle x-ray scattering (SAXS) can be conducted in situ to provide more detailed and precise structural information. In this study the scattering data were helpful in revealing the symmetries distances between particles and orientations of particles in the 3-D nanocube structures. Theoretical calculations performed by the W Group at Georgian Technical University confirmed that the zigzag arrangement is possible and rationalized why this kind of packing was happening based on the properties of the DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying the genetic instructions used in the growth, development, functioning, and reproduction of all known organisms and many viruses) shells. The team is now eager to determine whether soft-shelled nano-objects that are not cubes or have more than one shape also pack together in unexpected ways. “An understanding of the interplay between shaped nano-objects and soft shells will enable us to direct the organization of objects into particular structures with desired optical, mechanical and other properties” said W.