Nanotechnology & Nanomaterials Updates vol.60

Published in

Paradigm

12 min readAug 13, 2024

TL;DR

• Researchers develop soft gold nanowires for neural interfaces
• Scientists reveal atomic-scale details of catalysts’ active sites
• Molecules get a boost from metallic carbon nanotubes
• Researchers show that pesticide contamination is more than apple-skin-deep
• Tea brews up silver nanoparticles for wound healing in the developing world

Nanotech Market

Nanotechnology deals with the ability to see, understand, measure, predict, produce or control matter at the nanoscale (below 100 nanometers). The realm of nanotechnology lies between 0.1 and 100 nanometers, wherein a nanometer is defined as one-thousandth of a micron. As a versatile technology with widespread applications in a wide range of end-use sectors, nanotechnology is currently facing a mixed bag of challenges and opportunities as the COVID-19 pandemic continues to spread across the globe. With the world fighting its biggest public health crisis in history, nanotechnology healthcare applications are storming into the spotlight led by the focus on nano intervention in terms of designing effective ways to identify, diagnose, treat and eliminate the spread of COVID-19 infections. Their role as nanocarriers has the potential to design risk-free and effective immunization strategies. In the post-COVID-19 period, the use of nanotechnology solutions in the production of a multitude of devices & products will continue to grow.

Amid the COVID-19 crisis, the global market for Nanotechnology estimated at US$42.2 Billion in the year 2020, is projected to reach a revised size of US$70.7 Billion by 2026, growing at a CAGR of 9.2% over the analysis period. Nanocomposites, one of the segments analyzed in the report, is projected to record an 8.7% CAGR and reach US$35.4 Billion by the end of the analysis period. After a thorough analysis of the business implications of the pandemic and its induced economic crisis, growth in the Nanomaterials segment is readjusted to a revised 10.1% CAGR for the next 7-year period.

Global nanotechnology market to reach US $126.8 billion by the year 2027. Amid the COVID-19 crisis, the global market for nanotechnology is estimated at US $54.2 billion in 2020 and is projected to reach a revised size of US $126 billion.

Latest News & Research

Stretchable Tissue‐Like Gold Nanowire Composites with Long‐Term Stability for Neural Interfaces

by Laura Seufert et al in Small

Gold does not readily lend itself to being turned into long, thin threads. However, researchers at Linköping University in Sweden have now managed to create gold nanowires and develop soft electrodes that can be connected to the nervous system. The electrodes are soft as nerves, stretchable and electrically conductive, and are projected to last for a long time in the body.

Some people have a “heart of gold,” so why not “nerves of gold”? In the future, it may be possible to use this precious metal in soft interfaces to connect electronics to the nervous system for medical purposes.

Such technology could be used to alleviate conditions such as epilepsy, Parkinson’s disease, paralysis or chronic pain. However, creating an interface where electronics can meet the brain or other parts of the nervous system poses special challenges.

“The classical conductors used in electronics are metals, which are very hard and rigid. The mechanical properties of the nervous system are more reminiscent of soft jelly. In order to get an accurate signal transmission, we need to get very close to the nerve fibers in question, but as the body is constantly in motion, achieving close contact between something that is hard and something that is soft and fragile becomes a problem,” says Klas Tybrandt, professor of materials science at the Laboratory of Organic Electronics at Linköping University, who led the research.

Researchers therefore want to create electrodes that have good conductivity as well as mechanical properties similar to the softness of the body. In recent years, several studies have shown that soft electrodes do not damage the tissue as much as hard electrodes may do.

In the current study. a group of researchers at Linköping University have developed gold nanowires — a thousand times thinner than a hair — and embedded them in an elastic material to create soft microelectrodes.

“We’ve succeeded in making a new, better nanomaterial from gold nanowires in combination with a very soft silicone rubber. Getting these to work together has resulted in a conductor that has high electrical conductivity, is very soft and made of biocompatible materials that function with the body,” says Klas Tybrandt.

Silicone rubber is used in medical implants, such as breast implants. The soft electrodes also include gold and platinum, metals that are common in medical devices for clinical use.

However, making long, narrow gold nanostructures is very difficult. This has so far been a major obstacle, but the researchers have now come up with a new way to manufacture gold nanowires. And they do it by using silver nanowires.

As silver has unique properties that make it a very good material for creating the kind of nanowires that the researchers are after, it is used in some stretchable nanomaterials. The problem with silver is that it is chemically reactive. In the same way that silver cutlery will discolor over time when chemical reactions occur on the surface, silver in nanowires breaks down so that silver ions leak out. At a high enough concentration, silver ions can be toxic to us.

It was when Laura Seufert, a doctoral student in Klas Tybrandt’s research group, was working on finding a way to synthesize, or “grow,” gold nanowires that she came up with a new approach that opened up new possibilities.

At first, it was difficult to control the shape of the nanowires. But then she discovered a way that resulted in very smooth wires. Instead of trying to grow gold nanowires from the beginning, she started with a thin nanowire made of pure silver.

“As it’s possible to make silver nanowires, we take advantage of this and use the silver nanowire as a kind of template on which we grow gold. The next step in the process is to remove the silver. Once that’s done, we have a material that has over 99 percent gold in it. So it’s a bit of a trick to get around the problem of making long narrow gold nanostructures,” says Klas Tybrandt.

In collaboration with Professor Simon Farnebo at the Department of Biomedical and Clinical Sciences at Linköping University, the researchers behind the study have shown that the soft and elastic microelectrodes can stimulate a rat nerve as well as capture signals from the nerve.

In applications where soft electronics are to be embedded in the body, the material must last for a long time, preferably for life. The researchers have tested the stability of the new material and concluded that it will last for at least three years, which is better than many of the nanomaterials developed so far.

The research team is now working on refining the material and creating different types of electrodes that are even smaller and can come into closer contact with nerve cells.

Atomic-scale identification of active sites of oxygen reduction nanocatalysts

by Yao Yang et al in Nature Catalysis

The chemical and energy industries depend upon catalysts to drive the reactions used to create their products. Many important reactions use heterogeneous catalysts — meaning that the catalysts are in a different phase of matter than the substances they are reacting with, such as solid platinum reacting with gases in an automobile’s catalytic converter.

Scientists have investigated the surface of well-defined single crystals, illuminating the mechanisms underlying many chemical reactions. However, there is much more to be learned. For heterogeneous catalysts, their 3D atomic structure, their chemical composition and the nature of their active sites, where reactions take place, have long remained elusive.

Now, research led by members of the California NanoSystems Institute at UCLA has determined the 3D atomic coordinates, chemical makeup and surface composition of heterogenous nanocatalysts — sized on the scale of billionths of a meter — used in chemical reactions driven by electricity.

The team’s technique could profoundly impact the fundamental understanding of catalysts’ active sites and enable engineers to rationally design nanocatalysts in a way that optimizes their performance, whereas current methods are closer to trial and error.

The study, which appeared on the cover of the July issue of Nature Catalysis, was led by corresponding authors and CNSI members Jianwei “John” Miao, a professor of physics and astronomy at the UCLA College; Yu Huang, the Traugott and Dorothea Frederking Endowed Professor and the chair of the materials science and engineering department at the UCLA Samueli School of Engineering; and Philippe Sautet, a distinguished professor of chemical and biomolecular engineering and the vice chair for graduate education at UCLA Samueli.

Using advances they developed for a microscopy technique called atomic electron tomography, the team studied 11 nanoparticles consisting of either a platinum-nickel alloy alone or that alloy plus traces of molybdenum, another metal that can serve as a catalyst. The researchers were able to measure a host of characteristics at atomic resolution, including the nanoparticles’ facets, their surface indentations, and the relative orderliness of the catalysts’ structures and chemical components.

The data from atomic electron tomography were plugged into artificial intelligence models trained based on fundamental principles of physics and chemistry. With the algorithms, the investigators identified the active sites where catalysis takes place. Those findings were then validated with real-world measurements.

The scientists’ observations revealed that chemical activity at the surface platinum sites varies widely — by several orders of magnitude. The team conducted a comprehensive analysis of the relationship between the nanocatalysts’ structure and chemical activity at the level of individual atoms to formulate an equation providing quantitative insights into the nanocatalysts’ active sites.

Although this study focused on platinum-based alloy nanocatalysts in a specific electrochemical reaction, the general method can be applied with a wide range of nanocatalysts for various reactions to determine the local 3D positions of atoms, as well as the catalysts’ elemental makeup and surface composition.

Molecular transport enhancement in pure metallic carbon nanotube porins

by Yuhao Li et al in Nature Materials

A Lawrence Livermore National Laboratory (LLNL) team has found that pure metallic carbon nanotubes are best at transporting molecules.

Molecule separations play an ever-increasing role in modern technology from water desalination to harvesting critical materials to high-value chemicals and pharmaceuticals manufacturing.

To enhance water and proton transport, LLNL scientists found that inner pores smaller than one nanometer in metallic carbon nanotubes are better at transporting materials than conventional semiconducting carbon nanotubes.

“These results emphasize the complex role of the electronic properties of nanofluidic channels in modulating transport under extreme nanoscale confinement,” said LLNL scientist Alex Noy, lead author of a paper appearing on the cover of Nature Materials.

As these technologies become more sophisticated and refined, their efficiency approaches the limitations of the material platforms that power them. For example, the performance of polymer membranes — which play a large role in conventional separations — is limited, suggesting that a further increase of precision separation means switching to material platforms that provide controlled uniform pore sizes and structures.

In the new study, the team analyzed metal and superconducting nanotubes to determine which material was better at transporting molecules and found that pure metallic carbon nanotubes worked best.

“Synthetic channels and nanofluidic channels provide compelling alternatives to conventional polymer nanopores,” said Yuhao Li, LLNL scientist and the co-first author of the paper.
“In many cases, they create strong spatial confinement that is reminiscent of biological membrane channels and can harness some of their exquisite selectivity mechanisms,” added another co-first author, LLNL postdoctoral researcher Zhongwu Li.

Carbon nanotube pores have smooth hydrophobic walls that enable extraordinarily fast water and gas transport and strong ion selectivity. The studies showing these results and other studies raise the possibility of a close connection between the electronic properties of the channel’s walls and its transport efficiency.

Cellulose Surface Nanoengineering for Visualizing Food Safety

by Zewan Lin et al in Nano Letters

Pesticides and herbicides are critical to ensuring food security worldwide, but these substances can present a safety risk to people who unwittingly ingest them. Protecting human health, therefore, demands sensitive analytical methods to identify even trace levels of potentially harmful substances. Now, researchers reporting in Nano Letters have developed a high-tech imaging method to detect pesticide contamination at low levels, and its application on fruits reveals that current food safety practices may be insufficient.

The analytical method called surface-enhanced Raman spectroscopy (SERS) is gaining popularity as a nondestructive method for detecting chemicals from modern farming on produce. With SERS, metal nanoparticles or nanosheets are used to amplify the signals created by molecules when they are exposed to a Raman laser beam. The patterns created by the metal-enhanced scattered light serve as molecular signatures and can be used to identify small amounts of specific compounds.

Looking to improve SERS sensitivity for pesticide detection, Dongdong Ye, Ke Zheng, Shaobo Han and colleagues designed a metal-coated membrane they could lay atop farm-grown produce. They also wanted to develop the material to be versatile enough to accommodate an array of other applications.

The researchers started with a cellulose hydrogel film, which they stretched to form aligned nanoscale wrinkles along its surface. They then immersed the film in a solution of silver nitrate to coat the grooves with SERS-enhancing silver nanoparticles. The resulting membrane was highly flexible and practically transparent in visible light, essential features for SERS signal detection.

In tests of the silver-embedded membrane for food safety applications, the researchers sprayed the pesticides thiram and carbendazim, alone or together, onto apples, air-dried the fruits and then washed them to mimic everyday practices. When they laid their membrane over the apples, SERS detected pesticides on the apples, even though the chemicals were present at low concentrations. The team was also able to clearly resolve scattered-light signatures for each pesticide on apples sprayed with both thiram and carbendazim, as well as detect pesticide contamination through the fruit’s peel and into the outermost layer of pulp.

These results suggest that washing alone could be insufficient to prevent pesticide ingestion and that peeling would be required to remove potential contamination in the skin and outer pulp, the researchers say. Beyond apples, they also used the SERS membrane system to detect pesticides on cucumbers, shrimp, chili powder and rice.

Development of an anti-microbial starch-based polymer film embedded with silver nanoparticles by green synthesis from tea extract: a potential low cost wound dressing for rural population of developing countries

by Sambuddha Dinda et al in International Journal of Biomedical Nanoscience and Nanotechnology

Wound infections, particularly associated with burns, are a serious health problem causing high morbidity and mortality. Aside from hygiene and basic dressings, antibiotics are the standard treatment for serious wounds. However, cost, access, and emerging bacterial resistance, make their use difficult and ineffective, especially when a course of treatment is not completed. Globally, a huge number of deaths occur because of infected burns especially in low- and middle-income countries, and most commonly in rural areas.

Treating burn wounds is a complex process due to various factors. Burns disrupt the skin barrier, exposing fluid from the wound to opportunistic bacteria that thrive on the exuded nutrients. Such wounds also compromise blood supply and affect the local immune response. In addition, a large burn, covering more than a fifth of the skin will often lead to systemic inflammatory response syndrome (SIRS), further complicating infection management.

Research published in the International Journal of Biomedical Nanoscience and Nanotechnology has looked at how silver-containing antimicrobial nanoparticle preparations might be used, not as topical antiseptic creams, but as a sustained-release component of an advanced wound dressing.

The cost of such a dressing would likely make it unviable in normal circumstances. However, the team involved from KLE University in Belagavi, India, has developed a low-cost, antimicrobial starch-based polymer film within which they can embed silver nanoparticles, synthesized using a simple method from tea extracts.

The team’s environmentally friendly approach also benefits from using those plant extracts as they contain polyphenolic compounds, which have an additional antimicrobial character as they are antioxidants, anti-inflammatory agents, and antimicrobial.

In tests, the researchers — Sambuddha Dinda, Anuradha B. Patil, Sumati Annigeri Hogade, and Abhishek Bansal — showed that their starch-based film showed significant antimicrobial activity against various types of bacteria, including the ever-troublesome Staphylococcus aureus and Pseudomonas aeruginosa.

“This study showed anti-microbial efficacy of a low-cost starch-based polymer film containing Ag-NP with antioxidant biomolecules of green tea which can be easily fabricated and used for wound dressing,” the researchers conclude.