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ECL-RET in BP/MnO2 nanocomposites coupled with glutathione-loaded liposomes for the immunoassay of proteins.

Background: Circular RNAs (circRNAs), which generally act as microRNA (miRNA) sponges to competitively regulate the downstream target genes of miRNA, play an essential role in cancer biology. However, few studies have been reported on the role of circRNA based competitive endogenous RNA (ceRNA) network in hepatocellular carcinoma (HCC). Herein, we aimed to screen and establish the circRNA/miRNA/mRNA networks related to the prognosis and progression of HCC and further explore the underlying mechanisms of tumorigenesis. Methods: GEO datasets GSE97332, GSE108724, and GSE101728 were utilized to screen the differentially expressed circRNAs (DE-circRNAs), DE-miRNAs, and DEmRNAs between HCC and matched para-carcinoma tissues. After six RNA-RNA predictions and five intersections between DE-RNAs and predicted RNAs, the survival-related RNAs were screened by the ENCORI analysis tool. The ceRNA networks were constructed using Cytoscape software, based on two models of up-regulated circRNA/down-regulated miRNA/up-regulated mRNA and down-regulated circRNA/up-regulated miRNA/down-regulated mRNA. The qRT-PCR assay was utilized for detecting the RNA expression levels in HCC cells and tissues. The apoptosis, Edu, wound healing, and transwell assays were performed to evaluate the effect of miR-106b-5p productions on the proliferation, invasion, and metastasis of HCC cells. In addition, the clone formation, cell cycle, and nude mice xenograft tumor assays were used to investigate the influence of hsa_circ_0001495 (circCCNB1) silencing and overexpression on the proliferation of HCC cells in vitro and in vivo. Furthermore, the mechanism of downstream gene DYNC1I1 and AKT/ERK signaling pathway via the circCCNB1/miR-106b-5p/GPM6A network in regulating the cell cycle was also explored. Results: Twenty DE-circRNAs with a genomic length less than 2000bp, 11 survival-related DE-miRNAs, and 61 survival-related DE-mRNAs were screened out and used to construct five HCC related ceRNA networks. Then, the circCCNB1/miR-106b-5p/GPM6A network was randomly selected for subsequent experimental verification and mechanism exploration at in vitro and in vivo levels. The expression of circCCNB1 and GPM6A were significantly down-regulated in HCC cells and cancer tissues, while miR-106b-5p expression was up-regulated. After transfections, miR-106b-5p mimics notably enhanced the proliferation, invasion, and metastasis of HCC cells, while the opposite was seen with miR-105b-5p inhibitor. In addition, circCCNB1 silencing promoted the clone formation ability, the cell cycle G1-S transition, and the growth of xenograft tumors of HCC cells via GPM6A downregulation. Subsequently, under-expression of GPM6A increased DYNC1I1 expression and activated the phosphorylation of the AKT/ERK pathway to regulate the HCC cell cycle. Conclusions: We demonstrated that circCCNB1 silencing promoted cell proliferation and metastasis of HCC cells by weakening sponging of oncogenic miR-106b-5p to induce GPM6A underexpression. DYNC1I1 gene expression was up-regulated and further led to activation of the AKT/ERK signaling pathway.

A dual-wavelength ECL ratiometry sensing platform was constructed for H2S detection.

A spatially resolved ratiometric ECL immunosensor for myoglobin detection was developed via resonance energy transfer for signal amplification.

A novel ECL ratiometric sensor was developed based on H2O2 activated independently bidirectional regulation strategy.

Seed-borne Streptomyces can transmit vertically from generation to generation and be a mutualism between the endosymbionts and hosts. The aim of this study was to isolate and characterize endophytic Streptomyces strains from wheat sprouts, and to investigate their protection against wheat seed pathogenic fungi Penicillium. Endophytic Streptomyces sp. F6 and Streptomyces sp. F39 were isolated from wheat sprouts germinated under sterile conditions. Both Streptomyces strains could produce siderophores, and showed antagonistic activities against the seed pathogenic fungi Penicillium sp. Z17. The inoculation of Streptomyces sp. F39 and F6 could protect wheat seed germination and promote seedling growth under Penicillium sp. Z17 infection. However, the protection efficiency was impacted by the Streptomyces spore concentrations, the concentration ratios of Streptomyces spores to pathogen spores, and inoculation methods. The results suggested that wheat sprouts harbored diverse endophytic Streptomyces species which derived from wheat seeds, these strains should be more likely transmitted to the next generation, and confer competitive ability to pathogens on the offspring. Owing to the more intimate correlation between sprout endophytic flora with host plants, these strains are more suitable for mature plant interiors compared with those from rhizosphere soils and root interiors.

The understanding of areas for "classical" electrochemistry (including catalysis, electrolysis and sensing) and bio-electrochemistry at the micro/nanoscale are focus on the continued performance facilitations or the exploration of new features. In the recent 20 years, a different mode for driving electrochemistry has been proposed, which is called as bipolar electrochemistry (BPE). BPE has garnered attention owing to the interesting properties: (i) its wireless nature facilitates electrochemical sensing and high throughput analysis; (ii) the gradient potential distribution on the electrodes surface is a useful tool for preparing gradient surfaces and materials. These permit BPE to be used for modification and analytical applications on a micro/nanoscale surface. This review aims to introduce the principle and classification of BPE and BPE at micro/nanoscale; sort out its applications in electrocatalysis, electrosynthesis, electrophoresis, power supply and so on; explain the confined BPE and summarize its analytical application for single entities (single cells, single particles and single molecules), and discuss finally the important direction of micro/nanoscale BPE.

To achieve high sensitivity for biomolecule detection in photoelectrochemical (PEC) bioanalysis, the ideal photoelectrode and ingenious signaling mechanism play crucial roles. Herein, the feasibility of the photogenerated hole-induced chemical-chemical redox cycling amplification strategy on a Z-scheme heterostructure photoelectrode was validated, and the strategy toward enhanced multiple signal amplification for advanced PEC immunoassay application was developed. Specifically, a direct Z-scheme Bi2S3/Bi2MoO6 heterostructure was synthesized via a classic hydrothermal method and served as a photoelectrode for the signal response. Under the illumination, the PEC chemical-chemical redox cycling (PECCC) among 4-aminophenol generated by the enzymatic catalysis from a sandwich immunoassay, ferrocene as a mediator, and tris (2-carboxyethyl) phosphine as a reducing agent was run on the Z-scheme Bi2S3/Bi2MoO6 heterostructure photoelectrode. Exemplified by interleukin-6 (IL-6) as the target, the applicability of the strategy was studied in a PEC immunoassay. Thanks to the multiple signal amplification originating from the high efficiency of the PECCC redox cycling system, the enzymatic amplification, and the fine performance of the Z-scheme Bi2S3/Bi2MoO6 heterostructure photoelectrode, the assay for IL-6 exhibits a very low detection limit of 2.0 × 10-14 g/mL with a linear range from 5.0 × 10-14 to 1.0 × 10-8 g/mL. This work first validates the feasibility of the PECCC redox cycling on the Z-scheme heterostructure photoelectrode and the good performance of the strategy in PEC bioanalysis. We envision that it would provide a new prospective for highly sensitive PEC bioanalysis on the basis of a Z-scheme heterostructure.

Molecular logic computation has drawn extensive attention in the fields of bioanalysis, intelligent diagnostics of diseases and other nanotechnology areas. DNA-templated Au nanoclusters (DNA-AuNCs) possess some excellent features, including high luminescence, good photo-stability and easy preparation. Herein, taking these advantages of DNA-AuNCs, we have designed and constructed a universal platform of label-free and enzyme-free multiple molecular logic gates, including NOR, XNOR, IMPLY, OR, AND, and INHIBIT. The experimental results have demonstrated the feasibility of these logic gates operations using Hg2+, Cu2+, biothiols, melamine and pyrophosphate (PPi) as inputs. Thus, the universal platform can be utilized for the determination of biothiols, melamine and pyrophosphate (PPi) via logic outputs. The strategy exhibited low cost, easy operation and versatile design, and can offer a promising platform for the development of functional logic systems.

A chemical-chemical redox cycling amplification strategy was introduced into a photocathodic immunosensing system. To prove the applicability of the method, a novel self-powered photochemical system by integrating the photoanode and photocathode was designed for protein analysis.

A novel chemiluminescence (CL) immunosensor using functionalized tungsten disulfide nanosheets (WS2 NSs)–gold nanoparticles (Au NPs)–horseradish peroxidase (WS2–Au–HRP) as multiple signal amplification probe was developed for prostate specific antigen (PSA) analysis. The WS2–Au nanocomposites were synthesized by in situ growth of Au NPs on the surface of WS2 NSs. HRP and antibody for recognizing the target were subsequently functionalized on WS2–Au. Owing to the large loading capacity of the WS2 NSs, the WS2–Au–HRP nanoprobe exhibits synergistic enhancement to the luminol–H2O2 CL system. The kinetics and spectra of CL from the luminol–H2O2–WS2–Au–HRP system were studied and the CL mechanism is discussed. Exemplified by PSA as target, the ultrasensitive CL immunoassay of PSA was achieved owing to the multiple signal amplification of the WS2–Au–HRP nanoprobe. The detection limit is 3.0 × 10−14 g mL−1 with a linear range of 1.0 × 10−13 to 1.0 × 10−8 g mL−1. Furthermore, the method was applied to human serum sample analysis with high selectivity and reproducibility. The method provides a novel ultrasensitive CL detection tool for biomarkers in real samples.

Seasonal frozen soil accounts for about 53.50% of the land area in China. Frozen soil is a complex multiphase system where ice, water, soil, and air coexist. The distribution and migration of salts in frozen soil during soil freezing are notably different from those in unfrozen soil areas. However, little knowledge is available about the process and mechanisms of salt migration in frozen soil. This study explores the mechanisms of salt migration at the ice-liquid interface during the freezing of pore fluids through batch experiments. The results are as follows. The solute concentrations of liquid and solid phases at the ice-liquid interface ( C L * , C S * ) gradually increased at the initial stage of freezing and remained approximately constant at the middle stage. As the ice-liquid interface advanced toward the system boundary, the diffusion of the liquid phase was blocked but the ice phase continued rejecting salts. As a result, C L * and C S * rapidly increased at the final stage of freezing. The distribution characteristics of solutes in ice and the liquid phases before C L * and C S * became steady were mainly affected by the freezing temperature, initial concentrations, and particle-size distribution of media (quartz sand and kaolin). In detail, the lower the freezing temperature and the better the particle-size distribution of media, the higher the solute proportion in the ice phase at the initial stage of freezing. Meanwhile, the increase in concentration first promoted but then inhibited the increase of solutes in the ice phase. These results have insights and scientific significance for the tackling of climate change, the environmental protection of groundwater and soil, and infrastructure protection such as roads, among other things. © 2021 China Geology Editorial Office.

Potential-resolved electrochemiluminescence (ECL) ratiometric analysis has become a research hotspot in bioassays by virtue of its good accuracy, versatility and specificity. Current ECL ratiometry mainly focuses on the competition for the co-reactant or quantitative analysis using a variable signal and a changeless signal; the disorganized change or small difference between the two signals may affect the accuracy and sensitivity of detection. In this study, we have developed a novel ECL ratiometric sensor based on the bidirectional regulation of two independent co-reaction systems by H

Fluorescent adenine (A)-rich DNA-templated gold nanoclusters were demonstrated to be a novel probe for determination of biothiols (including cysteine, glutathione, and homocysteine). Fluorescence intensity of adenine-rich DNA-templated gold nanoclusters could be greatly quenched by Hg(II) ions through the formation of a gold nanoclusters-Hg(II) system. When biothiols (cysteine as the model) were introduced into the system, the fluorescence intensity recovered due to the formation of a more stable Hg(II)-thiol coordination complex using Hg-S metal-ligand bonds, which inhibited the Hg(II)-mediated fluorescence quenching of adenine-rich DNA-templated gold nanoclusters. Based on this fluorescence phenomenon, an on-off-on fluorescence strategy was designed for the sensitive determination of biothiols. The method allowed sensitive detection of cysteine with a linear detection range from 100 nM to 5 μM and a limit of detection of 30 nM. Additionally, the assay can be applied for detection of biothiol levels in human plasma samples. Therefore, it can provide a simple and rapid fluorescent platform for biothiol detection.

Photoactive materials with high photo-electron transfer efficiency and stable signal output hold a key role in constructing the photoelectrochemical (PEC) biosensing systems. In this study, the ternary CdS@Au-g-C3N4 heterojunction was first prepared and characterized, and its application in PEC bioanalysis was explored. The gold nanoparticles sandwiched between CdS and g-C3N4, acting as both plasmonic photosensitizer and electron relay, significantly boosted the light absorption and accelerated the charge transfer from g-C3N4 to CdS, both of which contributed to the enhancement of photoelectric conversion efficiency. Signal quenching with graphene oxide-CuS efficiently weakened the photocurrent from CdS@Au-g-C3N4. The combination of the excellent PEC properties of CdS@Au-g-C3N4 and the remarkable quenching effects of graphene oxide-CuS enabled construction of a sandwich-type PEC immunosensor for prostate specific antigen (PSA) detection. This immunosensor achieved sensitive PSA analysis by multiple signal amplification mechanisms, with a detection limit of 0.6 pg mL−1 and a wide linear range from 1.0 pg mL−1 to 10 ng mL−1. This work not only demonstrates the great potential of noble metal sandwiched ternary heterojunctions in the PEC field, but also lays a foundation for developing the general PEC immunoassays.

A series of heteronuclear group 5 metal-nickel carbonyls MNi(CO)7- (M = V, Nb, Ta) have been generated via a laser ablation ion source and studied by photoelectron velocity-map imaging spectroscopy. Quantum chemical calculations have been performed to probe the electronic and geometric structures and help to assign the spectra. The adiabatic detachment energies (ADEs) and vertical detachment energies (VDEs) are deduced from spectra to be 3.40/3.58, 3.34/3.55, 3.30/3.50 eV, which are consistent with quantum chemical computational results. The MNi(CO)7- (M = V, Nb, Ta) consists of three bridging carbonyls, one carbonyl terminally bonded to the Ni atom and three carbonyls terminally bonded to the M (M = V, Nb, Ta) atom. These geometries are different from homobinuclear Cr2(CO)7+, Ni2(CO)7+, Pd2(CO)7+, and Fe2(CO)7- and heterobinuclear CuFe(CO)7-, CoZn(CO)7+, and CO is largely activated by a bridging coordination mode. The experimental and theoretical results would provide important information to understand the chemisorbed CO molecules on alloy surfaces or interfaces, which is of great significance to elucidate CO molecule activation processes.

A potentiometric resolved photoelectrochemical (PEC) system based on CdS nanowires and SnNb2O6 nanosheets was developed. To prove the applicability of this system in PEC multi-biomarker analysis, a label free PEC immunosensor for two cardiac biomarkers, myoglobin and cardiac troponin I, was constructed.

Herein, a novel and facile dual-wavelength ratiometric electrochemiluminescence-resonance energy transfer (ECL-RET) sensor for hydrogen sulfide (H

Herein, a facile electrochemical sensor was proposed for accurate determination of theophylline (TP) based on dopamine-melanin nanosphere (DMN)–gold nanoparticles (AuNPs) nanocomposite-modified glass carbon electrode. The dopamine-melanin nanospheres (DMNs) were prepared facilely by a chemical route. The well-dispersed Au nanoparticles were anchored on the surface of DMNs via in situ reduction of Au precursor. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were adopted to investigate the electrochemical oxidation behavior of TP at the DMN-AuNPs-modified electrode. In 0.1 M H2SO4 medium, the developed electrochemical sensor displayed excellent electrocatalytic activity toward the oxidation of TP. The sensor showed high sensitivity for the determination of TP under the optimized conditions. The oxidation peak current of TP exhibited good linear relationship with its concentration in the range from 50 nM to 2 μM with detection limit of 9.6 nM (S/N = 3). The modified electrode showed excellent selectivity, long-term stability, and good repeatability for the determination of TP. This proposed method was successfully applied to determine the content of TP in tea and biological samples with acceptable recoveries.

For real-time evaluation of the cell behavior and function under in vivo-like 3D environment, the 3D functionalized scaffolds simultaneously integrate the function of 3D cell culture, and electrochemical sensing is a convincing candidate. Herein, Fe

A simple and highly selective fluorescence biosensor has been exploited for p-nitrophenol (p-NP) and alkaline phosphatase (ALP) activity detection based on the glutathione-stabilized copper nanoclusters (GSH-CuNCs) mediated-inner filter effect (IFE). The GSH-CuNCs were prepared by employing GSH as stabilizer and ascorbic acid (AA) as reductant. The obtained GSH-CuNCs exhibited a strong blue fluorescence emission at 420 nm with an excitation wavelength of 365 nm, which overlapped largely with the absorption spectra of p-nitrophenol (p-NP). Therefore, the luminescence of GSH-CuNCs could be quenched by p-NP through inner filter effect. In addition, ALP catalyzed the substrate p-nitrophenyl phosphate (p-NPP) to form p-nitrophenol (p-NP), which also leading to the fluorescence quenching of GSH-CuNCs. The fluorescent strategy was realized for the sensitive determination of p-NP and ALP activity with the promising limit of detection of 20 nM (for p-NP) and 0.003 mU⋅mL

The photoelectrochemical (PEC) self-powered system has attracted great attention in disease detection. The determination of a simple and efficient approach for disease-related biomarkers is highly interesting and appealing. Herein, an ingenious visible light-induced membraneless self-powered PEC biosensing platform was constructed, integrating a signal amplification strategy for ultrasensitive split-type PEC bioanalysis. The system was comprised of a Bi

A novel nitrogen and sulfur co-doped carbon dots (NS-CDs)-H2O2 chemiluminescence (CL) system was developed to detect carcinoembryonic antigen (CEA) by taking advantage of dual-signal amplification of functional Au@Ag nanoparticles (NPs) nanoprobes. Horseradish peroxidase (HRP) and the complementary DNA were co-immobilized onto Au@Ag NPs surface to shape the functional nanoprobes (HRP-Au@Ag-cDNA) for signal amplification. In this proposal, HRP-Au@Ag-cDNA was specifically hybridized with CEA aptamer-functionalized magnetic beads to form the double-strand hybridization nanocomposites (HRP-Au@Ag-dsDNA-MB). Upon the addition of CEA, the CEA aptamer preferred to bind with CEA instead of double-strand hybridization interaction, thus HRP-Au@Ag-dsDNA-MB was dehybridized and the HRP-Au@Ag-cDNA nanoprobe was released. The synergistic catalytic effects of HRP and Au @Ag NPs endow the nanoprobe producing a dual CL signal amplification in the NS-CDs-H2O2 CL system. The CL intensity of the developed strategy enhanced with CEA concentration increasing in the range of 0.3–80 ng mL−1. Benefiting from the synergistic effect, a detection limit as low as 94 pg mL−1 was obtained. Moreover, successful application of this CL sensing platform was achieved for the determination of CEA in human serum samples, demonstrating the promising prospect in the early tumor warning and therapeutic monitoring.

A rapid and label-free fluorescence sensing strategy has been established for the sensitive determination of melamine (MA) on the basis of poly(adenine) (poly (A))-templated Au nanoclusters (AuNCs). The poly(A)-templated AuNCs possessed excellent luminescence and photo-stability. In the presence of Hg2+, the luminescence of AuNCs was quenched by Hg2+ through the metallophilic interactions between Au+ and Hg2+. When melamine was introduced, the fluorescence intensity of sensing system could be recovered. There was a greater coordination interaction between Hg2+ and melamine, which blocked the Hg2+-mediated fluorescence quenching of AuNCs. The assay allowed sensitive determination of melamine with a linear detection range from 50 nM to 100 μM. The limit of detection was as low as 16.6 nM. Furthermore, the label-free strategy was successfully employed for the detection of melamine concentration in real samples.

The fluorescence intensity of poly(adenine) DNA-templated gold nanoclusters was shown to be significantly quenched by N-acetylcysteine through the formation of the Au-S metal-ligand bonds. On the b...

The energy transfer efficiency, strongly depending on the distance of donor–acceptor pair, is always a crucial factor for the construction of elegant electrochemiluminescence resonance energy transfer (ECL-RET)-based biosensors. In this paper, a novel and efficient ECL-RET in 2D/2D heterostructured g-C3N4/MnO2 was developed using g-C3N4 nanosheets (g-C3N4 NSs) as energy donor and MnO2 nanosheets (MnO2 NSs) as energy acceptor. In this system, MnO2 NSs in-situ grew on g-C3N4 NSs to form the 2D/2D heterostructure, greatly shortening the distance of the donor–acceptor pair (g-C3N4–MnO2) and thus greatly enhancing the RET efficiency. To demonstrate the performance of the system, a signal “off-on” ECL sensor was designed for glutathione (GSH) analysis. In the absence of GSH, MnO2 significantly quenched the ECL intensity of g-C3N4 owing to ECL-RET in this 2D/2D g-C3N4/MnO2 heterostructure (ECL signal “off”). Upon the addition of GSH, MnO2 was reduced to Mn2+ by GSH and g-C3N4 was released from the heterostructured g-C3N4/MnO2, generating a recovery of ECL intensity (ECL signal “on”). Under the optimal conditions, the designed ECL-RET signal “off-on” sensor realized the sensitive detection of GSH ranged from 0.2–100 μM with the detection limit of 0.05 μM. Furthermore, the as-prepared ECL-RET sensor exhibits good performance in the determination of GSH in human serum samples. The ECL-RET in 2D/2D heterostructure provides an ingenious way for the exploitation of novel ECL biosensing systems.

A series of Cu2O crystals with well–controlled cubic (C–Cu2O), star–shaped (S–Cu2O), and octahedral (O–Cu2O) structures were prepared by facile wet chemical method to explore the morphology–dependent electrocatalytic efficiency. When tested for the sensing of 4−aminophenol (4–AP), 4−chlorophenol (4–CP), and 4−nitrophenol (4–NP), it was found that the O–Cu2O exhibited the best current signals, which were mainly because of its more exposed {111} facets and higher surface area. Further, O–Cu2O crystals were homogeneously dispersed on graphene oxide (GO) surface to achieve a hierarchical reinforcement structure. The electrode modified by O–Cu2O@GO showed high electrocatalytic activity toward the oxidation of 4–AP, 4–CP, and 4–NP, and could realize the selective detection of phenolic compounds in ternary electrolyte solutions and industrial wastewater. This work is beneficial to morphology tailoring and provides novel way to improve the electrochemical property of oxide–based catalysts as the promising applications in electrochemical sensors.

Herein we report an effective Ru(NH3)63+/Ru(NH3)62+-mediated photoelectrochemical-chemical-chemical (PECCC) redox cycling amplification (RCA) strategy toward enhanced triple signal amplification for advanced split-type PEC immunoassay application. Specifically, alkaline phosphatase (ALP) label was confined via a sandwich immunorecognition to convert 4-aminophenyl phosphate to the signal reporter 4-aminophenol (AP), which was then directed to interact with Ru(NH3)62+ as a redox mediator and tris (2-carboxyethyl) phosphine (TCEP) as reducing agent in the detection buffer. Upon illumination, the system was then operated upon the oxidation of Ru(NH3)62+ by the photogenerated holes on the Bi2S3/BiVO4 photoelectrode, starting the chain reaction in which the Ru(NH3)62+ was regenerated by Ru(NH3)63+-enabled oxidization of AP to p-quinoneimine, which was simultaneously recovered by TCEP. Exemplified by interleukin-6 (IL-6) as the analyte, the Ru(NH3)63+/Ru(NH3)62+-mediated, AP-involved PECCC RCA coupled with ALP e...

Water splitting into hydrogen (H2) to produce clean energy is of great significance for sustainable development. Transition metal phosphides (e.g., Ni12P5 nanoparticles) may be used as non-precious earth-abundant electrocatalysts for the H2 evolution reaction, but their poor electronic conductivity and small surface area hinder efficient catalytic H2 production. In this research, we demonstrate for the first time the facile synthesis of porous carbon/Ni12P5 (C/NiP-C) composites with the dispersion of Ni12P5 nanoparticles onto a conductive porous carbon support in an ionic surfactant hexadecyl trimethyl ammonium bromide (CTAB)-mediated ethanol solution. The CTAB plays dual roles in the synthesis including (1) the introduction of carbon to increase the conductivity of the synthetic materials and (2) the formation of uniform Ni12P5 phosphides through the interaction between the H2PO2− anion, Ni2+, and C19H42N+ cation dissociated from CTAB. The obtained C/NiP-C composites may function as electrocatalysts for the hydrogen evolution reaction (HER) with excellent HER performance (η: 63 mV, η10: 176 mV, Tafel slope: 100 mV dec−1, wherein η represents the onset overpotential and η10 represents the overpotential required for a current density (j) value of −10 mA cm−2) compared with the NixPy composites synthesized in pure ethanol (η: 160 mV, η10: 392 mV, Tafel slope: 154 mV dec−1), the C/NiP-P composites synthesized in a P123-mediated ethanol solution (η: 75 mV, η10: 286 mV, Tafel slope: 210 mV dec−1), and the C/NiP-F composites synthesized in a F127-mediated ethanol solution (η: 80 mV, η10: 302 mV, Tafel slope: 189 mV dec−1). The enhanced HER performance can be attributed to the synergistic effects resulting from the unique structure of the porous C support and the well dispersed Ni12P5 nanoparticles.

The work is mainly to study the thermal stability including the phase stability, microstructure and tribo-mechanical properties of the AlB2-type WB2 and W–B–N (5.6 at.% N) films annealed in vacuum at various temperatures, which are deposited on Si and GY8 substrates by magnetron sputtering. For the WB2 and W–B–N films deposited on Si wafers, as the annealing temperature increases from 700 to 1000 °C, a-WB (700 °C) and Mo2B5-type WB2 (1000 °C) are successively observed in the AlB2-type WB2 films, which show many cracks at the temperature ≥ 800 °C resulting in the performance failure; by contrast, only slight α-WB is observed at 1000 °C in the W–B–N films due to the stabilization effect of a-BN phase, and the hardness increases to 34.1 GPa first due to the improved crystallinity and then decreases to 31.5 GPa ascribed to the formation of α-WB. For the WB2 and the W–B–N films deposited on WC–Co substrates, both the WB2 and W–B–N films react with the YG8 (WC–Co) substrates leading to the formation of CoWB, CoW2B2 and CoW3B3 with the annealing temperature increasing to 900 °C; a large number of linear cracks occur on the surface of these two films annealed at ≥ 800 °C leading to the film failure; after vacuum annealing at 700 °C, the friction performance of the W–B–N films is higher than that of the deposited W–B–N films, while the wear resistance of the WB2 films shows a slight decrease compared with that of the deposited WB2 films.

A novel fluorescence (FL) immunosensor for prostate-specific antigen (PSA) detection was developed based on the Forster resonance energy transfer (FRET) between nitrogen and sulfur co-doped carbon dot functionalized silica nanospheres (Si/NS-CDs) and Au@Ag NPs. The strategy utilized the PSA primary antibody labeled luminescent Si/NS-CDs as donors and PSA secondary antibody labeled Au@Ag NPs as acceptors. In the presence of PSA, the bio-affinity of the antigen and antibody caused the Si/NS-CDs and Au@Ag NPs to approach at a close enough distance for the FL intensity of the Si/NS-CDs to decline owing to the FRET effect. By virtue of the excellent optical properties of the Si/NS-CDs nanoprobe, the quantitative analysis of PSA has been successfully realized using both FL spectroscopy and a naked-eye readout. The fluorometric results present the desirable analytical performance for PSA detection in the range from 5.0 pg mL−1 to 10 ng mL−1 with a detection limit of 0.95 pg mL−1 (S/N = 3). Moreover, satisfactory results for the determination of the PSA target in samples of human serum were obtained, showing the great promise of the method for application in biochemical analysis.

The oxygen evolution reaction (OER) is a key process in water splitting, rechargeable metal–air batteries and fuel cells, and the design of highly efficient, stable and non-noble metal-based electrocatalysts for the OER remains a great challenge so far. Here, we report the rational design and synthesis of hierarchical ultrathin nanosheet-based CoOOH hollow nanospheres with rich oxygen vacancies using a room-temperature self-template strategy with organic–inorganic hybrid Pi-Co-glycerate hollow nanospheres as the templates. The anions (H2PO2−) in the templates enable the proceeding of anion-exchange reaction at room temperature, and the resultant unique structural features (i.e., ultrathin thickness, rich oxygen vacancies and central void space) endow the CoOOH hollow nanospheres with excellent performance in the electrocatalytic OER. The obtained CoOOH hollow nanospheres exhibit a Tafel slope of 49 mV dec−1 and a low overpotential of 275 mV at the current density of 10 mA cm−2, superior to the γ-CoOOH nanosheets with an overpotential of 304 mV and the bare Ni foam with an overpotential of 362 mV at the same current density. Importantly, these CoOOH hollow nanospheres possess the lowest overpotential of 340 mV at the current density of 200 mA cm−2 among the reported Co-based nanomaterials (370–770 mV). This research proposes a new chemical conversion mechanism and provides a new approach for the fabrication of hollow nanomaterials at room temperature, facilitating the development of efficient OER catalysts.

A spatial-resolved electrochemiluminescence (ECL) aptasensing platform for sensitive protein detection was constructed in a double-check mode. CdS-C composites as cathodic ECL emitters and luminol-gold nanoparticles (L-Au NPs) as anodic ECL emitters were immobilized on working electrode 1 (WE1) and working electrode 2 (WE2) of the dual-disk glassy carbon electrodes (DDCE), respectively. The platform was designed by integrating silver-polyamidoamine NCs-labeled biotin-aptamer (Ag-PAMAM-bio-Apt) with the ECL emitters on the DDCE. The in-situ consumption of co-reactants in the ECL system by Ag-PAMAM NCs resulted in the great ECL quenching on both WE1 and WE2. The resonance energy transfer between L-Au NPs and Ag-PAMAM NCs made the ECL on WE2 further decrease. In the presence of carcinoembryonic antigen (CEA), portions of Ag-PAMAM-bio-Apt detached from the DDCE because of the competitive reaction of CEA and cDNA toward to Ag-PAMAM-bio-Apt, generating an enhancement of ECL intensity. This strategy achieves the detection of CEA in a double-check mode with detection limits of 0.39 pg mL−1 for the cathodic assay (WE1) and 0.20 pg mL−1 for the anodic assay (WE2), respectively. Furthermore, the proposed method had been successfully applied to determine CEA in human serum sample with recoveries of 80.0–110.0%, showing great potential in cancer diagnosis.

Here, we report a three-dimensional (3D) network molecularly imprinted polymer (MIP) on electrode surface to achieve an efficient and specific detection of theophylline in foodstuffs, using theophylline as the template molecule, mesoporous silica nanospheres (MSNs) as the signal transducer to shuttle electrons, and both phenyltriethoxysilane and pyrrole as functional monomers. The electron microscope images reveal the presence of well-distributed hierarchically MSNs with a pomegranate-like morphology, topped with MIP uniform layer. Electrochemical characterizations were carried out to monitor the properties of the resulting sensing platform based on the MIP/gate effect employing hexacyanoferrate molecules as the electrochemical probe. The data show that due to the high conductivity and electron transfer ability of the prepared theophylline-imprinted membrane, this method exhibits excellent sensitivity and binding affinity with a linear dynamic concentration range in excess of six orders of magnitude and low detection limit (0.66 nM), meeting the requirements of theophylline trace analysis.

An interesting phenomenon is described that the fluorescence signal of poly(adenine) (A) DNA-templated gold nanoclusters (AuNCs) is greatly improved in the presence of L-histidine by means of L-histidine-DNA interaction. The modified nanoclusters display strong fluorescence emission with excitation/emission maxima at 290/475 nm. The fluorescence quantum yield (QY) is improved from 1.9 to 6.5%. Fluorescence enhancement is mainly ascribed to the L-histidine-DNA interaction leading to conformational changes of the poly(A) DNA template, which offer a better microenvironment to protect AuNCs. The assay enables L-histidine to be determined with good sensitivity and a linear response that covers the 1 to 50 nM L-histidine concentration range with a 0.3 nM limit of detection. The proposed method has been applied to the determination of imidazole-containing drugs in pharmaceutical samples. A turn-on fluorescent method has been designed for the sensitive detection of L-histidine as well as imidazole-containing drugs on the basis of the L-histidine-DNA interaction.