It is important and challenging to analyze nanocluster structure with atomic precision. Herein, α-hemolysin nanopore was used to identify nanoclusters at the single molecule level by providing two-dimensional (2D) dwell time–current blockage spectra and translocation event frequency which sensitively depended on their structures. Nanoclusters such as Anderson, Keggin, Dawson, and a few lacunary Dawson polyoxometalates with very similar structures, even with only a two-atom difference, could be discriminated. This nanopore device could simultaneously measure multiple nanoclusters in a mixture qualitatively and quantitatively. Furthermore, molecular dynamics (MD) simulations provided microscopic understandings of the nanocluster translocation dynamics and yielded 2D dwell time–current blockage spectra in close agreement with experiments. The nanopore platform provides a novel powerful tool for nanocluster characterization.
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Pathogenic bacteria have been throwing great threat on human health for thousands of years. Their real-time monitoring is in urgent need as it could effectively halt the spread of pathogenic bacteria and thus reducing the risk to human health. Up till now, diverse technologies such as electrochemistry, optics, piezoelectricity and calorimetry have been developed for bacteria sensing. Therein, electrochemical impedance spectroscopy (EIS)-based sensors show great potential in point-of-care bacterial analysis because of their low-cost, short read-out time, good reproducibility, and portable equipment construction. In this review, we will primarily summarize the typical applications of electrochemical impedance technology in bacteria sensing based on different electrodes in the last three years. As we know, the electrode materials play an extremely important role in the construction of EIS-based sensors because not only the immobilization of bio-recognition elements for bacteria, but also the sensitivity, economical efficiency and portability of the as-prepared sensors are mainly determined by the electrode materials. Therefore, in order to provide new researchers a clear preparation process for EIS-based sensors fabricated with different electrodes, we try to classify the EIS-based sensors according to the different electrode platforms. Moreover, present difficulties, future directionsand perspectives for their applications are also discussed. It can provide guidance in future study of novel EIS-based sensors for rapid, sensitive and accurate sensing of diverse pathogenic bacteria.
Edge effects are predicted to significantly impact the properties of low dimensional materials with layered structures. The synthesis of low dimensional materials with copious edges is desired for exploring the effects of edges on the band structure and properties of these materials. Here we developed an approach for synthesizing MoS2 nanobelts terminated with vertically aligned edges by sulfurizing hydrothermally synthesized MoO3 nanobelts in the gas phase through a kinetically driven process; we then investigated the electrical and magnetic properties of these metastable materials. These edge-terminated MoS2 nanobelts were found to be metallic and ferromagnetic, and thus dramatically different from the semiconducting and nonmagnetic two-dimensional (2D) and three-dimensional (3D) 2H-MoS2 materials. The transitions in electrical and magnetic properties elucidate the fact that edges can tune the properties of low dimensional materials. The unique structure and properties of this one-dimensional (1D) MoS2 material will enable its applications in electronics, spintronics, and catalysis.
Highly crystalline and thermally stable pure multi-walled Ni3Si2O5(OH)4 nanotubes with a layered structure have been synthesized in water at a relatively low temperature of 200–210 ℃ using a facile and simple method. The nickel ions between the layers could be reduced in situ to form size-tunable Ni nanocrystals, which endowed these nanotubes with tunable magnetic properties. Additionally, when used as the anode material in a lithium ion battery, the layered structure of the Ni3Si2O5(OH)4 nanotubes provided favorable transport kinetics for lithium ions and the discharge capacity reached 226.7 mA·h·g−1 after 21 cycles at a rate of 20 mA·g−1. Furthermore, after the nanotubes were calcined (600 ℃, 4 h) or reduced (180 ℃, 10 h), the corresponding discharge capacities increased to 277.2 mA·h·g−1 and 308.5 mA·h·g−1, respectively.