In this work, a facile ratiometric fluorescence sensor for GSH measurement was designed based on MnO2 nanosheet (NS), carbon dots (CDs), as well as a simple substrate o-phenylenediamine (OPD). ...Herein, MnO2 NS played triple essential roles in the sensing system. First, it could be reduced by GSH through a special reaction, and therefore served as GSH recognizer. Second, it played as a fluorescence nanoquencher to strongly quench the fluorescence of CDs. Third, it could directly oxidize OPD to yield a luminescent product 2, 3-diaminophenazine (DAP) via the intrinsic oxidase-like activity. It revealed that MnO2 NS could be reduced to Mn2+ in the presence of GSH. Thus its oxidase-like activity and fluorescence quenching abilities were inhibited, which then restricted the generation of DAP and recovered the fluorescence of CDs. Based on this phenomenon, a novel ratiometric fluorescence sensor for GSH determination was fabricated by measuring the ratio of fluorescent intensity of DAP to that of CDs. Besides, the constructed ratiometric fluorescent sensor, which could be facilely operated with single-wavelength excitation, exhibited high sensitivity and selectivity with a wider linear range and a lower detection limit.
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•A facile single-wavelength excitation ratiometric fluorescence sensor was constructed for GSH.•MnO2 nanosheets can not only effectively quench the fluorescence of CDs but also oxidize OPD into luminescent DAP due to its intrinsic oxidase-like activity.•DAP could also quench the fluorescence of CDs through the inner filter effect.
As one of the most promising and efficient approaches for remediating the deterioration of natural environments, semiconductor-based photocatalysis has received considerable attention. To date, ...numerous efforts have been focused to explore novel materials for highly efficient photocatalysis under visible light or sunlight irradiation. Among them, Ag-based compounds are emerging to be a promising candidate because of their excellent visible light-responsive photoelectrochemical properties. This review summarizes the recent progress in the design and fabrication of Ag-compound-based semiconductor photocatalysts and their applications in the photocatalytic decomposition of organic molecules. Initially, the mechanisms of the related photocatalytic reactions will be discussed, and then we will highlight some of the recent progresses in Ag-based micro- or nano-structured material fabrication that exhibit enhanced photocatalytic performance. These novel and highly efficient photocatalysts mainly include Ag 2 O, Ag 2 S, AgX (X = Cl, Br, I), Ag 2 CO 3 and Ag 3 PO 4 . We expect that the present tutorial review will provide insights in the direction of the future visible-light photocatalyst design.
In this work, a dual amplified signal enhancement approach based on coupling deoxyribozyme (DNAzyme)-driven bipedal DNA walkers (BDW) and terminal deoxynucleotidyl transferase (TdT)-mediated DNA ...elongation signal amplifications has been developed for highly sensitive and label-free electrochemical detection of thrombin in human serums. In presence of thrombin, the BDW complex, which is comprised from the target thrombin and two DNAzyme-containing probes, can exhibit autonomous cleavage behavior on the surface of the substrate DNA (SD) modified electrode, and remove the cleaved DNA fragment from the electrode surface. Subsequently, the TdT can catalyze the elongation of the SD with free 3′-OH termini and formation of many G-quadruplex sequence replicates with the presence of 2′-deoxyaguanosine-5′-triphosphate (dGTP) and adenosine 5′-triphosphate (dATP) at a molar ratio of 6:4. These G-quadruplex sequences bind hemin and generate drastically amplified current response for sensitive detection of thrombin in a “signal-on” and completely label-free fashion. Under optimized conditions, the response peak current was linear with the concentration of thrombin in the range from 0.5 pM to 100000 pM with detection limit of 0.31 pM. This research provides us a sustainable idea for the hyphenated multiple amplification strategies and a stable and effective method for the detection of protein biomarkers.
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•A new electrochemical biosensor was developed based on dual cascade amplification strategy of DNAzyme-driven bipedal DNA walkers.•The developed electrochemical biosensor was completely label-free in a “signal-on” fashion.•The work proves the possibility of the strategy based on DNA machine hyphenating diversified amplification methods.
This study demonstrates a first exploitation of the unique properties inherent in Pickering emulsions to develop a new kind of photocatalytic system. We engineered the system by using silver ...phosphate (Ag3PO4) as a photocatalytic active metal oxide semiconductor and multiwalled carbon nanotubes (MWNTs) as a hydrophobic conducting nanostructure to form the Pickering emulsions. The photocatalytic activity of the as-formed Ag3PO4/MWNT-stabilized Pickering emulsion-based system is studied toward dye decomposition and oxygen evolution. Results imply that the Pickering emulsion-based photocatalytic system exhibits a much higher efficiency, as compared with traditional solution-dispersed photocatalytic system. This high efficiency is elucidated in terms of the unique properties inherent in Pickering emulsions including (i) the self-assembled Ag3PO4/MWNT nanohybrid at water/oil interface, well ensuring a large surface area of the photocatalyst, (ii) the use of MWNTs to facilitate the formation of amphiphilic nanostructures self-assembled at water/oil interface, promoting the charge separation of the semiconductor through the π–π network of MWNTs by shuttling and storing photogenerated electrons from the visible light irradiated Ag3PO4, and (iii) the separation of the product (e.g., O2 evolved from water oxidation) from the reactants during the photocatalytic process, well accelerating the photocatalytic reactions. In addition to the high efficiency, the fast and simple procedures employed for demulsifying (e.g., sonication or centrifugation) and re-emulsifying (e.g., shaking) essentially make our Pickering emulsion-based photocatalytic system technically simple and thus practically applicable. This study opens a new way to developing novel photocatalytic systems with high efficiency and good practical applicability based on Pickering emulsion science and technology.
Magnoliaceae, a family of perennial woody plants, contains several endangered species whose taxonomic status remains ambiguous. The study of chloroplast genome information can help in the protection ...of Magnoliaceae plants and confirmation of their phylogenetic relationships. In this study, the chloroplast genomes were sequenced, assembled, and annotated in Woonyoungia septentrionalis and three Michelia species (Michelia champaca, Michelia figo, and Michelia macclurei). Comparative analyses of genomic characteristics, repetitive sequences, and sequence differences were performed among the four Magnoliaceae plants, and phylogenetic relationships were constructed with twenty different magnolia species. The length of the chloroplast genomes varied among the four studied species ranging from 159,838 bp (Woonyoungia septentrionalis) to 160,127 bp (Michelia macclurei). Four distinct hotspot regions were identified based on nucleotide polymorphism analysis. They were petA-psbJ, psbJ-psbE, ndhD-ndhE, and rps15-ycf1. These gene fragments may be developed and utilized as new molecular marker primers. By using Liriodendron tulipifera and Liriodendron chinense as outgroups reference, a phylogenetic tree of the four Magnoliaceae species and eighteen other Magnoliaceae species was constructed with the method of Shared Coding Sequences (CDS). Results showed that the endangered species, W. septentrionalis, is relatively genetically distinct from the other three species, indicating the different phylogenetic processes among Magnoliaceae plants. Therefore, further genetic information is required to determine the relationships within Magnoliaceae. Overall, complete chloroplast genome sequences for four Magnoliaceae species reported in this paper have shed more light on phylogenetic relationships within the botanical group.
This work establishes a highly sensitive and simple stripping voltammetric method for the direct determination of trace iodide. In the presence of abounding bromide and appropriate amount of ...cetylpyridine bromide (CPB), the iodine was accumulated on the glassy carbon electrode surface as ion association complex (CPBI2Br). After accumulation for a period of time, a linear sweep potential with negative scanning was applied and the I2 in CPBI2Br was reduced again into the solution. Under the optimization conditions, the stripping signals (peak current) were linear relationship with iodide concentration in range of 3.81×10−3µg/mL to 0.114 μg/mL and 0.127μg/mL to 2.54μg/mL, with a detection limit of 1.02ng/mL (S/N=3) for a accumulation time of 180s. Determination of trace iodine in pharmaceutical sample, kelp and table salt were performed with high accuracy and satisfactory recovery results.
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•A sensitive and simple electrochemical method to detect trace iodide was stablished.•The effect of different surfactants in the preconcentration process was investigated.•The formation of ion-associating compound remarkably increased the signal of iodide.•This method is suitable to determine trace iodine in real samples.
Magnetic materials and noble metal-based multifunctional hybrids have attracted much attention recently due to their unique properties and potential applications in a variety of fields. However, ...substantial challenges remain to directly obtain water-soluble hybrids with well-defined structures and to directly combine magnetic nanoparticles with nonspherical noble metals. We describe here for the first time a simple solvothermal method to synthesize a series of novel water-soluble nanohybrids composed of shape-tuned Ag cores and a Fe3O4 shell. We found that small Fe3O4 grains can be well-distributed directly on the surface on the Ag seeds. Such hybrids have both plasmonic and significant superparamagnetic properties, enabling magnetic separation. The plasmon resonance frequency of Ag nanostructures can be fine-tuned through the interactions between the two components. In addition, the decorated Fe3O4 nanoparticles stabilized the Ag nanostructures when exposed to air and natural light for a long time. Furthermore, an interesting structural transformation is observed in the one-dimensional Ag–Fe3O4 nanowires under high-energy electron beam. The Ag core can diffuse through the porous iron oxide shell, break away, and result in the formation of Ag nanocluster-decorated iron oxide tubes. Finally, the hybrids acted as a chemical template for the synthesis of Fe3O4/Au-AgCl double-layer nanotubes that display obvious near-infrared absorption. Importantly, the double-layer nanotubes exhibited enhanced photocatalytic inactivation of bacteria at very low concentrations under natural sunlight.
A simple, inexpensive and highly sensitive voltammetric method for the determination of tectoridin was developed using a poly(l-Arginine) modified electrode. The redox character of tectoridin at ...proposed electrode was studied systematically and some dynamic parameters were calculated for the first time. A reasonable reaction mechanism of tectoridin on the poly(l-Arginine)/GCE was also dicussed and proposed, which could be a reference for the pharmacological action of tectoridin in clinical study. And the electroanalytical method for determination of tectoridin was established by differential pulse voltammograms (DPV). Under optimum conditions, the response peak currents were linear relationship with tectoridin concentrations in the range of 5.0×10−8–2.0×10−6molL−1 with a detection limit of 4.0×10−8molL−1. Therefore, the high sensitivity for tectoridin sensing at the proposed electrode was achieved, and the proposed method could also be used to detect tectoridin in the Chinese medicinal herb Blackberrylily with satisfactory results.
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•Electrochemical properties of tectoridin were investigated for the first time.•The resulting sensor showed a significant voltammetric response to tectoridin.•Some dynamic parameters were calculated for the first time.•A feasible mechanism of tectoridin at modified electrode was proposed.•The proposed method detect tectoridin in nature samples with satisfactory results.
Abstract Here, we demonstrated dimethyldioctadecylammonium bromide (DODAB), a cationic lipid, bilayer coated Au nanoparticles (AuNPs) could efficiently deliver two types of plasmid DNA into human ...embryonic kidney cells (HEK 293) in the presence of serum. The transfection efficiency of AuNPs was about five times higher than that of DODAB. The interaction of AuNPs with DNA was characterized with dye intercalation assay and agarose gel electrophoresis. The morphology of the complex of AuNPs with DNA was observed with scanning electron microscope (SEM). The intracellular trafficking of the complex was monitored with transmission electron microscope (TEM). Based on experimental results, the possible mechanism was proposed and the barriers in the process of transfection were discussed. This work demonstrates a simple way to increase the transfection efficiency of cationic lipid through changing the stability of the complex of cationic lipid with DNA. It may provide some insights into understanding and controlling the interaction of cationic lipid with DNA. It also provides a novel way to construct gold nanoparticles-based gene vectors and some insights into learning the process of nanomaterials-mediated transfection.
