pH-Stimulated Self-Locked DNA Nanostructure for the Effective Discrimination of Cancer Cells and Simultaneous Detection and Imaging of Endogenous Dual-MicroRNAs

In this study, a pH-stimulated self-locked DNA nanostructure (SLDN) was developed to efficiently distinguish cancer cells from other cells for the simultaneous detection and imaging of endogenous dual-microRNAs (miRNAs). Impressively, the SLDN was specifically unlocked in the acidic environment of cancer cells to form unlocked-SLDN to disengage the i-motif sequence with a labeled fluorophore for the recovery of a fluorescence signal, resulting in the differentiation of cancer cells from normal cells. Meanwhile, unlocked-SLDN could combine and recognize the targets miRNA-21 and miRNA-155 simultaneously to trigger the hybridization chain reaction (HCR) amplification for sensitive dual-miRNA detection, with detection limits of 1.46 pM for miRNA-21 and 0.72 pM for miRNA-155. Significantly, compared with the current miRNA imaging strategy based on the traditional DNA nanostructure, the strategy proposed here remarkably eliminates the interference of normal cells to achieve high-resolution colocation imaging of miRNAs in tumor cells with an ultralow background signal. This work provided a specific differentiation method for tumor cells to materialize sensitive biomarker detection and distinguishable high-definition live-cell imaging for precise cancer diagnosis and multifactor research of tumor progression

Bacteria-Adsorbed Palygorskite Stabilizes the Quaternary Phosphonium Salt with Specific-Targeting Capability, Long-Term Antibacterial Activity, and Lower Cytotoxicity

In order to extend the antibacterial time of quaternary phosphonium salt in bacteria, palygorskite (PGS) is used as the carrier of dodecyl triphenyl phosphonium bromide (DTP), and a DTP-PGS hybrid is prepared. Antibacterial performance of this novel hybrid is investigated for both Gram-positive and Gram-negative bacteria. The results show that the DTP could be absorbed on the surface of PGS which had bacteria-adsorbed capability. The DTP-PGS hybrid, combining the advantages of PGS and DTP, display specific-targeting capability, long-term antibacterial activity, and lower cytotoxicity, suggesting the great potential application as PGS-based antibacterial powder

Three-Dimensional Hierarchical Structure ZnO@C@NiO on Carbon Cloth for Asymmetric Supercapacitor with Enhanced Cycle Stability

In this work, we synthesized the hierarchical ZnO@C@NiO core–shell nanorods arrays (CSNAs) grown on a carbon cloth (CC) conductive substrate by a three-step method involving hydrothermal and chemical bath methods. The morphology and chemical structure of the hybrid nanoarrays were characterized in detail. The combination and formation mechanism was proposed. The conducting carbon layer between ZnO and NiO layers can efficiently enhance the electric conductivity of the integrated electrodes, and also protect the corrosion of ZnO in an alkaline solution. Compared with ZnO@NiO nanorods arrays (NAs), the NiO in CC/ZnO@C@NiO electrodes, which possess a unique multilevel core–shell nanostructure exhibits a higher specific capacity (677 C/g at 1.43 A/g) and an enhanced cycling stability (capacity remain 71% after 5000 cycles), on account of the protection of carbon layer derived from glucose. Additionally, a flexible all-solid-state supercapacitor is readily constructed by coating the PVA/KOH gel electrolyte between the ZnO@C@NiO CSNAs and commercial graphene. The energy density of this all-solid-state device decreases from 35.7 to 16.0 Wh/kg as the power density increases from 380.9 to 2704.2 W/kg with an excellent cycling stability (87.5% of the initial capacitance after 10000 cycles). Thereby, the CC/ ZnO@C@NiO CSNAs of three-dimensional hierarchical structure is promising electrode materials for flexible all-solid-state supercapacitors

Orderly Aggregated Catalytic Hairpin Assembly for Synchronous Ultrasensitive Detecting and High-Efficiency Co-Localization Imaging of Dual-miRNAs in Living Cells

In this work, the orderly aggregated catalytic hairpin assembly (OA-CHA) was developed for synchronous ultrasensitive detection and high-efficiency colocalization imaging of dual-miRNAs by a carefully designed tetrahedral conjugated ladder DNA structure (TCLDS). Exactly, two diverse hairpin probes were fixed on tetrahedron conjugated DNA nanowires to form the TCLDS without fluorescence response, which triggered OA-CHA in the aid of output DNA 1 and output DNA 2 produced by targets miRNA-217 and miRNA-196a cycle to generate TCLDS with remarkable fluorescence response. Impressively, compared with the traditional CHA strategy, OA-CHA avoided the fluorescence group and quenching group from approaching again because of the spatial confinement effect to significantly enhance the fluorescence signal, resulting in the simultaneous ultrasensitive detection of dual-miRNAs with detection limits of 21 and 32 fM for miRNA-217 and miRNA-196a, respectively. Meanwhile, the TCLDS with lower diffusivity could achieve accurate localization imaging for reflecting the spatial distribution of dual-miRNAs in living cells. The strategy based on OA-CHA provided a flexible and programmable nucleic amplification method for the synchronous ultrasensitive detection and precise imaging of multiple biomarkers and had potential in disease diagnostics.

Hierarchical NiO@NiCo₂O₄ Core–shell Nanosheet Arrays on Ni Foam for High-Performance Electrochemical Supercapacitors

A facile solvothermal method followed by a postannealing process is used to prepare NiO@NiCo₂O₄ core–shell nanosheet arrays supported on Ni foam substrate for a high-performance supercapacitor. The hybrid electrode possesses a three-dimensional structure with the “shell” of NiCo₂O₄ nanoflakes anchored on the “core” of ordered NiO nanosheets. It shows high specific capacitance of 1623.6 F g^–1 (or specific capacity of 225.5 mAh g^–1) at 2 A g^–1 and excellent rate performance with a 96% capacitance retention rate at 20 A g^–1. The high cycling stability is proved by nearly 90% capacitance retention at 10 A g^–1 after 10000 cycles. Its asymmetric supercapacitor, assembled with NiO@NiCo₂O₄/Ni foam and the activated carbon/Ni foam as the positive and negative electrode, respectively, displays the specific energy of 52.5 W h kg^–1 at 387.5 W kg^–1. The excellent electrochemical performance of NiO@NiCo₂O₄ electrode indicates its great potential in applications of energy storage devices

Room-Temperature Valley Polarization in Band Gap Engineered WS_2<i>x</i>Se_{2(1–<i>x</i>)} Monolayers: Implications for Spintronics and Valleytronics

The generation and manipulation of valley-spin polarization are essential for two-dimensional (2D) layered transition-metal dichalcogenides for spin-/valleytronic applications. Here, high crystal quality WS2xSe2(1–x) monolayers with sulfur composition tuning from 0 to 1 were prepared through a controlled chemical vapor deposition method. The crystal structure retains perfect C3-rotation symmetry, with the circular polarization degree of second harmonic generation achieving near unit. Both steady-state and time-resolved circular polarization-resolved photoluminescence (PL) characterizations demonstrate that the valley polarization degree of WS2xSe2(1–x) monolayers can be monotonically improved with gradually increasing sulfur concentration. A phenomenological model and the corresponding rate equations were established to describe the valley polarization dynamics of the bandgap engineered monolayer WS2xSe2(1–x), and a real band-edge intervalley scattering lifetime can be determined by fitting the circularly polarized PL decay curves using this model. The physical origin of the phenomenon of increasing degree of valley polarization with the decreasing of the hot electron energy has been revealed due to the continuous tuning of the initially injected polarization with varying the composition ratio. Our work gives insights into the underlying valley depolarization mechanism in 2D alloyed monolayers and provides a potential pathway for controllable synthesis of high-quality atomically thin alloys with tunable valley physics, which contribute to spintronic and valleytronic applications