Tag Archives: nanotechnology
If you want to build a fully functional nanosized robot, you need to incorporate a host of capabilities, from complicated electronic circuits and photovoltaics to sensors and antennas. But just as importantly, if you want your robot to move, you need it to be able to bend.
Cornell researchers have created micron-sized shape memory actuators that enable atomically thin two-dimensional materials to fold themselves into 3D configurations. All they require is a quick jolt of voltage. And once the material is bent, it holds its shape – even after the voltage is removed. As a demonstration, the team created what is potentially the world’s smallest self-folding origami bird. And it’s not a lark.
The group’s paper, “Micrometer-Sized Electrically Programmable Shape Memory Actuators for Low-Power Microrobotics,” published in Science Robotics and was featured on the cover. The paper’s lead author is postdoctoral researcher Qingkun Liu. The project is led by Itai Cohen, professor of physics, and Paul McEuen, the John A. Newman Professor of Physical Science, both in the College of Arts and Sciences.
“We humans, our defining characteristic is we’ve learned how to build complex systems and machines at human scales, and at enormous scales as well,” said McEuen. “But what we haven’t learned how to do is build machines at tiny scales. And this is a step in that basic, fundamental evolution in what humans can do, of learning how to construct machines that are as small as cells.”
McEuen and Cohen’s ongoing collaboration has so far generated a throng of nanoscale machines and components, each seemingly faster, smarter and more elegant than the last.
“We want to have robots that are microscopic but have brains on board. So that means you need to have appendages that are driven by complementary metal-oxide-semiconductor (CMOS) transistors, basically a computer chip on a robot that’s 100 microns on a side,” Cohen said.
Imagine a million fabricated microscopic robots releasing from a wafer that fold themselves into shape, crawl free and go about their tasks, even assembling into more complicated structures. That’s the vision.
Researchers from Cleveland Clinic’s Global Center for Pathogen Research & Human Health have developed a promising new COVID-19 vaccine candidate that utilizes nanotechnology and has shown strong efficacy in preclinical disease models.
According to new findings published in mBio, the vaccine produced potent neutralizing antibodies among preclinical models and also prevented infection and disease symptoms in the face of exposure to SARS-CoV-2 (the virus that causes COVID-19). An additional reason for the vaccine candidate’s early appeal is that it may be thermostable, which would make it easier to transport and store than currently authorized COVID-19 vaccines.
“Our vaccine candidate delivers antigens to trigger an immune response via nanoparticles engineered from ferritin–a protein found in almost all living organisms,” said Jae Jung, PhD, director of the Global Center for Human Health & Pathogen Research and co-senior author on the study. “This protein is an attractive biomaterial for vaccine and drug delivery for many reasons, including that it does not require strict temperature control.”
Added Dokyun (Leo) Kim, a graduate student in Dr. Jung’s lab and co-first author on the study, “This would dramatically ease shipping and storage constraints, which are challenges we’re currently experiencing in national distribution efforts. It would also be beneficial for distribution to developing countries.”
Other benefits of the protein nanoparticles include minimizing cellular damage and providing stronger immunity at lower doses than traditional protein subunit vaccines against other viruses, like influenza.
The team’s vaccine uses the ferritin nanoparticles to deliver tiny, weakened fragments from the region of the SARS-CoV-2 spike protein that selectively binds to the human entry point for the virus (this fragment is called the receptor-binding domain, or RBD). When the SARS-CoV-2 RBD binds with the human protein called ACE2 (angiotensin-converting enzyme 2), the virus can enter host cells and begin to replicate.
The researchers tested their vaccine candidate on a ferret model of COVID-19, which reflects the human immune response and disease development better than other preclinical models. Dr. Jung, a foremost authority in virology and virus-induced cancers, previously developed the world’s first COVID-19 ferret model–a discovery that has significantly advanced research into SARS-CoV-2 infection and transmission.
With the advance in nanotechnology, researchers across the globe have been exploring how to use nanoparticles for efficient drug delivery. Similar to nanoshells and nanovesicles, nanomicelles are extremely small structures and have been noted as an emerging platform in targeted therapy. Nanomicelles are globe-like structures with a hydrophilic outer shell and a hydrophobic interior. This dual property makes them a perfect carrier for delivering drug molecules.
Now a multi-disciplinary, multi-institutional team has created a nanomicelle that can be used to deliver a drug named docetaxel, which is commonly used to treat various cancers including breast, colon and lung cancer.
Modus operandi: Once injected intravenously, these nanomicelles can easily escape the circulation and enter the solid tumours.
“The ideal goal for cancer therapy is destroying the cancer cells without harming healthy cells of the body, and chemotherapeutics approved for treatment of cancer are highly toxic. The currently used docetaxel is a highly hydrophobic drug, and is dissolved in a chemical mixture (polysorbate-80 and alcohol). This aggravates its toxic effects on liver, blood cells, and lungs. So, there was an urgent and unmet need to develop effective drug delivery vehicles for docetaxel without these side effects,” explains Avinash Bajaj, from the Laboratory of Nanotechnology and Chemical Biology at the Regional Centre for Biotechnology, Faridabad. He is one of the corresponding authors of the paper recently published in Angewandte Chemie.
The nanomicelles are less than 100nm in size and are stable at room temperature. Once injected intravenously these nanomicelles can easily escape the circulation and enter the solid tumours where the blood vessels are found to be leaky. These leaky blood vessels are absent in the healthy organs. “Chemical conjugation would render the phospholipid-docetaxel prodrug to be silent in the circulation and healthy organs. But once it enters the cancer cells, the enzymes will cleave the bond to activate the drug, and kill the cancer cells,” adds Dr. Bajaj.
The team tested the effectiveness of the nanomicelles in a mice breast tumour model and was found to help in tumour regression. Its toxicity was compared with the currently used FDA approved formulation and found to be less toxic. Similar promising results were seen when tested in higher model organisms including rats, rabbits and rhesus monkeys.
Producing clean water at a lower cost could be on the horizon after researchers from The University of Texas at Austin (UT Austin) and Penn State solved a complex problem that had baffled scientists for decades, until now. Desalination membranes remove salt and other chemicals from water, a process critical to the health of society, cleaning billions of gallons of water for agriculture, energy production and drinking. The idea seems simple — push salty water through and clean water comes out the other side — but it contains complex intricacies that scientists are still trying to understand.
The research team, in partnership with DuPont Water Solutions, solved an important aspect of this mystery, opening the door to reduce costs of clean water production. The researchers determined desalination membranes are inconsistent in density and mass distribution, which can hold back their performance. Uniform density at the nanoscale is the key to increasing how much clean water these membranes can create.
“Reverse osmosis membranes are widely used for cleaning water, but there’s still a lot we don’t know about them,” said Manish Kumar, an associate professor in the Department of Civil, Architectural and Environmental Engineering at UT Austin, who co-led the research. “We couldn’t really say how water moves through them, so all the improvements over the past 40 years have essentially been done in the dark.”
The paper documents an increase in efficiency in the membranes tested by 30%-40%, meaning they can clean more water while using significantly less energy. That could lead to increased access to clean water and lower water bills for individual homes and large users alike.
Reverse osmosis membranes work by applying pressure to the salty feed solution on one side. The minerals stay there while the water passes through. Although more efficient than non-membrane desalination processes, it still takes a large amount of energy, the researchers said, and improving the efficiency of the membranes could reduce that burden.
“Fresh water management is becoming a crucial challenge throughout the world,” said Enrique Gomez, a professor of chemical engineering at Penn State who co-led the research. “Shortages, droughts — with increasing severe weather patterns, it is expected this problem will become even more significant. It’s critically important to have clean water availability, especially in low-resource areas.”
The findings have been published in Science.
Researchers at the National Institute of Standards and Technology (NIST) have developed a new method of 3D-printing gels and other soft materials. Published in a new paper, it has the potential to create complex structures with nanometer-scale precision. Because many gels are compatible with living cells, the new method could jump-start the production of soft tiny medical devices such as drug delivery systems or flexible electrodes that can be inserted into the human body.
A standard 3D printer makes solid structures by creating sheets of material — typically plastic or rubber — and building them up layer by layer, like a lasagna, until the entire object is created.
Using a 3D printer to fabricate an object made of gel is a “bit more of a delicate cooking process,” said NIST researcher Andrei Kolmakov. In the standard method, the 3D printer chamber is filled with a soup of long-chain polymers — long groups of molecules bonded together — dissolved in water. Then “spices” are added — special molecules that are sensitive to light. When light from the 3D printer activates those special molecules, they stitch together the chains of polymers so that they form a fluffy weblike structure. This scaffolding, still surrounded by liquid water, is the gel.
Biocompatible interface shows that hydrogels (green tubing), which can be generated by an electron or X-ray beam 3D printing process, act as artificial synapses or junctions, connecting neurons (brown) to electrodes (yellow)
Typically, modern 3D gel printers have used ultraviolet or visible laser light to initiate formation of the gel scaffolding. However, Kolmakov and his colleagues have focused their attention on a different 3D-printing technique to fabricate gels, using beams of electrons or X-rays. Because these types of radiation have a higher energy, or shorter wavelength, than ultraviolet and visible light, these beams can be more tightly focused and therefore produce gels with finer structural detail. Such detail is exactly what is needed for tissue engineering and many other medical and biological applications. Electrons and X-rays offer a second advantage: They do not require a special set of molecules to initiate the formation of gels.
But at present, the sources of this tightly focused, short-wavelength radiation — scanning electron microscopes and X-ray microscopes — can only operate in a vacuum. That’s a problem because in a vacuum the liquid in each chamber evaporates instead of forming a gel.
Kolmakov and his colleagues at NIST and at the Elettra Sincrotrone Trieste in Italy, solved the issue and demonstrated 3D gel printing in liquids by placing an ultrathin barrier — a thin sheet of silicon nitride — between the vacuum and the liquid chamber. The thin sheet protects the liquid from evaporating (as it would ordinarily do in vacuum) but allows X-rays and electrons to penetrate into the liquid. The method enabled the team to use the 3D-printing approach to create gels with structures as small as 100 nanometers (nm) — about 1,000 times thinner than a human hair. By refining their method, the researchers expect to imprint structures on the gels as small as 50 nm, the size of a small virus.
In 1959, former Cornell physicist Richard Feynman delivered his famous lecture “There’s Plenty of Room at the Bottom,” in which he described the opportunity for shrinking technology, from machines to computer chips, to incredibly small sizes. Well, the bottom just got more crowded. A Cornell-led collaboration has created the first microscopic robots that incorporate semiconductor components, allowing them to be controlled – and made to walk – with standard electronic signals. These robots, roughly the size of paramecium, provide a template for building even more complex versions that utilize silicon-based intelligence, can be mass produced, and may someday travel through human tissue and blood.
The collaboration is led by Itai Cohen, professor of physics, Paul McEuen, the John A. Newman Professor of Physical Science – both in the College of Arts and Sciences – and their former postdoctoral researcher Marc Miskin, who is now an assistant professor at the University of Pennsylvania.
The walking robots are the latest iteration, and in many ways an evolution, of Cohen and McEuen’s previous nanoscale creations, from microscopic sensors to graphene-based origami machines. The new robots are about 5 microns thick (a micron is one-millionth of a meter), 40 microns wide and range from 40 to 70 microns in length. Each bot consists of a simple circuit made from silicon photovoltaics – which essentially functions as the torso and brain – and four electrochemical actuators that function as legs. As basic as the tiny machines may seem, creating the legs was an enormous feat.
“In the context of the robot’s brains, there’s a sense in which we’re just taking existing semiconductor technology and making it small and releasable,” said McEuen, who co-chairs the Nanoscale Science and Microsystems Engineering (NEXT Nano) Task Force, part of the provost’s Radical Collaboration initiative, and directs the Kavli Institute at Cornell for Nanoscale Science.
“But the legs did not exist before,” McEuen said. “There were no small, electrically activatable actuators that you could use. So we had to invent those and then combine them with the electronics.”
The team’s paper, “Electronically Integrated, Mass-Manufactured, Microscopic Robots,” has been published in Nature.
A team of researchers based in Manchester, the Netherlands, Singapore, Spain, Switzerland and the USA has published a new review on a field of computer device development known as spintronics, which could use graphene as a building block for next-generation electronics. Recent theoretical and experimental advances and phenomena in studies of electronic spin transport in graphene and related two-dimensional (2D) materials have emerged as a fascinating area of research and development.
Spintronics is the combination of electronics and magnetism at nanoscale and could allow electronic development at speeds exceeding Moore’s law, which observes that computer processing power roughly doubles every two years, while the price halves. Spintronic devices may offer higher energy efficiency and lower dissipation as compared to conventional electronics, which rely on charge currents. In principle, we could have phones and tablets operating with spin-based transistors and memories, greatly improving speed and storage capacity.
Since its isolation in 2004, graphene has opened the door for other 2D materials. Researchers can then use these materials to create stacks of 2D materials called heterostructures. These can be combined with graphene to create new ‘designer materials‘ to produce applications originally limited to science fiction. As published in APS Journal Review of Modern Physics, the review focuses on the new perspectives provided by heterostructures and their emergent phenomena, including proximity-enabled spin-orbit effects, coupling spin to light, electrical tunability and 2D magnetism. The average person already encounters spintronics in laptops and PCs, which are already using spintronics in the form of the magnetic sensors in the reading heads of hard disk drives. These sensors are also used in the automotive industry.
“The continuous progress in graphene spintronics, and more broadly in 2D heterostructures, has resulted in the efficient creation, transport and detection of spin information using effects previously inaccessible to graphene alone” said Dr Ivan Vera Marun, Lecturer in Condensed Matter Physics at The University of Manchester.
“As efforts on both the fundamental and technological aspects continue, we believe that ballistic spin transport will be realised in 2D heterostructures, even at room temperature. Such transport would enable practical use of the quantum mechanical properties of electron wave functions, bringing spins in 2D materials to the service of future quantum computation approaches.”
Controlled spin transport in graphene and other two-dimensional materials has become increasingly promising for applications in devices. Of particular interest are custom-tailored heterostructures, known as van der Waals heterostructures, that consist of stacks of two-dimensional materials in a precisely controlled order.
Billions of spintronic devices such as sensors and memories are already being produced. Every hard disk drive has a magnetic sensor that uses a flow of spins, and magnetic random access memory (MRAM) chips are becoming increasingly popular.
Tiny fibrils extracted from plants have been getting a lot of attention for their strength. These nanomaterials have shown great promise in outperforming plastics, and even replacing them. A team led by Aalto University (Finland) has now shown another remarkable property of nanocelluloses: their strong binding properties to form new materials with any particle.
Cohesion, the ability to keep things together, from the scale of nanoparticles to building sites is inherent to these nanofibrils, which can act as mortar to a nearly infinite type of particles as described in the study. The ability of nanocelluloses to bring together particles into cohesive materials is at the root of the study that links decades of research into nanoscience towards manufacturing.
In a paper just published in Science Advances, the authors demonstrate how nanocellulose can organize itself in a multitude of different ways by assembling around particles to form highly robust materials.
Nanocellulose can also form structures known from pulp technology with the particles
‘This means that nanocelluloses induce high cohesion in particulate materials in a constant and controlled manner for all particles types. Because of such strong binding properties, such materials can now be built with predictable properties and therefore easily engineered’, explained the main author, Dr Bruno Mattos, The moment anytime a material is created from particles, one has to first come up with a way to generate cohesion, which has been very particle dependent, ‘Using nanocellulose, we can overcome any particle dependency’, Mattos adds.
The universal potential of using nanocellulose as a binding component rises from their ability to form networks at the nanoscale, that adapt according to the given particles. Nanocelluloses bind micrometric particles, forming sheet-like structures, much like the paper-mâché as done in schools. Nanocellulose can also form tiny fishnets to entrap smaller particles, such as nanoparticles. Using nanocellulose, materials built from particles can be formed into any shape using an extremely easy and spontaneous process that only needs water. Importantly, the study describes how these nanofibers form network following precise scaling laws that facilitates their implementation. This development is especially timely in the era of the nanotechnologies, where combining nanoparticles in larger structures is essential. As Dr Blaise Tardy points out, ‘New property limits and new functionalities are regularly showcased at the nanoscale, but implementation in the real world is rare. Unraveling the physics associated with the scaling of the cohesion of nanofibers is therefore a very exciting first step towards connecting laboratory findings with current manufacturing practices’. For any success, strong binding among the particles is needed, an opportunity herein offered by nanocellulose.
People who are affected by Alzheimer’s disease have a specific type of plaque, made of self-assembled molecules called β-amyloid (Aβ) peptides, that build up in the brain over time. This buildup is thought to contribute to loss of neural connectivity and cell death. Researchers are studying ways to prevent the peptides from forming these dangerous plaques in order to halt development of Alzheimer’s disease in the brain.
In a multidisciplinary study, scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory, along with collaborators from the Korean Institute of Science and Technology (KIST) and the Korea Advanced Institute of Science and Technology (KAIST), have developed an approach to prevent plaque formation by engineering a nano-sized device that captures the dangerous peptides before they can self-assemble.
Transmission Electron Microscopy (TEM) images of Aβ peptide samples in the presence of the Aβ nanodevices (scale bar: 200 nm). The lack of grains in the image indicates the effectiveness of the nanodevice in trapping the peptides
We’ve taken building blocks from nanotechnology and biology to engineer a high-capacity cage’ that traps the peptides and clears them from the brain.” — Elena Rozhkova, scientist, Center for Nanoscale Materials
The β-amyloid peptides arise from the breakdown of an amyloid precursor protein, a normal component of brain cells,” said Rosemarie Wilton, a molecular biologist in Argonne’s Biosciences division.In a healthy brain, these discarded peptides are eliminated.”
In brains prone to the development of Alzheimer’s, however, the brain does not eliminate the peptides, leaving them to conglomerate into the destructive plaques.
The idea is that, eventually, a slurry of our nanodevices could collect the peptides as they fall away from the cells — before they get a chance to aggregate,” added Elena Rozhkova, a scientist at Argonne’s Center for Nanoscale Materials (CNM), a DOE Office of Science User Facility.