Perpendicular magnetic tunnel junction (pMTJ)-based true-random number generators (RNGs) can consume orders of magnitude less energy per bit than CMOS pseudo-RNGs. Here, we numerically investigate with a macrospin Landau–Lifshitz-Gilbert equation solver the use of pMTJs driven by spin–orbit torque to directly sample numbers from arbitrary probability distributions with the help of a tunable probability tree. The tree operates by dynamically biasing sequences of pMTJ relaxation events, called 'coinflips', via an additional applied spin-transfer-torque current. Specifically, using a single, ideal pMTJ device we successfully draw integer samples on the interval [0, 255] from an exponential distribution based on p-value distribution analysis. In order to investigate device-to-device variations, the thermal stability of the pMTJs are varied based on manufactured device data. It is found that while repeatedly using a varied device inhibits ability to recover the probability distribution, the device variations average out when considering the entire set of devices as a 'bucket' to agnostically draw random numbers from. Further, it is noted that the device variations most significantly impact the highest level of the probability tree, with diminishing errors at lower levels. The devices are then used to draw both uniformly and exponentially distributed numbers for the Monte Carlo computation of a problem from particle transport, showing excellent data fit with the analytical solution. Finally, the devices are benchmarked against CMOS and memristor RNGs, showing faster bit generation and significantly lower energy use.
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Nanotechnology encompasses the understanding of the fundamental physics, chemistry, biology and technology of nanometre-scale objects.
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Andrew Maicke et al 2024 Nanotechnology 35 275204
Ali Al Hassan et al 2024 Nanotechnology 35 295705
We report on the fabrication of a novel design of GaAs/(In,Ga)As/GaAs radial nanowire heterostructures on a Si 111 substrate, where, for the first time, the growth of inhomogeneous shells on a lattice mismatched core results in straight nanowires instead of bent. Nanowire bending caused by axial tensile strain induced by the (In,Ga)As shell on the GaAs core is reversed by axial compressive strain caused by the GaAs outer shell on the (In,Ga)As shell. Progressive nanowire bending and reverse bending in addition to the axial strain evolution during the two processes are accessed by in situ by x-ray diffraction. The diameter of the core, thicknesses of the shells, as well as the indium concentration and distribution within the (In,Ga)As quantum well are revealed by 2D energy dispersive x-ray spectroscopy using a transmission electron microscope. Shell(s) growth on one side of the core without substrate rotation results in planar-like radial heterostructures in the form of free standing straight nanowires.
Wei Cheat Lee et al 2024 Nanotechnology 35 295301
A hierarchical sea urchin-like hybrid metal oxide nanostructure of ZnO nanorods deposited on TiO2 porous hollow hemispheres with a thin zinc titanate interface layer is specifically designed and synthesized to form a combined type I straddling and type II staggered junctions. The HHSs, synthesized by electrospinning, facilitate light trapping and scattering. The ZnO nanorods offer a large surface area for improved surface oxidation kinetics. The interface layer of zinc titanate (ZnTiO3) between the TiO2 HHSs and ZnO nanorods regulates the charge separation in a closely coupled hierarchy structure of ZnO/ZnTiO3/TiO2. The synergistic effects of the improved light trapping, charge separation, and fast surface reaction kinetics result in a superior photoconversion efficiency of 1.07% for the photoelectrochemical water splitting with an outstanding photocurrent density of 2.8 mA cm−2 at 1.23 V versus RHE.
Yucheng Hu et al 2024 Nanotechnology 35 295702
Cathodoluminescence and electron backscatter diffraction have been applied to exactly the same grain boundaries (GBs) in a Cu(In,Ga)S2 solar absorber in order to investigate the influence of microstructure on the radiative recombination behaviour at the GBs. Two different types of GB with different microstructure were analysed in detail: random high angle grain boundaries (RHAGBs) and Σ3 GBs. We found that the radiative recombination at all RHAGBs was inhibited to some extent, whereas at Σ3 GBs three different observations were made: unchanged, hindered, or promoted radiative recombination. These distinct behaviours may be linked to atomic-scale grain boundary structural differences. The majority of GBs also exhibited a small spectral shift of about ±10 meV relative to the local grain interior (GI) and a few of them showed spectral shifts of up to ±40 meV. Red and blue shifts were observed with roughly equal frequency.
Syed Nabeel Ahmed and Waseem Haider 2018 Nanotechnology 29 342001
There has been a considerable amount of research in the development of sustainable water treatment techniques capable of improving the quality of water. Unavailability of drinkable water is a crucial issue especially in regions where conventional drinking water treatment systems fail to eradicate aquatic pathogens, toxic metal ions and industrial waste. The research and development in this area have given rise to a new class of processes called advanced oxidation processes, particularly in the form of heterogeneous photocatalysis, which converts photon energy into chemical energy. Advances in nanotechnology have improved the ability to develop and specifically tailor the properties of photocatalytic materials used in this area. This paper discusses many of those photocatalytic nanomaterials, both metal-based and metal-free, which have been studied for water and waste water purification and treatment in recent years. It also discusses the design and performance of the recently studied photocatalytic reactors, along with the recent advancements in the visible-light photocatalysis. Additionally, the effects of the fundamental parameters such as temperature, pH, catalyst-loading and reaction time have also been reviewed. Moreover, different techniques that can increase the photocatalytic efficiency as well as recyclability have been systematically presented, followed by a discussion on the photocatalytic treatment of actual wastewater samples and the future challenges associated with it.
Daniele Ielmini and Stefano Ambrogio 2020 Nanotechnology 31 092001
Artificial intelligence (AI) has the ability of revolutionizing our lives and society in a radical way, by enabling machine learning in the industry, business, health, transportation, and many other fields. The ability to recognize objects, faces, and speech, requires, however, exceptional computational power and time, which is conflicting with the current difficulties in transistor scaling due to physical and architectural limitations. As a result, to accelerate the progress of AI, it is necessary to develop materials, devices, and systems that closely mimic the human brain. In this work, we review the current status and challenges on the emerging neuromorphic devices for brain-inspired computing. First, we provide an overview of the memory device technologies which have been proposed for synapse and neuron circuits in neuromorphic systems. Then, we describe the implementation of synaptic learning in the two main types of neural networks, namely the deep neural network and the spiking neural network (SNN). Bio-inspired learning, such as the spike-timing dependent plasticity scheme, is shown to enable unsupervised learning processes which are typical of the human brain. Hardware implementations of SNNs for the recognition of spatial and spatio-temporal patterns are also shown to support the cognitive computation in silico. Finally, we explore the recent advances in reproducing bio-neural processes via device physics, such as insulating-metal transitions, nanoionics drift/diffusion, and magnetization flipping in spintronic devices. By harnessing the device physics in emerging materials, neuromorphic engineering with advanced functionality, higher density and better energy efficiency can be developed.
Karl Berggren et al 2021 Nanotechnology 32 012002
Recent progress in artificial intelligence is largely attributed to the rapid development of machine learning, especially in the algorithm and neural network models. However, it is the performance of the hardware, in particular the energy efficiency of a computing system that sets the fundamental limit of the capability of machine learning. Data-centric computing requires a revolution in hardware systems, since traditional digital computers based on transistors and the von Neumann architecture were not purposely designed for neuromorphic computing. A hardware platform based on emerging devices and new architecture is the hope for future computing with dramatically improved throughput and energy efficiency. Building such a system, nevertheless, faces a number of challenges, ranging from materials selection, device optimization, circuit fabrication and system integration, to name a few. The aim of this Roadmap is to present a snapshot of emerging hardware technologies that are potentially beneficial for machine learning, providing the Nanotechnology readers with a perspective of challenges and opportunities in this burgeoning field.
Achint Jain et al 2018 Nanotechnology 29 265203
Integrating layered two-dimensional (2D) materials into 3D heterostructures offers opportunities for novel material functionalities and applications in electronics and photonics. In order to build the highest quality heterostructures, it is crucial to preserve the cleanliness and morphology of 2D material surfaces that come in contact with polymers such as PDMS during transfer. Here we report that substantial residues and up to ∼0.22% compressive strain can be present in monolayer MoS2 transferred using PDMS. We show that a UV-ozone pre-cleaning of the PDMS surface before exfoliation significantly reduces organic residues on transferred MoS2 flakes. An additional 200 ◦C vacuum anneal after transfer efficiently removes interfacial bubbles and wrinkles as well as accumulated strain, thereby restoring the surface morphology of transferred flakes to their native state. Our recipe is important for building clean heterostructures of 2D materials and increasing the reproducibility and reliability of devices based on them.
Arne Laucht et al 2021 Nanotechnology 32 162003
Quantum phenomena are typically observable at length and time scales smaller than those of our everyday experience, often involving individual particles or excitations. The past few decades have seen a revolution in the ability to structure matter at the nanoscale, and experiments at the single particle level have become commonplace. This has opened wide new avenues for exploring and harnessing quantum mechanical effects in condensed matter. These quantum phenomena, in turn, have the potential to revolutionize the way we communicate, compute and probe the nanoscale world. Here, we review developments in key areas of quantum research in light of the nanotechnologies that enable them, with a view to what the future holds. Materials and devices with nanoscale features are used for quantum metrology and sensing, as building blocks for quantum computing, and as sources and detectors for quantum communication. They enable explorations of quantum behaviour and unconventional states in nano- and opto-mechanical systems, low-dimensional systems, molecular devices, nano-plasmonics, quantum electrodynamics, scanning tunnelling microscopy, and more. This rapidly expanding intersection of nanotechnology and quantum science/technology is mutually beneficial to both fields, laying claim to some of the most exciting scientific leaps of the last decade, with more on the horizon.
U Banin et al 2021 Nanotechnology 32 042003
This roadmap on Nanotechnology for Catalysis and Solar Energy Conversion focuses on the application of nanotechnology in addressing the current challenges of energy conversion: 'high efficiency, stability, safety, and the potential for low-cost/scalable manufacturing' to quote from the contributed article by Nathan Lewis. This roadmap focuses on solar-to-fuel conversion, solar water splitting, solar photovoltaics and bio-catalysis. It includes dye-sensitized solar cells (DSSCs), perovskite solar cells, and organic photovoltaics. Smart engineering of colloidal quantum materials and nanostructured electrodes will improve solar-to-fuel conversion efficiency, as described in the articles by Waiskopf and Banin and Meyer. Semiconductor nanoparticles will also improve solar energy conversion efficiency, as discussed by Boschloo et al in their article on DSSCs. Perovskite solar cells have advanced rapidly in recent years, including new ideas on 2D and 3D hybrid halide perovskites, as described by Spanopoulos et al 'Next generation' solar cells using multiple exciton generation (MEG) from hot carriers, described in the article by Nozik and Beard, could lead to remarkable improvement in photovoltaic efficiency by using quantization effects in semiconductor nanostructures (quantum dots, wires or wells). These challenges will not be met without simultaneous improvement in nanoscale characterization methods. Terahertz spectroscopy, discussed in the article by Milot et al is one example of a method that is overcoming the difficulties associated with nanoscale materials characterization by avoiding electrical contacts to nanoparticles, allowing characterization during device operation, and enabling characterization of a single nanoparticle. Besides experimental advances, computational science is also meeting the challenges of nanomaterials synthesis. The article by Kohlstedt and Schatz discusses the computational frameworks being used to predict structure–property relationships in materials and devices, including machine learning methods, with an emphasis on organic photovoltaics. The contribution by Megarity and Armstrong presents the 'electrochemical leaf' for improvements in electrochemistry and beyond. In addition, biohybrid approaches can take advantage of efficient and specific enzyme catalysts. These articles present the nanoscience and technology at the forefront of renewable energy development that will have significant benefits to society.
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Makoto Sakurai et al 2024 Nanotechnology 35 315301
A direct focused He+ beam direct machining is presented to fabricate solid-state nano-disk at the surface of a graphene multilayer micro-flake deposited on an Au/Ti/sapphire surface. At irradiation doses larger than 5.0 × 1017 ions cm−2 and with a beam size well below 1 nm, graphene disks down to 20 nm in diameter have been machined with for nano-disk down to 50 nm in diameter, a central hole for preparing the positioning of a rotation axle. The local heat generated by this irradiation is inducing a partial graphene amorphization and deformation, leading to a complete graphene nano-disk vaporization at doses larger than 5 × 1018 ions cm−2. A dry transfer printing technique followed by a graphene surface cleaning was used to transfer the nano-disks from its initial surface to a fresh and clean surface. Tapping mode atomic force micrograph have been recorded to follow the vaporization as a function of the He+ dose to confirm the graphene solid-state nano-disk fabrication limit to about 20 nm with this process.
Jingjing Zhang et al 2024 Nanotechnology 35 315602
The vertical gate-all-around (VGAA) metal-oxide-semiconductor field-effect transistor (MOSFET) holds remarkable potential in the three-dimensional (3D) integrated circuits (ICs), primarily owing to its capacity for vertical integration. The Si nanopillar, a crucial channel in the VGAA MOSFET, is conventionally shaped via the reactive ion etching (RIE) system employing SF6/O2. Past studies have indicated that high O2 gas conditions in RIE often result in Si grasses irregular nanostructures, such as nanospikes on the bottom surface, due to over-passivation. However, this study revealed that ultrahigh O2 proportions (>70%), especially when combined with low chamber pressure, inhibit the development of Si grasses in the RIE system (termed as super passivation). Nevertheless, this scenario leads to the segmentation of the Si nanopillar. To address this issue, a proposed partial sacrificing method, achieved by sacrificing the upper segment of the nanopillar through prolonged processing time and reduced mask size, successfully yielded Si nanopillars without Si grasses. Furthermore, an empirical model was developed to elucidate how experimental parameters influence etching characteristics, encompassing etching rate and Si nanopillar shape, through a systematic examination of the RIE etching process. This research significantly contributes to the production of VGAA MOSFETs and 3D ICs.
Yutao Zhou et al 2024 Nanotechnology 35 315601
The overuse of antibiotics currently results in the presence of various antibiotics being detected in water bodies, which poses potential risks to human health and the environment. Therefore, it is highly significant to remove antibiotics from water. In this study, we developed novel rod-like NiCo-phyllosilicate hybrid catalysts on calcined natural zeolite (NiCo@C-zeolite) via a facile one-pot process. The presence of the zeolite served as both a silicon source and a support, maintaining a high specific surface area of the NiCo@C-zeolite. Remarkably, NiCo@C-zeolite exhibited outstanding catalytic performance in antibiotic degradation under PMS activation. Within just 5 min, the degradation rate of metronidazole (MNZ) reached 96.14%, ultimately achieving a final degradation rate of 99.28%. Furthermore, we investigated the influence of catalyst dosage, PMS dosage, MNZ concentration, initial pH value, and various inorganic anions on the degradation efficiency of MNZ. The results demonstrated that NiCo@C-zeolite displayed outstanding efficacy in degrading MNZ under diverse conditions and maintained a degradation rate of 94.86% at 60 min after three consecutive cycles of degradation. Free radical quenching experiments revealed that SO•−4 played a significant role in the presence of NiCo@C-zeolite-PMS system. These findings indicate that the novel rod-like NiCo-phyllosilicate hybrid catalysts had excellent performance in antibiotic degradation.
Min Fu and Kevin Critchley 2024 Nanotechnology 35 302002
Inkjet printing (IJP) has become a versatile, cost-effective technology for fabricating organic and hybrid electronic devices. Heavy-metal-based quantum dots (HM QDs) play a significant role in these inkjet-printed devices due to their excellent optoelectrical properties. Despite their utility, the intrinsic toxicity of HM QDs limits their applications in commercial products. To address this limitation, developing alternative HM-free quantum dots (HMF QDs) that have equivalent optoelectronic properties to HM QD is a promising approach to reduce toxicity and environmental impact. This article comprehensively reviews HMF QD-based devices fabricated using IJP methods. The discussion includes the basics of IJP technology, the formulation of printable HMF QD inks, and solutions to the coffee ring effect. Additionally, this review briefly explores the performance of typical state-of-the-art HMF QDs and cutting-edge characterization techniques for QD inks and printed QD films. The performance of printed devices based on HMF QDs is discussed and compared with those fabricated by other techniques. In the conclusion, the persisting challenges are identified, and perspectives on potential avenues for further progress in this rapidly developing research field are provided.
Xinlong Yang et al 2024 Nanotechnology 35 305709
Recently, CrSe2, a new ferromagnetic van der Waals two-dimensional material, was discovered to be highly stable under ambient conditions, making it an attractive candidate for fundamental research and potential device applications. Here, we study the interlayer interactions of bilayer CrSe2 using first-principles calculations. We demonstrate that the interlayer interaction depends on the stacking structure. The AA and AB stackings exhibit antiferromagnetic (AFM) interlayer interactions, while the AC stacking exhibits ferromagnetic (FM) interlayer interaction. Furthermore, the interlayer interaction can be further tuned by tensile strain and charge doping. Specifically, under large tensile strain, most stacking structures exhibit FM interlayer interactions. Conversely, under heavy electron doping, all stacking structures exhibit AFM interlayer interactions. These findings are useful for designing spintronic devices based on CrSe2.
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Min Fu and Kevin Critchley 2024 Nanotechnology 35 302002
Inkjet printing (IJP) has become a versatile, cost-effective technology for fabricating organic and hybrid electronic devices. Heavy-metal-based quantum dots (HM QDs) play a significant role in these inkjet-printed devices due to their excellent optoelectrical properties. Despite their utility, the intrinsic toxicity of HM QDs limits their applications in commercial products. To address this limitation, developing alternative HM-free quantum dots (HMF QDs) that have equivalent optoelectronic properties to HM QD is a promising approach to reduce toxicity and environmental impact. This article comprehensively reviews HMF QD-based devices fabricated using IJP methods. The discussion includes the basics of IJP technology, the formulation of printable HMF QD inks, and solutions to the coffee ring effect. Additionally, this review briefly explores the performance of typical state-of-the-art HMF QDs and cutting-edge characterization techniques for QD inks and printed QD films. The performance of printed devices based on HMF QDs is discussed and compared with those fabricated by other techniques. In the conclusion, the persisting challenges are identified, and perspectives on potential avenues for further progress in this rapidly developing research field are provided.
Antonio del Bosque et al 2024 Nanotechnology 35 292003
The fundamentals, performance, and applications of piezoresistive strain sensors based on polymer nanocomposites are summarized herein. The addition of conductive nanoparticles to a flexible polymer matrix has emerged as a possible alternative to conventional strain gauges, which have limitations in detecting small strain levels and adapting to different surfaces. The evaluation of the properties or performance parameters of strain sensors such as the elongation at break, sensitivity, linearity, hysteresis, transient response, stability, and durability are explained in this review. Moreover, these nanocomposites can be exposed to different environmental conditions throughout their lifetime, including different temperature, humidity or acidity/alkalinity levels, that can affect performance parameters. The development of flexible piezoresistive sensors based on nanocomposites has emerged in recent years for applications related to the biomedical field, smart robotics, and structural health monitoring. However, there are still challenges to overcome in designing high-performance flexible sensors for practical implementation. Overall, this paper provides a comprehensive overview of the current state of research on flexible piezoresistive strain sensors based on polymer nanocomposites, which can be a viable option to address some of the major technological challenges that the future holds.
Songjun Feng and Hui Liu 2024 Nanotechnology 35 302001
Lithium-ion batteries (LIBs) has extensively utilized in electric vehicles and portable electronics due to their high energy density and prolonged lifespan. However, the current commercial LIBs are plagued by relatively low energy density. High-entropy materials with multiple components have emerged as an efficient strategic approach for developing novel materials that effectively improve the overall performance of LIBs. This article provides a comprehensive review the recent advancements in rational design of innovative high-entropy materials for LIBs, as well as the exceptional lithium ion storage mechanism for high-entropy electrodes and considerable ionic conductivity for high-entropy electrolytes. This review also analyses the prominent effects of individual components on the high-entropy materials' exceptional capacity, considerable structural stability, rapid lithium ion diffusion, and excellent ionic conductivity. Furthermore, this review presents the synthesis methods and their influence on the morphology and properties of high-entropy materials. Ultimately, the remaining challenges and future research directions are outlined, aimed at developing more effective high-entropy materials and improving the overall electrochemical performance of LIBs.
Haonan Zhao et al 2024 Nanotechnology 35 292002
Recent advances in materials science, device designs and advanced fabrication technologies have enabled the rapid development of transient electronics, which represents a class of devices or systems that their functionalities and constitutions can be partially/completely degraded via chemical reaction or physical disintegration over a stable operation. Therefore, numerous potentials, including zero/reduced waste electronics, bioresorbable electronic implants, hardware security, and others, are expected. In particular, transient electronics with biocompatible and bioresorbable properties could completely eliminate the secondary retrieval surgical procedure after their in-body operation, thus offering significant potentials for biomedical applications. In terms of material strategies for the manufacturing of transient electronics, silicon nanomembranes (SiNMs) are of great interest because of their good physical/chemical properties, modest mechanical flexibility (depending on their dimensions), robust and outstanding device performances, and state-of-the-art manufacturing technologies. As a result, continuous efforts have been made to develop silicon-based transient electronics, mainly focusing on designing manufacturing strategies, fabricating various devices with different functionalities, investigating degradation or failure mechanisms, and exploring their applications. In this review, we will summarize the recent progresses of silicon-based transient electronics, with an emphasis on the manufacturing of SiNMs, devices, as well as their applications. After a brief introduction, strategies and basics for utilizing SiNMs for transient electronics will be discussed. Then, various silicon-based transient electronic devices with different functionalities are described. After that, several examples regarding on the applications, with an emphasis on the biomedical engineering, of silicon-based transient electronics are presented. Finally, summary and perspectives on transient electronics are exhibited.
Zhongliang Xiao et al 2024 Nanotechnology 35 292001
In the context of 'energy shortage', developing a novel energy-based power system is essential for advancing the current power system towards low-carbon solutions. As the usage duration of lithium-ion batteries for energy storage increases, the nonlinear changes in their aging process pose challenges to accurately assess their performance. This paper focuses on the study LiFeO4(LFP), used for energy storage, and explores their performance degradation mechanisms. Furthermore, it introduces common battery models and data structures and algorithms, which used for predicting the correlation between electrode materials and physical parameters, applying to state of health assessment and thermal warning. This paper also discusses the establishment of digital management system. Compared to conventional battery networks, dynamically reconfigurable battery networks can realize real-time monitoring of lithium-ion batteries, and reduce the probability of fault occurrence to an acceptably low level.
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Zaragosa et al
This review focuses on the green synthesis methods, challenges, and applications of manganese oxide (Mn3O4) nanoparticles investigated in the past five years. Mn3O4 nanoparticles offer some unique properties that are attributed in part to the presence of mixed oxidation states of manganese (i.e., +2 and +3) in the particle, which can be utilized in a wide range of redox-sensitive applications, such as in developing supercapacitive energy storage materials. In addition, the green synthesis of Mn3O4 nanoparticles through plant extracts has potential uses in sustainable nanotechnology. Various plant extract-mediated synthesis techniques for Mn3O4 nanoparticles have been investigated and presented. By comparing the size and structure of the synthesized Mn3O4 nanoparticles, we have observed a consistent pattern of obtaining spherical particles with a size ranging from 16 to 50 nm. The morphology of the generated Mn3O4 nanoparticles can be influenced by the annealing temperature and the composition of the plant extract used during the nanoparticle synthesis. Additionally, numerous applications for the greenly produced Mn3O4 nanoparticles have been demonstrated. Mn3O4 nanoparticles derived from plant extracts have been found to possess antimicrobial properties, supercapacitive and electrochemical capabilities, and excellent pollutant degradation efficiency. However, the magnetic properties of these nanoparticles synthesized by plant extracts are yet to be explored for potential biomedical applications. Finally, challenges to existing synthetic methods and future perspectives on the potential applications of these green synthesized Mn3O4 nanoparticles are highlighted.
Joshi et al
Traditional therapies often struggle with specificity and resistance in case of cancer treatments. It is therefore important to investigate new approaches for cancer treatment based on nanotechnology. Zinc oxide nanoparticles (ZnONPs) are known to exhibit anti-cancer properties by inducing oxidative stress, apoptosis, and cell cycle arrest. Methotrexate (MTX) known anti-folate shows specificity to folate receptors (FR) and interrupts healthy functioning of cells. This study proposes the use of previously characterized biocompatible Methotrexate loaded Zinc oxide nanoparticles (MTX-ZnONPs) as a dual action therapeutic strategy against breast cancer cell lines, MCF-7 (MTX-sensitive) and MDA-MB-231 (MTX-resistant). To elucidate the cytotoxicity mechanism of MTX-ZnONPs in depth In-vitro study was carried out. In vitro assays, including cell cycle analysis, apoptosis assay, and western blot analysis to study the protein expression were performed. Results of these assays, further supported the anti-cancer activity of MTX-ZnONPs showing apoptotic and necrotic activity in MCF-7 and MDA-MB-231 cell line respectively. In vivo acute oral toxicity study to identify the LD50 in animals revealed no signs of toxicity and mortality up to 550 mg/kg body weight of animal, significantly higher LD50 values than anticipated therapeutic levels and safety of the synthesized nanosystem. The study concludes that MTX-ZnONPs exhibit anti-cancer potential against breast cancer cells offering a promising strategy for overcoming resistance.
Izadi et al
Candida auris, a rapidly emerging multidrug-resistant fungal pathogen, poses a global health threat, with cases reported in over 47 countries. Conventional detection methods struggle, and the increasing resistance of C. auris to antifungal agents has limited treatment options. Nanoparticle-based therapies, utilizing materials like silver, carbon, zinc oxide, titanium dioxide, polymer, and gold, show promise in effectively treating cutaneous candidiasis. This review explores recent advancements in nanoparticle-based therapies, emphasizing their potential to revolutionize antifungal therapy, particularly in combating C. auris infections. The discussion delves into mechanisms of action, combinations of nanomaterials, and their application against multidrug-resistant fungal pathogens, offering exciting prospects for improved clinical outcomes and reduced mortality rates. The aim is to inspire further research, ushering in a new era in the fight against multidrug-resistant fungal infections, paving the way for more effective and targeted therapeutic interventions.
Fan et al
Multi-photon reduction (MPR) based on femtosecond laser makes rapid prototyping and molding in micro-nano scale feasible, but is limited in material selectivity due to lack of the understanding of the reaction mechanism in MPR process. In this paper, additively manufacturing of complex silver-based patterns through MPR is demonstrated. The effects of laser parameters, including laser pulse energies and scanning speeds, on the structural and chemical characteristics of the printed structures are systematically investigated. The results show that the geometric size of printed cubes deviates from the designed size further by increasing laser pulse energies or decreasing scanning speeds. The reaction mechanism of MPR is revealed by studying the elemental composition and chemical structures of printed cubes. The evolution of Raman spectra upon the laser processing parameters suggests that the MPR process mainly includes two processes: reduction and decomposition. In the MPR process, silver ions are reduced and grow into particles by accepting the electrons from ethonal molecules; meanwhile carboxyl groups in polyvinylpyrrolidone are decomposed and form amorphous carbon that is attached on the surface of silver particles. The conductivity of silver wires fabricated by MPR reaches 2×105 S/m and stays relatively constant as varying their cross section area, suggesting excellent electrical conduction. The understanding of the MPR process would accelerate the development of MPR technology and the implementation of MPR in micro-electromechanical systems could therefore be envisioned.
Gupta et al
Self-assembly processes are widely used in nature to form hierarchically organized structures, prompting us to investigate such processes at the macroscopic scale. We report an unprecedented approach toward the self-assembly of alkyl-fullerene (C60) derivatives into a hexagonal array of hemispherical microparticles akin to the morphology of a compound eye. The method includes casting solvated alkyl-C60 compound on an air/water interface followed by controlled evaporation of the solvent under atmosphere-sealed conditions. This leads to the formation of a thin film floating on water with a diameter of up to 1.3 centimeters and exhibiting a hexagonally-packed hemispherical structure with a diameter of approximately 38 µm. Various measurements of the formed film reveal that amorphousness is necessary for suppressing uncontrollable crystallization, which affects the microparticle size and film formation mechanism. We tested the feasibility of this approach for the self-assembly of a relatively common C60 derivative, [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM), resulting in the formation of a film with a similar pattern of hexagonally-packed larger microparticles approximately 152 µm in size of diameter.
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Raffi Budakian et al 2024 Nanotechnology
The field of nanoscale magnetic resonance imaging (NanoMRI) was started 30 years ago. It was motivated by the desire to image single molecules and molecular assemblies, such as proteins and virus particles, with near-atomic spatial resolution and on a length scale of 100 nm. Over the years, the NanoMRI field has also expanded to include the goal of useful high-resolution nuclear magnetic resonance (NMR) spectroscopy of molecules under ambient conditions, including samples up to the micron-scale. The realization of these goals requires the development of spin detection techniques that are many orders of magnitude more sensitive than conventional NMR and MRI, capable of detecting and controlling nanoscale ensembles of spins. Over the years, a number of different technical approaches to NanoMRI have emerged, each possessing a distinct set of capabilities for basic and applied areas of science. The goal of this roadmap article is to report the current state of the art in NanoMRI technologies, outline the areas where they are poised to have impact, identify the challenges that lie ahead, and propose methods to meet these challenges. This roadmap also shows how developments in NanoMRI techniques can lead to breakthroughs in emerging quantum science and technology applications.
Min Fu and Kevin Critchley 2024 Nanotechnology 35 302002
Inkjet printing (IJP) has become a versatile, cost-effective technology for fabricating organic and hybrid electronic devices. Heavy-metal-based quantum dots (HM QDs) play a significant role in these inkjet-printed devices due to their excellent optoelectrical properties. Despite their utility, the intrinsic toxicity of HM QDs limits their applications in commercial products. To address this limitation, developing alternative HM-free quantum dots (HMF QDs) that have equivalent optoelectronic properties to HM QD is a promising approach to reduce toxicity and environmental impact. This article comprehensively reviews HMF QD-based devices fabricated using IJP methods. The discussion includes the basics of IJP technology, the formulation of printable HMF QD inks, and solutions to the coffee ring effect. Additionally, this review briefly explores the performance of typical state-of-the-art HMF QDs and cutting-edge characterization techniques for QD inks and printed QD films. The performance of printed devices based on HMF QDs is discussed and compared with those fabricated by other techniques. In the conclusion, the persisting challenges are identified, and perspectives on potential avenues for further progress in this rapidly developing research field are provided.
Khalfan Almarzooqi et al 2024 Nanotechnology 35 305606
Graphene oxide (GO)-based membranes hold significant promise for applications ranging from energy storage to protective coatings, to saline water and produced water treatment, owing to their chemical stability and unique barrier properties achieving a high selectivity for water permeation. However, unmodified GO membranes are not stable when submerged in liquid water, creating challenges with their commercial utilization in aqueous filtration and pervaporation applications. To mitigate this, we develop an approach to modify GO membranes through a combination of low temperature thermal reduction and metal cation crosslinking. We demonstrate that Zn2+–rGO and Fe3+–rGO membranes had the highest permeation flux of 8.3 ± 1.5 l m−2 h−1 and 7.0 ± 0.4 l m−2 h−1, for saline water separation, respectively, when thermally reduced after metal cross-linking; These membranes maintained a high flux of 7.5 ± 0.7 l m−2 h−1, and 5.5 ± 0.3 l m−2 h−1 for produced water separation, respectively. All the membranes had a salt rejection higher than 99%. Fe3+ crosslinked membranes presented the highest organic solute rejections for produced water of 69%. Moreover, long term pervaporation testing was done for the Zn2+–rGO membrane for 12 h, and only a minor drop of 6% in permeation flux was observed, while Zn2+–GO had a drop of 24%. Both modifiers significantly enhanced the stability with Fe3+–rGO membranes displaying the highest mechanical abrasion resistance of 95% compared to non-reduced and non-crosslinked GO. Improved stability for all samples also led to higher selectivity to water over organic contaminants and only slightly reduced water flux across the membrane.
Sabreen Jarrar et al 2024 Nanotechnology 35 305708
Carbon-based electrode materials have widely been used in supercapacitors. Unfortunately, the fabrication of the supercapacitors includes a polymeric binding material that leads to an undesirable addition of weight along with an increased charge transfer resistance. Herein, binder-free and lightweight electrodes were fabricated using powder processing of carbon nanofibers (CNFs) and graphene nanoplatelets (GNPs) resulting in a hybrid all-carbon composite material. The structural, morphological, and electrochemical properties of the composite electrodes were studied at different concentrations of GNPs. The specific capacitance (Cs) of the CNFs/GNPs composite was improved by increasing the concentration of GNPs. A maximum Cs of around 120 F g−1 was achieved at 90 wt% GNPs which is around 5-fold higher in value than the pristine CNFs in 1 M potassium hydroxides (KOH), which then further increased to 189 F g−1 in 6 M KOH electrolyte. The energy density of around 20 Wh kg−1 with the corresponding power density of 340 W kg−1 was achieved in the supercapacitor containing 90 wt% GNPs. The enhanced electrochemical performance of the composite is related to the presence of a synergistic effect and the CNFs establishing conductive/percolating networks. Such binder-free all-carbon electrodes can be a potential candidate for next-generation energy applications.
Justinas Jorudas et al 2024 Nanotechnology 35 305705
Fifty percents absorption by thin film, with thickness is much smaller than the skin depth and optical thickness much smaller than the wavelength, is a well-known concept of classical electrodynamics. This is a valuable feature that has been numerously widely explored for metal films, while chemically inert nanomembranes are a real fabrication challenge. Here we report the 20 nm thin pyrolyzed carbon film (PyC) placed on 300 nm thick silicon nitride (Si3N4) membrane demonstrating an efficient broadband absorption in the terahertz and near infrared ranges. While the bare Si3N4 membrane is completely transparent in the THz range, the 20 nm thick PyC layer increases the absorption of the PyC coated Si3N4 membrane to 40%. The reflection and transmission spectra in the near infrared region reveal that the PyC film absorption persists to a level of at least 10% of the incident power. Such a broadband absorption of the PyC film opens new pathways toward broadband bolometric radiation detectors.
Nanqin Mei et al 2024 Nanotechnology 35 305101
Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by the accumulation of amyloid plaques in the brain. The toxicity of amyloid to neuronal cell surfaces arises from interactions between small intermediate aggregates, namely amyloid oligomers, and the cell membrane. The nature of these interactions changes with age and disease progression. In our previous work, we demonstrated that both membrane composition and nanoscale structure play crucial roles in amyloid toxicity, and that membrane models mimicking healthy neuron were less affected by amyloid than model membranes mimicking AD neuronal membranes. This understanding introduces the possibility of modifying membrane properties with membrane-active molecules, such as melatonin, to protect them from amyloid-induced damage. In this study, we employed atomic force microscopy and localized surface plasmon resonance to investigate the protective effects of melatonin. We utilized synthetic lipid membranes that mimic the neuronal cellular membrane at various stages of AD and explored their interactions with amyloid-β (1–42) in the presence of melatonin. Our findings reveal that the early diseased membrane model is particularly vulnerable to amyloid binding and subsequent damage. However, melatonin exerts its most potent protective effect on this early-stage membrane. These results suggest that melatonin could act at the membrane level to alleviate amyloid toxicity, offering the most protection during the initial stages of AD.
Busra Arvas et al 2024 Nanotechnology 35 305602
Despite the discovery of many chemotherapeutic drugs that prevent uncontrolled cell division processes in the last century, many studies are still being carried out to develop drugs with higher anticancer efficacy and lower level of side effects. Herein, we designed, synthesized, and characterized six novel coumarin-triazole hybrids, and evaluated for anticancer activity of the one with the highest potential against the breast cancer cell line, MCF-7 and human cervical cancer cell line, human cervical adenocarcinoma (HeLa). Compound 21 which was the coumarin derivative including phenyl substituent with the lowest IC50 value displayed the highest cytotoxicity against the studied cancer cell line. Furthermore, the potential use of poly (lactic-co-glycolic acid) nanoparticles (PLGA NPs) prepared by the emulsifying solvent evaporation method as a platform for a drug delivery system was studied on a selected coumarin derivative 21. This coumarin derivative-loaded PLGA NPs were produced with an average size of 225.90 ± 2.96 nm, −16.90 ± 0.85 mV zeta potential, and 4.12 ± 0.90% drug loading capacity. The obtained 21-loaded PLGA nanoparticles were analyzed spectroscopically and microscopically with FT-IR, UV–vis, and scanning electron microscopy as well as thermogravimetric analysis, Raman, and x-ray diffraction. The in vitro release of 21 from the nanoparticles exhibited a controlled release profile just over one month following a burst release in the initial six hours and in addition to this a total release ratio of %50 and %85 were obtained at pH 7.4 and 5.5, respectively. 21-loaded PLGA nanoparticles displayed remarkably effective anticancer activity than 21. The IC50 values were determined as IC50 (21-loaded PLGA nanoparticles): 0.42 ± 0.01 mg ml−1 and IC50 (free 21 molecule): 5.74 ± 3.82 mg ml−1 against MCF-7 cells, and as IC50 (21-loaded PLGA nanoparticles): 0.77 ± 0.12 mg ml−1 and IC50 (free 21 molecule): 1.32 ± 0.31 mg ml−1 against HeLa cells after the incubation period of 24 h. Our findings indicated that triazole-substituted coumarins may be used as an anticancer agent by integrating them into a polymeric drug delivery system providing improved drug loading and effective controlled drug release.
Hon Nhien Le et al 2024 Nanotechnology 35 305601
Graphene oxide nanosheet (GO) is a multifunctional platform for binding with nanoparticles and stacking with two dimensional substrates. In this study, GO nanosheets were sonochemically decorated with zinc oxide nanoparticles (ZnO) and self-assembled into a hydrogel of GO–ZnO nanocomposite. The GO–ZnO hydrogel structure is a bioinspired approach for preserving graphene-based nanosheets from van der Waals stacking. X-ray diffraction analysis (XRD) showed that the sonochemical synthesis led to the formation of ZnO crystals on GO platforms. High water content (97.2%) of GO–ZnO hydrogel provided good property of ultrasonic dispersibility in water. Ultraviolet-visible spectroscopic analysis (UV–vis) revealed that optical band gap energy of ZnO nanoparticles (∼3.2 eV) GO–ZnO nanosheets (∼2.83 eV). Agar well diffusion tests presented effective antibacterial activities of GO–ZnO hydrogel against gram-negative bacteria (E. coli) and gram-positive bacteria (S. aureus). Especially, GO–ZnO hydrogel was directly used for brush painting on biodegradable polylactide (PLA) thin films. Graphene-based nanosheets with large surface area are key to van der Waals stacking and adhesion of GO–ZnO coating to the PLA substrate. The GO–ZnO/PLA films were characterized using photography, light transmittance spectroscopy, coating stability, scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopic mapping (EDS), antibacterial test and mechanical tensile measurement. Specifically, GO–ZnO coating on PLA substrate exhibited stability in aqueous food simulants for packaging application. GO–ZnO coating inhibited the infectious growth of E. coli biofilm. GO–ZnO/PLA films had strong tensile strength and elastic modulus. As a result, the investigation of antibacterial GO–ZnO hydrogel and GO–ZnO coating on PLA film is fundamental for sustainable development of packaging and biomedical applications.
Mathijs Mientjes et al 2024 Nanotechnology
Topological crystalline insulators (TCIs) are interesting for their topological surface states, which hold great promise for scattering-free transport channels and fault-tolerant quantum computing. A promising TCI is SnTe. However, Sn-vacancies form in SnTe, causing a high hole density, hindering topological transport from the surface being measured. This issue could be relieved by using nanowires with a high surface-to-volume ratio. Furthermore, SnTe can be alloyed with Pb reducing the Sn-vacancies while maintaining its topological phase. Here we present the catalyst-free growth of monocrystalline PbSnTe in molecular beam epitaxy (MBE). By the addition of a pre-deposition stage before the growth, we have control over the nucleation phase and thereby increase the nanowire yield. This facilitates tuning the nanowire aspect ratio by a factor of four by varying the growth parameters. These results allow us to grow specific morphologies for future transport experiments to probe the topological surface states in a Pb1-xSnxTe-based platform.
Marlen Alexis Gonzalez-Reyna et al 2024 Nanotechnology
For the first time, this study shows the nanoarchitectonic process to obtain an acetogenin-enriched nanosystem (AuNPs-Ac) using an aqueous extract from Annona cherimola Mill (ACM) composed of gold nanoparticles embedded in an organic matrix that acts as stabilizing agent and presents anti-inflammatory activity and cytotoxical effect against HepG2 cell line, promoting apoptosis. The synthesis of AuNPs-Ac was confirmed by X-ray diffraction analysis, showing metallic gold as the only phase, and the scanning transmission microscope showed an organic cap covering the AuNPs-Ac. Fourier-transformed infrared suggests that the organic cap comprises a combination of different annonaceous acetogenins, alkaloids, and phenols by the presence of bands corresponding to aromatic rings and hydroxyl groups. High-Performance Liquid Chromatography has demonstrated the presence of annonacin, a potent acetogenin, in the extract of ACM. An in vitro anti-inflammatory activity of the extract of ACM and the AuNPs-Ac was performed using the albumin denaturation method, showing a nonlinear response, which is better than sodium diclofenac salt in a wide range of concentrations that goes from 200 to 400 µg/mL with both samples. The viability assay was studied using trypan blue, treating IMR90 and HepG2 at different concentrations of AuNPs-Ac. The results defined a median lethal dose of 800 µg/mL against HepG2 through apoptosis according to the ratio of caspase-cleaved 9/alpha-tubulin evaluated. It was also demonstrated that the nanosystem presents a higher cytotoxic effect on the HepG2 cell line than in IMR90, suggesting a targeted mechanism. In addition, the nanosystem performs better than using only the extract of ACM in the anti-inflammatory or antiproliferative test, attributed to their higher surface area.