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Nowadays, aggregation quenching of most organic photosensitizers in aqueous media seriously restricts analytical and biomedical applications of photoelectrochemical (PEC) sensors. In this work, an aggregation-enhanced PEC photosensitizer was prepared by electrostatically bonding protoporphyrin IX (PPIX) with an ionic liquid of 1-butyl-3-methylimidazole tetrafluoroborate ([BMIm][BF

COFs were grafted with ABEI and applied for building a label-free ECL biosensor for cyt c detection.

Heterometallic nanomaterials (HMNMs) display superior physicochemical properties and stability to monometallic counterparts, accompanied by wider applications in the fields of catalysis, sensing, imaging, and therapy due to synergistic effects between multi-metals in HMNMs. So far, most reviews have mainly concentrated on introduction of their preparation approaches, morphology control and applications in catalysis, assay of heavy metal ions, and antimicrobial activity. Therefore, it is very important to summarize the latest investigations of activity modulation of HMNMs and their recent applications in sensing, imaging and therapy. Taking the above into consideration, we briefly underline appealing chemical/physical properties of HMNMs chiefly tailored through the sizes, shapes, compositions, structures and surface modification. Then, we particularly emphasize their widespread applications in sensing of targets (

Nowadays, continuous efforts have been devoted to searching highly efficient electrochemiluminescence (ECL) emitters for applications in clinical diagnosis and food safety. In this work, triazinyl-based hydrogen bond organic frameworks (Tr-HOFs) were synthesized by N···H hydrogen bond self-assembly aggregation, where 6,6'-(1,4-phenylene)bis(1,3,5-triazine-2,4-diamine) (phenyDAT) was prepared

In this work, metal–organic frameworks (MOFs) are utilized as effective ECL coreactant accelerator to enhance the ECL responses of N-(aminobutyl)-N-(ethylisoluminol) (ABEI). Zn-based MOFs (MOF-Zn-1) were prepared by chelating Zn ions with melamine and thiophenedicarboxylic acid (TPDA), which observably accelerated the electrocatalytic oxidation of tripropylamine (TPA). Then, ABEI-MOF-Zn-1 as a high-performance ECL emitter was synthesized via an amide reaction between ABEI and mercaptopropionic acid (MPA) modified MOF-Zn-1. Strikingly, the ABEI-MOF-Zn-1 showed the 18-fold increase in the ECL signals relative to pure ABEI by using TPA as a coreactant. Moreover, ferrocene (Fc) as a quencher was first linked with capture DNA (cDNA), and then used to modify the ABEI-MOF-Zn-1, thereby constructing a label-free ECL biosensor. After the linkage between chloramphenicol (CAP) and aptamer DNA (aptDNA), the ECL response was definitely recovered by releasing L-DNA from double-stranded DNA (dsDNA, hybridization of aptDNA and L-DNA). The resultant sensor showed a wide linear range of 1.00 nM–0.10 mM (R2 = 0.99) and a low limit of detection (LOD) down to 0.11 nM for detecting CAP. This work developed a novel pattern to design an efficient ECL enhanced emitter, coupled by expanding its potential applications in clinical diagnosis.

Exploring advanced nanocatalysts are of importance for hydrogen evolution reaction (HER) in alkaline electrolyte (e.g. 1.0 M KOH). Herein, porous iridium-palladium-plumbum wire-like nanonetworks (IrPdPb WNNs) were prepared by a facile one-pot aqueous method with octylphenoxypolyethoxyethanol (NP-40) as the structure-director. The resultant IrPdPb WNNs exhibited superior HER performance in the alkaline electrolyte, such as ultra-low overpotential (21 mV) to drive a current density of 10 mA cm−2, small Tafel slope (66 mV dec−1), and high exchange current density (4.87 mA cm−2), surpassing commercial Pt/C. This study provides a simple strategy for synthesis of advanced multi-metallic electrocatalysts in energy storage and conversion.

Development of ultra-sensitive and high specific aptasensors is important for early diagnosis of prostate cancer. Herein, ultrasensitive detection of prostate specific antigen (PSA) aptasensor was realized based on the “on-off-on” model via fluorescence (FL) covalent energy transfer between g-C3N4 quantum dot (g-CNQDs) and palladium triangular plates (Pd TPs). Specifically, the Pd TPs were primarily linked with PSA aptamer (PA) as the reporter probe, followed by attaching them onto the g-CNQDs surfaces, causing the highly enlarged FL quenching rate (ca. 75%). After the introduction of PSA, the FL intensities recovered again because of the distinctively stronger affinity of PA to PSA than that of g-CNQDs. The bond of pyridine N with Pd was identified as efficient energy transfer pathway through the X-ray photoelectron spectroscopy (XPS) and FL measurements. The surface plasmon resonance (SPR) experiments certified the remarkably different affinity of PA towards g-CNQDs and PSA. The as-constructed FL aptasensor can accurately quantify PSA with wide linear range of 10 pg mL−1-50 ng mL−1 and ultra-low limit of detection (LOD, 4.2 pg mL−1), indicating the promising applications in clinical assay and biological detection.

A biomimetic assembly of per-O-methylated-cyclodextrin dimer with cobalt proto-porphyrin (CoIII-PPIX@Py2CD) was achieved via covalent linkage between CoIII of CoIII-PPIX and pyridine N of Py2CD (primarily synthesized by the acyl chlorination reaction of two β-CDs monomers with 3,5-bis (bromomethyl) pyridine). Ultraviolet–visible (UV–vis) and circular dichroism (CD) absorption spectroscopy, and NMR hydrogen spectroscopy (H1-NMR) were adopted to carefully characterize the structure of Py2CD and its functional assembly with CoIII-PPIX. X-ray photoelectron spectroscopy (XPS) was employed to affirm the binding of the as-obtained CoIII-PPIX@Py2CD, whose electrochemical kinetics were extensively studied to validate the feasibility in the catalytic reduction of hydrogen peroxide (H2O2). The developed sensor displayed the wide linear range for H2O2 detection and the low detection limit of 2.47 × 10−7 M. This work sheds some constructive lights on rational design and synthesis of preeminently biomimic carrier and high cost-effectiveness catalyst for (bio)analytical applications.

Zinc ions (Zn2+) act as a transcription factor in eukaryotic cells for mediating protein-protein interactions in human healthy. The simple and sensitive detection of Zn2+ is the crucial mission in analytical field. This work demonstrated a novel and fast Zn2+ detection strategy based on “signal on” mode with electrochemiluminescence (ECL) luminophore, in which singlet oxygen was generated via electrocatalytic reduction of zinc proto-porphyrin IX grafted onto Pd nanocubes (ZnPPIX-Pd NCs). In protocol, Pd NCs were synthetized under hydrothermal conditions and aminated through thermal oxidative polymerization of 3-aminopropyltriethoxysilane (APTES), followed by further linking with PPIX via amide reaction. The resulting PPIX-Pd NCs effectively captured Zn2+ in chelation and monitored by Fourier transform infrared (FTIR) spectroscopy and ultraviolet-visible (UV-vis) absorption spectroscopy. By virtue of the metal resonance responses of Pd NCs, an intense monochromic, potential shuffling and enhanced ECL irradiation shows up for the hybrid nanocomposite with H2O2 as the coreactant. To this end, an ultrasensitive method based on the nanocomposite with a “signal-on” model was developed for Zn2+ detection with a low detection limit down to 0.38 nM (based on a S/N= 3), excellent precision and high stability. The ECL strategy reveals the potential application in molecular diagnosis and offers a new avenue for bioassay of structural Zn(II) proteins and zinc finger-binding nucleotides.

Aptamer-based bioassay of biomarker has broad applications in clinical research and disease diagnosis. In this work, a label-free aptamer biosensor for ultrasensitive thrombin (TB) detection was constructed based on highly enhanced electrochemiluminescence (ECL) of functional palladium nanocones (Pd NCs) with tripropylamine (TPA) system. Herein, well-defined Pd NCs were initially functionalized by mercaptoethanol (MCH) as an ECL emitter and immobilized onto the glassy carbon electrode (GCE) initially grafted with amine-terminated polyamidoamine (PAMAM) via electro-oxidation reaction. Under optimal conditions, the ECL intensity of the Pd NCs/TPA system was about 2.5 times enhancement when compared to that of bare GCE. The ECL and cyclic voltammetry (CV) were synchronously employed to illustrate the enhanced ECL mechanism. By virtue of the linkage of the modified Pd NCs with specified TB aptamer (TBA) containing sulfydryl group, a label-free ECL detection platform was designed. After full coverage of the nonspecific sites with bovine serum albumin (BSA), an ECL biosensor for TB detection was constructed by taking the advantage of the steric hindrance effects, showing the wider linear range, lower detection limit of TB (even down to 6.76 fM), superb selectivity and stability. The current strategy provides a highly sensitive platform for detection of various biomolecules in bioanalysis.

Herein, rhombic dodecahedral Cu3Pt nanoframes (Cu3Pt NFs) were prepared via solvothermal strategy using theobromine as the reductant and structure-directing agent, coupled with cetyltrimethylammonium chloride (CTAC) as the co-structure-director. The samples showed dramatically boosted catalytic performance for oxygen reduction reaction (ORR), owing to their highly open structures with enlarged specific surface areas. Using Cu3Pt NFs catalyzed ORR as signal amplification platform, a novel electrochemical immunosensor was constructed to monitor alpha-fetoprotein (AFP). The as-fabricated immunosensor displayed a wide linear range of 0.1–104 pg mL–1 and a low detection limit of 0.033 pg mL–1.

A novel sandwich-like immunosensor was efficiently fabricated for detection of carcinoembryonic antigen (CEA) with three dimensional sea-urchin-like PdAuCu nanocrystals (PdAuCu NCs)/ferrocene-grafted-polylysine (Fc-g-PLL) as the label of secondary antibodies (Ab2) and Au nanoparticles (Au NPs) as the substrate material. Herein, PdAuCu NCs were directly synthesized with polyethylene oxide (PEO) as a growth-directing agent by a facile one-step aqueous method without any organic solvent. Meanwhile, Fc-g-PLL was obtained by covalent linkage of Fc with PLL via Schiff-base reaction. The well-dispersed PdAuCu NCs by Fc-g-PLL have the enlarged surface area, enhanced catalytic properties and superior biocompatibility to amplify the current signals. The resultant immunosensor shows linear relationship of the electrochemical responses with the CEA concentrations within a broader linear range (0.001–100.0 ng mL–1) and a lower detection limit (0.23 pg mL–1, S/N = 3). Furthermore, the immunosensor was explored for practical assay of CEA in human serum samples with accredited results. The novel immunoassay provides a feasible platform for early medical diagnosis.

In this work, metal-organic frameworks (MOFs) are utilized as effective ECL coreactant accelerator to enhance the ECL responses of

Electrochemiluminescence (ECL) has attracted significant interest because of its superior properties and potential applications in bioanalysis, and therefore many luminescent nanomaterials have been developed. Herein, well-defined Pd nanocones (Pd NCs) were facilely obtained by a one-pot hydrothermal method with poly- l -lysine (PLL) as a green protecting ligand, which were mainly characterized by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Then, the as-obtained Pd NCs were first explored as an anodic ECL emitter, where tripropylamine (TPA) worked as the coreactant to boost the ECL emission. The possible ECL mechanism of Pd NCs/TPA system was extensively explored by ECL and electrochemical techniques. Briefly, the ECL emission underwent the oxidation-reduction route, in which both Pd NCs and TPA were initially oxidized, and then the oxidized TPA lost an proton to form reducing agent (TPA·) strongly reacted with the oxidized Pd NCs generating Pd NCs* for the emission. Furthermore, using dopamine (DA) as an ECL quencher, an ultrasensitive sensor was constructed for DA detection. The fabricated ECL sensor shows high sensitivity and selectivity, good stability, and wide linear range with the low detection limit of 0.46 pM. It offers a new avenue to exploit ECL illuminant and enriches the ECL emission theory.

Herein, a novel electrochemical ultrasensitive immunosensor was designed for detecting prostate-specific antigen (PSA) with three-dimensional (3D) PtCu hollow nanoframes (PtCu HNFs) as signal amplification. The highly opened PtCu HNFs were synthesized by a one-pot solvothermal method with cetyltrimethylammonium chloride (CTAC) and trishydroxymethyl aminomethane (Tris) as co-structuring directors. The architectures enlarged the loading of prostate specific antibodies (Ab) and efficiently catalyzed hydrogen peroxide (H2O2) reaction, ultimately amplifying the signals. And polylysine was used to disperse PtCu HNFs, improve the biocompatibility and bind the Ab on the electrode surface. The fabricated immunosensor exhibited lower detection limit (0.003 ng mL–1, S/N = 3), and wider linear range (0.01–100.0 ng mL–1), along with the improved reproducibility, selectivity and stability for the assay of PSA. Thus, it is a desirable platform for PSA detection in clinical diagnosis and practical applications.

It is a main challenge to synthesize highly efficient and durable nanocatalysts towards hydrogen evolution reaction (HER) and alcohol oxidation reaction in energy conversion and storage. Herein, a green wet-chemical approach was developed to directly prepare hollow Ag44Pt56 nanotube bundles (H-Ag44Pt56 NTBs), utilizing 5-azacytosine as a structure-directing agent. The obtained electrocatalyst displayed superior catalytic activity and durability for HER in acid media, and the great improvement in catalytic performance for ethylene glycol oxidation reaction (EGOR) in the alkaline electrolyte, outperforming home-made Ag34Pt66 nanoparticles (NPs), Ag70Pt30 NPs, and commercial Pt/C catalysts. The high electrocatalytic characters are mainly attributed to the special nanostructures and the synergetic effects between the bimetals.

Herein, well-defined hollow dendritic AuPtAg alloyed nanocrystals (ANCs) were synthesized by a simple L-proline-mediated one-pot aqueous method. More importantly, the synthesized hollow dendritic architectures provide a suitable platform for immobilization of anti-prostate specific antigen (PSA). The resultant label-free immunosensor exhibited the improved performance for highly sensitive detection of PSA based on the enhanced catalytic currents of K3[Fe(CN)6] as a signal probe. Impressively, the immunosensor showed the wide linear range of 0.05–50 ng mL–1 and low detection limit of 0.017 ng mL–1 under optimal conditions for the assay of PSA, couple with the improved stability, reproducibility and selectivity. It provides a promising platform for clinical research and diagnosis.

To realize the efficient and complete removal of organic pollutants in waste water, it is highly urgent for scalable synthesis of either self-supported bimetallic nanocatalysts or anchored on carbon-based materials. In this study, a simple one-pot coreduction method was developed for preparing well-dispersed AgPd alloyed nanoclusters uniformly dispersed on reduced graphene oxide (AgPd NCs/rGO) at room temperature by utilizing 5-azacytosine as the capping agent. The nanocomposites were characterized by a set of physical characterizations. The formation mechanism and catalytic mechanism were discussed in some details. Moreover, the prepared AgPd NCs/rGO exhibited dramatically increased catalytic properties towards the reduction of 4-nitrophenol (4-NP) in the presence of NaBH4 when compared to commercial Pd/C (20 wt.%).

Herein, self-supported hierarchical AuPd alloyed interconnected nanowire networks (AuPd NCNs) were fabricated by a one-pot co-reduction method. Theophylline was acted as the capping and structure-directing agents. The product was mainly characterized by a series of techniques such as transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The hierarchical nanostructures had the enlarged electrochemically active surface area (EASA), and the enhanced catalytic activity toward formic acid oxidation reaction (FAOR) and strengthened poisoning tolerance for poisoning CO-like intermediates by cyclic voltammetry and chronoamperometry, which outperformed commercial Pd black catalyst. This strategy supplies a simple and general method for mass preparation of AuPd NCNs with potential applications in fuel cells.

Mucin-1, an essential transmembrane glycoprotein, was regarded as a promising biomarker for colon, breast, ovarian and lung cancers. Thus, its highly sensitive and selective detection is important to develop new analytical strategies. In this work, Zn-based metal organic frameworks with pyridine (Zn-Bp-MOFs) were synthetized via coordination to enhance the ECL responses of zinc meso-tetra(4-sulfonatophenyl) porphine (Zn-TP). The synthesized Zn-Bp-MOFs substantially accelerated the electrocatalytic reduction of K2S2O8 and excited electron amount of Zn-TP. For that, the Zn-TP linked Zn-Bp-MOFs (terminated as Zn-TP@Zn-Bp-MOFs) displayed 32-fold magnification in the ECL efficiency relative to free Zn-TP. By assembly of capture DNA (cDNA), functional luminophore effectively captured the released linked DNA (L-DNA) from double-stranded DNA (dsDNA, hybridization of aptamer DNA (aptDNA) and L-DNA) via the strong interactions between the aptDNA and mucin-1. Consequently, thionine was implanted into the groove of newly-formed dsDNA and severely quenched the ECL intensity of the emitter. The resulting biosensor showed wide linear range from 1 pg mL-1 to 10 ng mL-1 with a limit of detection (LOD) as low as 0.23 pg mL-1. Hence, such MOFs hold substantial promise to broaden their applications in photoelectric detection field.

Nowadays, brain natriuretic peptide (BNP-32) is fundamental to early cardiovascular clinical diagnosis, whose accurate assay is of significance by photoelectrochemistry (PEC) for the low background and high precision. Herein, a novel enhanced PEC platform was built by successive deposition of N-doped ZnO nanopolyhedra (N–ZnO NP) and protoporphyrin IX (PPIX). Specifically, the N–ZnO NP with a narrow bandgap of 2.60 eV was synthesized by direct calcination of zeolitic imidazole framework-8 (ZIF-8), and performed as the substrate to enhance the photocurrents of PPIX (as photosensitizer) whose photoelectron transfer pathway and enhanced PEC mechanism were studied in detail. Under such foundation, a label-free PEC aptasensor was developed by deposition of DNA aptamer onto the PEC platform and then ultrasensitive assay of BNP-32 based on a “signal off” model. The biosensor showed a wide linear range (1 pg mL−1- 0.1 μg mL−1) with a limit of detection (LOD) as low as 0.14 pg mL−1. This doping technique of ZnO nanomaterials provides some valuable guidelines for synthesis of advanced PEC probes in bioanalysis.

The robust and strong electrochemiluminescence (ECL) emission of organic emitters in an aqueous solution is crucial for expanding their applications in early diagnosis. Herein, a Zn porphyrin-based metal–organic framework ((Zn)porphMOF) was facilely obtained by chelating Zn(II)meso-tetra (4-sulfonatophenyl) porphine (Zn-TSPP) with Zn ions, showing substantially enhanced ECL radiation with K2S2O8 as the coreactant via the “reduction-oxidation” route in aqueous media. In contrast with Zn-TSPP, (Zn)porphMOF displayed 22-fold increase in the ECL intensity because of the agglomeration effect. By virtue of the dramatic confinement towards the energy and electron transfer of ascorbic acid (AA) during the ECL process, an ultrasensitive biosensor was developed with a wide linear range (3.77 to 26.4 μM) and ultra-low detection limit of 0.29 μM at 3 times of the signal-to-noise ratio (3S/N). This work offers a feasible avenue to harvest the steady and boosted ECL responses of organic molecules in aqueous media, also greatly expanding the MOF applications in bioanalysis.

Novel and distinct enhancement in electrochemiluminescence (ECL) signals of advanced organic luminophores are of importance for expanding their applications in early diagnosis. This work reported the construction of an ultrasensitive label-free ECL aptasensor for thrombin (TB) detection by grafting zinc proto-porphyrin IX (ZnP) onto an aminated zeolitic imidazole framework-8 (defined as ZnP-NH-ZIF-8 for clarity) as the luminophore. The structure and optical properties of the resulting ZnP-NH-ZIF-8 were carefully characterized. For that, there appeared to be weak ECL radiation for ZnP in dichloromethane (DCM) containing tetra-n-butylammonium perchlorate (TBAP) because of the as-formed singlet-state oxygen via the "reduction-oxidation" route. More notably, the ECL signals display 153-times enhancement for ZnP-NH-ZIF-8, thanks to the excellent catalytic kinetics for the oxygen reduction reaction (ORR). By virtue of the specific interactions of the TB aptamer (TBA) with the TB protein and the highly efficient catalysis of the ZnP-NH-ZIF-8 for ORR, the as-prepared aptasensor showed a wider linear range (0.1 fM∼1 pM) and a lower detection limit (ca. 58.6 aM). This work provides some useful guidelines for synthesis of an advanced organic luminophore with largely boosted ECL signals in ultrasensitive analysis and clinical diagnosis.

A biomimetic assembly of per-O-methylated-cyclodextrin dimer with cobalt proto-porphyrin (Co

By integrating the amplified electrochemical signals and effective capture of antibodies together, advanced multimetallic superstructured nanocrystals endow label-free immunosensors promising applications in early diagnosis and monitoring of diseases. Herein, four-metallic PtCoCuPd hierarchical branch-like tripods (HBTPs) were directly synthesized by a green one-pot aqueous method without any seed or organic solvent involved, which were applied to construct a novel label-free immunosensor for detecting cardiac troponin I (cTnI). The specific hierarchical micro/nanostructures greatly improved the immobilization of antibodies and enhanced the catalytic activity for K3Fe(CN)6. Thus, the as-obtained architectures would effectively amplify the electrochemical signals, thereby improving the detection sensitivity. Under the optimal conditions, the as-developed immunosensor exhibited a wide linear range (0.001–100.0 ng mL−1) and a low detection limit (0.2 pg mL−1, S/N = 3) for the assay of cTnI. The immunosensor provides a powerful platform for quantitative detection of cTnI, which can be explored to detect other tumor markers in actual sample analysis.

Human epidermal growth factor receptor 2 (HER2) is believed as a clinically important breast cancer marker, and thereby it is extremely imperative to develop a highly sensitive and effective strategy for specific recognition and assay of HER2. In this work, a facile ratiometric electrochemical immunosensor was fabricated for sensitively monitoring HER2 as a model analyte, in which reduced graphene oxide-polydopamine-grafted-ferrocene/Au@Ag nanoshuttles (Au@Ag NSs) performed as electrode material and hollow Ni@PtNi yolk-shell nanocages-thionine (Ni@PtNi HNCs) as signal tags, which provided two distinct electrochemical signals from Fc and Thi, respectively. The Au@Ag NSs endowed the rGO-PDA-Fc with improved biocompatibility and dramatic magnification of the Fc signals upon sensing interface. Also, by integration of the hollow structure, enlarged specific surface area and superior catalytic ability together, the Ni@PtNi HNCs-Thi achieved substantial amplification in the detection signals from Thi. Benefiting from the above, the as-developed immunosensor exhibited a broad linear range (0.01 ∼ 100 ng mL–1) and a low detection limit (3.3 pg mL–1) for HER2 (S/N = 3), followed by exploring its application in actual serum samples with acceptable results. It holds great potential for clinical screening of cancer biomarkers and point of-care assays.

Breast cancer, one of common malignant tumors, is threatening woman's health and life with high mortality rate to this day, and thereby its early screening and detection are of significance in medical diagnosis and follow-up treatment. In view of the low sensitivity, cost-effectiveness and invasive procedures, conventional approaches generally exhibit limited applications in practice. Such oncologic diseases have close correlation with the tumor markers usually situated in tumor cells or secreted by tumor cells. The biomarkers can work as good indicators for developing highly sensitive and specific immmunoassays towards detecting breast cancer. This work provides an overview of recent researches to screen and detect the benchmarked biomarkers of breast cancer, and discuss the developed immunosensing strategies on selected works published early in the past five years. Particular emphasis is focused on remarkable amplification approaches of detection signals to improve the sensitivity. Concretely, the paper introduces the design, fabrication, and applications of such sensors mainly by electrochemistry, electrochemiluminescence, and photoelectrochemistry, coupled with improved stability and selectivity. For developing such high-efficiency biosensors, recent challenges and opportunities are finally discussed towards early diagnosis of breast cancer.

Developing a simple and sensitive method for detecting tumor biomarkers is practically important for early diagnosis and clinical treatment of diseases. However, it is still the major challenge to improve the sensitivity and accuracy. Here, “a dual-signal read out mode” ratiometric electrochemical immunosensor was developed based on well-dispersed hierarchical PtCoNi hollow multi-branches (HMBs)/ferrocene-grafted-ionic liquid (Fc-g-IL, synthesized via Schiff-base reaction) and Co N C nanosheets (NSs, obtained by a simple pyrolysis method) as signal amplification. Specifically, the PtCoNi HMBs were synthesized by solvothermal treatment and then etched with acetic acid. The PtCoNi HMBs/Fc-g-IL showed improved catalytic property and superior biocompatibility. Meanwhile, Au nanostars/thionine decorated Co N C NSs (Au-Thi-Co-N-C NSs) performed as the label of secondary antibody (Ab2) to greatly enhance the signals. This immunoassay for N-terminal pro-B-type natriuretic peptide (NT-proBNP) was realized by boosting the Thi signals while inversely decaying the Fc responses, in turn showing the linear relationship towards the analyte in the range of 0.001–10.0 ng mL–1 with the low detection limit down to 0.35 pg mL–1 (S/N = 3). This study displays a promising platform for determination of other tumor biomarkers in real medical applications.

Nowadays, serious restriction by aggregation quenching and proton attack in aqueous media, electrochemiluminescence (ECL) signals of emitter hardly match the requirement of ultrasensitive biomedical detection in practice. In this work, a novel flower-like metal-organic framework microsphere was formed by chelating Zn ion with carboxyl-rich tris(4,4′-dicarboxylic acid-2,2′-bipyridyl) ruthenium(II) (Ru(dcbpy)32+) in the presence of cetyltrimethylammonium bromide (CTAB), defined as ZnMOF(Ru) for simplicity. For that, the obtained ZnMOF(Ru) as a high-performance ECL emitter displayed 53-fold amplification in aqueous solution without any coreactant alternative to that of Ru(dcbpy)32+, coupled with the dramatically enhanced fluorescence quantum yield and stability of the intermediates. Thus, a “sandwich”-like ECL biosensor was developed for detecting breast cancer 1 gene (BRCA1), showing the wide linear range (1.0 fM–0.1 nM) and ultralow limit of detection (LOD) down to 0.71 fM. Hence, this work provides a universal and robust pattern to develop advanced ECL luminophores and exploit their potential applications in bioanalysis.

Herein, uniform dendritic PtCo nanoclusters supported on sheet-like polypyrrole (PtCo NCs/PPy) were prepared by a facile one-pot solvothermal method. Cetyltrimethylammonium chloride (CTAC) and pyrrole worked as the capping agent and reductant, respectively, and pyrrole was in-situ polymerized to form PPy sheets under solvothermal conditions. The dendritic PtCo NCs/PPy had the enlarged electrochemically active surface area (EASA, 30.95 m 2 g −1 ), and showed the superior catalytic performance and durability towards oxygen reduction reaction (ORR) and ethylene glycol oxidation reaction (EGOR) in comparison with Pt 1 Co 3 nanoparticles (NPs), Pt 3 Co 1 NPs and commercial Pt/C catalysts. This work displays a new strategy for rational design and synthesis of advanced functional nanocomposites as electrocatalysts in fuel cells.

For the efficient surface plasmon resonance (SPR)-based DNA assay researching, signal amplification tactics were absolutely necessary. In this work, a sensitive SPR-DNA sensor was developed by employing in situ synthesis of copper nanoparticles (CuNPs) templated by poly-T sequences DNA from terminal deoxynucleotidyl transferase (TdT)-mediated extension, and synergistically with nano-effect deposition as the mass relay. The objective of this strategy was manifold: firstly, tDNA hybridized with the optimal designed probes to active the TdT-mediated DNA extension onto the surface of SPR chip, resulted a long poly-T sequences ssDNA chain in dsDNA terminal onto surface of gold chip and characterized by SPR signal amplitudes. Secondly, copper ion (Cu2+) adsorbed into the skeleton of poly-T sequences DNA, with the aid of ascorbic acid (VC) to achieve the Cu2+ reduction, copper nanostructures (CuNPs) was synchronously generated onto the single nucleotide chain anchoring in dsDNA derivatives and the formation was featured by transmission electron micrographs (TEM) and electrochemistry. Lastly, dsDNA-complexed CuNPs (CuNPs@dsDNA) triggered the final signal amplification via real-time conversion of the additive catechol violet (CV) into oligomer or chelation precipitation by CuNPs-tagged reporters. With the proposed setups, a precise and replicable DNA sensing platform for specific target oligo was obtained with a detection limit down to 3.21 femtomolar, demonstrating a beneficial overlapping exploitation of nanomaterials and biochemical reaction as unique SPR infrastructure. Such triple-amplification strategic setups, the possibility of various methods abutment and biocompatibility weight reactor was amassed and adapted to more biological detection field.

Herein, bimetallic core-shell Au@Pt nanocrystals (Au@Pt NCs) were prepared by a simple one-pot aqueous method using 2-pyrrolidone-5-carboxylic acid sodium salt (PCA-Na) as a new and green growth-directing agent. The obtained architectures displayed excellent catalytic activity towards oxygen reduction reaction (ORR) compared with commercial Pt/C catalyst. A novel immunosensor was constructed via assembly prostate specific antibody on the surface of Au@Pt NCs. It was found that the ORR currents were significantly suppressed due to the specific antigen-antibody reaction. The ultra-sensitive determination of prostate specific antigen (PSA) was realized on account of the immunocomplex impeding the redox probe accessible to the electrode. The immunosensor exhibited good analytical performance for the assay of PSA with the wide linear range of 0.1 ~ 50ngmL-1 and low detection limit of 0.018ngmL-1 (S/N = 3), coupled with the improved stability, reproducibility and selectivity.

A highly efficient biomimetic catalyst was fabricated based on ultrathin carbon nitride nanosheets (C3N4)-supported cobalt(II) proto-porphyrin IX (CoPPIX). The periodical pyridinic nitrogen units in C3N4 backbone could serve as electron donors for great affinity with Co(2+) in PPIX, which resembled the local electronic structure as vitamin B12 and heme cofactor of hemoglobin. UV-vis kinetics and electrochemistry revealed its competitive (electro)catalysis with conventional peroxidase, while X-ray photoelectron spectroscopy and theoretical calculations suggest that the rehybridization of Co 3d with N orbitals from the backside can result in significant changes in enthalpy and charge density, which greatly promoted the activity of CoPPIX. The prepared nanocatalyst was further conjugated with streptavidin via multiple amines on the edge plane of C3N4 for facile tagging. Using biotinylated molecular beacon as the capture probe, a sensitive electrochemiluminescence-based DNA assay was developed via the electroreduction of H2O2 as the coreactant after the hairpin unfolded by the target, exhibiting linearity from 1.0 fM to 0.1 nM and a detection limit of 0.37 fM. Our results demonstrate a new paradigm to rationally design inexpensive and durable biomimics for electrochemiluminescence quenching strategy, showing great promise in bioanalytical applications.

A novel self-assembled glucose biosensor based on graphene oxide (GO) was constructed by using 1-pyrenebutyric acid-N-hydroxysuccinimide ester (PANHS) as linking molecular. The stepwise self-assembly process was performed for PANHS anchoring in N,N-dimethylformamide (DMF) solvent and the further glucose oxidase (GOD) binding in aqueous solution, respectively. The molecular interactions and the morphologic properties were characterized by Fourier transform infrared spectroscopy (FTIR), field emission scanning electronic microscopy (FESEM), and atomic force microscopy (AFM). In addition, the quantitative loadings of anchored PANHS and GOD were well elucidated by surface plasmon resonance (SPR) measurements. The obtained novel glucose sensor exhibited satisfactory analytical performance to glucose: wide linear range (4.0×10(-6) to 4.4×10(-3) M), fast response (10s), high sensitivity (40.5±0.4 mA M(-1) cm(-2)), and low detection limit (2 μM, S/N=3). Furthermore, the biosensor exhibited excellent long-term stability and satisfactory reproducibility.

A highly efficient surface plasmon resonance (SPR)-based DNA assay was developed, by employing noncovalently functionalized graphene nanosheets as a substrate, and enzymatic catalysis-induced polymerization as mass relay. The objective of this strategy was manifold: first of all, to sensitize the overall SPR output by in situ optimized electrogeneration of graphene thin-film, which was characterized by atomic force microscopic topography; secondly, to regulate the self-assembly and orientation of biotinylated capture probes on nickel-chelated nitrilotriacetic acid (NTA) scaffolds, that anchored onto graphene-supported pyrenyl derivatives; and lastly, to synergize the signal amplification via real-time conversion of the additive aniline into polyaniline precipitation by horseradish peroxidase-tagged reporters. With this setup, a precise and replicable DNA sensing platform for specific targets was achieved with a detection limit down to femtomolar, thus demonstrating a beneficial exploration and exploitation of two-dimensional nanomaterials as unique SPR infrastructure. The possibility of such ″bottom-up″ architecture mounted with ″top-down″ weight reactor would be most likely extensible and adaptable to protein determinations.

This paper, based on the practical demands of in-service pipeline detection, a set of X-ray digital image welding line defect intelligent recognition system is established. Taking the welding line image detected by X-ray as objects of study, self-adaptive median filter method filters noise, high frequency enhancement filter method conducts the image edge sharpening enhancement; a edge detection method for X-ray digital image based on morphological gradient is proposed; a group of characteristics parameters that accurately reflects the essence characteristic of defects is selected, using a self-organizing, self-adaptive three-layer feed-forward neural network, applying BP algorithm, the BP neural network recognition system is established, thus, to achieve detection and recognition of weld defects.

A homotopy analysis method (HAM) is presented for the primary resonance of multiple degree-of-freedom systems with strong non-linearity excited by harmonic forces. The validity of the HAM is independent of the existence of small parameters in the considered equation. The HAM provides a simple way to adjust and control the convergence region of the series solution by means of an auxiliary parameter. Two examples are presented to show that the HAM solutions agree well with the results of the modified Linstedt-Poincare method and the incremental harmonic balance method.

The pursuit of more specific and sensitive response is a perpetual goal for modern bioassays. This work proposed a novel label-free strategy about redox-related mass effect based on the surface plasmon resonance (SPR) technique for ultrasensitive determination of DNA. The protocol starts with the modification of SPR gilded disk with the capture DNA ( c DNA). After the conjugation of immobilized c DNA with the target DNA ( t DNA), the hybridization chain reaction was triggered by the introduction of mutual partial complementary primers to elongate the terminal into a nanoscale duplex. As it is reported that porphyrin could intercalate into the grooves of the double-stranded DNA ( ds DNA) scaffold, multiple positive-charged Fe III meso - tetra ( N -methyl-4-pyridyl) porphine (FeTMPyP) with symmetric structure were uptaken for in situ formation of porphyrin- ds DNA complex. Given FeTMPyP a highly efficient catalysis for the peroxide reduction, its presence as a biomimetic cofactor was validated via circular dichroism and UV–vis spectroscopy, demonstrating a tight binding as well as high catalytic activity and stability. Using 4-chloro-1-naphthol as a proton donor, the catalytic reduction of H 2 O 2 would oxidize it into insoluble benzo-4-chloro-hexadienone, which simultaneously deposited on the heterogeneous interface, leading to a significant amplification in both SPR response and topological height profile. The signal increment was proportional to the concentration of t DNA, thus an ultrasensitive SPR-based DNA assay was developed with a linear range over four orders of magnitudes and a sub -femtomolar detection limit of 0.73 fM. The developed methodology exemplifies a different way of thinking about mass-sensing modes, extending conventional SPR-based DNA analysis to relevant biomedical applications.

In this work, the electrodeposition of pyrocatechol violet (PCV) was initially investigated by the electrochemical surface plasmon resonance (ESPR) technique. Subsequently, PCV was used as redox-mediator and was electrodeposited on the surface of pencil graphite electrode (PGE) modified with single-wall carbon nanotubes (SWCNTs). Owing to the remarkable synergistic effect of SWCNTs and PCV, PGE/SWCNTs/PCV exhibited excellent electrocatalytic activity towards dihydronicotinamide adenine dinucleotide (NADH) oxidation at low potential (0.2V vs. SCE) with fast amperometric response (10s), broad linear range (1.3-280 μM), good sensitivity (146.2 μA mM(-1)cm(-2)) and low detection limit (1.3 μM) at signal-to-noise ratio of 3. Thus, this PGE/SWCNTs/PCV could be further used to fabricate a sensitive and economic ethanol biosensor using alcohol dehydrogenase (ADH) via a glutaraldehyde/BSA cross-linking procedure.

Starting from exploiting the applied detection system of gas transmission pipeline, a set of X-ray image processing methods and pipeline flaw quantificational evaluation methods are proposed. Defective and non-defective strings and rows in gray image were extracted and oscillogram was obtained. We can distinguish defects in contrast with two gray images division. According to the gray value of defects with different thicknesses, the gray level depth curve is founded. Through exponential and polynomial fitting way to obtain the attenuation mathematical model which the beam penetrates pipeline, thus attain flaw deep dimension. This paper tests on the PPR pipe in the production of simulated holes flaw and cracks flaw, 135KV used the X-ray source on the testing. Test results show that X-ray image processing method, which meet the needs of high efficient flaw detection and provide quality safeguard for thick oil recovery, can be used successfully in detecting corrosion of insulated pipe.