Nature nanotechnology最新文献

Antiferromagnetic conductors with suitably broken spatial symmetries host spin-polarized bands, which lead to transport phenomena commonly observed in metallic ferromagnets. In bulk materials, it is the given crystalline structure that determines whether symmetries are broken and spin-polarized bands are present. Here we show that, in the two-dimensional limit, an electric field can control the relevant symmetries. To this end, we fabricate a double-gate transistor based on bilayers of van der Waals antiferromagnetic semiconductor CrPS₄ and show how a perpendicular electric displacement field can switch the spin polarization of the conduction band on and off. Because conduction band states with opposite spin polarizations are hosted in the different layers and are spatially separated, these devices also give control over the magnetization of the electrons that are accumulated electrostatically. Our experiments show that double-gated CrPS₄ transistors provide a viable platform to create gate-induced conductors with near unity spin polarization at the Fermi level, as well as devices with a full electrostatic control of the total magnetization of the system.

All-dielectric optical nano-resonators have emerged as low-loss, versatile and highly adaptable components in nanophotonic structures for manipulating electromagnetic waves and enhancing light–matter interactions. However, achieving full three-dimensional characterization of near fields within dielectric nano-resonators poses great experimental challenges. Here we develop a technique to image near-field wave patterns inside dielectric optical nano-resonators using high-order sideband generation. By exploiting the phase sensitivity of various harmonic orders, which enables the detection of near-field distributions at distinct depths, we achieve three-dimensional tomographic and near-field imaging with a transverse resolution of ~920 nm and a longitudinal resolution of ~130 nm inside a micrometre-thick silicon anapole resonator. Our method offers high-contrast polarization sensitivity and phase-resolving capabilities, providing comprehensive vectorial near-field information and could be applied to diverse dielectric metamaterials.

The nuclear envelope serves as a highly regulated gateway for macromolecule exchange between the nucleus and cytoplasm in eukaryotes. Here we have developed a cell nucleus-mimicking polymeric membrane-enclosed system for long and self-regulated therapy. A polymeric nano-membrane with nanopores is conformally synthesized in situ on the surface of each insulin crystal, ensuring sustained, adjustable and zero-order drug release kinetics. Glucose- and β-hydroxybutyrate-dually sensitive microdomains are integrated into the nano-membranes. Under a normal state, the microdomains are uncharged and the channel is narrow enough to block insulin outflow. Under hyperglycaemia and ketonaemia, microdomains convert the high glucose and β-hydroxybutyrate concentration signals to the negative electric potential of membranes, widening the nanopores with rapid insulin outflow. In type 1 diabetic mice and minipigs, this system can maintain normoglycaemia for longer than 1 month and 3 weeks, respectively, with validated glucose- and β-hydroxybutyrate-triggered insulin release. Such membrane-enclosed drug crystal/powder formulation provides a broad platform for long-acting controlled release.

Multiscale cation inhomogeneity has been a major hurdle in state-of-the-art formamidinium–caesium (FA–Cs) mixed-cation perovskites for achieving perovskite solar cells with optimal power conversion efficiencies and durability. Although the field has attempted to homogenize the overall distributions of FA–Cs in perovskite films from both plan and cross-sectional views, our understanding of grain-to-grain cation inhomogeneity and ability to tailor it—that is, spatially resolving the FA–Cs compositional difference between individual grains down to the nanoscale—are lacking. Here we reveal that as fundamental building blocks of a perovskite film, individual grains exhibit cationic compositions deviating from the prescribed ideal composition, severely limiting the interfacial optoelectronic properties and perovskite layer durability. This performance-limiting nanoscopic factor is linked to thermodynamic-driven morphological grooving, leading to a segmented surface landscape. At the grain triple junctions, grooves form nanoscale groove traps that hinder the mixing of solid-state cations across grains and thus retard inter-grain FA–Cs mixing. By rationally modulating the heterointerfacial energies, we reduced the depth of these nanoscale groove traps by a factor of three, significantly improving cation homogeneity. Perovskite solar cells with shallower nanoscale groove traps demonstrate enhanced power conversion efficiencies (25.62%) and improved stability under various standardized international protocols. Our work highlights the significance of resolving surface nano-morphologies for homogeneous properties of perovskites.

Crossing the blood–brain barrier (BBB) and reaching intracranial tumours is a clinical challenge for current targeted interventions including antibody-based therapies, contributing to poor patient outcomes. Increased cell surface density of human epidermal growth factor receptor 3 (HER3) is associated with a growing number of metastatic tumour types and is observed on tumour cells that acquire resistance to a growing number of clinical targeted therapies. Here we describe the evaluation of HER3-homing nanobiological particles (nanobioparticles (NBPs)) on such tumours in preclinical models and our discovery that systemic NBPs could be found in the brain even in the absence of such tumours. Our subsequent studies described here show that HER3 is prominently associated with both mouse and human brain endothelium and with extravasation of systemic NBPs in mice and in human-derived BBB chips in contrast to non-targeted agents. In mice, systemically delivered NBPs carrying tumoricidal agents reduced the growth of intracranial triple-negative breast cancer cells, which also express HER3, with improved therapeutic profile compared to current therapies and compared to agents using traditional BBB transport routes. As HER3 associates with a growing number of metastatic tumours, the NBPs described here may offer targeted efficacy especially when such tumours localize to the brain.

The ordering of ions and solvent molecules around nanostructures is of profound fundamental importance, from understanding biological processes to the manipulation of nanomaterials to optimizing electrochemical devices. Classical models commonly used to describe these systems treat the solvent simplistically, an approach that endures, in part, due to the extreme difficulty of attaining experimental measurements that challenge this approximation. Here we perform total neutron scattering experiments on model systems—concentrated amide solutions of negatively charged carbon nanotubes and sodium counterions—and measure remarkably complex intermediate-range molecular solvent ordering. The charged surface orders the solvents up to ∼40 Å, even beyond its dense concentric solvation shells. Notably, the molecular orientation of solvent in direct contact with the nanotube surface itself is distinct, lying near-parallel and not interacting with desolvated sodium counterions. In contrast, beyond this layer the ordering of solvent is perpendicular to the surface. Our results underscore the critical importance of multibody interactions in solvated nanoscale systems and charged surfaces, highlighting competing ion/surface solvation effects.

Imbalanced redox homeostasis, involving either oxidative stress or reductive stress, can profoundly impact cellular functions, contributing to various diseases. While the implications of oxidative stress in the adverse effects of nanoparticles have been extensively studied, our comprehension of reductive stress within the context of nano-redox system interactions remains limited. Here we illuminate a domino effect initiated by the dehydrogenase-like activity of transition metal borides. Specifically, seven transition metal borides were identified to emulate the enzymatic activity of natural dehydrogenases, resulting in heightened levels of reductive constituents within critical biological redox pairs in cells. Mass cytometry analysis provides compelling evidence that reductive stress initiates an immunosuppressive environment within lung tissues, promoting the metastasis of breast cancer cells to the lungs. In summary, our study unveils the chemical basis of nano-induced reductive stress and establishes a mechanistic axis that interlinks dehydrogenase-like activity, reductive stress, immunosuppression and tumour metastasis.

Spin qubits in silicon are strong contenders for the realization of a practical quantum computer. Single- and two-qubit gates have shown fidelities above the fault-tolerant threshold, and entanglement of three qubits has been achieved. Furthermore, high-fidelity operation of two-qubit algorithms is possible. Here we implement a four-qubit silicon processor with all control fidelities above the fault-tolerant threshold. We demonstrate a three-qubit Grover’s search algorithm with a ~95% probability of finding the marked state. To this end, we fabricate the processor from three phosphorus atoms precision-patterned into isotopically pure silicon. We define three phosphorus nuclear spin qubits and one electron spin qubit. The long coherence times of the qubits enable single-qubit fidelities above 99.9% for all qubits. Moreover, the efficient single-pulse multi-qubit operation enabled by the electron–nuclear hyperfine interaction facilitates controlled-Z gates with above 99% fidelity between all pairs of nuclear spins when using the electron as an ancilla. These control fidelities, combined with high-fidelity non-demolition readout of all nuclear spins, allows the creation of a three-qubit Greenberger–Horne–Zeilinger state with 96.2% fidelity. Looking ahead, coupling neighbouring nuclear spin registers, as the one shown here, via electron–electron exchange may enable larger, yet fault-tolerant, quantum processors.