Inspired by the zinc protoporphyrin found in red blood cells during heme production, we have developed a novel type of bimetallic Fe, Zn/N/C catalyst with high metal loading (Fe 1.2 wt% and Zn 1.7 wt%), demonstrating high activity and high stability for oxygen reduction processes in acidic electrolytes.

•A well-designed turn on fluorescent nanoprobe has been constructed by integrating polyethyleneimine (PEI) modified-CDs (P-CDs) and hyaluronic acid (HA) conjugated doxorubicin (Dox) through electrostatic self-assembly.•The nanoprobe can effectively distinguish Hela cell (cancer cell) from NIH-3T3 cells (normal cell) based on expression of different amount of CD44 protein on surface of cells.•The MTT assay confirmed that the release of Dox from the turn-on fluorescent nanoprobe can efficiently induce apoptosis in HeLa cells.This paper reports a turn-on theranostic fluorescent nanoprobe P-CDs/HA-Dox obtained by electrostatic assembly of polyethylenimine (PEI)-modified carbon dots (P-CDs) and Hyaluronic acid (HA)-conjugated doxorubicin (Dox) for hyaluronidase (HAase) detection, self-targeted imaging and drug delivery. P-CDs/HA-Dox show weak emission in a physiological environment. By utilizing the high affinity of HA to CD44 receptors overexpressed on many cancer cells, P-CDs/HA-Dox are capable of targeting and penetrating into cancer cells, where they are activated by HAase. As a result, HA-Dox can be digested into small fragments, causing the release of Dox and thereby restoring the fluorescence of P-CDs. The theranostic fluorescent nanoprobe can effectively distinguish cancer cells from normal cells. The as-prepared nanoprobe achieves a sensitive assay of HAase with a detection limit of 0.65 U mL−1. Furthermore, upon Dox release, the Dox could efficiently induce apoptosis in HeLa cells, as confirmed by MTT assay. The design of such a turn-on theranostic fluorescent probe provides a new strategy for self-targeted and image-guided chemotherapy.

We report a novel synthesis route for creating 3D interconnected hierarchical porous nitrogen-doped carbon nanorods (3D-IPCRs) using 1D polyaniline nanorods as a precursor and SiO2 as a porogen. The 1D carbon nanorod/SiO2 composites initially formed during carbonization further act as raw materials for a KOH activation process. After subsequent removal of the templates, as-prepared 3D-IPCRs exhibit a high specific surface area (1765 m2 g−1), a large total pore volume (1.06 cm3 g−1), an interconnected porous structure, and a moderate nitrogen doping (2.63 wt%). This interconnectivity is beneficial to improving ion diffusion properties and electrolyte wettability. The resulting carbon exhibits a much lower impedance resistance and smaller contact angle, compared with conventional mesoporous carbon, and thus has better electric double layer performance. As obtained 3D-IPCR electrodes achieve a high specific capacitance of 302 F g−1 at a current density of 0.05 A g−1 in 6 M KOH (two-electrode system), high coulombic efficiency (99.8%) and excellent cycling stability (92.8% of capacitance retention after 10 000 cycles) even with a high mass loading (11 mg cm−2) and thick electrode film (300 μm). Furthermore, the energy density of 3D-IPCRs reaches 23 W h kg−1, and the power density can be as high as 18.2 kW kg−1 when the energy density remains at 9.11 W h kg−1 in an organic electrolyte.

We report a novel synthesis route for creating 3D interconnected hierarchical porous nitrogen-doped carbon nanorods (3D-IPCRs) using 1D polyaniline nanorods as a precursor and SiO2 as a porogen. The 1D carbon nanorod/SiO2 composites initially formed during carbonization further act as raw materials for a KOH activation process. After subsequent removal of the templates, as-prepared 3D-IPCRs exhibit a high specific surface area (1765 m2 g−1), a large total pore volume (1.06 cm3 g−1), an interconnected porous structure, and a moderate nitrogen doping (2.63 wt%). This interconnectivity is beneficial to improving ion diffusion properties and electrolyte wettability. The resulting carbon exhibits a much lower impedance resistance and smaller contact angle, compared with conventional mesoporous carbon, and thus has better electric double layer performance. As obtained 3D-IPCR electrodes achieve a high specific capacitance of 302 F g−1 at a current density of 0.05 A g−1 in 6 M KOH (two-electrode system), high coulombic efficiency (99.8%) and excellent cycling stability (92.8% of capacitance retention after 10 000 cycles) even with a high mass loading (11 mg cm−2) and thick electrode film (300 μm). Furthermore, the energy density of 3D-IPCRs reaches 23 W h kg−1, and the power density can be as high as 18.2 kW kg−1 when the energy density remains at 9.11 W h kg−1 in an organic electrolyte.

In the present work, polyelectrolyte multilayers (PEMs) and graphene sheets are applied to sequentially coat on the surface of hollow carbon spheres/sulfur composite by a flexible layer-by-layer (LBL) self-assembly strategy. Owing to the strong electrostatic interactions between the opposite charged materials, the coating agents are very stable and the coating procedure is highly efficient. The LBL film shows prominent impact on the stability of the cathode by acting as not only a basic physical barrier, and more importantly, an ion-permselective film to block the polysulfides anions by Coulombic repulsion. Furthermore, the graphene sheets can help to stabilize the polyelectrolytes film and greatly reduce the inner resistance of the electrode by changing the transport of the electrons from a “point-to-point” mode to a more effective “plane-to-point’’ mode. On the basis of the synergistic effect of the PEMs and graphene sheets, the fabricated composite electrode exhibits very stable cycling stability for over 200 cycles at 1 A g–1, along with a high average Coulombic efficiency of 99%. With the advantages of rapid and controllable fabrication of the LBL coating film, the multifunctional architecture developed in this study should inspire the design of other lithium–sulfur cathodes with unique physical and chemical properties.Keywords: coating; graphene; layer-by-layer; lithium−sulfur batteries; polyelectrolyte;

Accurate and sensitive detection of palladium (Pd) is essential for both environmental and human health applications. This paper describes a triphenylphosphine (PPh3)-assisted highly sensitive fluorescent chemosensor for ratiometric detection of Pd2+ concentrations up to 300 nM with an LOD of 1 nM. During the detection, PPh3 plays a crucial role in improving the sensitivity of this chemosensor. The chemosensor also has suitable water-solubility which allows detection of Pd2+ in solution. Our studies show that it exhibits excellent selectivity toward Pd2+ and undergoes a color change from colorless to yellow to allow visual detection of Pd2+. Besides detection in solution, this chemosensor also shows great potential as an imaging reagent to detect Pd2+ as low as 0.03 ppm in diverse cells.

The ratiometric fluorescence chemodosimeter N-butyl-4-(prop-1-en-1-yloxy)-1,8-naphthalic anhydride (NT-VE) was designed for Hg2+ recognition by oxymercuration at ambient temperature with high selectivity and no interference from other metal cations such as Cu2+, Ag+, Au3+, Fe3+, etc. The NT-VE could be incorporated into sodium dodecyl-benzenesulfonate (SDBS) micelles, which was confirmed by the clear emission enhancement observed in 0.1 mM SDBS. The hydrophobic core of the SDBS enhanced the solubility of NT-VE, enabling the detection of Hg2+ in aqueous solution, and the negatively charged micelle surface increased the local concentration of Hg2+ for amplified sensitivity. This work demonstrated the excellent performance of the NT-VE chemodosimeter for ratiometric detection of Hg2+ in aqueous solution. The NT-VE/SDBS system could detect Hg2+ over a linear range of 0.05–10 μM and a detection limit of 9 ppb (45 nM) in water.

We have grown CoMn2O4 spinel nanocrystals on poly (diallyldimethylammonium chloride) functionalized carbon nanotubes (PDDA-CNTs) by noncovalent functionalization and solvothermal techniques. PDDA plays an important role in homogeneously increasing the surface density of available functional groups, which can provide active sites for decoration of CoMn2O4 on CNTs. In addition, PDDA preserves the intrinsic properties of CNTs, increases the active sites of catalysts, and enhances the durability of the catalysts. Here, CoMn2O4 nanocrystals were uniformly deposited on PDDA-CNTs with loading amounts from 36% to 83%. The as-prepared CoMn2O4/PDDA-CNT catalyst showed high current densities for the oxygen reduction reaction (ORR) in alkaline and neutral conditions, which outperformed the Co3O4/PDDA-CNT and Pt/C catalysts at medium overpotential, mainly through a 4e reduction pathway. The obtained CoMn2O4/PDDA-CNT hybrid exhibited excellent activity and durability when subjected to an oxygen evolution reaction. These results indicate that the CoMn2O4/PDDA-CNT hybrid represents a promising alternative to Pt for ORR electrocatalysis, and this non-precious bifunctional electrocatalyst provides a corrosion resistant and protective cathode layer to fuel cells. The excellent activity and stability of the hybrid materials demonstrate the potential of noncovalent coupling inorganic/carbon composites as novel catalytic systems for lithium–air batteries and chlor-alkali production.

An aptamer–molecular beacon (MB) multiple fluorescent probe for adenosine triphosphate (ATP) assay is proposed in this article. The ATP aptamer was used as a molecular recognition part, and an oligonucleotide (short strand, SS) partially complementary with the aptamer and an MB was used as the other part. In the presence of ATP, the aptamer bound with it, accompanied by the hybridization of MB and SS and the fluorescence recovering. Wherever there is only very weak fluorescence can be measured in the absence of ATP. Based on the relationship of recovering fluorescence and the concentration of ATP, a method for quantifying ATP has been developed. The fluorescence intensity was proportional to the concentration of ATP in the range of 10 to 500 nM with a detection limit of 0.1 nM. Moreover, this method was able to detect ATP with high selectivity in the presence of guanosine triphosphate (GTP), cytidine triphosphate (CTP), and uridine triphosphate (UTP). This method is proved to be simple with high sensitivity, selectivity, and specificity.