Search

The ion permeability and selectivity of membranes are crucial in nanofluidic behavior, impacting industries ranging from traditional to advanced manufacturing. Herein, we demonstrate the engineering of ion-conductive membranes featuring angstrom-scale ion-transport channels by introducing ionic polyamidoamine (PAMAM) dendrimers for ion separation. The exterior quaternary ammonium-rich structure contributes to significant electrostatic charge exclusion due to enhanced local charge density; the interior protoplasmic channels of PAMAM dendrimer are assembled to provide additional degrees of free volume. This facilitates the monovalent ion transfer while maintaining continuity and efficient ion screening. The dendrimer-assembled hybrid membrane achieves high monovalent ion permeance of 2.81 mol m–2h–1(K+), reaching excellent mono/multivalent selectivity up to 20.1 (K+/Mg2+) and surpassing the permselectivities of state-of-the-art membranes. Both experimental results and simulating calculations suggest that the impressive ion selectivity arises from the significant disparity in transport energy barrier between mono/multivalent ions, induced by the “exterior–interior” synergistic effects of bifunctional membrane channels.

Photodynamic therapy (PDT) is a significant noninvasive therapeutic modality, but it is often limited in its application due to the restricted tissue penetration depth caused by the wavelength limitations of the light source. Two-photon (TP) fluorescence techniques are capable of having an excitation wavelength in the NIR region by absorbing two NIR photons simultaneously, which offers the potential to achieve higher spatial resolution for deep tissue imaging. Thus, the adoption of TP fluorescence techniques affords several discernible benefits for photodynamic therapy. Organic TP dyes possess a high fluorescence quantum yield. However, the biocompatibility of organic TP dyes is poor, and the method of coating organic TP dyes with silica can effectively overcome the limitations. Herein, based on the TP silica nanoparticles, a functionalized intelligent biogenic missile TP-SiNPs-G4(TMPyP4)-dsDNA(DOX)-Aptamer (TGTDDA) was developed for effective TP bioimaging and synergistic targeted photodynamic therapy and chemotherapy in tumors. First, the Sgc8 aptamer was used to target the PTK7 receptor on the surface of tumor cells. Under two-photon light irradiation, the intelligent biogenic missile can be activated for TP fluorescence imaging to identify tumor cells and the photosensitizer assembled on the nanoparticle surface can be activated for photodynamic therapy. Additionally, this intelligent biogenic missile enables the controlled release of doxorubicin (DOX). The innovative strategy substantially enhances the targeted therapeutic effectiveness of cancer cells. The intelligent biogenic missile provides an effective method for the early detection and treatment of tumors, which has a good application prospect in the real-time high-sensitivity diagnosis and treatment of tumors.

Rapid, specific, and on-site detection of virulent foodborne pathogenic strains plays a key role in controlling food safety. In this work, an ultrasensitive and specific Phage@DNAzyme signal probe was designed to detect foodborne pathogens. The proposed sensing probe was composed of the selected phage and functionalized DNAzyme, which realized the specific recognition of target foodborne pathogens at the strain level and the efficient catalysis of copper(II) based azide-alkyne cycloaddition (CuAAC) click reaction with fluorescent signal, respectively. As a proof of concept, the virulent Escherichia coliO157:H7 (E. coliO157:H7) as the representative analyte was first enriched and purified from the complex food samples by a 4-mercaptophenylboronic acid-modified gold slide. Following, the Phage@DNAzyme probes were specifically combined with the captured E. coliO157: H7 and catalyzed the click reaction between 3-azido-7-hydroxycoumarin and 3-butyn-1-ol with the assistance of Cu(II) to generate a visual fluorescent signal. Finally, the corresponding fluorescent signals were measured by a smartphone to quantify the target concentrations. Under optimized conditions, the bioassay exhibited a wide linear range from 102to 108CFU/mL and the detection limit was 50 CFU/mL (S/N= 3). It was further extended to the detection of another foodborne pathogen Salmonella typhimuriumwith satisfying sensing performances. This work gives a new path for developing rapid, specific, and on-site detection methods for trace levels of pathogenic strains in foods.

•A novel PDMS-PDA coated stir bar was made for specific extraction of TPM residues.•The stir bar was prepared by plasma cleaning to obtain the robust coating•A hand-held stirring device was installed with the stir bar for sorptive extraction.•The stir bar with a portable mass spectrometer can determine TPMs within 35 min.•The assay can on-site detect 4 TPMs residues in aquatic waters with LOD of 0.16 μg L−1.

Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC), the representative reaction of modern “click chemistry”, has been broadly employed in organic synthesis, bio-labeling, and surface functionalization. Nevertheless, it has limitations such as posing a dilemma of either using high concentrations of Cu(I) catalyst or suffering from slow kinetics. Herein, we demonstrate that a newly selected DNAzyme (CLICK-17; a 79-nucleotide, catalytic DNA single strand) can rapidly catalyze CuAAC to tether redox functionalities onto an electrode surface using low concentrations of either Cu(I) or Cu (II). Particularly, the CLICK-17 DNAzyme, at μM concentrations, facilitated the covalent immobilization of ethynylferrocene (Fc-C≡CH) onto 1-azido-11-undecanethiolate self-assembled monolayers on gold (N3C11S-Au SAMs); as low as 50 μM Cu(I) together with 4 μM DNAzyme was able to complete the coupling reaction within 30 min and the pseudo first-order reaction rate constant is 7 times higher than that using the Cu(I) catalyst alone. It was also remarkable that the CLICK-17 DNAzyme is functional with Cu(II) in the absence of an explicit reductant for the catalyzed surface immobilization of Fc-C≡CH on N3C11S-Au SAMs.

The proliferation speed of live foodborne pathogens is fast. A small number of pathogens will have a great impact on food and the environment if positive samples are not detected timely. In this study, transparent porous hydrogel stir bars, modified by two different phages (corresponding to two different bacteria (Escherichia coliand Hafnia sp)), have been developed for rapid detection of foodborne bacteria. A large number of samples can be analyzed simultaneously with a small animal live imager device to screen out the positive samples, while an adenosine triphosphate (ATP) bioluminescence sensor can be used to quantify the number of bacteria in the positive samples. The phage has good specificity and capture ability to bacteria, which makes the method highly sensitive. In addition, the use of multiple phages also enables the method to detect multiple bacteria simultaneously. The three-dimensional structure of the hydrogel allows it to modify more phages, and its transparent nature also allows the inside bioluminescence to be detected. Both can enhance the sensitivity of the detection. Finally, the reagents needed for bioluminescence, such as d-luciferin, can also be preencapsulated in the hydrogel, thus simplifying the detection step. Under the best conditions, the detection range of the method is 102–108CFU·mL–1, and the limit of detection is 30 CFU·mL–1within 11 min. The test results of actual samples show that there is no difference between using the method developed through this study and the traditional plate counting method, but the detection time is greatly shortened.

Sensitive and on-site discrimination of live and dead foodborne pathogenic strains remains a significant challenge due to the lack of appropriate assay and signal probes. In this work, a versatile platinum nanoparticle-decorated phage nanozyme (P2@PtNPs) that integrated recognition, bacteriolysis, and catalysis was designed to establish the bioluminescence/pressure dual-mode bioassay for on-site determination of the vitality of foodborne pathogenic strains. Benefiting from the bacterial strain-level specificity of phage, the target Salmonella typhimurium(S.T) was specially captured to form sandwich complexes with P2@PtNPs on another phage-modified glass microbead (GM@P1). As the other part of the P2@PtNPs nanozyme, the introduced PtNPs could not only catalyze the decomposition of hydrogen peroxide to generate a significant oxygen pressure signal but also produce hydroxyl radicals around the target bacteria to enhance the bacteriolysis of phage and adenosine triphosphate release. It significantly improved the bioluminescence signal. The two signals corresponded to the total and live target bacteria counts, so the dead target could be easily calculated from the difference between the total and live target bacteria counts. Meanwhile, the vitality of S.T was realized according to the ratio of live and total S.T. Under optimal conditions, the application range of this proposed bioassay for bacterial vitality was 102–107CFU/mL, with a limit of detections for total and live S.T of 30 CFU/mL and 40 CFU/mL, respectively. This work provides an innovative and versatile nanozyme signal probe for the on-site determination of bacterial vitality for food safety.

Multicolor fluorescence probes can show fluorescence of different colors when detecting different targets, and the excellent feature can create a highly differentiated multicolor sensing platform. However, most of the previously reported multicolor luminescent materials usually suffer from high toxicity and photobleaching, complex preparation procedures, and poor water solubility, which may not be conducive to bioanalytical applications. Two-dimensional metal organic frameworks (2D MOFs), which have large specific surface areas with long-range fluorescence quenching coupled with biomolecular recognition events, have encouraged innovation in biomolecular probing. Here, we propose a 2D-MOF-based multicolor fluorescent aptamer nanoprobe using a double stirring bar assisted target replacement system for enzyme-free signal amplification. It utilizes the interaction between 2D MOFs and DNA molecules to detect multiple antibiotics quickly, sensitively, and selectively. Since 2D MOFs have excellent quenching efficiency for luminescence of fluorescent-dye-labeled single-strand DNA (ssDNA), the background fluorescence can be largely reduced and the signal-to-noise ratio can be improved. When the adsorbed ssDNA formed double helix double-stranded DNA with its complementary ssDNA, its fluorescence can be almost fully recovered. The assay was tested by detecting chloramphenicol (CAP), oxytocin (OTC), and kanamycin (KANA) in biological samples. The developed aptasensor was sufficiently sensitive to detect the antibiotic residues as low as 1.5 pM CAP, 2.4 pM OTC, and 1 pM KANA (S/N = 3). It has been preliminarily used for multicolor imaging of three different antibiotics in fish tissue slices with satisfactory results.

The development of simple, rapid-response sensors for water detection in organic solvents is highly desirable in the chemical industry. Here we demonstrate a unique luminescence water sensor based on a dual-emitting europium-organic framework (Eu-MOF), which is assembled from a purposely selected 2-aminoterephthalic acid ligand with responsive fluorescence inherent in its intramolecular charge transfer (ICT) process. This ICT process can be rapidly switched-on in the presence of water owing to its ability to boost and stabilize the ICT state. In contrast, the Eu3+emission within the framework is insensitive to water and can serve as a reference, thus enabling highly sensitive water detection in a turn-on and ratiometric way. In addition, the significant ratiometric luminescence response induced by water makes Eu-MOF undergo a distinct change of emitting color from red to blue, which is favorable for visual analysis with the naked eye. Sensitive determination of water content (0.05–10% v/v) in various organic solvents is achieved in multiple readouts including ratiometric emission intensity, emission color, or the Commission Internationale de l’Eclairage (CIE) chromaticity coordinate. The present Eu-MOF sensor featuring high sensitivity and reusability, self-calibration, simple fabrication and operation, and capability for real-time and in situdetection is expected to have practical applications in water analysis for industrial processes.

Selective capturing and purification of C-reactive protein (CRP) from complex biological fluids plays a pivotal role in studying biological activities of CRP in various diseases. However, obvious nonspecific adsorption of proteins was observed on current affinity sorbents, and thus additional purification steps are often required, which could compromise the recovery of the target protein and/or introduce new impurities. In this study, inspired by the highly specific interaction between CRP and the cell membrane, an excellent anti-biofouling compound 2-(methacryloyloxy)ethyl phosphorylcholine and a highly hydrophilic crosslinker N,N′-methylenebisacrylamide were employed to fabricate a novel cell membrane biomimetic polymer for selective capture of CRP in the presence of calcium ions. Based on the polymer described above, a facile enrichment approach was established after systematic optimization of the washing and elution conditions. With its favorable properties, such as good porosity, weak electrostatic interaction, high hydrophilicity, and biocompatibility, the novel biomimetic polymer exhibits good specificity, selectivity, recovery (near 100%), purity (95%), and a lower nonspecific protein adsorption for CRP in comparison with commercial immobilized p-aminophenyl phosphoryl choline gel and other purification materials. Furthermore, the structural integrity and functionality of CRP in the elution fraction were well preserved and confirmed by circular dichroism spectroscopy, fluorescence spectroscopy, and immunoturbidimetric assay. Finally, the biomimetic polymer was successfully applied to the selective enrichment of CRP from sera of patients with inflammation and rats. The proposed novel enrichment approach based on the versatile biomimetic polymer can be used for effective CRP purification, which will benefit the in-depth study of its biological roles.

The tea tree is a perennial woody plant, and pruning is one of the most crucial cultivation measurements for tea plantation management. To date, the relationship between long-term pruning and metabolic flux enhancement in tea trees has not been studied. In this research, 11-year-old pruned tea trees from four different cultivars were randomly selected for transcriptome analysis and characteristic secondary metabolite analysis together with controls. The findings revealed that epigallocatechin gallate (EGCG) accumulation in pruned tea trees was significantly higher than that in unpruned tea trees. SCPL1Aexpression (encoding a class of serine carboxypeptidase), which has been reported to have a catalytic ability during EGCG biosynthesis, together with LAR, encoding leucoanthocyanidin reductase, was upregulated in the pruned tea trees. Moreover, metabolic flux enhancement and transcriptome analysis revealed low EGCG accumulation in the leaves of unpruned tea trees. Because of the bitter and astringent taste of EGCG, these results provide a certain understanding to the lower bitterness and astringency in teas from “ancient tea trees”, growing in the wild with no trimming, than teas produced from pruned plantation trees.

Bioimaging is widely used in various fields of modern medicine. Fluorescence imaging has the advantages of high sensitivity, high selectivity, noninvasiveness, in situ imaging, and so on. However, one-photon (OP) fluorescence imaging has problems, such as low tissue penetration depth and low spatiotemporal resolution. These disadvantages can be solved by two-photon (TP) fluorescence imaging. However, TP imaging still uses fluorescence intensity as a signal. The complexity of organisms will inevitably affect the change of fluorescence intensity, cause false-positive signals, and affect the accuracy of the results obtained. Fluorescence lifetime imaging (FLIM) is different from other kinds of fluorescence imaging, which is an intrinsic property of the material and independent of the material concentration and fluorescence intensity. FLIM can effectively avoid the fluctuation of TP imaging based on fluorescence intensity and the interference of autofluorescence. Therefore, based on silica-coated gold nanoclusters (AuNCs@SiO2) combined with nucleic acid probes, the dual-mode nanoprobe platform was constructed for TP and FLIM imaging of intracellular endogenous miRNA-21 for the first time. First, the dual-mode nanoprobe used a dual fluorescence quencher of BHQ2 and graphene oxide (GO), which has a high signal-to-noise ratio and anti-interference. Second, the dual-mode nanoprobe can detect miR-21 with high sensitivity and selectivity in vitro, with a detection limit of 0.91 nM. Finally, the dual-mode nanoprobes performed satisfactory TP fluorescence imaging (330.0 μm penetration depth) and FLIM (τave= 50.0 ns) of endogenous miR-21 in living cells and tissues. The dual-mode platforms have promising applications in miRNA-based early detection and therapy and hold much promise for improving clinical efficacy.

Herein, a facile, signal-on and homogenous fluorescence assay using novel aptamer-dsDNA antibody–quantum dot probes was designed for detecting antibiotic residues. In this assay, the fluorescent probes were fabricated by using a double-stranded DNA antibody (dsDNA Ab) covalently bonded on the surface of CdSe quantum dots. The antibody can bind double-stranded DNA (dsDNA) specifically. When dsDNA was added, the fluorescence could be efficiently quenched because the probes came into contact with each other with dsDNA as the bridge. The dsDNA was formed between an aptamer towards chloromycetin (CAP) and its complementary strand DNA (cDNA). When CAP was added into the reaction system, the aptamer reacted with CAP preferentially and the dsDNA was unwinded to single strand DNA (ssDNA) which cannot be recognized by the dsDNA antibody. Thus the probes were separated and fluorescence was recovered. Based on the scheme, a signal-on fluorescence assay for detecting antibiotics in a homogenous aqueous phase was developed. Under the optimized conditions, the assay shows a good liner range from 0.05 ng mL−1to 100 ng mL−1and the limit of detection (LOD) is 0.002 ng mL−1. If the analyte is changed, the assay can also be employed only by changing the corresponding aptamer and its cDNA. What's more, the probes can be reused at least 10 times with the recovery above 90%. The fluorescence assay is facile and has promising application for detecting antibiotic contaminants in biological and environmental samples.

An enzyme amplified immunosensor for highly sensitive detection of Ractopamine (RAC) in foodstuff was developed based on quartz crystal microbalance (QCM). The high sensitivity was achieved by enzyme-AuNPs signal amplification strategy and magnetic β-cyclodextrins (β-CD) enrichment capacity. The novel QCM immunosensor which combines with the advantages of high selectivity of immunoassays and the high sensitivity of QCM has been developed for the determination of trace residues of RAC in food production. Under optimum conditions, the differences in the frequencies (∆f) of the QCM were proportional to the concentration of RAC over the range from 0.01 to 10 ng mL-1. The minimal detection limit was 0.01 ng mL-1. Due to its high sensitivity, acceptable stability and good selectivity, the immunosensor realized reliable quantification of RAC in real foodstuff. The proposed project has the potential to become a successful on-site screening method in food safety.

A novel colorimetric aptasensor was developed for sensitive and selective determination of chloramphenicol (CAP) based on gold nanoparticles (AuNPs) labeled with Power Vision (PV) and magnetic separation. PV, with a high enzyme-to-antibody ratio, is composed of a compact enzyme-linker antibody conjunction. In this assay, an aptamer of CAP was immobilized on Fe3O4@Au magnetic nanoparticles as a capture probe (AuMNPs–Apt) to concentrate target CAP. The complementary DNA (cDNA) and PV were both labeled on AuNPs to form a nano-peroxidase polymer as a signal tag (cDNA–AuNPs–PV). And the special tags could hybridize with the aptamer and cDNA to form AuMNP–Apt/cDNA–AuNP–PV conjugates. In the presence of CAP, the aptamer preferentially bound to CAP and caused the dissociation of some cDNA–AuNPs–PV on the conjugates with magnetic separation. PV, carried on signal tags, could greatly catalyze 3,3′,5,5′-tetramethylbenzidine (TMB) leading to color development, which could be quantified by Ultraviolet-visible (UV-vis) spectroscopy. A linear response to CAP concentration in the range of 0.05–200 ng mL−1was obtained by this proposed method, with a low detection limit down to 0.02 ng mL−1. Besides, this assay was successfully employed to analyze CAP in fish and pork samples, whose results were consistent with those of the conventional enzyme-linked immunosorbent assay (ELISA) method.

An electrochemical sensor for estradiol was prepared by a molecularly imprinted polymer (MIP) film and its recognition properties for estradiol were investigated. The polypyrrole (PPy) film was prepared by electropolymerizing pyrrole on gold nanoparticles (Au NPs) and graphene (Gs) modified glassy carbon (GC) electrode. The electrochemical response of 17β-Estradiol (17β-E2) at the imprinted PPy-Gs-Au/GC electrode was investigated by cyclic voltammetry. The results indicated that the imprinted PPy-Gs-Au/GC electrode can effectively improve the electrochemical signal of 17β-E2 and eliminate interferences of other interfering substances. The results showed that a wide detection linear range (3.0 × 10-9 1.0 × 10-6 mol L-1) for the determination of 17β-E2 with the low detection limit of 1.0 × 10-9 mol L-1 (S/N = 3) was obtained. The proposed sensor exhibited fast balance response time of 10 min, which is propitious to rapid detect 17β-E2 in real samples. The merits of the imprinted electrode suggested an attractive and broadly applicable way for developing the chemical sensor used for the estrogen detection.

The macroporous materials were prepared from the transformation of cuttlebone as biotemplates under hydrothermal reactions and characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric/differential thermal analyses (TG-DTA), and scanning electron microscopy (SEM). Cell experimental results showed that the prepared materials as bone tissue engineering scaffolds or fillers had fine biocompatibility suitable for adhesion and proliferation of the hMSCs (human marrow mesenchymal stem cells). Histological analyses were carried out by implanting the scaffolds into a rabbit femur, where the bioresorption, degradation, and biological activity of the scaffolds were observed in the animal body. The prepared scaffolds kept the original three-dimensional frameworks with the ordered porous structures, which made for blood circulation, nutrition supply, and the cells implantation. The biotemplated syntheses could provide a new effective approach to prepare the bone tissue engineering scaffold materials.

This paper developed an electrochemiluminescence (ECL) method for detecting ultratrace levels of the highly toxic organic pollutant, 3,4-dichloroaniline (3,4-DCA), in water. This method has not been used previously for 3,4-DCA detection, and is based on a 96-well micro-plate modified with molecularly imprinted sol-gel films combined with multi-walled carbon nanotubes (MIF-MWCNTs). The increase in the ECL signal intensity was proportional to the 3,4-DCA concentration within a certain range, and an excellent response was obtained for 3,4-DCA concentrations ranging from 4 x 10[?]11 to 6 x 10[?]9 mol L[?]1, with a low detection limit (LOD) of 1 x 10[?]11 mol L[?]1. The detection sensitivity of the present method is higher than those of the most commonly used chromatography methods, with the recovery of 3,4-DCA from spiked samples of water ranging from 83.3 to 110.5%. Thermodynamic analysis showed that the adsorption of 3,4-DCA by the MIF-MWCNTs occurred spontaneously as an exothermic and entropy decreasing process (DH = [?]32.49 kJ mol[?]1, DS = [?]117.89 J mol[?]1). Kinetic equation fitting demonstrated that the adsorption of 3,4-DCA could be fitted by an intraparticle diffusion model, and that the adsorption isotherm data fitted the Freundlich model.

Based on the historical analysis and statistics of HAB events from 1933 to 2008, Skeletonema costatum, Prorocentrum donghaiense, Karenia mikimotoi, Noctiluca scintillans were identified as the most frequent HAB species reported in Zhejiang Coastal areas. Risk assessment considering the intensity, scale, duration, species, in accordance with the 0.25°×0.25°partition statistics, was adopted. Conclusion could be made that the extreme high HABs risk located at area A (30.5°N-30.75°N, 122.5°E-123°E), B (29.75°N-30.25°N, 122.25°E-122.75°E), C (28.25°N-28.5°N, 121.75°E-122°E), and D (27.25°N-27.5°N, 121.0°E-121.25°E), in which Prorocentrum donghaiense has the biggest causative risk.

Tahe oilfield of Triassic oil under low amplitude anticline group monolithic sandstone reservoirs with bottom water features, having a uniform oil-water interface, water energy sufficient. The current production wells generally see water, water cut rising too fast. Horizontal well bottom water coning phenomenon is outstanding, later period of high water cut stage manages difficulty to increase, water blocking measures have a low efficiency. Determine critical output, to improve production well life, efficient development reservoir has important significance .Based on the study of dynamic characteristics of single well and geological analysis of factors determining the critical output, and the application of numerical simulation method to verify the reasonable threshold quantity production. This method is simple and practical, can accurately make the critical output of single well.

The adsorption of Zn2+ from simulated seawater onto biomaterial derived from the macroalgae Sargassum horneri was investigated via batch experiments. The highest adsorption rate was 96.9%, which found in the lower Zn2+ concentration solution where pH was 8.0 and temperature was 15℃, and the maximum adsorption capacity of dead Sargassum horneri particle to Zn2+ could arrive to more than 0.20 mg.g-1. Sargassum horneri pretreated with CaCl2 can increase the adsorption rate. Infrared analysis results showed that carboxylic acid groups have an important contribution to Zn2+ adsorption. The adsorption equilibrium of Zn2+ could be represented by pseudo-second-order model and the capacity of dead alga for Zn2+ was approximately constant. Conclusions could be drawn that Sargassum horneri is a kind of efficient biosorbent for the treatment of waste waters containing heavy metals. It was because Zn2+ can easily be desorbed by competition between the hydrogen ions and metal ions on the cell surface binding sites, that hydrochloric acid was proved to have economic feasibility.

A new method has been established for the pre-enrichment of trace heavy metals(lead(II), cadmium(II), chromium(VI) and nickel(II)) by magnetic iron oxide(core) / zirconium dioxide(shell) and determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) in water samples. The factors affecting the separation and pre-enrichment of analytes such as amounts of magnetic iron oxide / zirconium dioxide, elution time and interfering ions were studied. The detection limits of the method (3σ) were 13.5ng/mL, 1.01ng/mL, 2.94ng/mL and 3.31mg/L respectively for lead(II), cadmium(II), chromium(VI) and nickel(II). The results showed that this method was simple, accurate, and sensitive which could be applied for the pre-enrichment, separation and determination of trace heavy metals in all kinds of water samples.

A simple, rapid and sensitive electrochemiluminescence (ECL) sensor was proposed for direct measurements of methyl parathion (MP) based on the strong affinity of a nano zirconia particles (ZrO2NPs) modified film on the electrode to the phosphoric group. ZrO2NPs, which could provide a larger absorption area to immobilize organophosphorus, was firstly modified on the glassy carbon electrode surface to prepare the proposed ECL sensor (ZrO2/GC). Subsequently, the ZrO2/GC electrode was scanned from −0.8 to +0.6 V to obtain the background signal at 0.44 V in a luminol/KCl solution. Then, a certain concentration of MP was added to an aqueous solution for 240 s, which was absorbed onto the ZrO2/GC electrode surface. Moreover, the MP absorbed on the surface of the ZrO2/GC electrode enhanced the ECL signal of luminol in the luminol/KCl solution, which increased with the concentration of MP. As a result, a novel ECL sensor was obtained in a luminol/KCl solution. The MP was determined in the range of from 3.8 × 10−11to 3.8 × 10−6mol L−1, with a low detection limit of 1.27 × 10−11mol L−1(S/N= 3). The proposed ECL sensor performance for MP detection will open a new field in the application of rapid and screen detection of ultra-trace amounts of organ phosphorus pesticides (OPs) of vegetables used in farm markets.

A novel enrichment and detection method for 6 kinds of main polychlorinated biphenyls(PCBs, PCB 28;2.PCB 52;3.PCB 101;4.PCB 153;5.PCB 101;6.PCB138) monomers was established. Target compounds were extracted by n-hexane/ methylene chloride (v/v,1:1) and methylene chloride, then enriched by rotary evaporator and purified by sulfuric acid. The detection signals were enhanced in the presence of different concentrations for the six kinds of PCBs from1 to 100 ng/mL with the coefficient of derivatives between 0.996 and 0.999. Recoveries of spiked tissues prepared with this method ranged from 76.7% to 106%, and the relative standard deviations (RSD) ranged from 4.0% to 11.1%. The method was used to extract PCBs from fish samples and determination of 6 kinds of main PCBs species with good accuracy and reproducibility.

A novel disposable screen-printed immunosensor for rapid determination of highly sensitive C reactiveprotein (hs-CRP) in human serum has been developed in the experiment. The sensor was constructed on one screen-printed carbon electrode (SPCE) with HRP labeled anti-hs-CRP antibody functionalized Fe3O4@Au magnetic nanoparticles (HRP labeled anti hs-CRP/ Fe3O4@Au) as the biorecognition probes attracted on the surface of Fe (III) phthalocyanine (FePc)/ chitosan membrane modified screen-printed carbon electrode (SPCE|FePc/Chit/chitosan) by external magnetic field. FePc was acted as electron immediate. The modified electrode shows an excellent electrocatalytic activity for hs-CRP in phosphate buffer solution (pH=7.0). After the immunosensor is incubated with hs-CRP antigen solution at 37? for 20 min, the access of activity center of the HRP to electrode is partly inhibited, which leads to a linear decrease of the catalytic efficiency of the HRP to the reduction of immobilized FePc by H2O2 at –50 mV in hs-CRP’s concentration ranges from 1.2 to 200 ng/mL. The detection limit was 0.5ng/mL. The immunosensor was successfully utilized for determination of hs-CRP in real serum samples of heart disease patients, whose results were consistent with that by ELISA method. The accuracy and precision of the assay were 91.5-104.4% and 15.8-24.4%, respectively. The immunosensor was reusable once constructed and can be regenerated by adding new nanoprobes on the surface of basal electrode through magnet on its bottom. It can greatly reduce the detection cost which is valuable for the early diagnosis of tumors.

One novel amperometric immunosensor for α-fetop- rotein was fabricated which was modified by antibody immobilized on nano ZrO2-Au-polyLysine composite membrane. Firstly, the deoxyribonucleic acid – phenoxyacetic acid isoniazid- Schiff base Co(II) complex (DNA-CoL) mixture film was casted on surface of multi carbon nanotubes(MWCNTs) modified glassy carbon electrode(GCE/CNTs/DNA-CoL). Then the composite nanoparticles (ZrO2-Au-pLL) was employed to immobilize the antibody of α-fetoprotein(AFP) to produce the probes(ZrO2-Au-pLL-anti AFP) for AFP. Finally the probes were modified on GCE/CNTs/DNA-CoL through the specific connection between DNA and ZrO2 to form a novel nanocomposite membrane immunosensor for AFP(GCE/CNTs/ DNA-CoL/ZrO2-Au–pLL-anti AFP). The function of immunosensor was investigated by scanning electron microscopy (SEM), cyclic voltammetry(CV), differential pulse voltammety (DPV) and electrochemical impedance spectroscopy experiment (EIS). The results indicated that combining the advantages of the MWNTs-DNA material and ZrO2-Au-pLL-anti AFP nano probes, the immunosensor with excellent sensitivity and selectivity to AFP was prepared successfully. The modified electrode was sensitive to AFP with a linear relationship between 0.05 and 10 ng · mL−1 and a correl- ation coefficient of 0.9905. The detection limit at a signal to noise ratio of 3 was 0.01 ng·mL−1 under the optimal conditions. The described immunosensor preparation and immunoassay methods offer promise for simple and cost-effective analysis of AFP in serum samples.

A novel three-dimensional, magnetic and electroactive nanoprobes were constructed for the first time. Using hemin (TPP) as electron mediator, mutli-walled carbon nanotubes with carboxyl groups (MCNTs) as supporter, a novel (MCNTs-TPP-Fe3O4) magnetic nanocomposites were first prepared. Then using alpha-fetoprotein (AFP) as model system, gold nanoparticles (Au NPs) as immobilizing matrix, the AFP/anti-AFP/Au NPs/ MCNTs-TPP-Fe3O4 nanoprobes were prepared and then dropped on the surface of screen-printed working electrode (SPCE) to construct a new amperometric immunosensors for detecting biomakers. The microstructure of different nanoparticles were observed by transmission electron microscopy (TEM) and X-ray fluorescence spectrometery (XRFS). Under optimal experimental conditions, the logarithm of response signal was proportional to the logarithm of AFP concentration from 0.1 to 200 ng/mL, with a correlation coefficient of 0.998. The detection limit was 0.04 ng/mL at a signal-to-noise ratio of 3. The proposed method offered a platform for fast, sensitive and simultaneous determination for serum samples.

A new method was established to construct a ultrasensitive electrochemiluminescence (ECL) immunosensor by using Ru@SiO2 (Ru(bpy)3 2+ doped silica) - doped Au (Ru@SiO2-Au) composite nanoparticles to label Ru-Ab2 (monoclonal α-fetoprotein (AFP) antibody labeled with Ru(bpy)32+). The primary antibody, anti-AFP was first immobilized on the multi-walled carbon nanotubes (MCNTs) modified with gold nanoparticles (MCNTs-Au) modified glassy carbon electrode due to the covalent conjugation, then the antigen and the Ru@SiO2-Au composite nanoparticles labeled Ru-Ab2 (Ru@SiO2-Au~Ru-Ab2)was conjugated successively to form a double-conjugated Ru(bpy)32+ sandwich-type immunocomplex through the specific interaction. Accordingly, through the ECL response of Ru@SiO2-Au~Ru-Ab2 and tripropylamine (TPA), a strong ECL signal was obtained and an amplification analysis of protein interaction was achieved. The present immunosensor performed high sensitivity and wide liner for detection α-fetoprotein (AFP) in the range of 0.05-80 ng mL−1 and the limit detection was 0.025 ng mL−1(defined as S/N=3). The morphologies of MCNTs, MCNTs-Au, Ru@SiO2 and Ru@SiO2-Au nanoparticles were characterized by using transmission electronic microscopy (TEM). The developed label and method is versatile, offers enhanced performances, and can be easily extended to other protein detection.

A disposable, magnetism-controlled, and amperometric immunosensor was fabricated for the determination of C reactive protein (CRP). Firstly, Fe3O4 (core)/Au (shell) nanoparticle (GMP)–coated multiwalled carbon nanotubes (MWCNT–GMP) were prepared. Then, monoclonal antibody (anti-CRP) was immobilized on MWCNT–GMP to prepare MWCNT–GMP/anti-CRP composite magnetic probes. At last, the probes was adsorbed on the surface of N,N''-bis-(2-hydroxy-methylene)-o-phenylenediamine cobalt (CoRb) modified, screen-printed carbon electrodes through external magnetic field.The amount of CRP in the serum sample was determined by one-step immunoassay. When different concentrations of CRP were added into25μL of phosphate-buffered solution (pH7.0) containing10-4M H2O2, the percentage of DPV cathodic peak current decrease (CR%) exhibited a linear relationship with the concentration of CRP in the range of 0.3–100 μg L-1.The detection limit was 0.16 μg L-1(3б).The immunosensor was used to determine CRP in serum samples of patients with heart diseases, and the results were consistent with those of the traditional ELISA method. The proposed amperometric immunosensor was sensitive, rapid, magnetic field–controlled, and disposable; therefore, it could be used to determine even traces of CRP in the blood serums of patients with heart diseases.

A novel and sensitive electrochemical enzyme-linked immunosorbent assay (ELISA) system of Hydroquinones (HQ)- peroxide hydantoin (CP) -horseradish-peroxidase (HRP) by using magnetic DNA linked core-shell Fe3O4@ZrO2（ZMPs）nanoparticles as labels and signal amplification was established. In the presence of carcinoembryonic antigen (CEA) analyte, the sandwich-type immunocomplex could be formed between HRP labeled CEA second antibody（CEA Ab2） modified DNA-ZMPs probes (DNA / (ZMPs-HRP-CEA Ab2) n) and nano-gold CEA modified glassy carbon electrode (GCE | CEA Ab1) as an immune electrode.The concentration of CEA was determined based on the current signal, which was generated in the reaction between HQ and CP catalyzed by HRP on the sandwich-type immunocomplex. ZMPs nanoparticles as label material can not only perform the rapid separation and purification of signal antibody on magnetic field, but also immensely enhance the labeled capacity of HRP-anti-CEA which can amplify the catalytic current signal. Furthermore, the electrode modification process was not required. The method provided a linear response range between 0.01 and 200 ng·mL-1 with a detection limit of 4 pg·mL-1. Moreover, the proposed electrochemical ELISA method exhibited good precision, high sensitivity and acceptable reproducibility, and could be further developed for clinical detections of CEA and other biomarkers.

PMMA-b-PDMAEMA/polysulfone composite membranes for CO2 separation was prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization techniques. The chemical composition and structure of the polymers were characterized by Fourier transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR), and molecular weight and its distribution were measured by Gel permeation chromatography (GPC). CO2 permeation performance of the PMMA-b-PDMAEMA/ polysulfone composite membranes was test. The results showed that the resulted composited membrane posses good permeation performance for CO2.

Taking “Introduction to Oceanography” as an example, which is the basic course and opened in the colleges covering the major of marine science, this paper discusses how to take the initiative to adapt to the national strategic plan and local economic development in the process of basic education of marine science. According to China's current situation of the marine industry structure, this paper presents that the interface between marine science education and the secondary industry should be strengthened, meanwhile the integration among the basic courses and the actual production and the scientific research should be focused on. Colleges covering the major of marine science should take the initiative to explore training modes to enhance the qualities of talents of different level, and to carry out featured training based on their own characteristics of personnel positioning.

This paper introduces a novel amperometric immunosensor consisting of hemin (Fe(III)-protoporphyrinIX) layers formed by layer-by-layer assembly for determination of clenbuterol (CLB). Layer-by-layer assembly of hemin with Poly(allylamine hydrochloride) (PAH) is achieved on the electrode surface which is modified by single-wall carbon nanotubes (SWCNTs) based on the electrostatic attraction between negatively charged hemin and positively charged Poly(allylamine hydrochl- oride). The modified electrodes were characterized by cyclic voltammetry (CV), scanning electron microscope (SEM), and X-ray photo electron spectrum (XPS). The decrease of current results from the increasing concentration of CLB antigen, which leads to a linear decrease in CLB antigen concentration ranges from 0.5 ~ 10 ng/mL with the detection limit of 0.2 ng/mL (3σ).

A novel amperometric immunosensor for the determination of alpha-fetoprotein (AFP) was constructed using multi-wall carbon nanotubes modified glass carbon electrode.thionine as the mediator,were immobilized by DNA throngh the layer-by-layer method. Thionine was first fabricated on carbon nanotubes modified glass carbon throngh 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide/N-hydroxysuccinimide(EDC/NHS).then a negatively charged DNA film was absorbed on the positively charged thionine,and the DNA was uesd as cross-linker to immobiled amount thionine.nano-Au-was used to immobilized anti-AFP.The electrochemical sensor have a relatively low detection limit of 0.02ng/ml.

Conventional polymeric membranes are broadly employed in water treatment processes; however, most of them suffer from relatively low water permeance and severe membrane fouling phenomena owing to their relatively hydrophobic nature. In this work, a novel class of inorganic–organic composite membranes was developed through a newly developed vapor-ventilated in situ chemical deposition method, where the Ti and Si precursors were first hydrolyzed and then conferred into metal oxides to form a continuous TiO2–SiO2modification layer. Owing to the distinct physicochemical properties, the Ti and Si precursors were leveraged as quasi-molecular regulators to tune the membrane surface chemistry and pore aperture (within the nanoscale) to benefit highly efficient water purification by underpinning the rapid transport of water molecules and featuring an excellent fouling-resistant and fouling-releasing property against typical pollutants. The as-developed TiO2–SiO2/PES composite membrane showed a high water permeance of 187.4 L·m–2·h–1·bar–1, together with a relatively small mean pore aperture of 4.2 nm, showing an outstanding permeating efficiency among state-of-the-art membranes with a similar separation accuracy. This study provides a paradigm shift in membrane materials that could open avenues for developing high-performance inorganic–organic composite membranes for complex wastewater treatment.

The biological effects of aluminium have received much attention in recent years. Speciation of Al is of basic relevance as it concerns its reactivity and bioavailability. A differential pulse voltammetry (DPV) procedure is proposed for speciation analysis of AlIII in natural waters and biological fluids using six catechols (L-dopa, dopamine, epinephrine, norepinephrine, caffeic acid and o-benzenediol) as electroactive ligands. The decrease of the DPV anodic peak current for each catechol ligand is linear with the increase of Al concentration. This speciation analysis idea is based on the measurement of the complexation capacity, namely, different affinities of AlIII for catechols and organic ligands under two pH conditions. The labile monomeric Al fraction (mainly inorganic aluminium) is determined at pH 4.6, while the total monomeric Al fraction is determined at pH 8.5. The principle for AlIII speciation analysis by an electrochemical method is discussed. This sensitive and simple fractionation method is successfully applied to the speciation analysis of Al in natural waters and the results agree well with those of Driscoll’s method. The speciation analysis of Al in biological fluids is also explored and the results are compared with those obtained by ultrafiltration and dialysis. Compared with other speciation protocols the electrochemical method possesses some remarkable advantages: rapidity, high sensitivity, cheap instrumentation and a simple operation procedure.

An electrochemical procedure is proposed for the speciation of aluminum (Al) by derivative adsorption chronopotentiometry on a hanging mercury drop electrode (HMDE) using pyrocatechol violet (PCV) as a complexing agent. Labile monomeric Al fraction (mainly inorganic Al) was determined at pH 4.9 (accumulation time 60 s, accumulation potential −0.45 V, PCV concentration 1.5×10−6mol dm−3and stripping current 5 μA), while total monomeric Al fraction was determined at pH 8.2 (accumulation time 60 s, accumulation potential −0.50 V, PCV concentration 2.5×10−6mol dm−3and stripping current 5 μA). This sensitive and simple fractionation method was successfully applied to the speciation of Al in natural water samples. Five fractions were determined and measured: i) labile monomeric Al (Ali); ii) total monomeric Al (Ala); iii) acid reactive Al (Alr); iv) nonlabile monomeric Al (Alo); v) acid soluble Al (Als). The results were satisfactorily in agreement with those of the 8‐hydroxyquinoline extraction/ion exchange method.

An electrochemical procedure is proposed for the speciation of aluminum (Al) by derivative adsorption chronopotentiometry on a hanging mercury drop electrode (HMDE) using pyrocatechol violet (PCV) as a complexing agent. Labile monomeric Al fraction (mainly inorganic Al) was determined at pH 4.9 (accumulation time 60 s, accumulation potential –0.45 V, PCV concentration 1.5×10^–6 mol dm^–3 and stripping current 5 μA), while total monomeric Al fraction was determined at pH 8.2 (accumulation time 60 s, accumulation potential –0.50 V, PCV concentration 2.5×10^–6 mol dm^–3 and stripping current 5 μA). This sensitive and simple fractionation method was successfully applied to the speciation of Al in natural water samples. Five fractions were determined and measured: i) labile monomeric Al (Ali); ii) total monomeric Al (Ala); iii) acid reactive Al (Alr); iv) nonlabile monomeric Al (Alo); v) acid soluble Al (Als). The results were satisfactorily in agreement with those of the 8-hydroxyquinoline extraction/ion exchange method.

A differential pulse voltammetric (DPV) procedure is proposed for the speciation of aluminium in natural waters using Pyrocatechol Violet chemically modified electrodes (PCV-CMEs). This novel speciation idea is based on the selective determination of different Al^III forms under two pH conditions. The labile monomeric Al fraction (mainly inorganic Al) is analysed at pH 4.8 (0.20 mol dm⁻³ NaOAc–HOAc) and the total monomeric Al fraction is analysed at pH 8.5 (0.20 mol dm⁻³ NH₃·H₂O–NH₄Cl). The difference is thought to be caused by the weak competition ability of PCV to sequester Al^III from Al^III–natural organic matter complexes. This sensitive and simple speciation method has been applied successfully to aluminium speciation in natural waters sampled from different regions of China. Five fractions are measured directly or indirectly: (i) labile monomeric Al; (ii) total monomeric Al; (iii) acid reactive Al; (iv) non-labile monomeric Al; and (v) acid soluble Al. The results are in satisfactory agreement with those obtained by Driscoll’s 8-hydroxyquinoline extraction–ion exchange method.

Indirect determination of total monomelic and acid-reactive aluminum in natural waters by a.c. oscillopolarography in the presence of pyrocatechol violet (PCV) is presented in this paper. In 0.5 mol 1-1 NH4Ac buffer solution (pH 6.4) containing l×lO-3 mol 1-1 PCV, PCV yields two incisions on the a.c oscillogram at the potentials of - 0.80 and - 1.20 V, respectively. The incision depth declines when adding aluminum in the solution. The decreases of incision depth (Ep = -1.20 V) has a linear relationship with increasing Al concentrations (4×10-7 - 4×10-6 mol 1-). It is the basis for indirect quantitative analysis. The relative standard deviation is 8.3% for 1×10-6 mol 1-1 Al (n = 10) and the detection limit is 2 × 10-7 mol 1-1. The proposed method has been applied to determine total and acid-reactive Al in natural waters and the results are compared with Driscoll's 8-HQ-MIBK-GF/AAS and PCV colorimetric methods.

ABSTRACTA simple and sensitive electrochemical method for the direct determination of labile (monomeric inorganic Al speciation) Al concentration in natural waters is developed in this paper. It is based on the use of a.c. oscillopolarography in the presence of rubeanic acid (RA). The optimal experimental conditions are: 1 mol/L NaAc-HAc buffer (pH 5.4) and a RA concentration of 6x10−4mol/L. The response is linear over the 2x10−7to 2x10−6mol/L concentration range. The detection limit is 1x10−7mol/L and the relative standard deviation (at the 1.2 x 10−6mol/L level) is 5.5%. The method has been applied to the direct determination of labile monomeric Al concentrations in various natural samples. The results were verified by the classic ion exchange method.

Biological fluorescence imaging technologies have attracted a lot of attention and have been widely used in biomedical fields. Compared with other technologies, fluorescence imaging has a lower cost, higher sensitivity, and easier operation. However, due to the disadvantages of one-photon (OP) fluorescence imaging, such as low spatial and poor temporal resolution and poor tissue permeability depth, the application of OP fluorescence imaging has some limitations. Though two-photon (TP) fluorescence imaging can well overcome these shortcomings of OP, the single-mode imaging remains deficient. Therefore, dual-mode imaging combined with TP imaging and magnetic resonance imaging (MRI) can make up for the deficiency well, which make dual-mode imaging for the early diagnosis of diseases more accurate. Hence, a dual-mode nanoprobe TP-CQDs@MnO2was designed for probing the fluorescence/MR dual-mode imaging strategy of intracellular H+by using TP-CQDs (two photon-carbon quantum dots) and MnO2nanosheets. The MnO2nanosheets treated as fluorescence quenching agents of TP-CQDs exhibited a supersensitive response to H+, which made the fluorescence signals turn “off” to “on” for TP fluorescence imaging, in the meantime, large amounts of Mn2+were generated for MRI. A dual-mode nanoprobe TP-CQDs@MnO2can monitor intracellular wide pH (4.0–8.0), and the fluorescence intensity of TP-CQDs@MnO2has recovered up to more than six times and the corresponding results of MRI were satisfactory. TP fluorescence imaging of cells and tissues showed higher detection sensitivity and deeper tissue penetration (240.0 μm) than OP. The dual-mode imaging platform hold great promise for pH-related early diagnosis and treatment, which has great potential to improve clinical efficacy.

This paper developed an electrochemiluminescence (ECL) method for detecting ultratrace levels of the highly toxic organic pollutant, 3,4-dichloroaniline (3,4-DCA), in water. This method has not been used previously for 3,4-DCA detection, and is based on a 96-well micro-plate modified with molecularly imprinted sol-gel films combined with multi-walled carbon nanotubes (MIF-MWCNTs). The increase in the ECL signal intensity was proportional to the 3,4-DCA concentration within a certain range, and an excellent response was obtained for 3,4-DCA concentrations ranging from 4 × 10−11to 6 × 10−9mol L−1, with a low detection limit (LOD) of 1 × 10−11mol L−1. The detection sensitivity of the present method is higher than those of the most commonly used chromatography methods, with the recovery of 3,4-DCA from spiked samples of water ranging from 83.3 to 110.5%. Thermodynamic analysis showed that the adsorption of 3,4-DCA by the MIF-MWCNTs occurred spontaneously as an exothermic and entropy decreasing process (ΔH = −32.49 kJ mol−1, ΔS = −117.89 J mol−1). Kinetic equation fitting demonstrated that the adsorption of 3,4-DCA could be fitted by an intraparticle diffusion model, and that the adsorption isotherm data fitted the Freundlich model.

One novel electrochemical immunosensor was constructed by immobilizing capture antibody of alpha-fetoprotein (AFP Ab1) on a nafion/nanogold-particle modified glassy carbon electrode. With a sandwich immunoassay, one DNA-derived magnetic nanoprobe, simplified as DNA/(ZMPs—HRP-AFP Ab2)n, was employed for the detection of AFP. The fabricated procedure of the proposed biosensor was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The performance and factors influencing the performance of the biosensor were also evaluated. Under optimal conditions, the developed biosensor exhibited a well-defined electrochemical behavior toward the reduction of AFP ranging from 0.01 to 200?ng/mL with a detection limit of 4?pg/mL (??/??=3). The biosensor was applied to the determination of AFP in serum with satisfactory results. It is important to note that the sandwich nanochainmodified electro-immunosensor provided an alternative substrate for the immobilization of other tumor markers.