Electron Microscopy Data Research Articles

Enhancements of critical current density in Bi1.6Pb0.4Sr2Ca2Cu3O10+δ superconductors by additions of SnO2 nanoparticles

The impact of adding SnO2 nanoparticles on the enhancements of critical current density (Jc) of the Bi1.6Pb0.4Sr2Ca2Cu3O10+δ superconductors was studied. Polycrystalline superconductors with stoichiometry of (Bi1.6Pb0.4Sr2Ca2Cu3O10+δ)1−x(SnO2)x where was x was ranged from 0.000, 0.002, 0.004, 0.006, 0.008 to 0.010 were made through traditional solid state reaction technique. X-ray diffraction data revealed that all fabricated samples consisted of Bi-2223 and Bi-2212 superconducting phases. The volume fraction of the Bi-2223 phase decreased with SnO2 addition. Analyses of textural structure using scanning electron microscopy data evidenced a clear decrease in grain orientation and porosity with increased doping levels. SnO2 presence in connection to Bi-2223 deceleration reduced the critical temperature. Values of Jc deduced from the magnetization hysteresis loops measured at different temperatures of 35 K, 45 K, 55 K, 65 K were found to enhance for the SnO2 added samples. In the x = 0.002 samples, the field dependent Jc achieved its maximum values. In order to have a deeper understanding in the improvements of flux pinning properties, small and large bundle fields were determined by using the collective pinning theory. The obtained values indicate the expansion of the two corresponding regimes with appropriate. By analyzing the dependence of normalized Jc versus normalized critical temperature, the dominant flux pinning mechanisms in all samples were consistent with δl pinning. Besides, the addition of SnO2 nanoparticles was likely to produce pinning centers in form of core point as evidenced by using the Dew–Hughes model.

Online citizen science with the Zooniverse for analysis of biological volumetric data.

Public participation in research, also known as citizen science, is being increasingly adopted for the analysis of biological volumetric data. Researchers working in this domain are applying online citizen science as a scalable distributed data analysis approach, with recent research demonstrating that non-experts can productively contribute to tasks such as the segmentation of organelles in volume electron microscopy data. This, alongside the growing challenge to rapidly process the large amounts of biological volumetric data now routinely produced, means there is increasing interest within the research community to apply online citizen science for the analysis of data in this context. Here, we synthesise core methodological principles and practices for applying citizen science for analysis of biological volumetric data. We collate and share the knowledge and experience of multiple research teams who have applied online citizen science for the analysis of volumetric biological data using the Zooniverse platform ( www.zooniverse.org ). We hope this provides inspiration and practical guidance regarding how contributor effort via online citizen science may be usefully applied in this domain.

Electron beam additive manufacturing of composite alloy from stainless steel and aluminum bronze: Microstructure and mechanical properties

The authors investigated the microstructure, phase composition and mechanical properties of the steel-bronze composite obtained by electron beam additive manufacturing with simultaneous supply of aluminum bronze wires BrAMc9-2 and stainless steel 06Kh18N9T. X-ray diffraction analysis revealed that the composite contains 25 % (vol.) of aluminum bronze, which leads to the formation of a three-phase structure consisting of γ-Fe, α-Fe and α-Cu grains. According to scanning electron microscopy, the volume fraction of austenite, ferrite and bronze in the steel – 25 % bronze composite is 40.7, 35.7 and 23.6 %, respectively. Unstable conditions of the electron beam additive manufacturing process lead to the release of dispersed particles in austenite and ferrite grains. Dispersion-hardened copper particles with an average particle size of 40 nm, the volume fraction of which is 47 %, are isolated in austenite grains. Dispersion-hardened NiAl particles with a volume fraction of 20 % are isolated in ferrite grains, the average size of which is 44 nm. Transmission electron microscopy data indicate the coherent conjugation of arrays of dispersion-hardened particles with the matrix. Such a composite structure provides an increase in yield strength and tensile strength by an average of 400 and 600 MPa compared with yield strength and tensile strength of 06Kh18N9T steel obtained by electron beam additive manufacturing without bronze addition. Microhardness of the composite is on average 2.2 GPa, which is 0.4 GPa higher than that of 06Kh18N9T steel obtained by electron beam additive manufacturing without bronze addition.

Zinc Oxide Nanoparticles-Solution-Based Synthesis and Characterizations.

Zinc oxide (ZnO) nanoparticles have shown great potential because of their versatile and promising applications in different fields, including solar cells. Various methods of synthesizing ZnO materials have been reported. In this work, controlled synthesis of ZnO nanoparticles was achieved via a simple, cost-effective, and facile synthetic method. Using transmittance spectra and film thickness of ZnO, the optical band gap energies were calculated. For as-synthesized and annealed ZnO films, the bandgap energies were found to be 3.40 eV and 3.30 eV, respectively. The nature of the optical transition indicates that the material is a direct bandgap semiconductor. Spectroscopic ellipsometry (SE) analysis was used to extract dielectric functions where the onset of optical absorption of ZnO was observed at lower photon energy due to annealing of the nanoparticle film. Similarly, X-ray diffraction (XRD) and scanning electron microscopy (SEM) data revealed that the material is pure and crystalline in nature, with the average crystallite size of ~9 nm.

Real-time monitoring of biofilm growth identifies andrographolide as a potent antifungal compound eradicating Candida biofilms

Candida species cause life-threatening infections with high morbidity and mortality rates and their resistance to conventional therapy is closely linked to biofilm formation. Thus, the development of new approaches to study Candida biofilms and the identification of novel therapeutic strategies could yield improved clinical outcomes. In the current study, we have set up an impedance-based in vitro system to study Candida spp. biofilms in real-time and to evaluate their sensitivity to two conventional antifungal groups used in clinical practice - azoles and echinocandins. Both fluconazole and voriconazole were unable to inhibit biofilm formation in most strains tested, while echinocandins showed biofilm inhibitory capacity at relatively low concentrations (starting from 0.625 mg/L). However, assays performed on 24 h Candida albicans and C. glabrata biofilms revealed that micafungin and caspofungin failed to eradicate mature biofilms at all tested concentrations, evidencing that once formed, Candida spp. biofilms are extremely difficult to eliminate using currently available antifungals. We then evaluated the antifungal and anti-biofilm effect of andrographolide, a natural compound isolated from the plant Andrographis paniculata with known antibiofilm activity on Gram-positive and Gram-negative bacteria. Optical density measures, impedance evaluation, CFU counts, and electron microscopy data showed that andrographolide strongly inhibits planktonic Candida spp. growth and halts Candida spp. biofilm formation in a dose-dependent manner in all tested strains. Moreover, andrographolide was capable of eliminating mature biofilms and viable cell numbers by up to 99.9% in the C. albicans and C. glabrata strains tested, suggesting its potential as a new approach to treat multi-resistant Candida spp. biofilm-related infections.

Unsupervised machine learning discovery of structural units and transformation pathways from imaging data

We show that unsupervised machine learning can be used to learn chemical transformation pathways from observational Scanning Transmission Electron Microscopy (STEM) data. To enable this analysis, we assumed the existence of atoms, a discreteness of atomic classes, and the presence of an explicit relationship between the observed STEM contrast and the presence of atomic units. With only these postulates, we developed a machine learning method leveraging a rotationally invariant variational autoencoder (VAE) that can identify the existing molecular fragments observed within a material. The approach encodes the information contained in STEM image sequences using a small number of latent variables, allowing the exploration of chemical transformation pathways by tracing the evolution of atoms in the latent space of the system. The results suggest that atomically resolved STEM data can be used to derive fundamental physical and chemical mechanisms involved, by providing encodings of the observed structures that act as bottom-up equivalents of structural order parameters. The approach also demonstrates the potential of variational (i.e., Bayesian) methods in the physical sciences and will stimulate the development of more sophisticated ways to encode physical constraints in the encoder–decoder architectures and generative physical laws and causal relationships in the latent space of VAEs.

Growth of non-polar m-plane GaN pseudo-substrates by Molecular beam epitaxy

Non-polar m-plane GaN films were grown by Plasma Assisted Molecular Beam Epitaxy on γ-LiAlO2 (100) substrates by a controlled coalescence of GaN nanocolumns obtained by a two-step process including a top-down nanopillars etching from a GaN buffer and a subsequent bottom-up overgrowth. Transmission electron microscopy data show a significant reduction of extended defects density in the coalesced film as compared to the initial GaN buffer, most likely due to a filter effect by the regrowth process on the nanopillars inclined walls. Low temperature photoluminescence spectra back this reduction by a strong intensity decrease of the stacking faults fingerprint emission peaks, while a very intense donor-bound excitonic emission at 3.472 eV, 2.8 meV wide, becomes dominant.

Effect of Graphite Defect Type and Heterogeneous Atomic Doping Structure on the Electromagnetic Wave Absorption Properties of Sulfur-Doped Carbon Fibers

The heterogeneous atom-doped structure breaks the atomic-level symmetry of the local microstructure, and it and the defect design are considered to be an efficient way to fabricate microwave absorbers with a wide effective bandwidth and strong absorption capability. Herein, we have successfully designed and synthesized sulfur-doped carbon fibers by combining a strategy of introducing heterogeneous atoms with defect engineering. The analysis of Raman spectroscopy and transmission electron microscopy data reveals the correspondence between the type of graphite defects in sulfur-doped carbon fibers and their microwave absorption properties. The heterostructure formed by graphite and amorphous carbon can be considered a boundary-type defect, which is beneficial for microwave absorption. The introduction of vacancy defects and sulfur atom doping in graphite crystals breaks the symmetry of the graphite structure and leads to changes in dipole polarization. The ratio of the two sulfur-doped structures, C═S and C–S–C, is controlled to achieve the microwave absorption properties of the material in the high-frequency region. The three-dimensional structure formed by the cross-linking of one-dimensional fibers is more conducive to the formation of macroscopic eddy current losses. The strong absorption of microwaves at extremely thin thicknesses has been achieved with S-doped carbon fibers due to the synergy of multiple loss mechanisms. When the absorber thickness is only 0.98 mm, the optimized S-doped carbon fiber can reach a minimum reflection loss (RL) of −69.232 dB, and when the thickness is 1.04 mm, the widest effective bandwidth reaches 3.9 GHz (14.1–18 GHz), demonstrating a strong electromagnetic wave absorption capability.

Nickel catalyzed chemical vapor deposition grown carbon nanoforest for the efficient removal of potentially toxic chemicals from water

The present study demonstrates Ni-catalyzed growth of carbon nanoforest (CNF)-supported on activated carbon fiber (ACF) via a combination of three steps, viz., calcination, H2-reduction, and catalytic chemical vapour deposition (CCVD) in the presence of acetylene (C2H2) as the carbon source to grow CNF. The physicochemical properties of the material are evaluated by various characterization tools. Transmission electron microscopic (TEM) data confirm that the growth of CNF follows tip-growth mechanism. The material is further tested for its adsorption capacities towards two potentially toxic organic compounds such as 4-nitrophenol (4-NP) and methylene blue (MB) at variable pH values. The material shows excellent adsorption of 4-NP (maximum adsorption capacity of 325.80 mg/g at a pH value of 2) and MB (maximum adsorption capacity of 480.90 mg/g at pH = 12). The high adsorption of 4-NP may be ascribed to the strong π-π interactions between 4-NP and the adsorbent, whereas, excellent adsorption of MB may be attributed to the combined effects of negative surface charge, high surface area, and hydrophilic characteristics of the material. The maximum adsorption capacity data obtained for both 4-NP and MB systems in the present study are superior to most of the literature data. The synthesized material may be useful in the removal of several other potentially toxic organic and inorganic pollutants from water.

A "Phase Scrambling" Algorithm for Parallel Multislice Simulation of Multiple Phonon and Plasmon Scattering Configurations.

Multislice simulations of 4D scanning transmission electron microscopy (4D STEM) data are computationally demanding due to the large number of STEM probe positions that must be calculated. For accurate analysis, inelastic scattering from phonons and plasmons must also be included. However, current frozen phonon and Monte Carlo plasmon techniques require a separate calculation for each different phonon/plasmon configuration, and are therefore not suitable for scaling up to 4D STEM. Here a phase scrambling algorithm (PSA) is proposed, which treats all phonon/plasmon configurations simultaneously. A random phase is introduced to maintain incoherence between the different inelastic scattering events; this is the phase scrambling part of the algorithm. While for most applications, a few tens of frozen phonon iterations are sufficient for convergence, in the case of plasmon scattering as many as tens of thousands of iterations may be required. A PSA is statistically more representative of inelastic scattering, and achieves significant savings in computation time for plasmons. The increase in speed is a pre-requisite for 4D STEM inelastic scattering simulations.

Compact aerosol aggregate model (CA2M): A fast tool to estimate the aerosol properties of fractal-like aggregates

The structure of fractal-like aggregates is of increasing interest to a variety of fields extending from combustion soot formation to synthesis of engineered nanoparticles. Nanoparticle aggregates and agglomerates formed of solid primary particles have been extensively studied, along with their subsequent processing, using increasingly sophisticated modelling techniques over the last decade. However, there is still a need for the community to have a simple and versatile tool, able to run on a single processor, which can estimate aerosol properties and compare them to experimental results. Many aerosol studies have focused on measuring the properties related to particle mass and momentum transfer and exchange with their surroundings. Often, simplified theories are available to support the experimental results (e.g., charging or transport) but show discrepancies due to the omission of complex phenomena related to particle morphology. Thus, there is a trade-off when one wants to use computer simulations to generate and process nanoaggregates through realistic scenarios in a limited amount of time. The tool presented here provides an efficient and realistic means to estimate mass, volume, projected-area, surface-area, mobility diameter, aerodynamic diameter, and effective density. Critical features treated here include the overlap and polydispersity of primary particles composing the aggregate. Computer-generated micrographs are also available for Scanning Electron Microscopy and Transmission Electron Microscopy data comparison. The code – available on request – originally runs on MATLAB and is built such that users can adapt it and extend it for their own studies.

Correlation between cation order/disorder and the electrocaloric effect in the MLCCs of complex perovskite ferroelectrics

The physical properties (dielectric, ferroelectric, piezoelectric, etc.) of complex perovskite ferroelectrics depend on the degree of order/disorder and the scale of the ordered domains. In this study, the electrocaloric (EC) properties of three representative complex perovskite ferroelectrics, Pb(Mg1/3Nb2/3)O3–8PbTiO3 (PMN-8PT), 1mol% Sm-doped Pb(Mg1/3Nb2/3)O3–8PbTiO3 (1S-PMN-8PT) and Pb(Sc1/2Ta1/2)O3 (PST) are evaluated. Multi-layer ceramic capacitors (MLCCs) with identical structural configurations were fabricated for these three compounds, and their EC properties were characterized by direct measurement using a thermocouple. The EC temperature change ΔT of PMN-8PT, 1S-PMN-8PT and PST MLCCs under 20 V μm−1 at room temperature were found to be 1.42 K, 1.54 K, and 3.10 K, respectively. X-ray diffraction and high-resolution transmission electron microscopy data suggests that the high EC performance of PST is related to the ordering of B-site cations (Sc3+ and Ta5+) with the ordering parameter S = 0.82 and a long coherence length of ∼100 nm, such that the sample transitioned from a relaxor ferroelectric to a normal ferroelectric. These results provide pathway towards design of high performance EC materials required for solid state refrigeration and air-conditioning technologies.

Enhanced Antibacterial Activity of Novel Fluorescent Glutathione-Capped Ag Nanoclusters.

Ag nanomaterials are promising candidates for the discovery of next-generation antibiotics with a high antibacterial effect against multi-drug resistant strains. This paper reports a simple synthesis of novel water-soluble glutathione-capped silver nanoclusters (GSH-Ag NCs) with an enhanced antibacterial activity. According to thin layer chromatography (TLC), the synthesized GSH-Ag NCs are an individual fraction of the same composition without any impurities. According to matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) and energy dispersive X-ray (EDX) analyses, the silver core of the GSH-Ag NCs contains approximately 35 silver atoms, and the molecular weight of these nanoclusters is about 11 kDa. The fabricated silver nanoclusters have a reddish fluorescence (λex/λem = 509/645 nm), with a large Stokes shift (>130 nm), and ultra-small size (less than 2 nm) according to transmission electron microscopy (TEM) data and dynamic light scattering (DLS) analysis. The antibacterial activity and minimal inhibitory concentrations of the silver nanoclusters towards Escherichia coli, Staphylococcus aureus, Bacillus cereus and Enterobacter cloacae were evaluated using the agar well-diffusion method and resazurin metabolism assay. The antibacterial activity of chelated silver in the nanoclusters was found to be significantly higher compared to the activity of free silver ions. To explain the possible mechanisms underlying the antibacterial actions of the GSH-Ag nanoclusters, molecular docking was performed, and prospective bacterial targets were identified using AutoDock.

Water-Soluble Binders That Improve Electrochemical Sodium-Ion Storage Properties in a NaTi2(PO4)3 Anode

Water-soluble binders are demonstrated to provide significantly better capacity, cycle life stability and rate response for NASICON-type NaTi2(PO4)3 Na-ion battery anodes during reversible sodiation compared to electrodes made using polyvinylidene difluoride-containing slurries. The role of carboxymethyl cellulose (CMC) binders on the physical structure and chemical interfacial reactions with sodium-poor NaTi2(PO4)3 are uncovered using electron microscopy and spectroscopy data and we show that a more stable NASICON NaTi2(PO4)3 structure is found from the desodiation process from compensation of sodium deficiencies in the NaTi2(PO4)3 by extra sodium from the CMC binder. When the binder comprises CMC and a styrene butadiene rubber (SBR) additive, the electrode delivers significantly better voltammetric and galvanostatic electrochemical response with a specific capacity of ∼120 mAh g−1 with capacity retention of 90.5% for 500 cycles at 0.2 C (1 C = 133 mAh g−1), and ∼54 mAh g−1 at 20 C. The durability of the electrode during cycling and the stability of the redox processes ensures a higher capacity, longer cycle life electrode which is important for sustainable materials development for Na-ion technologies.

Nanoscale imaging of quantum dot dimers using time-resolved super-resolution microscopy combined with scanning electron microscopy

Time-resolved super-resolution microscopy was used in conjunction with scanning electron microscopy to image individual colloidal CdSe/CdS semiconductor quantum dots (QD) and QD dimers. The photoluminescence (PL) lifetimes, intensities, and structural parameters were acquired with nanometer scale spatial resolution and sub-nanosecond time resolution. The combination of these two techniques was more powerful than either alone, enabling us to resolve the PL properties of individual QDs within QD dimers as they blinked on and off, measure interparticle distances, and identify QDs that may be participating in energy transfer. The localization precision of our optical imaging technique was ∼3 nm, low enough that the emission from individual QDs within the dimers could be spatially resolved. While the majority of QDs within dimers acted as independent emitters, at least one pair of QDs in our study exhibited lifetime and intensity behaviors consistent with resonance energy transfer from a shorter lifetime and lower intensity donor QD to a longer lifetime and higher intensity acceptor QD. For this case, we demonstrate how the combined super-resolution optical imaging and scanning electron microscopy data can be used to characterize the energy transfer rate.

Supramolecular Gel-to-Gel Transition Induced by Nanoscale Structural Perturbation via the Rotary Motion of Feringa's Motor.

Supramolecular rather than covalent molecular engineering on Feringa motors can provide an alternative toolkit for tuning the properties of motorized materials through appropriate supramolecular structural perturbations, which are underexplored. Herein, a multicomponent supramolecular gel system is successfully prepared by employing an ultra-low molecular weight gelator and a modulator-Feringa motor. The electron microscopic, spectroscopic, and rheological data revealed that the morphology and mechanical properties of the gel can be tuned via a crystallographic mismatch branching (CMB) mechanism simply by adding varied amounts of motor modulators. Notably, the rotary motion of the motor is preserved in such a multicomponent gel system, and the morphology and rheology of the gel can be further altered by the motor's rotary motion that promotes the structural perturbation, resulting in seldomly seen gel-to-gel transition events. The work shown here offers prospects to utilize a supramolecular perturbation strategy to deliver responsiveness from molecular motors to the corresponding bulk materials.

Ultrastructural Localization of Endogenous LC3 by On-Section Correlative Light-Electron Microscopy.

The visualization of autophagic organelles at the ultrastructural level by electron microscopy (EM) is essential to establish their identity and reveal details that are important for understanding the autophagic process. However, EM methods often lack molecular information, obstructing the correlation of ultrastructural information obtained by EM to fluorescence microscopy-based localization of specific autophagy proteins. Furthermore, the rarity of autophagosomes in unaltered cellular conditions hampers investigation by EM, which requires high magnification, and hence provides a limited field of view. In answer to both challenges, an on-section correlative light-electron microscopy (CLEM) method based on fluorescent labeling was applied to correlate a common autophagosomal marker, LC3, to EM ultrastructure. The method was used to rapidly screen cells in fluorescence microscopy for LC3 labeling in combination with other relevant markers. Subsequently, the underlying ultrastructural features of selected LC3-labeled spots were identified by CLEM. The method was applied to starved cells without adding inhibitors of lysosomal acidification. In these conditions, LC3 was found predominantly on autophagosomes and rarely in autolysosomes, in which LC3 is rapidly degraded. These data show both the feasibility and sensitivity of this approach, demonstrating that CLEM can be used to provide ultrastructural insights on LC3-mediated autophagy in native conditions-without drug treatments or genetic alterations. Overall, this method presents a valuable tool for ultrastructural localization studies of autophagy proteins and other scarce antigens by bridging light microscopy to EM data.

Chitosan Hydrogels Cross-Linked with Trimesic Acid for the Delivery of 5-Fluorouracil in Cancer Therapy.

Chitosan exhibits unique properties making it a suitable material for drug delivery. Considering the rising popularity of hydrogels in this field, this work offers a comprehensive study of hydrogels constituted by chitosan and cross-linked with 1,3,5-benzene tricarboxylic acid (BTC; also known as trimesic acid). Hydrogels were prepared by cross-linking chitosan with BTC in different concentrations. The nature of the gels was studied through oscillatory amplitude strain and frequency sweep tests within the linear viscoelastic region (LVE) limit. The flow curves of the gels revealed shear thinning behavior. High G' values imply strong cross-linking with improved stability. The rheological tests revealed that the strength of the hydrogel network increased with the cross-linking degree. Hardness, cohesiveness, adhesiveness, compressibility, and elasticity of the gels were determined using a texture analyzer. The scanning electron microscopy (SEM) data of the cross-linked hydrogels showed distinctive pores with a pore size increasing according to increasing concentrations (pore size range between 3-18 µm). Computational analysis was performed by docking simulations between chitosan and BTC. Drug release studies employing 5-fluorouracil (5-FU) yielded a more sustained release profile with 35 to 50% release among the formulations studied in a 3 h period. Overall, this work demonstrated that the presence of BTC as cross-linker leads to satisfactory mechanical properties of the chitosan hydrogel, suggesting potential applications in the sustained release of cancer therapeutics.

Electrosynthesis of silver metallonanocomposites in the 1-vinyl-1.2.4-triazole copolymer matrix with methacrylic acid

Silver nanocomposites were synthesized by the electrochemical method in the matrix of a copolymer of 1-vinyl-1,2,4-triazole with methacrylic acid, by combining the process of electrochemical polymerization with cathodic precipitation of metals on metal electrodes. In the electronic spectra of nanocomposites, absorption bands appear with a maximum in the region of 417–421 nm, which is typical for systems with zero valence silver. The IR spectra show that the polymer structure hardly changes during the formation of nanocomposites and films. The presence of silver in the amorphous polymer phase is indicated by the results of X-ray diffraction studies. The silver content in nanocomposites is 0–9%, which leads to an increase in the viscosity of nanocomposite solutions compared to solutions of the initial copolymers. Transmission electron microscopy data show that the synthesized nanocomposites consist of particles with a diameter of 1–12 nm, predominantly spherical.

Electrochemical Redox Cycling Behavior of Gold Nanoring Electrodes Microfabricated on a Silicon Micropillar.

We report the microfabrication and characterization of concentric gold nanoring electrodes (Au NREs), which were fabricated by patterning two gold nanoelectrodes on the same silicon (Si) micropillar tip. Au NREs of 165 ± 10 nm in width were micropatterned on a 6.5 ± 0.2 µm diameter 80 ± 0.5 µm height Si micropillar with an intervening ~ 100 nm thick hafnium oxide insulating layer between the two nanoelectrodes. Excellent cylindricality of the micropillar with vertical sidewalls as well as a completely intact layer of a concentric Au NRE including the entire micropillar perimeter has been achieved as observed via scanning electron microscopy and energy dispersive spectroscopy data. The electrochemical behavior of the Au NREs was characterized by steady-state cyclic voltammetry and electrochemical impedance spectroscopy. The applicability of Au NREs to electrochemical sensing was demonstrated by redox cycling with the ferro/ferricyanide redox couple. The redox cycling amplified the currents by 1.63-fold with a collection efficiency of > 90% on a single collection cycle. The proposed micro-nanofabrication approach with further optimization studies shows great promise for the creation and expansion of concentric 3D NRE arrays with controllable width and nanometer spacing for electroanalytical research and applications such as single-cell analysis and advanced biological and neurochemical sensing.