Rectangular Coordination Polymer Nanoplates: Large-Scale, Rapid Synthesis and Their Application as a Fluorescent Sensing Platform for DNA Detection

In this paper, we report on the large-scale, rapid synthesis of uniform rectangular coordination polymer nanoplates (RCPNs) assembled from Cu(II) and 4,4′-bipyridine for the first time. We further demonstrate that such RCPNs can be used as a very effective fluorescent sensing platform for multiple DNA detection with a detection limit as low as 30 pM and a high selectivity down to single-base mismatch. The DNA detection is accomplished by the following two steps: (1) RCPN binds dye-labeled single-stranded DNA (ssDNA) probe, which brings dye and RCPN into close proximity, leading to fluorescence quenching; (2) Specific hybridization of the probe with its target generates a double-stranded DNA (dsDNA) which detaches from RCPN, leading to fluorescence recovery. It suggests that this sensing system can well discriminate complementary and mismatched DNA sequences. The exact mechanism of fluorescence quenching involved is elucidated experimentally and its use in a human blood serum system is also demonstrated successfully

Poly(m-Phenylenediamine) Nanospheres and Nanorods: Selective Synthesis and Their Application for Multiplex Nucleic Acid Detection

In this paper, we demonstrate for the first time that poly(m-phenylenediamine) (PMPD) nanospheres and nanorods can be selectively synthesized via chemical oxidation polymerization of m-phenylenediamine (MPD) monomers using ammonium persulfate (APS) as an oxidant at room temperature. It suggests that the pH value plays a critical role in controlling the the morphology of the nanostructures and fast polymerization rate favors the anisotropic growth of PMPD under homogeneous nucleation condition. We further demonstrate that such PMPD nanostructures can be used as an effective fluorescent sensing platform for multiplex nucleic acid detection. A detection limit as low as 50 pM and a high selectivity down to single-base mismatch could be achieved. The fluorescence quenching is attributed to photoinduced electron transfer from nitrogen atom in PMPD to excited fluorophore. Most importantly, the successful use of this sensing platform in human blood serum system is also demonstrated

Preparation of silver nanoparticles by heating a quaternary ammonium polyelectrolyte-AgNO₃ aqueous solution in basic conditions

1266-1269Silver nanoparticles (~ 2 nm in size) have been prepared by heating an aqueous solution containing quaternary ammonium polyelectrolyte poly(diallyldimethylammonium chloride) and AgNO₃ in the presence of NaOH. The formation of silver nanoparticles has been confirmed by UV-vis, TEM, and XPS data and the formation process traced by time-dependent UV-vis spectra. It is observed that addition of NaOH to the solution is crucial to the formation of silver nanoparticles

Efficient Electrochemical Water Splitting Catalyzed by Electrodeposited Nickel Diselenide Nanoparticles Based Film

In this contribution, we demonstrate that electrodeposited nickel diselenide nanoparticles based film on conductive Ti plate (NiSe₂/Ti) is an efficient and robust electrode to catalyze both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in basic media. Electrochemical experiments show this electrode affords 10 mA cm^–2 at HER overpotential of 96 mV and 20 mA cm^–2 at OER overpotential of 295 mV with strong durability in 1.0 M KOH. The corresponding two-electrode alkaline water electrolyzer requires a cell voltage of only 1.66 V to achieve 10 mA cm^–2 water-splitting current. This development provides us an attractive non-noble-metal catalyst toward overall water splitting applications

Interactions between cytokinin and nitrogen contribute to grain mass in wheat cultivars by regulating the flag leaf senescence process

Premature senescence after anthesis reduces crop yields. Delaying leaf senescence could maintain photosynthetic activity for a longer period and lead to a higher photosynthetic rate. Recent studies have provided some insights into the interaction between cytokinin and nitrogen (N) in the regulation of plant development. In the present study, foliar application of exogenous 6-benzylaminopurine (6-BA) and lovastatin, an inhibitor of cytokinin synthesis, was combined with three N rates [0 kg ha−1 (low nitrogen, LN), 240 kg ha−1 (normal nitrogen, NN), and 360 kg ha−1 (high nitrogen, HN)] in two wheat cultivars, Wennong 6 (with a staygreen phenotype) and Jimai 20 (with a non-staygreen phenotype). Flag leaf senescence was assessed using a Gompertz growth curve. Grain mass, dry matter accumulation and distribution, total N of flag leaf, and concentrations of zeatin riboside (ZR) and abscisic acid (ABA) were also used to evaluate the functional characteristics of flag leaves. Grain mass was negatively correlated with initial senescence rate (r0) and duration of rapid chlorophyll loss (Chlloss), whereas it was positively correlated with maximum senescence rate (rmax), average senescence rate (raver), persistence phase (Chlper), total duration of flag leaf (Chltotal) and inflection point cumulative temperature (M). Compared to Jimai 20, Wennong 6 had larger raver, Chlper, and Chltotal. The concentration of ZR was highest under the 6-BA × NN treatment, followed by the 6-BA × HN and 6-BA × LN treatments. However, the concentration of ABA showed the opposite trend. It was concluded that the staygreen phenotype Wennong 6 was associated with greater grain mass and altered cytokinin metabolism and could be classified as a functional staygreen type. Foliar application of 6-BA interacting with N at the NN level (240 kg ha−1) may be a beneficial strategy for improving grain yield of wheat by regulating endogenous hormones and the flag leaf senescence process. Increasing endogenous cytokinin promoted the transport of dry matter to grain. Keywords: Triticum aestivum L., Interaction, Cytokinin, Nitrogen, Staygreen wheat, Flag leaf senescenc

Self-Supported FeP Nanorod Arrays: A Cost-Effective 3D Hydrogen Evolution Cathode with High Catalytic Activity

Developing non-noble-metal hydrogen evolution reaction electrocatalysts with high activity is critical for future renewable energy systems. The direct growth of active phases on current collectors not only eliminates using polymer binder but also offers time-saving preparation of electrode. In this Letter, we develop self-supported FeP nanorod arrays on carbon cloth (FeP NAs/CC) via low-temperature phosphidation of its Fe₂O₃ NAs/CC. As a novel 3D hydrogen evolution cathode in acidic media, the FeP NAs/CC exhibits high catalytic activity and only needs an overpotential of 58 mV to afford current density of 10 mA/cm². This electrode also works efficiently in both neutral and alkaline solutions