Search

The transition metal oxides with multiple oxidation states and large electrical conductivity have been extensively studied in energy storage capacitors. Herein, the core-shell cobalt sulfide/manganese molybdate composites grown on reduced graphene oxide/Ni foam (CoS/MMO/rGO/NF) have been successfully prepared via hydrothermal and followed by electrodeposition methods. It is found that the deposition mass of CoS has a significant effect on the morphologies and electrochemical properties of CoS/MMO/rGO/NF electrodes. When the mass of CoS is 0.4 mg cm−2 (CoS-0.4/MMO/rGO/NF), the composite yields a remarkable specific capacitance of 3074.5 F g−1 (1 A g−1) and a good cycling performance of 87% through 5000 cycles. Moreover, an asymmetric device based on the CoS-0.4/MMO/rGO/NF composite shows a maximum energy density (50.3 W h kg−1 at 415.8 W kg−1) and a good long-term stability (retention 96% even after 8000 cycles). These characteristics of CoS-0.4/MMO/rGO/NF are mainly attributed to the high conductivity of reduced graphene oxide and the synergistic effects of MnMoO4 and CoS, as well as its unique morphology. These superior properties of CoS-0.4/MMO/rGO/NF demonstrate its potential application as electrode material in energy storage capacitors.

Herein, zinc cobalt layered double hydroxide (ZnCo-LDH) hybrid composites with different Zn/Co molar ratios are in-suit grown onto Ni foam by a simple and cost-effective hydrothermal approach. It is found that the Zn/Co molar ratios have an important influence on the morphology and electrochemical performance of the ZnCo-LDH composites. An interconnected nanowires structure and the highest specific capacitance were achieved when the Zn/Co molar ratio is 1: 2 (Zn1Co2-LDH).Moreover, interconnected Zn1Co2-LDH is further combined with reduced graphene oxide stuck onto Ni foam (Zn1Co2-LDH@rGO/NF) to improve its electrochemical properties. Benefiting from its unique structural feature and excellent electrical conductance ability, the as-prepared material exhibits an enhanced specific capacitance of 2142.0 F g−1 as supercapacitor electrode. Remarkably, the assembled asymmetric supercapacitor device based on Zn1Co2-LDH@rGO/NF and active carbon delivers a high specific capacitance (149.6 F g−1), high energy density (53.2 Wh kg−1), and excellent long cycling stability (90.9% capacitance retention after 6000 cycles at 3 A g−1), which holds huge potential for practical application in energy conversion and storage fields.

Ternary metal sulfides such as manganese-cobalt-sulfide (MCS) with the unique physical, chemical properties and high specific capacity can be used as energy storage material for supercapacitor. Herein, we prepared a MCS nanosheet array stick onto reduced graphene oxide (rGO)/Ni foam (MCS/rGO/NF) by a carefully controlled sulfurization time process. As the reaction time increased, the thickness of MCS/rGO/NF nanosheet arrays charged from thin to thick. After 3 h of sulfurization reaction (MCS/rGO/NF-3h), the nanosheets became rough due to the formation of some small sheets, and the composite showed the best electrochemical performance. The MCS/rGO/NF-3h composite exhibited a large specific capacity of 1356 C g−1 at a current density of 1 A g−1, and a long-term cyclic stability of 92.9% at a current density of 10 A g−1 through 3000 cycles. Moreover, a hybrid supercapacitor (HSC) device was assembled using MCS/rGO/NF-3h and rGO as the positive and negative electrodes, respectively. The MCS/rGO/NF-3h//rGO HSC exhibited a high energy density of 45.4 W h kg−1 at a power density of 850.2 W kg−1. The prominent electrochemical performance suggests that MCS/rGO/NF composites are promising electrode materials for energy storage applications.

Biofilm is difficult to thoroughly cure with conventional antibiotics due to the high mechanical stability and antimicrobial barrier resulting from extracellular polymeric substances. Encouraged by the great potential of magnetic micro-/nanorobots in various fields and their enhanced action in swarm form, we designed a magnetic microswarm consisting of porous Fe3O4 mesoparticles (p-Fe3O4 MPs) and explored its application in biofilm disruption. Here, the p-Fe3O4 MPs microswarm (p-Fe3O4 swarm) was generated and actuated by a simple rotating magnetic field, which exhibited the capability of remote actuation, high cargo capacity, and strong localized convections. Notably, the p-Fe3O4 swarm could eliminate biofilms with high efficiency due to synergistic effects of chemical and physical processes: (i) generating bactericidal free radicals (•OH) for killing bacteria cells and degrading the biofilm by p-Fe3O4 MPs; (ii) physically disrupting the biofilm and promoting •OH penetration deep into biofilms by the swarm motion. As a demonstration of targeted treatment, the p-Fe3O4 swarm could be actuated to clear the biofilm along the geometrical route on a 2D surface and sweep away biofilm clogs in a 3D U-shaped tube. This designed microswarm platform holds great potential in treating biofilm occlusions particularly inside the tiny and tortuous cavities of medical and industrial settings.

Designing a novel, efficient and cost-effective nanocomposite with the advantage of robust structure and outstanding conductivity is highly promising for the electrode materials of high-performance supercapacitors. Herein, we designed and synthesized a hierarchical structured NiMoO4@rGO/NF via a facile and scalable approach by growing NiMoO4 nanowires onto the skeleton of reduced graphene oxide (rGO)/Ni foam (NF). The as-made NiMoO4@rGO/NF exhibits a superior electrochemical behavior owing to the coupling effect of homogeneous NiMoO4 nanowires and high conductivity of rGO, and it exhibits a superb capacitance value of 1877 F g−1 at 1 A g−1 and shows a ultralong life span with over 98% capacitance retention after 4000 cycles at 5 A g−1 in 2 M KOH electrolyte. Moreover, an asymmetric device employing NiMoO4@rGO/NF composite and activated carbon is assembled with an aqueous electrolyte, and it displays a maximum energy density of 40 Wh kg−1 at a specific power 218.2 W kg−1. Interestingly, the asymmetric device can remain 111.2% of its initial value even after 8000 charge/discharge cycles. These results demonstrate that the NiMoO4@rGO/NF binder-free electrode provides greatly enhanced electrochemical performance and shows promising application as an anode for energy storage.

Raman scattering and fluorescence spectroscopy permeate analytic science and are featured in the plasmon-enhanced spectroscopy (PES) family. However, the modest enhancement of plasmon-enhanced fluorescence (PEF) significantly limits the sensitivity in surface analysis and material characterization. Herein, we report a Ag nanoantenna platform, which simultaneously fulfills very strong emission (an optimum average enhancement of 105-fold) and an ultrafast emission rate (∼280-fold) in PES. For applications in surface science, this platform has been examined with a diverse array of fluorophores. Meanwhile, we utilized a finite-element method (FEM) and time-dependent density functional theory (TD-DFT) to comprehensively investigate the mechanism of largely enhanced radiative decay. PES with a shell-isolated Ag nanoantenna will open a wealth of advanced scenarios for ultrasensitive surface analysis.

Designer DNA nanodevices have attracted extensive interest for detection of specific targets in living cells. However, it still remains a great challenge to construct DNA sensing devices that can be activated at desired time with a remotely applied stimulus. Here we report a rationally designed, synthetic DNA nanodevice that can detect ATP in living cells in an upconversion luminescence-activatable manner. The nanodevice consists of a UV light-activatable aptamer probe and lanthanide-doped upconversion nanoparticles which acts as the nanotransducers to operate the device in response to NIR light. We demonstrate that the nanodevice not only enables efficient cellular delivery of the aptamer probe into live cells, but also allows the temporal control over its fluorescent sensing activity for ATP by NIR light irradiation in vitro and in vivo. Ultimately, with the availability of diverse aptamers selected in vitro, the DNA nanodevice platform will allow NIR-triggered sensing of various targets as well as modulation of biological functions in living systems.

Creating nanoparticle dimers has attracted extensive interest. However, it still remains a great challenge to synthesize heterodimers with asymmetric compositions and synergistically enhanced functions. In this work, we report the synthesis of high quality heterodimers composed of porphyrinic nanoscale metal-organic frameworks (nMOF) and lanthanide-doped upconversion nanoparticles (UCNPs). Due to the dual optical properties inherited from individual nanoparticles and their interactions, absorption of low energy photons by the UCNPs is followed by energy transfer to the nMOFs, which then undergo activation of porphyrins to generate singlet oxygen. Furthermore, the strategy enables the synthesis of heterodimers with tunable UCNP size and dual NIR light harvesting functionality. We demonstrated that the hybrid architectures represent a promising platform to combine NIR-induced photodynamic therapy and chemotherapy for efficient cancer treatment. We believe that such heterodimers are capable of expanding their potential for applications in solar cells, photocatalysis, and nanomedicine.

Decorated graphite-like carbon nitride (g-C3N4) exhibits high photo-catalytic activity and is a central research area in the field of energy shortage. In this reported study, g-C3N4 was used as a precursor from which six kinds of metal sulfides (Ce, Zn, Ni, Cu, Bi, In) were produced with varying atomic ratios. This library of thousands of catalysts was applied (MySx/g-C3N4) to a semiconductor chip using ink-jet printing and the active catalysts were selected employing high throughput screening. Using visible blue light, the high throughput technique revealed four very active catalysts (Ce0.06Ni0.19Bi0.08Zn0.04Cu0.13In0.50)S/g-C3N4, (Ce0.03Ni0.52Bi0.38Zn0.01Cu0.04In0.03)S/g-C3N4, (Ce0.19Ni0.10Bi0.08Zn0.11Cu0.22In0.28) S/g-C3N4, (Ce0.21Ni0.10Bi0.08Zn0.11Cu0.22In0.28)S/g-C3N4 and one catalyst with low catalytic activity (Ce0.05Ni0.08Bi0.17Zn0.33Cu0.24In0.12)S/g-C3N4.

In this study, a serial microbubble imaging technology (sMBI) is proposed as a new high-throughput technology (HTE) detection method for rapid screening of hydrogen-evolution catalytic materials. The mechanism for the screening is based on capturing the variation in the growth of microbubbles in a system involving thousands of catalysts to evaluate numerous reactions. As an example of the process, three catalysts with high catalytic activity were rapidly selected from 1260 candidates.

The presence of large hydrophobic aromatic residues in cell-penetrating peptides or proteins has been demonstrated to be advantageous for their cell penetration. This phenomenon has also been observed when AuNPs were modified with peptides containing aromatic amino acids. However, it is still not clear how the presence of hydrophobic and aromatic groups on the surface of anionic AuNPs affects their interaction with lipid bilayers. Here, we studied the interaction of a range of anionic amphiphilic AuNPs coated by different combinations of hydrophobic and anionic ligands with four different types of synthetic lipid vesicles. Our results demonstrated the important role of the surface aromatic or bulky groups, relative to the hydrocarbon chains, in the interaction of anionic AuNPs with lipid bilayers. Hydrophobic interaction itself arising from the insertion of aromatic/bulky ligands on the surface of AuNPs into lipid bilayers is sufficiently strong to cause overt disruption of lipid vesicles and cell membranes. Moreover, by comparing the results obtained from AuNPs coated with aromatic ligands and cyclohexyl ligands lacking aromaticity respectively, we demonstrated that the bulkiness of the terminal groups in hydrophobic ligands instead of the aromatic character might be more important to the interaction of AuNPs with lipid bilayers. Finally, we further correlated the observation on model liposomes with that on cell membranes, demonstrating that AuNPs that are more disruptive to the more negatively charged liposomes are also substantially more disruptive to cell membranes. In addition, our results revealed that certain cellular membrane domains that are more susceptible to disruption caused by hydrophobic interactions with nanoparticle surfaces might determine the threshold of AuNP-mediated cytotoxicity.

The hierarchical core-shell ZnCo2O4@Ni-Co-S nanosheets with microsphere structures for supercapacitors were prepared through a facile three-step method including hydrothermal reaction, subsequent annealing and electrodeposition process. The influences of deposition cycles on its structure and electrochemical performances were studied in detail. On account of a synergistic effect of the ZnCo2O4 and Ni-Co-S composite and its unique core-shell nanostructure, the as-prepared electrode reveals excellent supercapacitor properties. The ZnCo2O4@Ni-Co-S with 6 electrodeposition cycles (ZCO@NCS-6) shows high specific capacitance values of 1762.6 F g−1 at 1 A g−1, outstanding rate performance with 81.3% at 50 A g−1, and remarkable long-term stability of 18.6% capacity loss through 5000 cycles. Moreover, the asymmetric supercapacitor (ASC) device was further constructed by using of ZCO@NCS-6 and active carbon to evaluate the practical values of the fabricated composite materials. The assembled ASC device shows the maximum voltage window up to 1.7 V, high energy density of 37.1 W h kg−1 and the excellent cycling life-span (only 9.71% capacitance loss after 8000 cycles). All these results suggest that ZnCo2O4@Ni-Co-S could be the hopeful electrode materials for energy storage devices.

Inspired by the primitive role of lipopolysaccharide (LPS) and taking advantage of the membrane-philic properties of amphiphilic gold nanoparticles (AuNPs), we established a facile and efficient fluorescence turn-on detection strategy for LPS. Upon binding onto the surface of liposomes, LPS can tailor the accessibility of liposomes towards AuNPs, reminiscent of its primitive function on the surface of bacteria. Thus, while the fluorescence of the dyes labeled on liposomes can be markedly quenched by the membrane-philic AuNPs, the quenching effect can be efficiently prevented by the surface-bound LPS. The de-quenching effect is highly selective to LPS, relative to other negatively charged bio-analytes, which is due to not only the extremely high affinity of LPS to lipid bilayers, but also the unique molecular structure of LPS. Furthermore, this easy-to-construct method offers a limit of detection of ∼0.65 nM, which is comparable to that obtained from the superb synthetic sensors for LPS reported in the literature. This study would open up a new route for the design of sensing systems for LPS exploiting its unique structural pattern and primitive function.

A simple method was created and implemented through the technology of ink-jet printing to study the effects of three chemical factors (chemical reagents) to the ninhydrin reaction. The effects of each single reagent and their interactions on the reaction were studied in one experiment. The three reagents all have effects on ninhydrin reaction, and the effects under the different combinations of reagents were presented on a chip. This work was completed efficiently with a smaller experimental workload compared with the traditional method.