Proteins play essential roles in virtually all cellular functions, and accurate profiling of the cellular proteome is critical for understanding biological processes and diagnosing diseases. However, current protein identification methods often lack the sensitivity required to reliably detect low-abundance proteins such as signaling molecules or early-stage biomarkers. Over the past decade, highly sensitive single-molecule protein identification methods, referred to as single-molecule protein sequencing, have been proposed, mainly those based on nanopore and fluorescence techniques. Yet, a fully developed method capable of identifying full-length proteins has not been realized. This Progress Report highlights recent developments in single-molecule protein identification methods using nanomechanical approaches that leverage 2D materials for label-free mass detection. We discuss strategies to enhance nanoelectromechanical resonators for precise mass measurements of single protein molecules and outline the prospects and remaining challenges of protein identification using 2D material-based nanodevices.

Tracing fast nanopore-translocating analytes requires a high-frequency measurement system that warrants a temporal resolution better than 1 µs. This constraint may practically shift the challenge from increasing the sampling bandwidth to dealing with the rapidly growing noise with frequencies typically above 10 kHz, potentially making it still uncertain if all translocation events are unambiguously captured. Here, a numerical simulation model is presented as an alternative to discern translocation events with different experimental settings including pore dimension, bias voltage, the charge state of the analyte, salt concentration, and electrolyte viscosity. The model allows for simultaneous analysis of forces exerting on a large analyte cohort along their individual trajectories; these forces are responsible for the analyte movement leading eventually to the nanopore translocation. Through tracing the analyte trajectories, the Brownian force is found to dominate the analyte movement in electrolytes until the last moment at which the electroosmotic force determines the final translocation act. The mean dwell time of analytes mimicking streptavidin decreases from ≈6 to ≈1 µs with increasing the bias voltage from ±100 to ±500 mV. The simulated translocation events qualitatively agree with the experimental data with streptavidin. The simulation model is also helpful for the design of new solid-state nanopore sensors.

We present results from the first 22 GHz space very long baseline interferometric (VLBI) imaging observations of M87 by RadioAstron. As a part of the Nearby AGN Key Science Program, the source was observed in 2014 February at 22 GHz with 21 ground stations, reaching projected (u, v) spacings up to ∼11 Gλ. The imaging experiment was complemented by snapshot RadioAstron data of M87 obtained during 2013-2016 from the AGN Survey Key Science Program. Their longest baselines extend up to ∼25 Gλ. For all of these measurements, fringes are detected only up to ∼2.8 Earth diameter or ∼3 Gλ baseline lengths, resulting in a new image with angular resolution of ∼150 μas or ∼20 Schwarzschild radii spatial resolution. The new image not only shows edge-brightened jet and counterjet structures down to submilliarcsecond scales but also clearly resolves the VLBI core region. While the overall size of the core is comparable to those reported in the literature, the ground-space fringe detection and slightly superresolved RadioAstron image suggest the presence of substructures in the nucleus, whose minimum brightness temperature exceeds T B , min ∼ 10 12 K. It is challenging to explain the origin of this record-high T B , min value for M87 by pure Doppler boosting effect with a simple conical jet geometry and known jet speed. Therefore, this can be evidence for more extreme Doppler boosting due to a blazar-like small jet viewing angle or highly efficient particle acceleration processes occurring already at the base of the outflow.

The electrical properties of a single facet of an individual ZnO microwire were investigated. Electrode patterns with a Hall bar structure were deposited on the surface of the top facet of the ZnO microwire. Using a suspended and cross-linked poly(methyl methacrylate) ribbon structure, it was possible to define the electrical connections only at the top surface, while avoiding those on the other five sides of the ZnO microwire. Current-voltage characteristics were examined, and Hall measurements were conducted with various magnetic fields. Through our device structure, the electrical properties could be directly probed at specific points on the ZnO surface in a reliable manner. The estimated electrical characteristics demonstrate that the carrier concentration and mobility of the ZnO surface varied along the axial direction of the wire. These results indicate that the charge carrier concentration on the surface of the micro-/nanowire can be sensitively changed according to the synthesis environment. In addition, it is worth noting that the nanoscale local Hall probes, fabricated by our technique, could probe the very slight variation of carrier concentration, which is difficult to detect by a standard transport measurement along the wire.

In this study, high-performance few-layered ReS₂ field-effect transistors (FETs), fabricated with hexagonal boron nitride (h-BN) as top/bottom dual gate dielectrics, are presented. The performance of h-BN dual gated ReS₂ FET having a trade-off of performance parameters is optimized using a compact model from analytical choice maps, which consists of three regions with different electrical characteristics. The bottom h-BN dielectric has almost no defects and provides a physical distance between the traps in the SiO₂ and the carriers in the ReS₂ channel. Using a compact analyzing model and structural advantages, an excellent and optimized performance is introduced consisting of h-BN dual-gated ReS₂ with a high mobility of 46.1 cm² V⁻¹ s⁻¹, a high current on/off ratio of ≈10⁶, a subthreshold swing of 2.7 V dec⁻¹, and a low effective interface trap density (N_t,eff) of 7.85 × 10¹⁰ cm⁻² eV⁻¹ at a small operating voltage (<3 V). These phenomena are demonstrated through not only a fundamental current–voltage analysis, but also technology computer aided design simulations, time-dependent current, and low-frequency noise analysis. In addition, a simple method is introduced to extract the interlayer resistance of ReS₂ channel through Y-function method as a function of constant top gate bias.