Nanoscale Horizons最新文献

Artificial neuronal devices that emulate the dynamics of biological neurons are pivotal for advancing brain emulation and developing bio-inspired electronic systems. This paper presents the design and demonstration of an artificial neuron circuit based on a Pt/V/AlO_x/Pt threshold switching memristor (TSM) integrated with an external resistor. By applying voltage pulses, we successfully exhibit the leaky integrate-and-fire (LIF) behavior, as well as both spatial and spatiotemporal summation capabilities, achieving the asynchronous signal integration. Notably, the Pt/V/AlO_x/Pt TSM demonstrates ultrafast switching speeds (on/off times ∼165 ns/310 ns) and remarkable stability (endurance >10² cycles with cycle-to-cycle variations <2.5%). These attributes render the circuit highly suitable as a spike generator in neuromorphic computing applications. The Pt/V/AlO_x/Pt TSM-based spike encoder can output current spikes at frequencies ranging from approximately 200 kHz to 800 kHz. The modulation of output spike frequency is achievable by adjusting the external resistor and capacitor within the spike encoder circuit, providing considerable operational flexibility. Additionally, the Pt/V/AlO_x/Pt TSM boasts a lower threshold voltage (V_th ∼ 0.84 V) compared to previously reported VO_x-based TSMs, leading to significantly reduced energy consumption for spike generation (∼2.75 nJ per spike).

Recent developments in optical imaging techniques, particularly multi-photon excitation microscopy that allows studies of biological interactions at a deep cellular level, have motivated intensive research in developing multi-photon absorption fluorophores. Biological tissues are optically transparent in the near-infrared region. Therefore, fluorophores that can absorb light in the near-infrared (NIR) region by multi-photon absorption are particularly useful in bio-imaging. For instance, photoluminescence from ligand-protected gold nanoclusters has drawn extensive research interest in the past decade due to their bright, non-blinking, stable emission and tunability from the blue to the NIR emission. In this work, using the control of single metal doping on silver nanoclusters (Ag₂₅ protected by thiolate SR = 2,4-dimethylbenzenethiol (DMBT) ligand), we aim to explore the effects of metal doping on the (photo)stability and nonlinear optical response of liganded nanoclusters. We study two-photon excited photoluminescence and the second harmonic response upon excitation in the NIR (780-950 nm) range. Particular emphasis is placed on the effect of metal doping on the second-order nonlinear optical scattering properties (first hyperpolarizability, β(2ω)) of Ag₂₅ nanoclusters. In addition, β(2ω) values are one order higher than the one reported for Au₂₅ nanoclusters and represent the largest values ever reported for ligand-protected nanoclusters. Such enhanced hyperpolarizability leads to a strong second harmonic response and renders them attractive targets in bioimaging.

Over the last two decades, advancements in nanomaterials and nanoscience have paved the path for the emergence of nano-medical convergence science, significantly impacting healthcare. In our review, we highlight how these advancements are applied in various biomedical technologies such as drug delivery systems, bio-imaging for diagnostic and therapeutic purposes. Recently, novel inorganic nanohybrid drugs have been developed, combining multifunctional inorganic nanomaterials with therapeutic agents (known as inorganic medicinal nanoarchitectonics). These innovative drugs are actively utilized in cutting-edge medical treatments, including targeted anti-cancer therapy, photo and radiation therapy, and immunotherapy. This review provides a detailed overview of the current development status of inorganic medicinal nanoarchitectonics and explores potential future directions in their advancements.

The Nanoscale Horizons Editorial Board and Editorial Office reflect on the exciting events, activities and updates from the journal in 2024 and look forward to celebrating 10 years since the journal was inaugurated in 2025.

It is challenging to reconfigure devices at molecular length scales. Here we report molecular junctions based on molecular switches that toggle stably and reliably between multiple operations to reconfigure electronic devices at molecular length scales. Rather than static on/off switches that always revert to the same state, our voltage-driven molecular device dynamically switches between high and low conduction states during six consecutive proton-coupled electron transfer steps. By changing the applied voltage, different states are accessed resulting in in operando reconfigurable electronic functionalities of variable resistor, diode, memory, and NDR (negative differential conductance). The switching behavior is voltage driven but also has time-dependent features making it possible to access different memory states. This multi-functional switch represents molecular scale hardware operable in solid-state devices (in the form of electrode-monolayer-electrode junctions) that are interesting for areas of research where it is important to have access to time-dependent changes such as brain-inspired (or neuromorphic) electronics.

Our Emerging Investigator Series features exceptional work by early-career nanoscience and nanotechnology researchers. Read Mita Dasog's Emerging Investigator Series article 'Unlocking the secrets of porous silicon formation: insights into magnesiothermic reduction mechanism using in situ powder X-ray diffraction studies' (https://doi.org/10.1039/D4NH00244J) and read more about her in the interview below.

Expression of concern for 'Carbon quantum dots as a dual platform for the inhibition and light-based destruction of collagen fibers: implications for the treatment of eye floaters' by Alexandre Barras et al., Nanoscale Horiz., 2021, 6, 449-461, https://doi.org/10.1039/D1NH00157D.

The utilization of precise materials in heterogeneous catalysis will provide various new possibilities for developing superior catalysts to tackle worldwide energy and environmental issues. In recent years, single atom catalysts (SACs) with excellent atom utilization and isolated active sites have progressed dramatically as a thriving sector of catalysis research. Additionally, SACs bridge the gap between homogeneous and heterogeneous catalysts and overcome the limitations of both categories. Current research on SACs is highly oriented towards the organic synthesis of high-significance molecules with promising potential for large-scale applicability and industrialization. In this context, this review aims to comprehensively analyze the state-of-the-art research in the synthesis of SACs and analyze their structural, electronic, and geometric properties. Moreover, the unprecedented catalytic performance of the SACs towards various organic transformation reactions is succinctly summarized with recent reports. Further, a detailed summary of the current state of the research field of SACs in organic transformation is discussed. Finally, a critical analysis of the existing challenges in this emerging field of SACs and the possible countermeasures are provided. We believe that SACs have the potential to profoundly alter the chemical industry, pushing the boundaries of catalysis in new and undiscovered territory.

The supramolecular self-assembly of peptides offers a promising avenue for both materials science and biological applications. Peptides have garnered significant attention in molecular self-assembly, forming diverse nanostructures with α-helix, β-sheet, and random coil conformations. These self-assembly processes are primarily driven by the amphiphilic nature of peptides and stabilized by non-covalent interactions, leading to complex nanoarchitectures responsive to environmental stimuli. While extensively studied in biomedical applications, including drug delivery and tissue engineering, their potential applications in the fields of piezoresponsive materials, conducting materials, catalysis and energy harvesting remain underexplored. This review comprehensively elucidates the diverse material characteristics and applications of self-assembled peptides. We discuss the multi-stimuli-responsiveness of peptide self-assemblies and their roles as energy harvesters, catalysts, liquid crystalline materials, glass materials and contributors to electrical conductivity. Additionally, we address the challenges and present future perspectives associated with peptide nanomaterials. This review aims to provide insights into the versatile applications of peptide self-assemblies while concisely summarizing their well-established biomedical roles that have previously been extensively reviewed by various research groups, including our group.

In this work, we explore focused electron beam induced etching (FEBIE) of niobium thin films with the XeF₂ precursor as a route to edit, on-the-fly, superconducting devices. We report the effect of XeF₂ pressure, electron beam current, beam energy, and dwell time on the Nb etch rate. To understand the mass transport and reaction rate limiting mechanisms, we compare the relative electron and XeF₂ gas flux and reveal the process is reaction rate limited at low current/short dwell times, but shifts to mass transport limited regimes as both are increased. The electron stimulated etching yield is surprisingly high, up to 3 Nb atoms/electron, and for the range studied has a maximum at 1 keV. It was revealed that spontaneous etching accompanies the electron stimulated process, which was confirmed by varying the etched box size. An optimized etch resolution of 17 nm was achieved. Given that the Nb superconducting coherence length is 38 nm and scales with thickness, this work opens the possibility to direct write Nb superconducting devices via low-damage FEBIE.