Tag Archives: nanomagnets

Using nanomagnets to remove plastic from water

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it seems Australian researchers are working hard to find ways of removing microplastics from water. I have two items, first, a November 29, 2022 news item on Nanowerk announces some of the latest work,

Researchers at RMIT University have found an innovative way to rapidly remove hazardous microplastics from water using magnets.

Lead researcher Professor Nicky Eshtiaghi said existing methods could take days to remove microplastics from water, while their cheap and sustainable invention achieves better results in just one hour.

The team says they have developed adsorbents, in the form of a powder, that remove microplastics 1,000 times smaller than those currently detectable by existing wastewater treatment plants. 

The researchers have successfully tested the adsorbents in the lab, and they plan to engage with industry to further develop the innovation to remove microplastics from waterways.

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A November 30, 2022 RMIT University press release, which originated the news item, provides more technical detail about the work,

“The nano-pillar structure we’ve engineered to remove this pollution, which is impossible to see but very harmful to the environment, is recycled from waste and can be used multiple times,” said Eshtiaghi from RMIT’s School of Environmental and Chemical Engineering.

“This is a big win for the environment and the circular economy.”

How does this innovation work?

The researchers have developed an adsorbent using nanomaterials that they can mix into water to attract microplastics and dissolved pollutants.

Muhammad Haris, the first author and PhD candidate from RMIT’s School of Environmental and Chemical Engineering, said the nanomaterials contained iron, which enabled the team to use magnets to easily separate the microplastics and pollutants from the water.

“This whole process takes one hour, compared to other inventions taking days,” he said.

Co-lead researcher Dr Nasir Mahmood said the nano-pillar structured material was designed to attract microplastics without creating any secondary pollutants or carbon footprints.

“The adsorbent is prepared with special surface properties so that it can effectively and simultaneously remove both microplastics and dissolved pollutants from water,” said Mahmood from Applied Chemistry and Environmental Science at RMIT.

“Microplastics smaller than 5 millimetres, which can take up to 450 years to degrade, are not detectable and removable through conventional treatment systems, resulting in millions of tonnes being released into the sea every year. This is not only harmful for aquatic life, but also has significant negative impacts on human health.”

The team received scientific and technical support from the Microscopy and Microanalysis Facility and the Micro Nano Research Facility, part of RMIT’s newly expanded Advanced Manufacturing Precinct, to complete their research. 

What are the next steps?

Developing a cost-effective way to overcome these signficant challenges posed by microplastics was critical, Eshtiaghi said.

“Our powder additive can remove microplastics that are 1,000 times smaller than those that are currently detectable by existing wastewater treatment plants,” she said.

“We are looking for industrial collaborators to take our invention to the next steps, where we will be looking at its application in wastewater treatment plants.”

Eshtiaghi and her colleagues have worked with various water utilities across Australia, including with Melbourne Water and Water Corporation in Perth on a recent Australian Research Council Linkage project to optimise sludge pumping systems.

Here’s a link to and a citation for the paper,

Self-assembly of C@FeO nanopillars on 2D-MOF for simultaneous removal of microplastic and dissolved contaminants from water by Muhammad Haris, Muhammad Waqas Khan, Ali Zavabeti, Nasir Mahmood and Nicky Eshtiaghi. Chemical Engineering Journal Available online 23 November 2022, 140390 DOI: https://doi.org/10.1016/j.cej.2022.140390

This paper is behind a paywall.

Back in 2019

Caption: This visual abstract depicts the findings of Kang et al.. Novel and robust nanocarbon springs were synthesized via solid pyrolysis with a controlled morphology, and simultaneously engineered nitrogen dopants and encapsulated magnetic nanoparticles. The carbocatalysts can effectively catalyze peroxymonosulfate to generate highly reactive radicals under hydrothermal conditions for decomposing microplastics into harmless substances in water. Credit: Kang et al/Matter

This July 31, 2019 Cell Press news release on EurekAlert announces a different approach, from an Australian team, to removing plastics from water,

Plastic waste that finds its way into oceans and rivers poses a global environmental threat with damaging health consequences for animals, humans, and ecosystems. Now, using tiny coil-shaped carbon-based magnets, researchers in Australia have developed a new approach to purging water sources of the microplastics that pollute them without harming nearby microorganisms. Their work appears July 31 in the journal Matter.

“Microplastics adsorb organic and metal contaminants as they travel through water and release these hazardous substances into aquatic organisms when eaten, causing them to accumulate all the way up the food chain” says senior author Shaobin Wang, a professor of chemical engineering at the University of Adelaide (Australia). “Carbon nanosprings are strong and stable enough to break these microplastics down into compounds that do not pose such a threat to the marine ecosystem.”

Although often invisible to the naked eye, microplastics are ubiquitous pollutants. Some, such as the exfoliating beads found in popular cosmetics, are simply too small to be filtered out during industrial water treatment. Others are produced indirectly, when larger debris like soda bottles or tires weather amid sun and sand.

To decompose the microplastics, the researchers had to generate short-lived chemicals called reactive oxygen species, which trigger chain reactions that chop the various long molecules that make up microplastics into tiny and harmless segments that dissolve in water. However, reactive oxygen species are often produced using heavy metals such as iron or cobalt, which are dangerous pollutants in their own right and thus unsuitable in an environmental context.

To get around this challenge, the researchers found a greener solution in the form of carbon nanotubes laced with nitrogen to help boost generation of reactive oxygen species. Shaped like springs, the carbon nanotube catalysts removed a significant fraction of microplastics in just eight hours while remaining stable themselves in the harsh oxidative conditions needed for microplastics breakdown. The coiled shape increases stability and maximises reactive surface area. As a bonus, by including a small amount of manganese, buried far from the surface of the nanotubes to prevent it from leaching into water, the minute springs became magnetic.

“Having magnetic nanotubes is particularly exciting because this makes it easy to collect them from real wastewater streams for repeated use in environmental remediation,” says Xiaoguang Duan, a chemical engineering research fellow at Adelaide who also co-led the project.

As no two microplastics are chemically quite the same, the researchers’ next steps will center on ensuring that the nanosprings work on microplastics of different compositions, shapes and origins. They also intend to continue to rigorously confirm the non-toxicity of any chemical compounds occurring as intermediates or by-products during microplastics decomposition.

The researchers also say that those intermediates and byproducts could be harnessed as an energy source for microorganisms that the polluting plastics currently plague. “If plastic contaminants can be repurposed as food for algae growth, it will be a triumph for using biotechnology to solve environmental problems in ways that are both green and cost efficient,” Wang says.

Here’s a link to and a citation for the paper,

Degradation of Cosmetic Microplastics via Functionalized Carbon Nanosprings by Jian Kang, Li Zhou, Xiaoguang Duan, Hongqi Sun, Zhimin Ao, Shaobin Wang. Matter Volume 1, Issue 3, 4 September 2019, Pages 745-758 DOI: https://doi.org/10.1016/j.matt.2019.06.004

This paper is open access.

Comments

I’m glad to see this work and as for which approach might be preferable, I don’t know if there’s a clear winner. The 2022 work removes both microplastics and pollutants in one hour! An impressive feat, which leaves us with microplastics and pollutants to deal with. By contrast , the 2019 work transforms the microplastics into materials that don’t pose harm to the aquatic environment. Great although it takes eight hours. I wish the best for all the researchers working on this microplastics problem.

Tiny nanomagnets interact like neurons in the brain for low energy artificial intelligence (brainlike) computing

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Saving energy is one of the main drivers for the current race to make neuromorphic (brainlike) computers as this May 5, 2022 news item on Nanowerk comments, Note: Links have been removed,

Researchers have shown it is possible to perform artificial intelligence using tiny nanomagnets that interact like neurons in the brain.

The new method, developed by a team led by Imperial College London researchers, could slash the energy cost of artificial intelligence (AI), which is currently doubling globally every 3.5 months. [emphasis mine]

In a paper published in Nature Nanotechnology (“Reconfigurable training and reservoir computing in an artificial spin-vortex ice via spin-wave fingerprinting”), the international team have produced the first proof that networks of nanomagnets can be used to perform AI-like processing. The researchers showed nanomagnets can be used for ‘time-series prediction’ tasks, such as predicting and regulating insulin levels in diabetic patients.

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A May 5, 2022 Imperial College London (ICL) press release (also on EurekAlert) by Hayley Dunning, which originated the news item delves further into the research,

Artificial intelligence that uses ‘neural networks’ aims to replicate the way parts of the brain work, where neurons talk to each other to process and retain information. A lot of the maths used to power neural networks was originally invented by physicists to describe the way magnets interact, but at the time it was too difficult to use magnets directly as researchers didn’t know how to put data in and get information out.

Instead, software run on traditional silicon-based computers was used to simulate the magnet interactions, in turn simulating the brain. Now, the team have been able to use the magnets themselves to process and store data – cutting out the middleman of the software simulation and potentially offering enormous energy savings.

Nanomagnetic states

Nanomagnets can come in various ‘states’, depending on their direction. Applying a magnetic field to a network of nanomagnets changes the state of the magnets based on the properties of the input field, but also on the states of surrounding magnets.

The team, led by Imperial Department of Physics researchers, were then able to design a technique to count the number of magnets in each state once the field has passed through, giving the ‘answer’.

Co-first author of the study Dr Jack Gartside said: “We’ve been trying to crack the problem of how to input data, ask a question, and get an answer out of magnetic computing for a long time. Now we’ve proven it can be done, it paves the way for getting rid of the computer software that does the energy-intensive simulation.”

Co-first author Kilian Stenning added: “How the magnets interact gives us all the information we need; the laws of physics themselves become the computer.”

Team leader Dr Will Branford said: “It has been a long-term goal to realise computer hardware inspired by the software algorithms of Sherrington and Kirkpatrick. It was not possible using the spins on atoms in conventional magnets, but by scaling up the spins into nanopatterned arrays we have been able to achieve the necessary control and readout.”

Slashing energy cost

AI is now used in a range of contexts, from voice recognition to self-driving cars. But training AI to do even relatively simple tasks can take huge amounts of energy. For example, training AI to solve a Rubik’s cube took the energy equivalent of two nuclear power stations running for an hour.

Much of the energy used to achieve this in conventional, silicon-chip computers is wasted in inefficient transport of electrons during processing and memory storage. Nanomagnets however don’t rely on the physical transport of particles like electrons, but instead process and transfer information in the form of a ‘magnon’ wave, where each magnet affects the state of neighbouring magnets.

This means much less energy is lost, and that the processing and storage of information can be done together, rather than being separate processes as in conventional computers. This innovation could make nanomagnetic computing up to 100,000 times more efficient than conventional computing.

AI at the edge

The team will next teach the system using real-world data, such as ECG signals, and hope to make it into a real computing device. Eventually, magnetic systems could be integrated into conventional computers to improve energy efficiency for intense processing tasks.

Their energy efficiency also means they could feasibly be powered by renewable energy, and used to do ‘AI at the edge’ – processing the data where it is being collected, such as weather stations in Antarctica, rather than sending it back to large data centres.

It also means they could be used on wearable devices to process biometric data on the body, such as predicting and regulating insulin levels for diabetic people or detecting abnormal heartbeats.

Here’s a link to and a citation for the paper,

Reconfigurable training and reservoir computing in an artificial spin-vortex ice via spin-wave fingerprinting by Jack C. Gartside, Kilian D. Stenning, Alex Vanstone, Holly H. Holder, Daan M. Arroo, Troy Dion, Francesco Caravelli, Hidekazu Kurebayashi & Will R. Branford. Nature Nanotechnology (2022) DOI: https://doi.org/10.1038/s41565-022-01091-7 Published 05 May 2022

This paper is behind a paywall.

Lifesaving moths and nanomagnets

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Rice University bioengineers use a magnetic field to activate nanoparticle-attached baculoviruses in a tissue. The viruses, which normally infect alfalfa looper moths, are modified to deliver gene-editing DNA code only to cells that are targeted with magnetic field-induced local transduction. Courtesy of the Laboratory of Biomolecular Engineering and Nanomedicine

Kudos to whomever put that diagram together! That’s a lot of well conveyed information.

Now for the details about how this technology might save lives. From a November 13, 2018 news item on Nanowerk,

A new technology that relies on a moth-infecting virus and nanomagnets could be used to edit defective genes that give rise to diseases like sickle cell, muscular dystrophy and cystic fibrosis.

Rice University bioengineer Gang Bao has combined magnetic nanoparticles with a viral container drawn from a particular species of moth to deliver CRISPR/Cas9 payloads that modify genes in a specific tissue or organ with spatial control.

A November 12, 2018 Rice University news release (also on EurekAlert published on November 13, 2018), which originated the news item, provides detail,

Because magnetic fields are simple to manipulate and, unlike light, pass easily through tissue, Bao and his colleagues want to use them to control the expression of viral payloads in target tissues by activating the virus that is otherwise inactivated in blood.

The research appears in Nature Biomedical Engineering. In nature, CRISPR/Cas9 bolsters microbes’ immune systems by recording the DNA of invaders. That gives microbes the ability to recognize and attack returning invaders, but scientists have been racing to adapt CRISPR/Cas9 to repair mutations that cause genetic diseases and to manipulate DNA in laboratory experiments.

CRISPR/Cas9 has the potential to halt hereditary disease – if scientists can get the genome-editing machinery to the right cells inside the body. But roadblocks remain, especially in delivering the gene-editing payloads with high efficiency.

Bao said it will be necessary to edit cells in the body to treat many diseases. “But efficiently delivering genome-editing machinery into target tissue in the body with spatial control remains a major challenge,” Bao said. “Even if you inject the viral vector locally, it can leak to other tissues and organs, and that could be dangerous.”

The delivery vehicle developed by Bao’s group is based on a virus that infects Autographa californica, aka the alfalfa looper, a moth native to North America. The cylindrical baculovirus vector (BV), the payload-carrying part of the virus, is considered large at up to 60 nanometers in diameter and 200-300 nanometers in length. That’s big enough to transport more than 38,000 base pairs of DNA, which is enough to supply multiple gene-editing units to a target cell, Bao said.

He said the inspiration to combine BV and magnetic nanoparticles came from discussions with Rice postdoctoral researcher and co-lead author Haibao Zhu, who learned about the virus during a postdoctoral stint in Singapore but knew nothing about magnetic nanoparticles until he joined the Bao lab. The Rice team had previous experience using iron oxide nanoparticles and an applied magnetic field to open blood vessel walls just enough to let large-molecule drugs pass through.

“We really didn’t know if this would work for gene editing or not, but we thought, ‘worth a shot,'” Bao said.

The researchers use the magnetic nanoparticles to activate BV and deliver gene-editing payloads only where they’re needed. To do this, they take advantage of an immune-system protein called C3 that normally inactivates baculoviruses.

“If we combine BV with magnetic nanoparticles, we can overcome this deactivation by applying the magnetic field,” Bao said. “The beauty is that when we deliver it, gene editing occurs only at the tissue, or the part of the tissue, where we apply the magnetic field.”

Application of the magnetic field allows BV transduction, the payload-delivery process that introduces gene-editing cargo into the target cell. The payload is also DNA, which encodes both a reporter gene and the CRISPR/Cas9 system.

In tests, the BV was loaded with green fluorescent proteins or firefly luciferase. Cells with the protein glowed brightly under a microscope, and experiments showed the magnets were highly effective at targeted delivery of BV cargoes in both cell cultures and lab animals.

Bao noted his and other labs are working on the delivery of CRISPR/Cas9 with adeno-associated viruses (AAV), but he said BV’s capacity for therapeutic cargo is roughly eight times larger. “However, it is necessary to make BV transduction into target cells more efficient,” he said.

Here’s a link to and a citation for the paper,

Spatial control of in vivo CRISPR–Cas9 genome editing via nanomagnets by Haibao Zhu, Linlin Zhang, Sheng Tong, Ciaran M. Lee, Harshavardhan Deshmukh, & Gang Bao. Nature Biomedical Engineering (2018) DOI: https://doi.org/10.1038/s41551-018-0318-7 Published: 12 November 2018

This paper is behind a paywall.