查看更多>>摘要：Mercapto- and amino-functionalized magnetic nanoparticles, Fe3O4@SiO2@MPTMS (SMNPs-MPTMS) and Fe3O4@SiO2@APTES (SMNPs-APTES), have been applied as magnetic solid-phase extraction (MSPE) sorbents to directly extract arsenite (As(III)) and arsenate (As(V)) respectively, followed by inductively coupled plasma-mass spectrometry (ICP-MS) detection. Various MSPE parameters were optimized including dose of magnetic adsorbent, pH of sample solution, loading and elution conditions of analytes, adsorption capacity and reusability of SMNPs-MPTMS and SMNPs-APTES for As(III) and As(V) respectively. Under the optimized MSPE conditions, this combined scheme possesses excellent selectivity and strong anti-interference ability without any oxidation or reduction prior to capture of these two species. It is found that with a 25-fold enrichment factor, the limits of detection of As(III) and As(V) were 23.5 and 10.5 ng L-1, respectively. To verify the reliability of the proposed protocol, a certified reference material of environmental water was analyzed, and the results for inorganic arsenic species were in close agreement with the certified values. The applicability of the combination strategy for speciation analysis of inorganic arsenic was evaluated in spiked tap, river, lake and rain water samples. Good recoveries of 89%-96% and 90%-102% were achieved for As(III) and As(V), respectively, with the relative standard deviation ranges of 3.2%-8.0% and 2.5%-7.6%. Through the characterization of functionalized magnetic nanoparticles and the optimization of MSPE experiment, it is confirmed that the existence of mercapto and amino groups on SMNPs-MPTMS and SMNPs-APTES sorbents are responsible for the extraction of As(III) and As (V), respectively, via coordination and electrostatic interactions.
查看更多>>摘要：Sulfur dioxide (SO2) plays an extremely important role in the basic processes of physiology and pathology. As an antioxidant, SO2 can maintain the redox homeostasis in the cell. Excessive inhalation of SO2 would lead to irreparable respiratory damage, resulting in respiratory diseases, neurological disorders, and even cardiovascular disease. Thus, it is urgent to exploit an excellent way to monitor SO2 derivatives in biological system. Herein, we design a water-soluble ratiometric fluorescent probe to fast detect the level of SO2 derivatives in living cells in vivo. The probe displays obvious fluorescence signal at long wavelength, which is helpful for imaging of biological system. After respond to SO2 derivatives, the fluorescence signal at 465 nm increases rapidly due to the Michael addition reaction is triggered, further causing the disruption of large conjugated system. The probe exhibits high selectivity and fast respond to SO2 derivatives, which can be able to sensitive and real-time monitoring of SO2 derivatives level in living cells. Moreover, the probe reveals a low detection limit and a great linear relationship to SO2 derivatives. Based on the negligible cytotoxicity and good biocompatibility of the probe, which is employed to detect exogenous and endogenous SO2 derivatives in living cells. In addition, it is also served as a potential chemical tool to detect SO2 derivatives in mice model of sinusitis.
查看更多>>摘要：Copper sulfate is a widely used agent to control insects, bacteria and algae for fishery. However, excess amount of copper ions in water accumulate in aquatic products through the ecological cycle system, highly threatening food safety and public health. Therefore, it is urgent to develop a rapid and efficient method for the determination of copper content in aquatic products. In this study, we developed a label-free biosensor for Cu(II) based on a graphene field-effect transistor gated by structure-switching aptamer probes (SSA-GFET) against Cu(II) we obtained before. The detection mechanism of the biosensor is attributed to the surface charge shift and the potential change of the gate electrode upon the specific binding of Cu(II). The SSA-GFET biosensor has a low detection limit of 10 nM and a linear range of 10 nM to 3 mu M to Cu(II). In addition to the excellent selectivity to Cu(II), the biosensor also showes the advantage of high recovery rate for detection of Cu(II) in real fish samples. Because of the detection characteristics of label-free SSA-GFET, it has great advantages in the field of food safety and environmental detection.
查看更多>>摘要：We describe a reagent-free acid-base titration method, in which only water is added and the titrant is online electrodialytically produced. Electrodialytic eluent generator, a well-established technique in ion chromatography to produce high purity base or acid eluent through precise control of an electric current, has been for the first time used for titration, termed as electrodialytic titrant generator (ETG). Three kinds of titrants produced by ETG have been demonstrated, including potassium hydroxide, methanesulfuric acid and sulfuric acid. A series of titrants with different concentration up to at least 140 mM (e.g. KOH) could be accurately and reproducibly obtained by manipulating current and the KOH titrant showed extremely high purity. The titration results achieved by ETG were in a good agreement with those obtained by the regular way and their ratio was in the range of 0.9918 and 1.0034. Good accuracy and precision were achieved for ETG titration, as indicated by 2.2% of relative error and 0.17% of relative standard error. Its utility was demonstrated to measure pKa-differentiated capacity of anion exchange resins.
Le, Hien T. NgocKim, DaesooPhan, Le Minh TuCho, Sungbo...
9页
查看更多>>摘要：In this paper, we developed a new ultrasensitive capacitance sensor for detection of amyloid beta 1-40 (a beta 40) protein (one of Alzheimer's disease core biomarkers) in human serum based on the high supramolecular recognition of the beta-cyclodextrin/reduced graphene oxide (beta-CD/RGO) nanohybrid toward the anti-a beta 40 antibody molecule. The sensor was established by immobilizing specific anti-a beta 40 antibody onto the beta-CD/RGO nanohybrid functionalized on indium tin oxide micro-disk electrode (anti-a beta 40/beta-CD/RGO/ITO). Detection of a beta 40 in the human serum (HS) using the sensor anti-a beta 40/beta-CD/RGO/ITO is carried out by capacitance measurement without a redox probe to prevent protein denaturation, serving as a convenient strategy for point-of care diagnosis. In comparison with other studies, the sensor shows a very low limit of detection of 0.69 fg mL(-1) in HS, demonstrating its ability for the ultrasensitive detection of a beta 40. Using this sensor, the dissociation constant K-D of the binding interaction between anti-a beta 40 and a beta 40 in HS is found to be 2.9 x 10(-7) nM, indicating the high binding affinity of antibody-antigen and the suitability of the anti-a beta 40/beta-CD/RGO/ITO sensor for a beta 40 protein detection. The good selectivity of the anti-a beta 40/beta-CD/RGO/ITO sensor in the presence of differential analytes was also performed in this paper.
查看更多>>摘要：In this work, we propose a two-step coating method, combining C-ZIF67@Ni with molecular imprinting polymer (MIP), to develop a high-sensitivity and high-selectivity Carbendazim (CBD) electrochemical sensor. ZIF67@Ni was prepared by a simple chemical bath method, and C-ZIF67@Ni was obtained by high-temperature carbonization of ZIF67@Ni. Then, MIP layer was prepared by electrochemical in-situ polymerization, with O-amino phenol as functional monomers, CBD acting as template on the surface of the C-ZIF67@Ni-modified glassy carbon electrode (GCE). During the preparation process, the types of functional monomers, the polymerization solution pH, the ratio of functional monomers to template molecules, and the incubation time are optimized. The morphological characteristics, composition information and electrochemical properties of MIP/C-ZIF67@Ni/GCE were investigated in detail under optimal conditions. Physical characterization and electrochemical tests revealed that ZIF67@Ni significantly improves the electron transmission capacity and surface area of the sensor after high-temperature carbonization. C-ZIF67@ Ni has a good synergistic effect on MIP, allowing rapid and specific identification of the test substance. MIP/C-ZIF67@Ni/GCE showed a good linear relationship with CBD in the concentration range from 4 x 10(-13) M to 1 x 10(-9) M, the lowest detection limit was 1.35 x 10(-13) M (S/N = 3) R-2 = 0.9983 and RSD = 2.34. Additionally, the sensor showed good repeatability, stability, and selectivity, and can be used for the detection of carbendazim in soil and water with a recovery of 98% above.
查看更多>>摘要：Abnormal expression of microRNAs is greatly associated with the occurrence of various cancer types, revealing great potential of microRNA as biomarkers for cancer diagnosis and prognosis. Herein, a MXene-MoS2 heterostructure enhancing electrochemical biosensor coupled with catalytic hairpin assembly (CHA) amplification approach for label-free determination of microRNA-21 (miR-21) was successfully assembled. In particular, the unique micro-nano heterostructure with large specific area and favorable electroconductivity exhibited the ability of excellent confinement effect. Thus, rendered the MXene-MoS2 heterostructure the ability to trigger more target recycling reaction, giving new vitality to the traditional CHA amplification method. Meanwhile, thionine (Thi) and gold nanoparticles (AuNPs) were anchoring at the surface of MXene-MoS2 heterostructure, respectively, empowered the sensor the capability of capture probes fixation and miR-21 label-free determination. When numerous electronegative double-stranded DNA generated, the electron transfer was greatly hindered, resulting in signal decrease. Accordingly, the design denoted a broad dynamic range from 100 fM to 100 nM and a detection limit of about 26 fM, comparable or lower than previous reported methods for miR-21 detection. Furthermore, the sensing platform supplied satisfactory selectivity, reproducibility and stability towards the miR-21 detection. The real sample determination also showed a promising performance under clinical circumstance. Finally, from the clinical standpoint, the proposed biosensor is a considerable platform toward early disease detection and monitoring.
查看更多>>摘要：During recent decades, we have witnessed a great improvement in the performance of aptamer-based sensors, specifically when aptamers are combined with new nanomaterials; as a platform for biosensors. The design of hollow carbon-based materials has also received a lot of attention due to its excellent properties in various applications. Herein, we aim at designing hierarchical porous Ni(OH)(2) nanosheets on hollow N-doped carbon nanoboxes Ni(OH)(2)@N-C n-box). In this sense, we obtained the hollow N-C n-box skeletons from the Fe2O3 nanocubes template. The development of label-free electrochemical aptasensor was carried out using the covalently immobilizing NH2-functionalized aptamer on Ni(OH)(2)@N-C n-box as an efficient substrate. The Ni (OH)(2)@N-C n-box was characterized using scanning fourier transform infrared spectroscopy (FTIR), X-ray Diffraction (XRD), Brunauer, Emmett and Teller (BET), transmission electron microscopes (TEM) and electron microscopy (FESEM). The electrochemical evaluations clarified the fact that a linear relationship exists between the alpha-fetoprotein (AFP) contents and the charge transfer resistance (R-ct) (from 1 fg mL(-1) to 100 ng mL(-1)) with a low detection limit of 0.3 fg mL(-1). Moreover, regarding the aptasensor, the superior detection recoveries were experienced in real biological samples, illustrating its great detection performance and practical feasibility. Considering the aptasensor application, these studies showed that Ni(OH)(2)@N-C n-box possesses different enhanced electrochemical features, making it appropriate as an electrode material for aptasensor application.
查看更多>>摘要：H2S has been reported to play essential roles in a variety of physiological and pathological procedures. In this work, a novel fluorescent probe, Rho-HS, for detecting H2S was developed by introducing the ortho-halogen to activate the least reactive recognition group 2,4-dinitrophenyl moiety. In combination of the structures from both Rhodamine B and fluorescein, Rho-HS could generate both the colorimetric and fluorescent responses. This feature was not frequently achieved and could lead to the quantitative and convenient for the end-user. In comparison with recent probes for H2S, the major advantages of Rho-HS included suiting wide pH range (6.0-10.0), relatively rapid response (within 15 min) and the high selectivity among the competing species including the biothiols. With low cytoxicity, Rho-HS was further applied in the biological imaging in living MCF7 cells and Caenorhabditis elegans. We hope that the designing strategy in this work might provide useful information for more preferable implements in this field.
查看更多>>摘要：A kind of organic-inorganic hybrid silica nanoparticles loaded with 1,8-naphthalimide borate ester (NIB@SiO2) was used to detect trace hydrogen peroxide (H2O2) vapor via turn-off mechanism. The detailed studies showed that utilizing silica nanoparticles can improve the adsorption properties and hydrophilicity of the sensing film, accelerate the deboronation reaction between the sensing material and H2O2, and then shorten the response time successively, which is always the disturbing challenge for this deboronation-type fluorescent probe to H2O2 vapor. The fluorescence of NIB@SiO2 film was quenched greatly under H2O2 saturated vapor within 5 s at room temperature and limit of detection (LOD) was estimated to be 184 ppt, which are among the best reported results. Thus, this study provides an ultrafast and highly sensitive organic-inorganic hybrid fluorescent probe to H2O2 vapor, moreover, a new design strategy for promising H2O2 fluorescent probe is revealed.
NSTL
Elsevier