NiCoAl layered double hydroxides (NiCoAl-LDHs) with different morphology, structure, size and pseudocapacior properties have been prepared by tuning the ratio of metallic elements via a hydrothermal method. The optimized element proportion of 2D NiCo2Al-LDH consisting of hexagonal nanosheets delivers a significantly enhanced specific capacitance 2369.4 F g−1 at a current density of 1 A g−1. A circle-like growth mechanism is proposed to explain the formation of the 2D NiCo2Al-LDH structures. Its 2D structure and the synergistic effect of three metallic elements assure its high electrochemical performance. An asymmetric supercapacitor (ASC) based on NiCo2Al-LDH exhibits an ultra-high energy density of 91.0 Wh kg−1 at a power density of 758.2 W kg−1 as well as long-term stability (92% of its initial capacitance retention at 8 A g−1 over 5000 cycles), outperforming most of LDH and metal oxides ASCs.

Copper nanoparticles (Cu NPs) spaced reduced graphene oxide (rGO) films are fabricated by integrating electrophoresis deposition (EPD) with thermal H2 annealing. The Cu NPs are formed through thermal aggregation and reduction of Cu(II) ions which are counter cations of GO. By tuning the annealing temperature from 400 to 850 °C, the mean diameter of the Cu NPs increases from 35 to 124 nm. Chemical characterizations reveal that the EPD technique may partially remove the O-containing groups of the GO film, while complete removal of the O-containing groups and effective repair of the graphene defects are achieved by thermal H2 treatment. With the implantation of Cu NPs, the resultant rGO/Cu NP films exhibit high porosity and amazing electric conductivities, enabling their direct use as lithium-ion battery (LIB) electrodes (vs. Li/Li+) without a general current collector, binder, and other additives. This novel LIB has a high charge/discharge capacity (>463 mA h g−1), an excellent reversibility, and a high coulombic efficiency (nearly 100%) for 300 cycles at a current density of 0.2 A g−1. It also exhibits good rate capacity: 849 mA h g−1@0.1 A g−1, 618 mA h g−1@0.2 A g−1, 516 mA h g−1@0.3 A g−1, and 470 mA h g−1@0.5 A g−1. Our new technique provides advanced design strategies for high performance LIBs and ultracapacitors, which might be used for mobile phone and electrical vehicles with unprecedented performances.

In this paper, we report a novel label-free electrochemical aptasensor for detecting proteins in whole blood based on a three-component nanocomposite, in which ferriferrous oxide and three-dimensional graphene nanocomposite were modified with the plasma-polymerized 4-vinyl pyridine (Fe3O4@3D-rGO@PP4VP). In this novel sensing strategy, large amounts of amino groups in PP4VP facilitated the immobilization of aptamer strands via the strong electrostatic interaction between positively charged ammonium groups of the nanocomposites and negatively charged phosphate groups of aptamers. In the presence of thrombin, LYS (LYS), and platelet-derived growth factor-BB (PDGF-BB), the adsorbed aptamer strands on the developed nanocomposite surface caught the targeted proteins at the electrode interface. The aptamer preferred to be a barrier for electrons and inhibited electron transfer, leading to the decreased peak current of cyclic voltammetry measurements and the increased electron transfer resistance of electrochemical impedance spectroscopy. The determination of the thrombin, PDGF-BB, and LYS concentrations with this novel strategy showed low detection limits of 4.5, 29.4, and 14 pg·mL−1, and the analytical ranges extend from 0.01 to 50, 0.1 to 100, and 0.1 to 200 ng·mL−1, respectively. The resultant aptasensor exhibited high selectivity, acceptable reproducibility, and stability toward thrombin. The aptasensor could be used to detect thrombin in whole blood samples, thereby suggesting its possible application in clinical settings.

A new core-shell nanostructure of CoO@MnO2nanowire@nanosheetarrays(NNSs) was designed and directly grown on a 3D nickel foam by a simple two step solution method combined with a post annealing treatment in Ar gas. The MnO2 nanosheets can grow directly on the CoO precuor nanowires without any pretreatment, and its thickness on the CoO nanowire arrays (NAs) can also be tailored by easily adjusting the second step hydrothermal time. When acting as a electrochemical supercapacitor, the CoO@MnO2 NNAs delivers a highly enhanced specific capacitance of 3.03 F cm−2 (about 1515 F g−1) with a wide potential window of 0.8 V at 2.0 mA cm−2, which is superior to most reported Co3O4 based core-shell NNAs supercapacitive electrodes. An asymmetric supercapacitor devices based on these CoO@MnO2 NNAs and aqueous electrolyte showed with a high-energy density of 0.37 mWh cm−2 at a power density of 1.7 mW cm−2, a high power density of 34.4 mW cm−2 at 0.20 mWh cm−2 and a long-term cycling ability, implying its great potential application in high-performance electrochemical supercapacitor.

•CoO@MnO2 core-shell nanoarray was prepared by a novel solvothermal reaction without pre-carbonization treatment.•Density of MnO2 nanosheets on the CoO nanosheets can be tailored.•The CoO@MnO2 delivers an ultra-high areal specific capacitance of 2.40 F cm−2.•The asymmetric supercapacitor achieves a high-energy density of 1.4 mWh cm−3.•Excellent long-term stability: 90.0% capacitance retention after 10 000 cycles.Hierarchical hybrid electrodes CoO@MnO2 nanosheet@nanosheet arrays (NNAs) for high-performance supercapacitors are designed and grown on a 3D nickel foam by a simple two step solution method combined with a post annealing treatment in Ar gas. The MnO2 nanosheets can grow directly on the CoO precursor nanosheet arrays without any pretreatment, and its thickness on the CoO NAs can also be tailored by adjusting the hydrothermal time. The NNAs with the elegant synergy between CoO and MnO2 lead to a highly enhanced areal capacitance (2.40 F cm−2 at 2.0 mA cm−2, with a wide potential window of 0.8 V). We further fabricated asymmetric supercapacitor device based on the CoO@MnO2 NNAs and active carbon, which achieved a high-energy density of 1.4 mWh cm−3 at a power density of 9.6 mW cm−3, a high power density of 192.3 mW cm−3 at 0.7 mWh cm−3 and good cyclic stability.

In this study, a nanocomposite consisting of three-dimensional reduced graphene oxide (3D-rGO) and plasma-polymerized propargylamine (3D-rGO@PpPG) was prepared and used as a highly sensitive and selective DNA sensor for detecting Hg2+. Given the high density of amino groups in the resultant 3D-rGO@PpPG nanocomposite, thymine-rich and Hg2+-targeted DNA was preferentially immobilized on the fabricated sensor surface via the strong electrostatic interaction between DNA strands and the amino-functionalized nanocomposites, followed by detecting Hg2+ through T–Hg2+–T coordination chemistry between DNA and Hg2+. The results of electrochemical measurements revealed that the anchored amount of DNA strands anchored on the 3D-rGO@PpPG nanofilm surface affects the determination of Hg2+ in aqueous solution. It showed high sensitivity and selectivity toward Hg2+ within concentrations ranging from 0.1 to 200 nM and displayed a low detection limit of 0.02 nM. The new strategy proposed also provides high selectivity of Hg2+ against other interfering metal ions, good stability, and repeatability. The excellent applicability of the developed sensor confirms the potential use of plasma-modified nanofilms for the detection of heavy metal ions in real environmental samples and water.

This article describes an aptasensor for lysozyme that is based on a gold electrode modified with an aptamer-wrapped composite consisting of three-dimensional reduced graphene oxide, cuprous oxide, and plasma-polymerized propargylamine (Cu2O@rGO@PpPG) as the sensing layer. The nanocomposite consisting of Cu2O@rGO was synthesized by simultaneously reducing GO and Cu(II) ions with glucose and then modified by plasma-enhanced chemical vapor deposition using propargylamine as the monomer gas. The resulting amine-rich nanofilms of Cu2O@rGO@PpPG nanocomposite were deposited on a gold electrode. Differential pulse voltammetry and electrochemical impedance spectroscopy show these layers to exhibit a good amperometric response and variation of the charge transfer resistance to lysozyme after aptamer strands had been immobilized on the films via electrostatic interaction between the negatively charged phosphate groups of the aptamer and the positively charged amino groups on the electrode. The sensor, when operated at 0.22 V (vs. Ag/AgCl), can detect lysozyme in the 0.1 nM to 200 nM concentration range with a 0.06 nM limit of detection. In addition, the sensor displays excellent selectivity and repeatability. In our perception, this strategy for preparing aptasensors holds a great potential with respect to the use of plasma-modified nanocomposites in clinical analysis.

Inspired by how geckos abduct, rotate, and adduct their setal foot toes to adhere to different surfaces, we have developed an artificial muscle material called ion-exchange polymer–metal composite (IPMC), which, as a synthetic adhesive, is capable of changing its adhesion properties. The synthetic adhesive was cast from a Si template through a sticky colloid precursor of poly(methylvinylsiloxane) (PMVS). The PMVS array of setal micropillars had a high density of pillars (3.8 × 103 pillars/mm2) with a mean diameter of 3 μm and a pore thickness of 10 μm. A graphene oxide monolayer containing Ag globular nanoparticles (GO/Ag NPs) with diameters of 5–30 nm was fabricated and doped in an ion-exchanging Nafion membrane to improve its carrier transfer, water-saving, and ion-exchange capabilities, which thus enhanced the electromechanical response of IPMC. After being attached to PMVS micropillars, IPMC was actuated by square wave inputs at 1.0, 1.5, or 2.0 V to bend back and forth, driving the micropillars to actively grip or release the surface. To determine the adhesion of the micropillars, the normal adsorption and desorption forces were measured as the IPMC drives the setal micropillars to grip and release, respectively. Adhesion results demonstrated that the normal adsorption forces were 5.54-, 14.20-, and 23.13-fold higher than the normal desorption forces under 1.0, 1.5, or 2.0 V, respectively. In addition, shear adhesion or friction increased by 98, 219, and 245%, respectively. Our new technique provides advanced design strategies for reversible gecko-inspired synthetic adhesives, which might be used for spiderman-like wall-climbing devices with unprecedented performance.Keywords: adhesion; friction; ion-exchange polymer−metal composite (IPMC); poly(methylvinylsiloxane) (PMVS); setal micropillar; synthetic adhesive

•A feasible synthesis of Mn3(PO4)2@BSA nanoflower using BSA as template.•Mn3(PO4)2@BSA nanoflower was used as the support of Pt catalyst.•Mn3(PO4)2@BSA@PtNPs exhibits higher electrocatalytic activity than that of MWCNTs@PtNPs.We report the production of a novel nanoflower material of Mn3(PO4)2@BSA hybrid which is made of both protein and manganese (II) phosphate, and its application as a new support material for platinum nanoparticles (PtNPs). The Mn3(PO4)2@BSA@PtNPs catalyst is synthesized using this new material. The average size of PtNPs on the Mn3(PO4)2@BSA nanoflower is approximately 2 nm. The obtained Mn3(PO4)2@BSA@PtNPs nanocomposites are characterized by X-ray diffraction, high resolution transmission electron microscopy, and scanning electron microscopy. Electrochemical results show that the Mn3(PO4)2@BSA@PtNPs catalyst also shows excellent electrocatalytic activity toward methanol oxidation with higher electrochemically active surface area. The microstructure of the supporting material serves a crucial function in the electrochemical performance of the Pt-based catalyst.

We report a novel electrochemical sensor for the sensitive detection of Cu(II) ions based on hollow TiO2 spheres modified by fluorescein hydrozine-3,6-diacetic acid (FH). Herein, hollow TiO2 spheres were synthesized via the hydrothermal method with the carbon spheres as the template then modified by (3-aminopropyl) trimethoxysilane (APTMS) to form the amino group-modified TiO2 spheres (TiO2–APTMS). Simultaneously, FH was activated by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride/N-hydroxysuccinimide, in which the carboxyl groups were changed to active ester groups. Consequently, TiO2–APTMS spheres could be modified by FH with the activated ester groups via the bonding of amide groups to produce the composite electrode with TiO2 and FH (Au–TiO2–FH). The resulting Au–TiO2–FH was used to develop the electrochemical sensor for the highly sensitive detection of Cu2+ in aqueous solution because of the coordination between Cu2+ and FH, the whole process of which was determined via electrochemical impedance spectroscopy. The results showed that a detection limit of 4.29 pM of the developed sensor within the range from 5 pM to 1 μM was obtained. Furthermore, the interference from other metal ions, such as K+, Na+, Ag+, Ni2+, Mn2+, Zn2+, Mg2+, and Fe3+, associated with Cu2+ analysis could be effectively inhibited. Most importantly, the developed electrochemical sensor could be reproduced and degraded by UV light irradiation because of the light degradation ability of TiO2 toward FH. This novel sensor could also be used to detect other heavy metal ions when TiO2 spheres are modified by the relative FH.

A feasible method for different ZnO nanostructures fabrication via the O2 plasma surface modification was reported in the present work. After the as-prepared ZnO nanoparticles were dispersed in the aqueous solution of Na2CO3, the resultant nanomatter was treated by O2 plasma for different times at high plasma input power of 200 W. It shows different nanostructures of ZnO were observed, such as nanowire, nanosheet, nanoneedles, and nanoparticles. Also, the chemical and crystal performances of the resultant ZnO nanostructures were depended on the duration of plasma. On these bases, the formation mechanism of new nanostructured ZnO-related materials was discussed. In comparison with the pristine ZnO, the plasma modified ZnO nanostructures (p-ZnO) exhibited a relative high electrochemical performance and sensitivity toward the detection of ractopamine (RAC) with a detection limit of 1.18 ng mL−1 within the range of 5–500 ng mL−1. It hints that the p-ZnO nanostructure could be used as a new alternative electrochemical biosensor for the detection of the food additives.

•TiO2 spheres and plasma poly(acrylic acid) nanocomposite-based aptasensor for detecting lysozyme.•Good electrochemical performance of the sensing layer due to the presence of hollow TiO2 spheres.•High sensitivity and selectivity of lysozyme detecton with low detection limit of 0.015 ng mL−1.A composite made of polyacrylic acid and hollow TiO2 spheres (TiO2@PPAA) was prepared by the plasma polymerization method and subsequently used as an electrode material for detecting lysozyme. The chemical structure, surface morphology, and electrochemical performance of the TiO2@PPAA composite were mainly affected by the plasma input power used during plasma polymerization. After optimizing plasma conditions, aptamer strands exhibited high adsorption affinity toward the surface of TiO2@PPAA composite via synergistic effects between TiO2 and PPAA. Electrochemical impedance spectroscopy results showed that the developed TiO2@PPAA aptasensor presents highly sensitive detection ability toward lysozyme; the limit of detection of the proposed aptasensor is 0.015 ng mL−1 (1.04 pM) within the range of 0.05–100 ng mL−1 in terms of 3σ value. The film further showed excellent selectivity toward lysozyme in the presence of interfering proteins, such as thrombin, bovine serum albumin, and immunoglobulin E. Thus, this aptasensing strategy might broaden the applications of plasma polymerized nanomaterials in the field of biomedical research and early clinical diagnosis.

A label-free and effective aptasensor based on an amino-functionalized nanocomposite of graphene and plasma-polymerized allylamine (G–PPAA) was developed for thrombin detection. Graphene was assembled on the substrate, followed by the self-assembly of octadecylamine (OTA) to protect the graphene from etching by subsequent plasma irradiation. Afterward, PPAA was deposited onto the graphene surface with the self-assembled OTA, and the nanocomposite with amino groups was fabricated. The label-free thrombin aptamer was immobilized onto the amino-functionalized nanocomposite matrix via electrostatic interaction between the phosphate groups of the aptamer and the amino groups in PPAA. The process was investigated using impedimetric detection and a quartz crystal microbalance (QCM). The chemical compositions, surface morphology, and electrochemical properties were found to be dependent on the plasma conditions used in the polymer deposition. The amounts and kinetics of aptamer immobilization and thrombin detection were determined using QCM measurements. A relatively high affinity constant of aptamer immobilization and low detection limit for thrombin were achieved by using the G–PPAA film as the biosensor matrix. Results suggest that G–PPAA films can be applied in gene therapy and protein detection.

In this paper, we report on the facile one-step synthesis of porous cuprous oxide microspheres on reduced graphene oxide (Cu2OMS–rGO) by synchronously reducing Cu2+ ions and GO with ascorbic acid sodium, followed by their application as electrochemical biosensors for the detection of mercury ions in water. After detailed characterization of the basic chemical components, crystal structure, surface morphology, and electrochemical properties of the Cu2OMS–rGO composites, single-stranded and thymine (T)-rich oligonucleotides were successively immobilized onto the surface of the composite electrode modified by Cu2OMS–rGO. Upon introduction of the target analyte, Hg2+ ions were intercalated into the DNA polyion complex membrane based on T–Hg2+–T coordination chemistry. The results show that the Cu2OMS–rGO composite has high sensitivity for the detection of Hg2+, with a detection limit of 8.62 pM within the range of 0.05 nM to 40 nM. Therefore, the Cu2OMS–rGO composite could be utilized as a novel biosensor for the detection of heavy metal ions in water or in the environment. The strategy yielded excellent selectivity of Hg2+ against other interfering metal ions. In addition, the developed DNA sensor for the determination of Hg2+ ions could be reproduced up to 10 cycles, and the recovery was approximately 95%.

This study focused on the synthesis of novel chiral Ag2S and Ag2S–Zn nanocrystals (NCs) with chiral Pen as a capping reagent in an aqueous solution. Luminescence studies indicated that all the prepared Ag2S and Ag2S–Zn NCs exhibited size-tunable photoluminescence (PL) emission at 500–700 nm. Compared with Ag2S, the PL emission of the Ag2S–Zn NCs could improve by around 2.4-fold. XRD peaks of the as-prepared Ag2S NCs were weak, whereas the XRD peaks of the Ag2S–Zn NCs had the characteristics of a monoclinic crystal structure. The circular dichroism (CD) test showed that the prepared NCs revealed a clear mirror-image relationship in their CD signals at 300–700 nm, and Zn2+ played a key role in the Cotton effect of the NCs. The chiral and fluorescent properties of these NCs are likely to find widespread applications in bioimaging, chemical and biosensing, and possibly in asymmetry catalysis.

We report a route of synthesizing water-soluble chiral luminescent Ag nanoclusters (NCs) using d-penicillium and l-penicillium as stabilizer agents by photo-reduction method. These Ag NCs exhibit characteristic of tunable fluorescence from 603 nm to 640 nm, controllable Cotton effects or circular dichroism (CD) signals with an opposite sign (mirror–image relationship) in metal-based electronic transition regions by varying irradiating time and are stable under ambient conditions. The hemolysis results show that the prepared Ag NCs are better biocompatibility compared with that of CdTe quantum dots (QDs). The stability, chirality, biocompatibility and fluorescent properties of these Ag NCs are likely to find widespread applications in bioimaging, chemical and biosensing, and also possibly in asymmetry catalysis.Graphical abstractFluorescence spectra of the Ag nanocluster after different periods of UV irradiation: 1) 20, 2) 30, 3) 40, 4) 50, and 5) 70 min.Highlights► The Ag NCs are prepared using chiral penicillium as ligand and UV light to reduce a silver salt. ► The Ag NCs exhibit defined emission wavelength and controllable chirality by varying irradiating time. ► The hemolysis results show that the Ag NCs are better biocompatibility compared with that of CdTe QDs.

Novel Sm-based enantiomeric pair, generally formulated Sm(DBM)3L (LR,R in 1, LS,S in 2, DBM = dibenzoylmethanate) have been successfully prepared via the reaction of Sm(DBM)3·2H2O with chiral ligands LR,R (−)-4,5-pinene bipyridine and LS,S (+)-4,5-pinene bipyridine (Scheme 1), respectively. The crystal structure analysis of 1 and 2 reveal that they crystallize in chiral space group P21 of monoclinic system. The central Sm(III) ion is octacoordinate with six β-diketonate oxygen atoms and two chiral pinene bipyridine nitrogen atoms, forming a coordination polyhedron best described as the distorted square antiprism (SA). The CD spectra (Fig. S1) further confirm that 1 and 2 are enantiomers. The photoluminescence investigations of 1 and 2 demonstrate that they display deep-red luminescence characteristic of the Sm3+.Novel Sm-based enantiomeric pair with chiral ligand have been initially synthesized and characterized by crystal structure analysis and spectroscopic methods. They are isostructural, while octacoordinate Sm(III) is situated in a distorted square antiprism (SA) geometrical environment. The investigations on photoluminescence properties reveal that they display deep-red luminescence characteristic of the Sm3+.

Copper nanoparticles (Cu NPs) spaced reduced graphene oxide (rGO) films are fabricated by integrating electrophoresis deposition (EPD) with thermal H2 annealing. The Cu NPs are formed through thermal aggregation and reduction of Cu(II) ions which are counter cations of GO. By tuning the annealing temperature from 400 to 850 °C, the mean diameter of the Cu NPs increases from 35 to 124 nm. Chemical characterizations reveal that the EPD technique may partially remove the O-containing groups of the GO film, while complete removal of the O-containing groups and effective repair of the graphene defects are achieved by thermal H2 treatment. With the implantation of Cu NPs, the resultant rGO/Cu NP films exhibit high porosity and amazing electric conductivities, enabling their direct use as lithium-ion battery (LIB) electrodes (vs. Li/Li+) without a general current collector, binder, and other additives. This novel LIB has a high charge/discharge capacity (>463 mA h g−1), an excellent reversibility, and a high coulombic efficiency (nearly 100%) for 300 cycles at a current density of 0.2 A g−1. It also exhibits good rate capacity: 849 mA h g−1@0.1 A g−1, 618 mA h g−1@0.2 A g−1, 516 mA h g−1@0.3 A g−1, and 470 mA h g−1@0.5 A g−1. Our new technique provides advanced design strategies for high performance LIBs and ultracapacitors, which might be used for mobile phone and electrical vehicles with unprecedented performances.

A label-free and effective aptasensor based on an amino-functionalized nanocomposite of graphene and plasma-polymerized allylamine (G–PPAA) was developed for thrombin detection. Graphene was assembled on the substrate, followed by the self-assembly of octadecylamine (OTA) to protect the graphene from etching by subsequent plasma irradiation. Afterward, PPAA was deposited onto the graphene surface with the self-assembled OTA, and the nanocomposite with amino groups was fabricated. The label-free thrombin aptamer was immobilized onto the amino-functionalized nanocomposite matrix via electrostatic interaction between the phosphate groups of the aptamer and the amino groups in PPAA. The process was investigated using impedimetric detection and a quartz crystal microbalance (QCM). The chemical compositions, surface morphology, and electrochemical properties were found to be dependent on the plasma conditions used in the polymer deposition. The amounts and kinetics of aptamer immobilization and thrombin detection were determined using QCM measurements. A relatively high affinity constant of aptamer immobilization and low detection limit for thrombin were achieved by using the G–PPAA film as the biosensor matrix. Results suggest that G–PPAA films can be applied in gene therapy and protein detection.

A polymer-dispersed azobenzene and GO nanocomposite film was fabricated with shape memory polyurethane as a matrix. Upon mechanical stretching, the nanocomposite film exhibited a photoresponsive triple shape-memory effect by successive exposure to UV and NIR light. Here, azobenzene and GO may act as photo-harvesters for UV and NIR light, respectively, and their photoresponsiveness was transferred to the host polymer films. On one hand, UV light caused the photomechanical motion of azobenzene materials, leading to the photoinduced bending behavior for the composite film. On the other hand, NIR brought about the photothermal effect of GO, heating the film and triggering the thermoresponsive shape-memory of polyurethane. The nanocomposite film showed good mechanical properties, which can be self-healed upon NIR irradiation. Benefitting from these light-directed triple shape-memory properties, simulation of flower blooming and fading was successfully achieved, indicating its potential application as a biomimetic actuator and other functional devices.