Wireless nanopore electrodes (WNEs) exploit bipolar electrochemistry to provide stable and reproducible nanoscale electrochemical interfaces. The conductive material at the nanopore tip serves as a well-defined sensing interface. This feature enables high spatial and temporal resolution while eliminating the need for traditional wire sealing and thereby avoiding noise or instability arising from the contacted electrode. Therefore, the WNE has become a powerful tool in nanoelectrochemistry with broad applications across electroanalysis and electrocatalysis. This perspective outlines the fabrication of closed-type and open-type WNEs and discusses their applications in monitoring the growth of catalytic materials, assessing electrocatalytic activity, and performing intracellular measurements. Special emphasis is placed on their integration with mass spectrometry and optical spectroscopy to achieve multidimensional insights. Finally, we highlight future research directions, focusing on enhancing stability, precise surface functionalization, and the development of miniaturized, portable devices for practical use.

Regulating magnetism of a metal-organic framework (MOF) is highly desirable in magnetoelectric devices. Single-crystalline MOFs of [(CH3)2NH2]2[FeIIIFe2-xIICoxII(HCOO)9] (x = 0, 0.2, 0.3, 0.6) with an unprecedented (412·63)1(49·66)2 topology were synthesized. These MOFs exhibit distinct antiferromagnetism, and the Néel temperature (TN) changes from 32.8 to 29.0 K with increasing x. After field cooling from above TN to 2 K, these MOFs demonstrate giant exchange bias (EB) featured by a significant vertical and simultaneous horizontal shift in an almost linear curve of magnetization (M) versus the field (H). As the temperature rises, the M-H curve becomes hysteretic, with significantly increased coercivity and a diminished EB field. In combination with the Monte Carlo simulations, this EB effect is attributed to a large enough (negligible) anisotropy of FeII (FeIII) ions and antiferromagnetic exchange coupling between FeII and FeIII ions. This work provides a clue to designing a linear magnetic field sensor by using MOFs.

Magneto-ionics, an emerging field controlling magnetism via electric-field-driven ion migration, faces a critical bottleneck: slow switching speed. Utilizing the inherent ion migration in resistive switching (RS) devices offers a potential solution for the fast electric control of magnetism. In this work, we inserted a 3 nm-thick Ta layer between the NiO and HfO2 layers to prepare the Co/NiO/Ta/HfO2 device, which exhibited repeatable and reversible RS performance. Under negative voltage, the device switches from a high-resistance state (HRS) to a low-resistance state (LRS), accompanied by an increase in coercivity (H C) and a decrease in exchange bias field (H E). In contrast, positive voltage resets the device to HRS, with H C decreased and H E increased simultaneously. The above electric control of exchange bias (EB) is attributed to oxidation/reduction of the interfacial Co layer in combination with oxygen ions migrating into/out of the NiO layer during the RS cycling process. This improved magneto-ionic control method by using a multiresistive-layer structure provides a clue to developing multifunctional spintronic devices with low energy consumption.

Voltage control of perpendicular magnetic anisotropy (VCPMA) by resistive switching (RS) is an approach for manipulating perpendicular magnetization, which is of significant importance in realizing energy-efficient and high-speed spintronic devices. However, simultaneously achieving good RS performance and effective VCPMA poses a considerable challenge. In this study, we investigated the VCPMA in the RS device with a stack of Pt/Co/Ta/HfO2/Pt. With the aid of Ta's strong oxygen affinity and the high mobility of oxygen ions in the resultant Ta-oxide layer, the insertion of an appropriately thick Ta layer can not only improve the RS performance but also modulate the PMA effectively. When a negative voltage is applied and increased to the "set" voltage, oxygen ions may migrate from the HfO2 layer to the Ta layer, resulting in a transition from the high resistance state (HRS) to the low resistance state (LRS) and a weakening of PMA as well. On the contrary, when a positive voltage is applied and increased to the "reset" voltage, oxygen ions will return to the HfO2 layer, leading to the device switching from LRS to HRS and partial recovery of PMA. This work provides a clue to the design of energy-efficient spintronic devices.

Spin–orbit torque-induced perpendicular magnetization switching has attracted much attention due to the advantages of nonvolatility, high density, infinite read/write counts, and low power consumption in spintronic applications. To achieve field-free deterministic switching of perpendicular magnetization, additional magnetic field, magnetic layer assistance, or artificially designed structural symmetry breaking are usually required, which are not conducive to the high-density integration and application of low-power devices. However, 2D type-II Weyl semimetals with low-symmetry structures have recently been found to generate z-spin-polarized currents, which may induce out-of-plane damping-like torques to their neighboring ferromagnetic layers, and realize deterministic perpendicular magnetization switching at zero magnetic field. In this Letter, we report that current-induced field-free magnetization switching at room temperature can be achieved in a perpendicularly magnetized TaIrTe4/Pt/Co/Pt device, and the critical switching current density can be lowered to be about 2.64 × 105 A·cm−2. When the current is applied along the low-symmetry TaIrTe4a-axis, the out-of-plane and in-plane spin Hall conductivities are estimated to be 0.61 × 105 × ℏ/2e (Ω m)−1 and 3.13 × 105 × ℏ/2e (Ω m)−1, respectively. This study suggests that TaIrTe4 has great potential for the design of room-temperature efficient spintronic devices.

The aim of voltage control of magnetism is to reduce the power consumption of spintronic devices. For a spin valve, the relative magnetic orientation for the two ferromagnetic layers is a key factor determining the giant magnetoresistance (GMR) ratio. However, achieving full voltage manipulation of the magnetization directions between parallel and antiparallel states is a significant challenge. Here, we demonstrate that by utilizing two exchange-biased Co/IrMn bilayers with opposite pinning directions and with ferromagnetic interlayer coupling between the two Co layers, the magnetization alignment of the two Co layers of a spin valve can be switched between antiparallel and nearly parallel states by voltage-induced strain, leading to a full voltage control of GMR in a repeatable manner. The magnetization rotating processes for the two Co layers under different voltages can be clearly demonstrated by simulations based on the Landau-Lifshitz-Gilbert equation. This work provides valuable references for the development of full voltage-controlled spintronic devices with low energy consumption.

The key to rationally and rapidly designing high-performance materials is the monitoring and comprehension of dynamic processes within individual particles in real-time, particularly to gain insight into the anisotropy of nanoparticles. The intrinsic property of nanoparticles typically varies from one crystal facet to the next under realistic working conditions. Here, we introduce the operando collision electrochemistry to resolve the single silver nanoprisms (Ag NPs) anisotropy in photoelectrochemistry. We directly identify the effect of anisotropy on the plasmonic-assisted electrochemistry at the single NP/electrolyte interface. The statistical collision frequency shows that heterogeneous diffusion coefficients among crystal facets facilitate Ag NPs to undergo direction-dependent mass transfer toward the gold ultramicroelectrode. Subsequently, the current amplitudes of transient events indicate that the anisotropy enables variations in dynamic interfacial electron transfer behaviors during photothermal processes. The results presented here demonstrate that the measurement precision of collision electrochemistry can be extended to the sub-nanoparticle level, highlighting the potential for high-throughput material screening with comprehensive kinetics information at the nanoscale.

Oxygen production within human cells plays a critical role in cellular metabolism and is implicated in various diseases, including cancer. Investigating cellular heterogeneity under oxygen stimulation is crucial for elucidating disease mechanisms and advancing early therapeutic design. In this study, the platinum-based wireless nanopore electrode (WNE) with a diameter of approximate to 200 nm is employed as a powerful tool to produce oxygen molecules near the cell nucleus. The oxygen production can be quantitatively controlled by adjusting the applied voltage. Through delivering oxygen near the cancer cell nucleus, this technique shows the capacity to alleviate the hypoxia microenvironment, a key factor in chemotherapy resistance. Furthermore, by modulating oxygen levels within individual living cells and delivering chemotherapeutic agents to the cancer cell nucleus, this approach offers significant potential for single-cell manipulation and the investigation of cellular heterogeneity under oxygen stimulation. An Pt-based wireless nanopore electrode capable of generating oxygen through the electro-catalytic decomposition of H2O2 is developed. By simultaneously delivering doxorubicin (Dox) and generating oxygen within hypoxic MCF-7 cells, a significantly enhanced tumor cell killing efficiency compared to cells treated with Dox alone is observed. This method offers a powerful tool for manipulating the intracellular microenvironment and enhancing the efficacy of chemotherapeutic agents by directly targeting the hypoxic regions of tumors. image

Electrocatalysis is considered promising in renewable energy conversion and storage, yet numerous efforts rely on catalyst design to advance catalytic activity. Herein, a hydrodynamic single-particle electrocatalysis methodology is developed by integrating collision electrochemistry and microfluidics to improve the activity of an electrocatalysis system. As a proof-of-concept, hydrogen evolution reaction (HER) is electrocatalyzed by individual palladium nanoparticles (Pd NPs), with the development of microchannel-based ultramicroelectrodes. The controlled laminar flow enables the precise delivery of Pd NPs to the electrode-electrolyte interface one by one. Compared to the diffusion condition, hydrodynamic collision improves the number of active sites on a given electrode by 2 orders of magnitude. Furthermore, forced convection enables the enhancement of proton mass transport, thereby increasing the electrocatalytic activity of each single Pd NP. It turns out that the improvement in mass transport increases the reaction rate of HER at individual Pd NPs, thus a phase transition without requiring a high overpotential. This study provides new avenues for enhancing electrocatalytic activity by altering operating conditions, beyond material design limitations.

Abstract BACKGROUND A cell operates as an interconnected bioelectrical circuit, utilising electron transfer processes for intracellular communication, with cytochrome c (Cyt c) playing a pivotal role. The redox processes of Cyt c, occurring via electron tunnelling, are essential for its translocation into the cytosol and modulation of its conformation to bind apoptotic protease activating factor 1. This highlights the need for novel technologies capable of interacting with these processes at the atomic scale to control downstream effects and induce apoptosis in cancer cells. METHODS We demonstrate that ‘bio-nanoantennae’, when supplied with an electrical current, enable quantum biological tunnelling for electron transfer (QBET) and facilitate cellular apoptosis in patient-derived IDH wild-type glioblastoma from both the infiltrative tumour margin and proliferative core. The bio-nanoantennae were constructed from gold nanoparticles functionalised with reduced Cyt c and zinc porphyrin as a redox couple. RESULTS Electrical polarisation of these bio-nanoantennae via resonant alternating currents in preclinical glioblastoma cells led to decreased metabolic activity and reduced cell viability by oxidizing Cyt c, thus inducing cellular stress. No significant effect was observed in healthy human astrocyte counterparts. The cytosol localised bio-nanoantennae induced differential gene expression related to ion channels, apoptosis, cancer proliferation and tumour suppression upon activation, in tumour relative to astrocyte cell populations. The bio-nanoantennae were also tested in 3D glioblastoma spheroid models, showing similar effects, and in vivo studies demonstrated a significant reduction in glioblastoma xenograft tumour size. CONCLUSION We propose that bio-nanoantennae modulate the redox state of Cyt c under an electrical field through QBET. To validate this, we investigated the tunnel junction energy and plasmon resonance scattering, and developed a mathematical model to explain the system’s behaviour. This innovative wireless electrical–molecular nanodevice, capable of inducing cancer cell apoptosis, paves the way for further applications of quantum signalling as a new (non-pharmacological) therapeutic paradigm.

Quantum biological tunnelling for electron transfer is involved in controlling essential functions for life such as cellular respiration and homoeostasis. Understanding and controlling the quantum effects in biology has the potential to modulate biological functions. Here we merge wireless nano-electrochemical tools with cancer cells for control over electron transfer to trigger cancer cell death. Gold bipolar nanoelectrodes functionalized with redox-active cytochrome c and a redox mediator zinc porphyrin are developed as electric-field-stimulating bio-actuators, termed bio-nanoantennae. We show that a remote electrical input regulates electron transport between these redox molecules, which results in quantum biological tunnelling for electron transfer to trigger apoptosis in patient-derived cancer cells in a selective manner. Transcriptomics data show that the electric-field-induced bio-nanoantenna targets the cancer cells in a unique manner, representing electrically induced control of molecular signalling. The work shows the potential of quantum-based medical diagnostics and treatments.

Monitoring interparticle chemical communication plays a critical role in the nanomaterial synthesis as this communication controls the final structure and stability of global nanoparticles (NPs). Yet most ensemble analytical techniques, which could only reveal average macroscopic information, are unable to elucidate NP-to-NP interactions. Herein, we employ stochastic collision electrochemistry to track the morphology transformation of Ag NPs in photochemical process at the single NP level. By further statistical analysis of time-resolved current transients, we quantitatively determine the dynamic chemical potential difference and interparticle communication between populations of large and small Ag NPs. The high sensitivity of stochastic collision electrochemistry enables the in situ investigation of chemical communication-dependent transformation kinetics of NPs in photochemical process, shedding light on designing nanomaterials.

Single-entity electrochemistry focusing on the study of transient electrochemical process at the confined interface, has become a promising field that addresses questions from multi-disciplines such as cellular biology, material chemistry, organic chemistry, etc. It offers the fruitful information hidden in bulk electrochemical measurements. As the optical techniques improve in spatial and temporal resolution, the combination of electrochemistry with optical microspectroscopy provides more comprehensive information of single-entity electrochemistry. Herein, we review recent progress made in optical–electrochemical measurements covering three aspects from the precise localization and temperature measurements of single compartments, to the in-situ tracking of dynamic behaviors of single nanoparticles in electrochemical process, and to the monitoring confinement-controlled electrochemistry at the single molecule/ion level. The review demonstrates how these optical methods are innovatively integrated with single-entity sensing. It also reveals how these optical–electrochemical combinations push single-entity electrochemistry forward.

Single nanoparticle (NP) collisions technique has been widely employed in electrocatalysis. Howev-er, the short collision duration of single NPs hinders the further improvement in their electrocata-lytic performance. Here, to increase the dynamic collision duration of single NPs in the electron tunneling region, enhanced near-wall hindered diffusion is introduced in the stochastic collision process by coupling a Au ultramicroelectrode (UME) with a confined microchannel. In the case of single palladium nanoparticle (Pd NP) collisions for the hydrogen evolution reaction (HER), the hydrodynamic trapping confined in the microchannel effectively permits the activation of the HER on the single Pd NPs. The microchannel-based Au UME is promising in the application of single-NP collisions to energy conversion.

Light irradiation on silver nanoparticles(Ag NPs)could cause the energy conversion,thus,the fragmentation of Ag NPs.It is important to detect the changes of fragmented Ag NPs in the aspects of physical and chemical properties.Herein,benefit-ing from the high sensitivity,high temporal resolution,and high-throughput,single entity electrochemistry(SEE)method is intro-duced to in-situ track the dynamic laser fragmentation of single Ag NP.Compared with UV-Vis absorption spectroscopy and trans-mission electron microscopy(TEM),SEE methods enables an accurate in-situ measurements of light-induced fragmentation of single Ag NP.The variation in the statistic current amplitude displays the real-time changes of single Ag NP upon laser irradiation for 60 min,which indicates that the laser of 532 nm wavelength is the most effective laser for the dynamic fragmentation.By virtue of the excellent sensing performance,SEE is further applied in revealing the heterogeneity in Ag NPs'intrinsic physicochemical proper-ties,such as size,crystal structure,surface charge density.The study highlights the potential of SEE to advancing the real-time char-acterization of nanomaterials in the chemical reactions.

Nanopores technique is a label-free, high-throughput, high-spatial-temporal resolution electrochemical measurement method for single-molecule level analysis, which is widely used for single-entity measurements such as single molecules, single particles, and single cells. Nanopores not only have adjustable three-dimensional space to confine single analytes, but also possess an ability to enhance the electrical and magnetic fields. In short, the nanopores exhibit unique sub-wavelength optical properties. In this review, we introduce the principle of nanopore electrochemical analysis, and give a perspective and detailed overview of its application in electro-optical binding measurements.