NT/ Peering into nanofluidic mysteries one photon at a time
Nanotechnology & nanomaterials biweekly vol.40, 4th September — 18th September
TL;DR
- Researchers at the University of Manchester and the École polytechnique fédérale de Lausanne (EPFL), Switzerland, have revealed an innovative approach to tracking individual molecule dynamics within nanofluidic structures, illuminating their response to molecules in ways never before possible.
- Optical-resolution photoacoustic microscopy is an up-and-coming biomedical imaging technique for studying a broad range of diseases, such as cancer, diabetes, and stroke. However, its insufficient sensitivity has been a longstanding obstacle to its wider application. Recently, a research team developed a multi-spectral, super-low-dose photoacoustic microscopy system with a significant improvement in the system sensitivity limit, enabling new biomedical applications and clinical translation in the future.
- Scientists from Nanyang Technological University, Singapore (NTU Singapore) have developed a flexible battery as thin as a human cornea, which stores electricity when it is immersed in saline solution, and which could one day power smart contact lenses.
- A recent study presents an exciting new way to listen to ‘the crackling’ noise of atoms shifting at the nanoscale when materials are deformed, providing potentially improved methods for discontinuities in novel, new materials, such as those proposed for future domain-wall electronics. ‘Crackling noise microscopy’ presents a new opportunity for generating advanced knowledge about nanoscale features across a wide range of applications and material systems.
- Pouring flecks of rust into the water usually makes it dirtier. However, researchers have developed special iron oxide nanoparticles called ‘smart rust’ that actually make it cleaner. The magnetic nanoparticles attract different pollutants by changing the particles’ coating and are removed from water with a magnet. Now, the team is reporting a smart rust that traps estrogen hormones, which are potentially harmful to aquatic life.
- Graphene-based two-dimensional materials have recently emerged as a focus of scientific exploration due to their exceptional structural, mechanical, electrical, optical, and thermal properties. Among them, nanosheets based on graphene-oxide (GO), an oxidized derivative of graphene, with ultrathin and extra wide dimensions and oxygen-rich surfaces are quite promising. Researchers have recently presented an innovative approach called “countercation engineering” to impart the desired thermoresponsive ability to GO nanosheets themselves.
- Aqueous rechargeable zinc ion batteries are promising components for electric grid storage due to their low cost and intrinsic safety. However, their practical implementation is hindered by poor reversibility of the zinc anode, primarily caused by the chaotic Zn deposition present as dendrite and side reactions. Recently, a research group has proposed a strategy using “ion carriers” by importing macromolecular Zn2+ carriers with a large mass-to-charge ratio to decouple the ion flux from the inhomogeneous electric field and substrate. This method provides an efficient pathway to overcome the dendrite and side reaction problems.
- A team of scientists from the University of California, Irvine, believe they have discovered a special antibody that may lead to a treatment for retinitis pigmentosa, a condition that causes loss of central vision, as well as night and color vision.
- A new nanoscience study led by a researcher at the Department of Energy’s Oak Ridge National Laboratory takes a big-picture look at how scientists study materials at the smallest scales.
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 a 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 the year 2020, and is projected to reach a revised size of US $126 billion.
Latest News & Research
Liquid-activated quantum emission from pristine hexagonal boron nitride for nanofluidic sensing
by Nathan Ronceray, Yi You, Evgenii Glushkov, Martina Lihter, Benjamin Rehl, Tzu-Heng Chen, Gwang-Hyeon Nam, Fanny Borza, Kenji Watanabe, Takashi Taniguchi, Sylvie Roke, Ashok Keerthi, Jean Comtet, Boya Radha, Aleksandra Radenovic in Nature Materials
Researchers at the University of Manchester and the École polytechnique fédérale de Lausanne (EPFL), Switzerland, have revealed an innovative approach to track individual molecule dynamics within nanofluidic structures, illuminating their response to molecules in ways never before possible.
Nanofluidics, the study of fluids confined within ultra-small spaces, offers insights into the behaviour of liquids on a nanometer scale. However, exploring the movement of individual molecules in such confined environments has been challenging due to the limitations of conventional microscopy techniques. This obstacle prevented real-time sensing and imaging, leaving significant gaps in our knowledge of molecular properties in confinement.
A team led by Professor Radha Boya in the Department of Physics at The University of Manchester makes nanochannels which are only one-atom to few-atom thin using two-dimensional materials as building blocks.
Prof Boya said: “Seeing is believing, but it is not easy to see confinement effects at this scale. We make these extremely thin slit-like channels, and the current study shows an elegant way to visualise them by super-resolution microscopy.”
The partnership with the EPFL team allowed for optical probing of these systems, uncovering hints of liquid ordering induced by confinement.
Thanks to an unexpected property of boron nitride, a graphene-like 2D material that possesses a remarkable ability to emit light when in contact with liquids, researchers at EPFL’s Laboratory of Nanoscale Biology (LBEN) have succeeded in directly observing and tracing the paths of individual molecules within nanofluidic structures.
This revelation opens the door to a deeper understanding of the behaviours of ions and molecules in conditions that mimic biological systems.
Professor Aleksandra Radenovic, head of LBEN, explains: “Advancements in fabrication and material science have empowered us to control fluidic and ionic transport on the nanoscale. Yet, our understanding of nanofluidic systems remained limited, as conventional light microscopy couldn’t penetrate structures below the diffraction limit. Our research now shines a light on nanofluidics, offering insights into a realm that was largely uncharted until now.”
This newfound understanding of molecular properties has exciting applications, including the potential to directly image emerging nanofluidic systems, where liquids exhibit unconventional behaviours under pressure or voltage stimuli.
The research’s core lies in the fluorescence originating from single-photon emitters at the hexagonal boron nitride’s surface.
Doctoral student Nathan Ronceray, from LBEN, said: “This fluorescence activation came unexpected as neither hexagonal boron nitride (hBN) nor the liquid exhibit visible-range fluorescence on their own. It most likely arises from molecules interacting with surface defects on the hBN crystal, but we are still not certain of the exact mechanism,”
Dr Yi You, a post-doc from The University of Manchester engineered the nanochannels such that the confining liquids mere nanometers from the hBN surface which has some defects.
Surface defects can be missing atoms in the crystalline structure, whose properties differ from the original material, granting them the ability to emit light when they interact with certain molecules.
The researchers further observed that when a defect turns off, one of its neighbours lights up, because the molecule bound to the first site hopped to the second. Step by step, this enables reconstructing entire molecular trajectories.
Using a combination of microscopy techniques, the team monitored colour changes to successfully demonstrate that these light emitters emit photons one at a time, offering pinpoint information about their immediate surroundings within around one nanometer. This breakthrough enables the use of these emitters as nanoscale probes, shedding light on the arrangement of molecules within confined nanometre spaces.
The potential for this discovery is far-reaching. Nathan Ronceray envisions applications beyond passive sensing.
He said: “We have primarily been watching the behaviour of molecules with hBN without actively interacting with, but we think it could be used to visualize nanoscale flows caused by pressure or electric fields.
“This could lead to more dynamic applications in the future for optical imaging and sensing, providing unprecedented insights into the intricate behaviours of molecules within these confined spaces.”
Super‐Low‐Dose Functional and Molecular Photoacoustic Microscopy
by Yachao Zhang, Jiangbo Chen, Jie Zhang, Jingyi Zhu, Chao Liu, Hongyan Sun, Lidai Wang in Advanced Science
Optical-resolution photoacoustic microscopy is an up-and-coming biomedical imaging technique for studying a broad range of diseases, such as cancer, diabetes and stroke. But its insufficient sensitivity has been a longstanding obstacle for its wider application. Recently, a research team from City University of Hong Kong (CityU) developed a multi-spectral, super-low-dose photoacoustic microscopy system with a significant improvement in the system sensitivity limit, enabling new biomedical applications and clinical translation in the future.
Photoacoustic microscopy is a biomedical imaging technique that combines ultrasound detection and laser-induced photoacoustic signals to create detailed images of biological tissue. When biological tissue is irradiated with a pulsed laser, it generates ultrasonic waves, which are then detected and converted into electric signals for imaging. This attention-getting technique can achieve up to capillary-level or sub-cellular resolution at greater depths than traditional optical microscopy methods. However, insufficient sensitivity has hindered the technology’s wider application.
“High sensitivity is important for high-quality imaging. And it helps detect chromophores (molecules that confer colour on materials by absorbing particular wavelengths of visible light) that do not strongly absorb light. It also helps lessen photobleaching and phototoxicity, reduce perturbation to the biological tissues of delicate organs, and broaden the choices of low-cost, low-power lasers in a wide spectrum,” explained Professor Wang Lidai, Associate Professor in the Department of Biomedical Engineering at CityU.
For instance, in an ophthalmic examination, a low-power laser is preferred for more safety and comfort. Long-term monitoring of pharmacokinetics or blood flow requires low-dose imaging to alleviate perturbation to tissue functions, he added.
To overcome the sensitivity challenge, Professor Wang and his research team recently developed a multi-spectral, super-low-dose photoacoustic microscopy (SLD-PAM) system, which breaks through the sensitivity limit of traditional photoacoustic microscopy, significantly improving sensitivity by about 33 times.
They achieved the breakthrough by combining improvement in the photoacoustic sensor design and innovation of a 4D spectral-spatial filter algorithm for computation. They improved the sensor design by using a lab-customized high-numerical-aperture acoustic lens, optimizing the optical and acoustic beam combiner, and improving the optical and acoustic alignment. The SLD-PAM also utilizes a low-cost multi-wavelength pulsed laser, providing 11 wavelengths, ranging from green to red light. The laser operates at a repetition frequency up to megahertz, and the spectral switching time is in sub-microseconds.
To demonstrate the significance and novelty of SLD-PAM, the team tested it thoroughly via in vivo animal imaging at super-low pulse energy with green-light and red-light sources, resulting in remarkable findings.
First, SLD-PAM enabled high-quality in vivo anatomical and functional imaging. The super-low laser power and high sensitivity significantly reduced perturbations in eye and brain imaging, paving an avenue for clinical translation. Second, without compromising image quality, SLD-PAM reduced photobleaching by about 85%, using lower laser power, and enabled the use of a much broader range of molecular and nano-probes. In addition, the system cost is significantly lower, making it more affordable for research laboratories and clinics.
“SLD-PAM enables non-invasive imaging of biological tissue with minimal damage to the subjects, offering a powerful and promising tool for anatomical, functional and molecular imaging,” said Professor Wang. “We believe that SLD-PAM can help advance the applications of photoacoustic imaging, enable numerous new biomedical applications, and pave a new avenue for clinical translation.”
Next, Professor Wang and his research team will test a broader range of small molecules and genetically encoded biomarkers in biological imaging using the SLD-PAM system. They also plan to adopt more types of low-power light sources in wider spectra to develop wearable or portable microscopy.
A tear-based battery charged by biofuel for smart contact lenses
by Jeonghun Yun, Zongkang Li, Xinwen Miao, Xiaoya Li, Jae Yoon Lee, Wenting Zhao, Seok Woo Lee in Nano Energy
Scientists from Nanyang Technological University, Singapore (NTU Singapore) have developed a flexible battery as thin as a human cornea, which stores electricity when it is immersed in saline solution, and which could one day power smart contact lenses.
Smart contact lenses are high-tech contact lenses capable of displaying visible information on our corneas and can be used to access augmented reality. Current uses include helping to correct vision, monitoring wearers’ health, and flagging and treating diseases for people with chronic health conditions such as diabetes and glaucoma. In the future, smart contact lenses could be developed to record and transmit everything a wearer sees and hears to cloud-based data storage.
However, to reach this future potential a safe and suitable battery needs to be developed to power them. Existing rechargeable batteries rely on wires or induction coils that contain metal and are unsuitable for use in the human eye, as they are uncomfortable and present risks to the user.
The NTU-developed battery is made of biocompatible materials and does not contain wires or toxic heavy metals, such as those in lithium-ion batteries or wireless charging systems. It has a glucose-based coating that reacts with the sodium and chloride ions in the saline solution surrounding it, while the water the battery contains serves as the ‘wire’ or ‘circuitry’ for electricity to be generated.
The battery could also be powered by human tears as they contain sodium and potassium ions, at a lower concentration. Testing the current battery with a simulated tear solution, the researchers showed that the battery’s life would be extended an additional hour for every twelve-hour wearing cycle it is used. The battery can also be charged conventionally by an external power supply.
Associate Professor Lee Seok Woo, from NTU’s School of Electrical and Electronic Engineering (EEE), who led the study, said: “This research began with a simple question: could contact lens batteries be recharged with our tears? There were similar examples for self-charging batteries, such as those for wearable technology that are powered by human perspiration.
“However, previous techniques for lens batteries were not perfect as one side of the battery electrode was charged and the other was not. Our approach can charge both electrodes of a battery through a unique combination of enzymatic reaction and self-reduction reaction. Besides the charging mechanism, it relies on just glucose and water to generate electricity, both of which are safe to humans and would be less harmful to the environment when disposed, compared to conventional batteries.”
Co-first author Dr Yun Jeonghun, a research fellow from NTU’s EEE said:
“The most common battery charging system for smart contact lenses requires metal electrodes in the lens, which are harmful if they are exposed to the naked human eye. Meanwhile, another mode of powering lenses, induction charging, requires a coil to be in the lens to transmit power, much like wireless charging pad for a smartphone. Our tear-based battery eliminates the two potential concerns that these two methods pose, while also freeing up space for further innovation in the development smart contact lenses.”
The team demonstrated their invention using a simulated human eye. The battery, which is about 0.5 millimetres-thin generates electrical power by reacting with the basal tears — the constant tears that create a thin film over our eyeballs — for the devices embedded within the lenses to function.
The flexible and flat battery discharges electricity through a process called reduction when its glucose oxidase coating reacts with the sodium and chloride ions in the tears, generating power and current within the contact lenses.
The team demonstrated that the battery could produce a current of 45 microamperes and a maximum power of 201 microwatts, which would be sufficient to power a smart contact lens.
Laboratory tests showed that the battery could be charged and discharged up to 200 times. Typical lithium-ion batteries have a lifespan of 300 to 500 charging cycles.
The team recommends that the battery should be placed for at least eight hours in a suitable solution that contains a high quantity of glucose, sodium and potassium ions, to be charged while the user is asleep.
Crackling noise microscopy
by Cam-Phu Thi Nguyen, Peggy Schoenherr, Ekhard K. H. Salje, Jan Seidel in Nature Communications
A recent UNSW-led paper published in Nature Communications presents an exciting new way to listen to avalanches of atoms in crystals.
The nanoscale movement of atoms when materials deform leads to sound emission. This so-called crackling noise is a scale-invariant phenomenon found in various material systems as a response to external stimuli such as force or external fields.
Jerky material movements in the form of avalanches can span many orders of magnitude in size and follow universal scaling rules described by power laws. The concept was originally studied as Barkhausen noise in magnetic materials and now is used in diverse fields from earthquake research and building materials monitoring to fundamental research involving phase transitions and neural networks.
The new method for nanoscale crackling noise measurements developed by UNSW and University of Cambridge researchers is based on SPM nanoindentation.
“Our method allows us to study the crackling noise of individual nanoscale features in materials, such as domain walls in ferroelectrics,” says lead author Dr Cam Phu Nguyen. “The types of atom avalanches differ around these structures when the material deforms.”
One of the method’s most intriguing aspects is the fact that individual nanoscale features can be identified by imaging the material surface before indenting it. This differentiation enables new studies that were not possible previously.
In a first application of the new technology the UNSW researchers have used the method to investigate discontinuities in ordered materials, called domain walls.
“Domain walls have been the focus of our research for some time. They are highly attractive as building blocks for post-Moore’s law electronics,” says author Prof Jan Seidel, also at UNSW. “We show that critical exponents for avalanches are altered at these nanoscale features, leading to a suppression of mixed-criticality, which is otherwise present in domains.”
From the perspective of applications and novel material functionalities, crackling noise microscopy presents a new opportunity for generating advanced knowledge about such features at the nanoscale. The study discusses experimental aspects of the method and provides a perspective on future research directions and applications.
The presented concept opens the possibility of investigating the crackling of individual nanoscale features in a wide range of other material systems.
Cleaning water with ‘smart rust’ and magnets
by American Chemical Society
Pouring flecks of rust into water usually makes it dirtier. But researchers have developed special iron oxide nanoparticles they call “smart rust” that actually makes it cleaner. Smart rust can attract many substances, including oil, nano- and microplastics, as well as the herbicide glyphosate, depending on the particles’ coating. And because the nanoparticles are magnetic, they can easily be removed from water with a magnet along with the pollutants. Now, the team is reporting that they’ve tweaked the particles to trap estrogen hormones that are potentially harmful to aquatic life.
The researchers will present their results today at the fall meeting of the American Chemical Society (ACS).
“Our ‘smart rust’ is cheap, nontoxic and recyclable,” says Marcus Halik, Ph.D., the project’s principal investigator. “And we have demonstrated its use for all kinds of contaminants, showing the potential for this technique to improve water treatment dramatically.”
For many years, Halik’s research team has been investigating environmentally friendly ways to remove pollutants from water. The base materials they use are iron oxide nanoparticles in a superparamagnetic form, which means they are drawn to magnets, but not to each other, so the particles don’t clump.
To make them “smart,” the team developed a technique to attach phosphonic acid molecules onto the nanometer-sized spheres.
“After we add a layer of the molecules to the iron oxide cores, they look like hairs sticking out of these particles’ surfaces,” says Halik, who is at Friedrich-Alexander-Universität Erlangen-Nürnberg.
Then, by changing what is bound to the other side of the phosphonic acids, the researchers can tune the properties of the nanoparticles’ surfaces to strongly adsorb different types of pollutants.
Early versions of smart rust trapped crude oil from water collected from the Mediterranean Sea and glyphosate from pond water collected near the researchers’ university. Additionally, the team demonstrated that smart rust could remove nano- and microplastics added to lab and river water samples.
So far, the team has targeted pollutants present in mostly large amounts. Lukas Müller, a graduate student who’s presenting new work at the meeting, wanted to know if he could modify the rust nanoparticles to attract trace contaminants, such as hormones. When some of our body’s hormones are excreted, they are flushed into wastewater and eventually enter waterways. Natural and synthetic estrogens are one such group of hormones, and the main sources of these contaminants include waste from humans and livestock. The amounts of estrogens are very low in the environment, says Müller, so they are difficult to remove. Yet even these levels have been shown to affect the metabolism and reproduction of some plants and animals, although the effects of low levels of these compounds on humans over long periods aren’t fully known.
“I started with the most common estrogen, estradiol, and then four other derivatives that share similar molecular structures,” says Müller.
Estrogen molecules have a bulky steroid body and parts with slight negative charges. To exploit both characteristics, he coated iron oxide nanoparticles with two sets of compounds: one that’s long and another that’s positively charged. The two molecules organized themselves on the nanoparticles’ surface, and the researchers hypothesize that together, they build many billions of “pockets” that draw in the estradiol and trap it in place.
Because these pockets are invisible to the naked eye, Müller has been using high-tech instruments to verify that these estrogen-trapping pockets exist. Preliminary results show efficient extraction of the hormones from lab samples, but the researchers need to look at additional experiments from solid-state nuclear magnetic resonance spectroscopy and small-angle neutron scattering to verify the pocket hypothesis.
“We are trying to use different puzzle pieces to understand how the molecules actually assemble on the nanoparticles’ surface,” explains Müller.
In the future, the team will test these particles on real-world water samples and determine the number of times that they can be reused. Because each nanoparticle has a high surface area with lots of pockets, the researchers say that they should be able to remove estrogens from multiple water samples, thereby reducing the cost per cleaning.
“By repeatedly recycling these particles, the material impact from this water treatment method could become very small,” concludes Halik.
Countercation Engineering of Graphene-Oxide Nanosheets for Imparting a Thermoresponsive Ability
by Koki Sano et al in ACS Applied Materials & Interfaces
Graphene-based two-dimensional materials have recently emerged as a focus of scientific exploration due to their exceptional structural, mechanical, electrical, optical, and thermal properties. Among them, nanosheets based on graphene-oxide (GO), an oxidized derivative of graphene, with ultrathin and extra wide dimensions and oxygen-rich surfaces are quite promising. Researchers led by Assistant Professor Koki Sano and Mr. Shoma Kondo from the Department of Chemistry and Materials at Shinshu University in Japan has recently presented an innovative approach called “countercation engineering” to impart the desired thermoresponsive ability to GO nanosheets themselves. Their work was published in ACS Applied Materials & Interfaces.
Functional groups containing oxygen, such as carboxy and acidic hydroxy groups, generate dense negative charges, making GO nanosheets colloidally stable in water. As a result, they are valuable building blocks for next-generation functional soft materials.
In particular, thermoresponsive GO nanosheets have garnered much attention for their wide-ranging applications, from smart membranes and surfaces and recyclable systems to hydrogel actuators and biomedical platforms. However, the prevailing synthetic strategies for generating thermoresponsive behaviors entail modifying GO nanosheet surfaces with thermoresponsive polymers such as poly (N-isopropylacrylamide). This process is complex and has potential limitations in subsequent functionalization efforts.
Dr. Sano explains, “This study introduces a simplified and efficient route to achieving thermoresponsiveness by capitalizing on countercations (positively charged ions) inherently present in GO nanosheets. The control over these countercations offer a powerful tool for engineering stimuli-responsive nanomaterials.”
In their study, the researchers established a robust synthetic protocol involving a two-step reaction in water to synthesize GO nanosheets with specific countercations. An exchange reaction first replaced the countercations of the carboxy and acidic hydroxy groups with protons. This was followed by an acid–base reaction using a hydroxide anion with the target counteranions, resulting in the desirable GO nanosheets.
Systematic investigations into their thermoresponsive behavior revealed that GO nanosheets harboring tetrabutylammonium (Bu4N+) countercations exhibited an inherent thermoresponsive nature in aqueous environments without requiring any thermoresponsive polymers.
Additionally, the researchers demonstrated a reversible sol−gel transition marked by self-assembly and disassembly processes. Upon heating, the lamellar Bu4N+-based GO nanosheets with electrostatic repulsion (sol state) between them reassembled to form an interconnected network dominated by van der Waals attraction (gel state) instead.
This remarkable transition can, in fact, be harnessed to develop a direct writing ink for constructing three-dimensionally designable gel architectures of the GO nanosheets, pointed out the researchers.
Overall, the study’s findings have profound implications. “The controlled synthesis of GO nanosheets with tailored countercations has unveiled a pathway to versatile and simplified thermoresponsive materials. The thermoresponsive GO nanosheets are promising building blocks for biomedical, energy, and environmental applications, such as smart membranes, soft robotics, and recyclable systems, hydrogel actuators, and biomedical solutions,” says Dr. Sano.
“Moreover, the ability to directly write with GO nanosheet dispersions offers a new dimension to material design, enabling the construction of intricate gel structures with ease,” he concludes.
MOF Nanosheets as Ion Carriers for Self-Optimized Zinc Anode
by Hanmiao Yang et al in Energy & Environmental Science
Aqueous rechargeable zinc ion batteries are promising components for electric grid storage due to their low cost and intrinsic safety. However, their practical implementation is hindered by poor reversibility of the zinc anode, primarily caused by the chaotic Zn deposition present as dendrite and side reactions. Recently, a research group led by Prof. Yang Weishen and Dr. Zhu Kaiyue from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) has proposed a strategy using “ion carriers” by importing macromolecular Zn2+ carriers with a large mass-to-charge ratio to decouple the ion flux from the inhomogeneous electric field and substrate. This method provides an efficient pathway to overcome the dendrite and side reaction problems.
The researchers found that metal-organic framework (MOF) nanosheets featuring migration capability under electric field due to their one-dimensional channel structure and preferential Zn2+ adsorption, as well as unique reductive chemistry due to the weak coordination between ligands and zinc ions, enables them to serve as dynamic Zn2+ ion carriers.
The dynamic MOF nanosheets could continually optimize zinc anode during cycling. Specifically, the zinc electrode was gradually reconstructed towards a horizontally aligned lamellae-like morphology and enhanced (002) texture, showing a relative texture coefficient of a 96.9 (maximum value of 100). This optimization on the morphology and texture could be attributed to the horizontal alignment of Zn2+ ions by the constraints of MOF nanosheets.
Additionally, the presence of MOF ligands contributed to the elimination of undesirable Zn4SO4(OH)6·4H2O byproducts. These byproducts were spontaneously converted into useful MOF nanosheets through unique properties of ligands. Consequently, Zn||Zn symmetric cells and Zn||(NH4)2V10O25·8H2O full cells employing MOF nanosheets in electrolytes exhibited outstanding cycling performance at both low and high rates.
“The versatility of the ‘ion carrier’ strategy holds promise for potential expansion into achieving highly reversible cycling in other rechargeable metal cells, owing to its broad applicability to various ligands, substrates and electrolytes,” said Prof. Yang.
Structural basis for the allosteric modulation of rhodopsin by nanobody binding to its extracellular domain
by Arum Wu et al in Nature Communications
A team of scientists from the University of California, Irvine, believe they have discovered a special antibody that may lead to a treatment for retinitis pigmentosa, a condition that causes loss of central vision, as well as night and color vision.
Retinitis pigmentosa (RP) is a group of inherited eye diseases that affect the retina in the back of the eye. It is caused by the death of cells that detect light signals, known as photoreceptor cells. There is no known cure for RP, and the development of new treatments for this condition relies on cell and gene therapies.
UCI researchers have targeted their study on a specific molecule that they believe will provide a treatment for rhodopsin-associated autosomal dominant RP (adRP). The molecule, rhodopsin, is a key light-sensing molecule in the human retina. It is found in rod photoreceptor cells, and mutations in the rhodopsin gene are a primary cause of adRP.
“More than 150 mutations in rhodopsin can cause retinitis pigmentosa, making it challenging to develop targeted gene therapies,” said Krzysztof Palczewski, Ph.D., Donald Bren Professor, UCI School of Medicine. “However due to the high prevalence of RP, there has been significant investment in research and development efforts to find novel treatments.”
Although rhodopsin has been studied for over a century, key details of its mechanism for converting light into a cellular signal have been difficult to experimentally address. For this study, researchers used a special type of llama-derived antibody, known as a nanobody, that can halt the process of rhodopsin photoactivation, allowing it to be investigated at high resolution.
“Our team has developed nanobodies that work through a novel mechanism of action. These nanobodies have high specificity and can recognize the target rhodopsin extracellularly,” said David Salom, Ph.D., researcher and project scientist, UCI School of Medicine. “This enables us to lock this GPCR in a non-signaling state.”
Scientists discovered that these nanobodies target an unexpected site on the rhodopsin molecule, near the location where retinaldehyde binds. They also found that the stabilizing effect of these nanobodies can also be applied to rhodopsin mutants that are associated with retinal disease, suggesting their use as therapeutics.
“In the future, we hope to involve the in vitro evolution of these initial set of nanobodies,” said Arum Wu, Ph.D., researcher and project scientist, UCI School of Medicine. “We will also evaluate the safety and effectiveness of a future nanobody gene therapy for RP.”
Researchers hope to improve nanobodies’ ability to recognize rhodopsin from other species including mice, for which several pre-clinical models of adRP are available. They also have plans to use these nanobodies to address a long-term goal in the field of structurally resolving the key intermediate states of rhodopsin from the inactive state to the fully ligand-activated state.
Imaging beyond the surface region: Probing hidden materials via atomic force microscopy
by Amir Farokh Payam et al in Science Advances
A new nanoscience study led by a researcher at the Department of Energy’s Oak Ridge National Laboratory takes a big-picture look at how scientists study materials at the smallest scales.
The paper, published in Science Advances, reviews leading work in subsurface nanometrology, the science of internal measurement at the nanoscale level, and suggests quantum sensing could become the foundation for the field’s next era of discoveries. Potential applications could range from mapping intracellular structures for targeted drug delivery to characterizing quantum materials and nanostructures for the advancement of quantum computing.
“Our goal was to define the state of the art and to consider what’s been done and where we need to go,” said Ali Passian, an ORNL senior research scientist and senior author of the study.
“Everybody wants to know what’s below the surface of materials, but finding out what’s really there tends to be incredibly challenging at any scale. We hope to inspire a new generation of scientists to tackle this challenge by exploiting quantum phenomena or whatever the most promising opportunities may be, so we can push the boundaries of sensing and imaging science toward greater discoveries and understanding.”
Particles at the nanoscale act as the building blocks of quantum science — just small enough to enable scientists to tweak major properties of materials with maximum precision. One nanometer equals a billionth of a meter, a millionth of a millimeter and a thousandth of a micrometer. The average sheet of paper, for example, runs about 100,000 nanometers thick.
Passian and co-author Amir Payam of Ulster University suggest the nanoscale level may be not only where intricate molecular assemblies of biological systems such as cell membranes form but also where the dimensions of emerging materials such as metasurfaces and quantum materials align. So far, it’s an underexplored opportunity, they conclude.
Breakthrough tools like the scanning probe microscope, which uses a sharp-tipped probe to inspect samples at the atomic level, have helped speed advances in the nanometrology of surfaces. Subsurface studies have achieved fewer comparable breakthroughs, the authors note.
“All of our senses are geared toward surfaces,” Passian said. “Though still difficult, we have extended our reach to the nanoscale by somehow disturbing the material using light, sound, electrons and tiny needles. But once there, measuring what’s beneath remains extremely challenging. We need new methods that allow us to peer inside these materials while leaving them intact. Quantum science may offer opportunities here, particularly quantum sensing, where for example, the quantum states of the probe, the light and the sample could be capitalized upon.”
The authors suggest quantum sensing techniques now in the early stages of development could hold the key to advances in subsurface exploration. Quantum probes, for example, could employ skyrmions — subatomic quasiparticles created by disruptions in magnetic fields and already under consideration for other quantum applications — to probe deeper than any current technique allows.
“People are working hard to push the limits of detection and create new measurement modalities,” Passian said. “I think the next few years will be exciting in terms of materialization and user-friendly implementation of these techniques toward achieving quantum nanometrology of surfaces and the subsurface regions.”
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