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Hierarchically porous metal oxide materials including titanium dioxide (TiO 2 ), ferric oxide (Fe 2 O 3 ), zinc oxide (ZnO), and ceria (CeO 2 ) were prepared on a large scale by an improved sol–gel method assisted with evaporation-induced surfactant self-assembly. Hierarchical metal oxide networks with well-defined macroporous windows and mesoporous walls were obtained after the surfactant molecules were removed by calcination. The factors influencing the morphology, pore structure and size of these porous metal oxides were studied. Moreover, this method can also be used for one-pot synthesis of hierarchical nanohybrids loaded with noble-metal nanoparticles. The synthesis and catalytic properties of Au/TiO 2 nanohybrids with different Au loading (2, 5, and 10 wt.%) were typically demonstrated. Benefiting from the uniform dispersion of Au nanoparticles, the Au/TiO 2 nanohybrids show favorable catalytic activity in both the photooxidation of rhodamine B (RhB) under visible light and the catalytic reduction of 4-nitrophenol with sodium borohydride to 4-aminophenol. The photooxidation mechanism of RhB in aqueous solution over Au/TiO 2 nanohybrid was verified experimentally. This work provides a general method for the scalable preparation of diverse hierarchically porous metal oxides and noble-metal/oxide nanohybrids, which are expected to have more applications in catalysis and energy conversion. [ABSTRACT FROM AUTHOR]

The development of functional materials with both light–heat conversion and thermal energy storage properties is of crucial importance for efficient utilization of sunlight to meet the growing demand for sustainable energy. In this work, the shape-stabilized phase change composites were designed and prepared by integration of stearic acid (SA) and acid-treated carbon nanotubes (a-CNTs). The a-CNTs not only acted as a flexible matrix but also endowed the composites high light–heat conversion ability. The reversible phase transitions shifted from high temperatures ( T m = 74 °C, T f = 57 °C) of pure SA to near room temperature ( T m = ∼30 °C, T f = ∼22 °C) of SA/a-CNTs composites, probably resulting from the strong interface confinement effect. The phase change enthalpy of the SA/a-CNTs composite could also be tailored by changing the mass ratio of SA and a-CNTs. The composites containing SA of 54.2 wt.%, 67.8 wt.% and 79.5 wt.% presented the melting enthalpy of 76.3 J/g, 98.8 J/g and 111.8 J/g, respectively. Moreover, the phase transition of SA/a-CNTs composite could be driven by sunlight for the energy storage/release. Therefore, this research provides a new platform for improving solar utilization, and understanding the phase transition behaviors of organic PCMs in dimensionally confined environments as well. [ABSTRACT FROM AUTHOR]

The drainage and rupture of solution/frother interface is a prerequisite to predict the adsorption of frother onto the bubble surface. Using a high-speed motion acquisition system, we investigated the dynamic penetration of bubble at the solution/frother interface under four factors that height, capillary inner diameter, ion concentration and ionic valence. Since the kinetic energy of bubble was proportional to the radius and rising velocity, the kinetic energy increased with increasing the height and capillary inner diameter while decreased with increasing the ion concentration and ionic valence. The variation of kinetic energy followed the order: capillary inner diameter > ion concentration > height > ionic valence. The drainage time of the bubble at the solution/frother interface was found to decrease as the kinetic energy increased independently of these factors, indicating that the rupture of the hydration film was significantly influenced by the kinetic energy. A solution column caused by the bubble penetrating the solution/frother interface was observed. The column height increased as the kinetic energy increased for the factors of height and capillary while an opposite trend was presented by the factors of ion concentration and ionic valence. IFT was discussed to be the essential reason for the difference in the penetration. IFT of the solution/air interface increased as the ion concentration increased independently of ion species, and the IFT of different interfaces followed the order: solution/air > frother/air > solution/frother. Our results can provide valuable insight into the development of technology for surfactant adsorption and mineral flotation. [Display omitted] • Drainage time decreased as bubble kinetic energy increased independently of the four factors. • Solution column connecting to the bubble was formed and its height was related to bubble kinetic energy and ions. • IFT of solution/air, frother/air and solution/frother interfaces was the essential reason for the difference in drainage. [ABSTRACT FROM AUTHOR]

• MCAC shows a maximum specific surface area of 1188.00 m2/g. • Methylene blue adsorption capacity is 238.56 mg/g. • The adsorption rate can still reach 88% at a cycle index of 5. • It has potential applications in organic pollutant wastewater treatment. Environmentally friendly magnetic coal-based activated carbon (MCAC) with high adsorption performance has been synthesized by using a facile one-step method. The samples were prepared with ratios of ferrocene to Ningxia coking coal to be 0:1, 1:2, 1:1, 2:1 and 3:1 (denoted as CAC, MCAC-1:2, MCAC-1:1, MCAC-2:1 and MCAC-3:1, respectively). Scanning electron microscopy (SEM) observation indicated that there were a large number of pores with diameters below 500 nm on surface of the MCAC. Magnetic properties of the samples were characterized by vibrating sample magnetometer (VSM), with saturation magnetizations of 9.55–22.48 emu/g. Due to the activation of KOH and the introduction of magnetic particles, the MCAC had a maximum specific surface area of 1188.00 m2/g and a maximum total porosity of 0.50 cm3/g. As a result, the MCAC exhibited excellent adsorption properties to remove methylene blue (MB), with an adsorption capacity of 238.56 mg/g, while the adsorption rate was still 88% after 5 cycles. Therefore, this strategy can be used as a reference for the clean and efficient use of coal. [ABSTRACT FROM AUTHOR]

Background: The early allopolyploid Brassica napus was a hybrid of two Brassica species, that had undergone a whole genome duplication event followed by genome restructuring, including deletions and small scale duplications. A large number of homologous genes appeared functional divergence during species domestication. Due to the high conservation of de novo glycerolipid biosynthesis, multiple homologues of glycerol-3-phosphate acyltransferases (GPATs) have been found in B. napus. Moreover, the functional variances among these homologous GPAT-encoding genes are unclear., Results: In this study, four B. napus homologous genes encoding glycerol-3-phosphate acyltransferase 9 (BnaGPAT9) were characterized. Although a bioinformatics analysis indicated high protein sequence similarity, the homologues demonstrated tissue-specific expression patterns and functional divergence. Yeast genetic complementation assays revealed that BnaGPAT9-A1/C1 homologues but not BnaGPAT9-A10/C9 homologues encoded functional GPAT enzymes. Furthermore, a single nucleotide polymorphism of BnaGPAT9-C1 that occurred during the domestication process was associated with enzyme activity and contributed to the fatty acid composition. The seed-specific expression of BnGPAT9-C1 1124A increased the erucic acid content in the transformant seeds., Conclusions: This study revealed that BnaGPAT9 gene homologues evolved into functionally divergent forms with important roles in erucic acid biosynthesis., (© 2024. The Author(s).)

Nanopore analysis relies on ensemble averaging of translocation signals obtained from numerous molecules, requiring a relatively high sample concentration and a long turnaround time from the sample to results. The recapture and subsequent re-reading of the same molecule is a promising alternative that enriches the signal information from a single molecule. Here, we describe how an asymmetric nanopore improves molecular ping-pong by promoting the recapture of the molecule in the trans reservoir. We also demonstrate that the molecular recapture could be improved by linking the target molecule to a long DNA carrier to reduce the diffusion, thereby achieving over 100 recapture events. Using this ping-pong methodology, we demonstrate its use in accurately resolving nanostructure motifs along a DNA scaffold through repeated detection. Our method offers novel insights into the control of DNA polymer dynamics within nanopore confinement and opens avenues for the development of a high-fidelity DNA detection platform.

Nanopores have developed into powerful single-molecule sensors capable of identifying and characterizing small polymers, such as DNA, by electrophoretically driving them through a nanoscale pore and monitoring temporary blockades in the ionic pore current. However, the relationship between nanopore signals and the physical properties of DNA remains only partly understood. Herein, we introduce a programmable DNA carrier platform to capture carefully designed DNA nanostructures. Controlled translocation experiments through our glass nanopores allowed us to disentangle this relationship. We vary DNA topology by changing the length, strand duplications, sequence, unpaired nucleotides, and rigidity of the analyte DNA and find that the ionic current drop is mainly determined by the volume and flexibility of the DNA nanostructure in the nanopore. Finally, we use our understanding of the role of DNA topology to discriminate circular single-stranded DNA molecules from linear ones with the same number of nucleotides using the nanopore signal.

Multiplexed nucleic acid sensing methods with high specificity are vital for clinical diagnostics and infectious disease control, especially in the postpandemic era. Nanopore sensing techniques have developed in the past two decades, offering versatile tools for biosensing while enabling highly sensitive analyte measurements at the single-molecule level. Here, we establish a nanopore sensor based on DNA dumbbell nanoswitches for multiplexed nucleic acid detection and bacterial identification. The DNA nanotechnology-based sensor switches from an "open" into a "closed" state when a target strand hybridizes to two sequence-specific sensing overhangs. The loop in the DNA pulls two groups of dumbbells together. The change in topology results in an easily recognized peak in the current trace. Simultaneous detection of four different sequences was achieved by assembling four DNA dumbbell nanoswitches on one carrier. The high specificity of the dumbbell nanoswitch was verified by distinguishing single base variants in DNA and RNA targets using four barcoded carriers in multiplexed measurements. By combining multiple dumbbell nanoswitches with barcoded DNA carriers, we identified different bacterial species even with high sequence similarity by detecting strain specific 16S ribosomal RNA (rRNA) fragments.

Respiratory infections are the major cause of death from infectious disease worldwide. Multiplexed diagnostic approaches are essential as many respiratory viruses have indistinguishable symptoms. We created self-assembled DNA nanobait that can simultaneously identify multiple short RNA targets. The nanobait approach relies on specific target selection via toehold-mediated strand displacement and rapid readout via nanopore sensing. Here we show that this platform can concurrently identify several common respiratory viruses, detecting a panel of short targets of viral nucleic acids from multiple viruses. Our nanobait can be easily reprogrammed to discriminate viral variants with single-nucleotide resolution, as we demonstrated for several key SARS-CoV-2 variants. Last, we show that the nanobait discriminates between samples extracted from oropharyngeal swabs from negative- and positive-SARS-CoV-2 patients without preamplification. Our system allows for the multiplexed identification of native RNA molecules, providing a new scalable approach for the diagnostics of multiple respiratory viruses in a single assay., (© 2023. The Author(s).)

While the solid-state nanopore shows increasing potential during sensitive and label-free single molecular analysis, target concentration and signal amplification method is in urgent need. In this article, a solution via designing a model nucleic acid circuit reaction that can produce "Y" shape-structure three-way DNA oligomers with controllable size and polymerization degree is proposed. Such a so-called lego-like three-way catalytic hairpin assembly (LK-3W-CHA) can provide both concentration amplification (via CHA circuit) and programmable size control (via lego-like building mode) to enhance spatiotemporal resolution in single molecular sensing of solid-state nanopore. Oligomers containing 1-4 DNA three-way junctions (Y monomers, Y1-Y4) are designed in proof-of-concept experiments and applications. When the oligomers are applied to direct translocation measurements, Y2-Y4 can significantly increase the signal resolution and stability than that of Y1. Meanwhile, Y1 to Y4 can be used as the tags on the long DNA carrier to provide very legible secondary signals for specific identification, multiple assays, and information storage. Compared with other possible tags, Y1-Y4 provides higher signal density and amplitude, and quasi-linear "inner reference" for each other, which may provide more systematic, reliable, and controllable experimental results., (© 2022 Wiley-VCH GmbH.)

DNA nanotechnology provides a unique opportunity for molecular computation, with strand displacement reactions enabling controllable reorganization of nanostructures. Additional DNA strand exchange strategies with high selectivity for input will enable novel complex systems including biosensing applications. Herein, we propose an autocatalytic strand displacement (ACSD) circuit: initiated by DNA breathing and accelerated by a seesaw catalytic reaction, ACSD ensures that only the correct base sequence starts the catalytic cycle. Analogous to an electronic circuit with a variable resistor, two ACSD reactions with different rates are connected in parallel to mimic a parallel circuit containing branches with different resistances. Finally, we introduce a multiplexed nanopore sensing platform to report the output results of a parallel path selection system at the single-molecule level. By combining the ACSD strategy with fast and sensitive single-molecule nanopore readout, a new generation of DNA-based computing tools is established.

Background: Genetic improvement of soybean oil content depends on in-depth study of the glycerolipid biosynthesis pathway. The first acylation reaction catalysed by glycerol-3-phosphate acyltransferase (GPAT) is the rate-limiting step of triacylglycerol biosynthesis. However, the genes encoding GPATs in soybean remain unknown., Methods: We used a novel yeast genetic complementation system and seed-specific heterologous expression to identify GmGPAT activity and molecular function in glycerolipid biosynthesis., Results: Sixteen GmGPAT genes were cloned by reverse transcription-PCR for screening in yeast genetic complementation. The results showed that GmGPAT9-2 could restore the conditional lethal double knockout mutant strain ZAFU1, and GmGPAT1-1 exhibited low acyltransferase activity in serial dilution assays. In addition, the spatiotemporal expression pattern of GmGPAT9-2 exhibited tissue specificity in leaves, flowers and seeds at different developmental stages. Furthermore, both the proportion of arachidic acid and erucic acid were significantly elevated in Arabidopsis thaliana transgenic lines containing the seed-specific GmGPAT9-2 compared wild type, but the oil content was not affected., Conclusion: Together, our results provide reference data for future engineering of triacylglycerol biosynthesis and fatty acid composition improvement through GPATs in soybean., (© 2022. The Author(s), under exclusive licence to Springer Nature B.V.)

Construction of delicate nanostructures with a facile, mild-condition and economical method is a key issue for building high-performance electrode materials. We demonstrate a facile and novel "reassembling strategy" to hollow MnCoS nanospheres derived from dual-ZIF for supercapacitors. The spherical shell's surface structure, thickness and Mn distribution were controlled by regulating the solvothermal reaction time. The chemical composition, phases, specific surface areas and microstructure were studied and the electrochemical performances were systematically estimated. As the unique low-crystalline and optimized hollow nanosphere structure contributes to increasing active sites, MnCoS nanospheres exhibit excellent electrochemical performance. The test results show that the specific capacitance increases with increasing solvothermal time, and the MCS with a 5 h reaction time exhibits optimal electrochemical properties with a high specific capacity of 957 C g -1 (1 A g -1 ). Furthermore, an MCS-5//AC asymmetric supercapacitor device delivers a specific energy as high as 36.9 W h kg -1 at a specific power of 750 W kg -1 ., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Assembly of DNA structures based on hybridization like split G-quadruplex (GQ) have great potential for the base-pair specific identification of nucleic acid targets. Herein, we combine multiple split G-quadruplex (GQ) assemblies on designed DNA nanostructures (carrier) with a solid-state nanopore sensing platform. The split GQ probes recognize various nucleic acid sequences in a parallel assay that is based on glass nanopore analysis of molecular structures. Specifically, we split a GQ into two asymmetric parts extended with sequences complementary to the target. The longer G-segment is in solution, and the shorter one is on a DNA carrier. If the target is present, the two separate GQ parts will be brought together to facilitate the split GQ formation and enhance the nanopore signal. We demonstrated detection of multiple target sequences from different viruses with low crosstalk. Given the programmability of this DNA based nanopore sensing platform, it is promising in biosensing.

Nanopore sensing is an emerging technology that has many biosensing applications ranging from DNA sequencing using biological pores to biomolecular analysis using solid-state pores. Solid-state nanopores that are more stable are an attractive choice for biosensing applications. Still, biomolecule interactions with the nanopore surface reduce nanopore stability and increase usage costs. In this study, we investigated the biosensing capability for 102 quartz glass nanopores with a diameter of 11-18 nm that were fabricated using laser-assisted capillary pulling. Nanopores were assembled into multiple microfluidic chips that were repeatedly used for up to 19 weeks. We find that using vacuum storage combined with minimal washing steps improved the number of use cycles for nanopores. The single-molecule biosensing capability over repeated use cycles was demonstrated by quantitative analysis of a DNA carrier designed for detection of short single-stranded DNA oligonucleotides., Competing Interests: U.F.K., K.C., and M.A. are founders of Cambridge Nucleomics. Other authors do not have competing interests., (© 2022.)

A jet-stirring coupling flotation device (JSCFD) was proposed to analyze the distribution characteristics of gas holdup and bubble Sauter mean diameter ( D 32 ) in a gas-liquid system under various parameters. Results of studies suggested that the gas holdup increased with methyl isobutyl carbinol concentration, feeding pressure, and gas flow rate. The maximal gas holdup in the absence of the stirring impeller was ∼23.29% for the bubble size of 0.59 mm, which was considerably lower than the maximum gas holdup of 66.27% for the bubble size of 0.31 mm in the presence of the stirring impeller; the gas holdup was raised by ∼43% due to the bubbles torn by the stirring impeller to generate extensive smaller size bubbles and increase the content of small bubbles, and increasing the stirring impeller speed was conducive to reduce the bubble size and increase the gas holdup in JSCFD. Compared to traditional flotation machines, the size of bubbles generated by JSCFD was smaller, and the gas holdup distribution conforms to the following order: JSCFD > mechanical flotation machine > column flotation, which demonstrated that the JSCFD had a noticeable effect on increasing the gas holdup and reducing the bubble size., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

Since the discovery of the G-quadruplex (G4) structure in telomeres in 1980s, studies have established the role it plays in various biological processes. Here we report binding between DNA G4 and a self-assembled tetrahedral metal-organic cage 1 and consequent formation of aggregates, whereby the cage protects the DNA G4 from cleavage by S1 nuclease. We monitor DNA-cage interaction using fluorescence spectroscopy, firstly by quenching of a fluorescent label appended to the 5' end of G4. Secondly, we detect the decrease in fluorescence of the G4-selective dyes thioflavin-T and Zn-PPIX bound to various DNA G4 sequences following the addition of cage 1 . Our results demonstrate that 1 interacts with a wide range of G4s. Moreover, gel electrophoresis, circular dichroism and dynamic light scattering measurements establish the binding of 1 to G4 and indicate the formation of aggregate structures. Finally, we find that DNA G4 contained in an aggregate of cage 1 is protected from cleavage by S1 nuclease., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Deoxyribonucleic acid (DNA) nanostructure-based data encoding is an emerging information storage mode, offering rewritable, editable, and secure data storage. Herein, a DNA nanostructure-based storage method established on a solid-state nanopore sensing platform to save and encrypt a 2D grayscale image is proposed. DNA multi-way junctions of different sizes are attached to a double strand of DNA carriers, resulting in distinct levels of current blockades when passing through a glass nanopore with diameters around 14 nm. The resulting quaternary encoding doubles the capacity relative to a classical binary system. Through toehold-mediated strand displacement reactions, the DNA nanostructures can be precisely added to and removed from the DNA carrier. By encoding the image into 16 DNA carriers using the quaternary barcodes and reading them in one simultaneous measurement, the image is successfully saved, encrypted, and recovered. Avoiding any proteins or enzymatic reactions, the authors thus realize a pure DNA storage system on a nanopore platform with increased capacity and programmability., (© 2021 The Authors. Small published by Wiley-VCH GmbH.)

Three-dimensional mesoporous lepidocrocite-type layered sodium titanate (LST) was constructed at room temperature by the electrostatic interaction between Ti 1-δ O 2 4δ- nanosheets and Na + ions. The results of a systematic X-ray diffraction investigation manifested the transition from the Ti 1-δ O 2 4δ- nanosheets phase to the titanate/titania phase, which determined a phase diagram as a function of the temperature and NaCl concentration. In addition, scanning electron microscopy, inductively coupled plasma-mass spectrometry, thermogravimetric and differential thermal, N 2 adsorption-desorption, Raman spectroscopy, Fourier transform infrared spectroscopy, as well as ζ-potential analyses were utilized for adequate characterization of the LST physical and chemical properties. Furthermore, batch adsorption experiments demonstrated that LST had superior adsorption property and adsorption selectivity toward cationic dyes compared to those of anionic dyes. A multifarious influencing effect on the cationic dye adsorption behavior during the adsorption process was systematically investigated. Moreover, the pseudo-second-order kinetic model felicitously depicted the cationic dye adsorption behavior through an elaborate kinetic study, namely, chemisorption was the main adsorption action. Meanwhile, different adsorption isotherm models were utilized to process the experimental data, uncovering that the adsorption isotherms of cationic dyes on LST were suitable for a Langmuir isothermal model. More importantly, an ion-exchange mechanism was proposed for the cationic dye adsorption on LST, and the ion-exchange reaction occurred with a stoichiometric exchange between 1 mol of Na + ions in the LST interlayer and 1 mol of MB molecules in the solution. In parallel, the electrochemical impedance spectroscopy and cyclic voltammogram measurements verified that the high ionic conductivity of Na + ions in the LST interlayer resulted in a superior adsorption property. A two-step acid-base procedure was ultimately adopted to effectively regenerate LST adsorbent. This work provides not only an alternative adsorbent with superior adsorption capacity and adsorption selectivity but also some guiding significance for research on the adsorption mechanism of layered titanates.

The toehold-mediated strand displacement reaction (SDR) is a powerful enzyme-free tool for molecular manipulation, DNA computing, signal amplification, etc. However, precise modulation of SDR kinetics without changing the original design remains a significant challenge. We introduce a new means of modulating SDR kinetics using an external stimulus: a water-soluble Fe II 4 L 4 tetrahedral cage. Our results show that the presence of a flexible phosphate group and a minimum toehold segment length are essential for Fe II 4 L 4 binding to DNA. SDRs mediated by toehold ends in different lengths (3-5) were investigated as a function of cage concentration. Their reaction rates all first increased and then decreased as cage concentration increased. We infer that cage binding on the toehold end slows SDR, whereas the stabilization of intermediates that contain two overhangs accelerates SDR. The tetrahedral cage thus serves as a versatile tool for modulation of SDR kinetics.

A series of samples including leaf-like and rod-like rutile TiO 2 nanoparticles with various facets exposed on the surface, parallelepiped-shaped anatase nanoparticles with [111] vertical facet exposed on the surface, irregular anatase nanoparticles, microsized six-point star-like anatase aggregates, and almond-like brookite aggregates had been hydrothermally synthesized from lepidocrocite-type layered titanate nanosheets. A systematical investigation was established to uncover the phase transition and morphological evolution from nanosheets to TiO 2 polymorphs, and a phase diagram was determined by adjusting the synthesis parameters of the pH value and temperature. Two kinds of mechanisms composed of the dissolution-deposition process following Ostwald's ripening mechanism and the in situ topochemical conversion process following Ostwald's step rule had been proposed based on the time-dependent hydrothermal experiments. Briefly, the formation of the single-crystalline rutile phase appeared only at high temperatures with very low pH values, and similarly, the brookite phase strictly formed at high temperatures with a very high pH value. Nevertheless, the anatase phase could moderately appear in a wide range of temperatures and pH values. In addition, the single-crystalline rutile adopted a leaf-like morphology at low temperatures with high pH values and a rod-like morphology at high temperatures with low pH values, while the morphological evolution of anatase particles proceeded from irregular to parallelepiped-shaped and finally to six-point star-like morphology, and the crystal size was reduced from 1000 to 5 nm with decreasing pH values. Meanwhile, with the prolongation of the hydrothermal time, the layered titanate nanosheets first dissolved into the amorphous state and further converted into small anatase nanoparticles and finally to rutile or anatase nanoparticles based on the dissolution-deposition process, or the {010}-faceted layered titanate structure first converted into the [111]-vertical faceted anatase nanosheets by the topochemical transformation reaction and then split into the [111]-vertical faceted anatase nanoparticles. More importantly, the mesoporous [111]-vertical faceted anatase nanoparticles exhibited enhanced photocatalytic performance compared to that of Degussa P25, which was ascribed to its superior electronic band structure and effective charge separation. The systematical investigation in this work would be significant for consummating the preparation of the TiO 2 polymorphs from layered titanate nanosheets and provided some reference values and guide schemes for the preparation of TiO 2 nanoparticles with outstanding photocatalytic performance.

A water-soluble self-assembled supramolecular Fe II 4 L 4 tetrahedron binds to single stranded DNA, mismatched DNA base pairs, and three-way DNA junctions. Binding of the coordination cage quenches fluorescent labels on the DNA strand, which provides an optical means to detect the interaction and allows the position of the binding site to be gauged with respect to the fluorescent label. Utilizing the quenching and binding properties of the coordination cage, we developed a simple and rapid detection method based on fluorescence quenching to detect unpaired bases in double-stranded DNA.

Bacterial cells are critically dependent upon pH regulation. Here we demonstrate that indole plays a critical role in the regulation of the cytoplasmic pH of Escherichia coli. Indole is an aromatic molecule with diverse signalling roles. Two modes of indole signalling have been described: persistent and pulse signalling. The latter is illustrated by the brief but intense elevation of intracellular indole during stationary phase entry. We show that under conditions permitting indole production, cells maintain their cytoplasmic pH at 7.2. In contrast, under conditions where no indole is produced, the cytoplasmic pH is near 7.8. We demonstrate that pH regulation results from pulse, rather than persistent, indole signalling. Furthermore, we illustrate that the relevant property of indole in this context is its ability to conduct protons across the cytoplasmic membrane. Additionally, we show that the effect of the indole pulse that occurs normally during stationary phase entry in rich medium remains as a "memory" to maintain the cytoplasmic pH until entry into the next stationary phase. The indole-mediated reduction in cytoplasmic pH may explain why indole provides E. coli with a degree of protection against stresses, including some bactericidal antibiotics.

Thioflavin T (ThT) was once regarded to be a specific fluorescent probe for the human telomeric G-quadruplex, but more other kinds of DNA were found that can also bind to ThT in recent years. Herein, we focus on G-rich parallel-stranded DNA and utilize fluorescence, absorbance, circular dichroism, and surface plasmon resonance spectroscopy to investigate its interaction with ThT. Pyrene label and molecular modeling are applied to unveil the binding mechanism. We find a new class of non-G-quadruplex G-rich parallel-stranded ( ps) DNA with the sequence of TG(GA) n can bind to ThT and increase the fluorescence with an enhancement ability superior to G-quadruplex. The optimal binding specificity for ThT is conferred by two parts. The first part is composed of two bases TG at the 5' end, which is a critical domain and plays an important role in the formation of the binding site for ThT. The second part is the rest alternative d(GA) bases, which forms the ps homoduplex and cooperates with the TG bases at the 5' end to bind the ThT.

Metal-organic anion channels based on Zn 10 L 15 pentagonal prisms have been prepared by subcomponent self-assembly. The insertion of these prisms into lipid membranes was investigated by ion-current and fluorescence measurements. The channels were found to mediate the transport of Cl - anions through planar lipid bilayers and into vesicles. Tosylate anions were observed to bind and plug the central channels of the prisms in the solid state and in solution. In membranes, dodecyl sulfate blocked chloride transport through the central channel. Our Zn 10 L 15 prism thus inserts into lipid bilayers to turn on anion transport, which can then be turned off through addition of the blocker dodecyl sulfate., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Single nucleotide polymorphisms (SNPs) play a crucial role as molecular markers in medical and diagnostic application. We demonstrate a nanopore based method for SNP detection at the single molecule level. Designed DNA carriers are used to distinguish DNA strands containing only one single base difference and follow strand displacement kinetics.

We proposed a new three-way DNA junction-driven strand displacement mode and fabricated an aptamer-based label-free fluorescent sensing platform on the basis of this mechanism. Assembling the aptamer sequence into the three-way DNA junction makes the platform sensitive to the target of the aptamer. A label-free signal readout method, split G-quadruplex enhanced fluorescence of protoporphyrin IX (PPIX), was used to report the final signal. Here, adenosine triphosphatase (ATP) was taken as a model and detected through this approach, and DNA strand could also be detected by it. The mechanism was investigated by native polyacrylamide gel electrophoresis. Furthermore, on the basis of this molecular platform, we built a logic circuit with ATP and DNA strands as input. Aptamer played an important role in mediating the small molecule ATP to tune the DNA logic gate. Through altering the aptamer sequence, this molecular platform will be sensitive to various stimuli and applied in a wide field.

In this work, a novel dot-blot DNAzyme-linked aptamer assay (DLAA) for protein detection is developed with thrombin as a model protein. A peroxidase-like DNAzyme which serves as the catalytic label is tethered to a 15-mer thrombin-binding aptamer to form a label-free DNAzyme-linked aptamer probe. Based on specific interaction of the aptamer with target protein immobilized on nitrocellulose membrane, a DNAzyme layer is introduced onto the membrane. The DNAzyme can catalyze the H(2)O(2)-mediated oxidation of 3,3',5,5'-tetramethylbenzidine to produce a colored insoluble product that is apt to be adsorbed onto the nitrocellulose membrane. As a result, blue dots appear on the membrane, in contrast to the colorless background. As the concentration of thrombin increases, the color of dots gets deep. Such a protein concentration-dependent color change can be quantified via an image-processing software, with a detection limit of 0.6 microM. Furthermore, this assay has been applied successfully to the detection of thrombin in biological samples (e.g., human serum), indicating its practicality for bioanalysis.