Nature nanotechnology最新文献

One of the most promising approaches towards large-scale quantum computation uses devices based on many Josephson junctions. Yet, even today, open questions regarding the single junction remain unsolved, such as the detailed understanding of the quantum phase transitions, the coupling of the Josephson junction to the environment or how to improve the coherence of a superconducting qubit. Here we design and build an engineered on-chip reservoir connected to a Josephson junction that acts as an efficient bolometer for detecting the Josephson radiation under non-equilibrium, that is, biased conditions. The bolometer converts the a.c. Josephson current at microwave frequencies up to about 100 GHz into a temperature rise measured by d.c. thermometry. A circuit model based on realistic parameter values captures both the current–voltage characteristics and the measured power quantitatively. The present experiment demonstrates an efficient, wide-band, thermal detection scheme of microwave photons and provides a sensitive detector of Josephson dynamics beyond the standard conductance measurements.

Although charge-converting nanoparticles (NPs) potentially penetrate tumours deeply, conventional charge conversion strategies possess limitations, including low selectivity and slow, inconsistent conversion rate within the tumour microenvironment. In this study, we synthesized a zwitterionic near-infrared cyclodextrin derivative of heptamethine cyanine and complexed it with pheophorbide-conjugated ferrocene to produce multifunctional theranostic nanotherapeutics. Our NPs demonstrated enhanced tumour-targeting ability, enabling the highly specific imaging of rectal tumours, with tumour-to-rectum signal ratios reaching up to 7.8. The zwitterionic surface charge of the NPs was rapidly converted to a cationic charge within the tumours on 880 nm near-infrared laser irradiation, promoting the tumoural penetration of NPs via transcytosis. After penetration, photodynamic/chemodynamic therapy was initiated using a 660 nm laser. Our NPs eradicated clinically relevant-sized heterotopic tumours (~250 mm³) and orthotopic rectal tumours, displaying their potential as theranostic nanoplatforms for targeting rectal cancer.

Microstrain and the associated surface-to-bulk propagation of structural defects are known to be major roadblocks to developing high-energy and long-life batteries. However, the origin and effects of microstrain during the synthesis of battery materials remain largely unknown. Here we perform microstrain screening during real-time and realistic synthesis of sodium layered oxide cathodes. Evidence gathered from multiscale in situ synchrotron X-ray diffraction and microscopy characterization collectively reveals that the spatial distribution of transition metals within individual precursor particles strongly governs the nanoscale phase transformation, local charge heterogeneity and accumulation of microstrain during synthesis. This unexpected dominance of transition metals results in a counterintuitive outward propagation of defect nucleation and growth. These insights direct a more rational synthesis route to reduce the microstrain and crystallographic defects within the bulk lattice, leading to significantly improved structural stability. The present work on microstrain screening represents a critical step towards synthesis-by-design of defect-less battery materials.

In the fractional quantum Hall effect, quasiparticles are collective excitations that have a fractional charge and show fractional statistics as they interchange positions. While the fractional charge affects semi-classical characteristics such as shot noise and charging energies, fractional statistics is most notable through quantum interference. Here we study fractional statistics in a bilayer graphene Fabry–Pérot interferometer. We tune the interferometer from the Coulomb-dominated regime to the Aharonov–Bohm regime, both for integer and fractional quantum Hall states. Focusing on the fractional quantum Hall state with a filling factor ν = 1/3, we follow the evolution of the Aharonov–Bohm interference of quasiparticles while varying the magnetic flux through an interference loop and the charge density within the loop independently. When their combined variation is such that the Landau filling remains 1/3, the charge density in the loop varies continuously. We then observe pristine Aharonov–Bohm oscillations with a period of three flux quanta, as expected for quasiparticles of one-third of the electron charge. Yet, when the combined variation leads to discrete events of quasiparticle addition or removal, phase jumps emerge and alter the phase evolution. Notably, across all cases with discrete and continuous charge variation, the average phase consistently increases by 2π with each addition of one electron to the loop, as expected for quasiparticles, obeying fractional statistics.

Heteromeric pore-forming proteins often contain recognition patterns or stereospecific selection filters. However, the construction of heteromeric pore-forming proteins for single-molecule sensing is challenging due to the uncontrollability of producing position isomers and difficulties in purification of regio-defined products. To overcome these preparation obstacles, we present an in situ strategy involving single-molecule chemical modification of a heptameric pore-forming protein to build a stereo- and regio-specific heteromeric nanopore (hetero-nanopore) with a subunit stoichiometric ratio of 3:4. The steric hindrance inherent in the homo-nanopore of K238C aerolysin directs the stereo- and regio-selective modification of maleimide derivatives. Our method utilizes real-time ionic current recording to facilitate controlled voltage manipulation for stoichiometric modification and position-based side-isomer removal. Single-molecule experiments and all-atom molecular dynamics simulations revealed that the hetero-nanopore features an asymmetric stereo- and regio-defined residue structure. The hetero-nanopore produced was characterized by mass spectrometry and single-particle cryogenic electron microscopy. In a proof-of-concept single-molecule sensing experiment, the hetero-nanopore exhibited 95% accuracy for label-free discrimination of four peptide stereoisomers with single-amino-acid structural and chiral differences in the mixtures. The customized hetero-nanopores could advance single-molecule sensing.

Complexes of extracellular nucleic acids (NAs) with endogenous proteins or peptides, such as LL37, break immune balance and cause autoimmune diseases, whereas NAs with arginine-enriched peptides do not. Inspired by this, we synthesize a polyarginine nanoparticle PEG-TK-NP_Arg, which effectively inhibits Toll-like receptor-9 (TLR9) activation, in contrast to LL37. To explore the discrepancy effect of PEG-TK-NP_Arg and LL37, we evaluate the periodic structure of PEG-TK-NP_Arg-NA and LL37-NA complexes using small-angle X-ray scattering. LL37-NA complexes have a larger inter-NA spacing that accommodates TLR9, while the inter-NA spacing in PEG-TK-NP_Arg-NA complexes mismatches with the cavity of TLR9, thus inhibiting an interaction with multiple TLR9s, limiting their clustering and damping immune induction. Subsequently, the inhibitory inflammation effect of PEG-TK-NP_Arg is proved in an animal model of rheumatoid arthritis. This work on how the scavenger-NA complexes inhibit the immune response may facilitate proof-of-concept research translating to clinical application.

Rapid sensing of molecules is increasingly important in many studies and applications, such as DNA sequencing and protein identification. Here, beyond atomically thin 2D nanopores, we conceptualize, simulate and experimentally demonstrate coupled, guiding and reusable bilayer nanopore platforms, enabling advanced ultrafast detection of unmodified molecules. The bottom layer can collimate and decelerate the molecule before it enters the sensing zone, and the top 2D pore (~2 nm) enables position sensing. We varied the number of pores in the bottom layer from one to nine while fixing one 2D pore in the top layer. When the number of pores in the bottom layer is reduced to one, sensing is performed by both layers, and distinct T- and W-shaped translocation signals indicate the precise position of molecules and are sensitive to fragment lengths. This is uniquely enabled by microsecond resolution capabilities and precision nanofabrication. Coupled nanopores represent configurable multifunctional systems with inter- and intralayer structures for improved electromechanical control and prolonged dwell times in a 2D sensing zone.