Molecular "light switch" [Ru(phen)2dppzidzo](2+) monitoring the aggregation of tau.

Monitoring the aggregation of the tau protein is a key protocol for elucidating the pathogenic mechanism of Alzheimer's disease. In the present article, [Ru(phen)2dppzidzo](2+), a "light switch" ruthenium(ii) complex, was presented as a new monitoring probe for the aggregation of a tau R3 peptide, the third repeat unit of the tau microtubule-binding domain. Having little impact on the aggregation process, large fixed Stokes shift and small background luminescence made the complex a better probe for monitoring the aggregation process and quantitatively detecting tau filaments compared to thioflavin S, a commonly used fluorescent dye for staining neurofibrillary tangles and monitoring tau aggregation. Furthermore, a long luminescence lifetime of this complex could also expand its potential usage in the detection of tau filaments in the presence of short-lived fluorescent backgrounds.

A new fluorescence "switch on" assay for heparin detection by using a functional ruthenium polypyridyl complex.

In the present study, a new strategy for heparin detection and quantification in biological media, such as fetal bovine serum (FBS), is developed by monitoring the emission change of a functional ruthenium polypyridyl complex ([Ru(phen)(2)dppz-idzo](2+), complex 1) in buffer solution. Polyanionic heparin is found to interact with a positively charged Ru-complex through electrostatic effects and/or hydrogen bonding interactions, which leads to a significant fluorescence enhancement of the Ru-complex. To get insight into this fluorescence "switch on" behavior, the binding model of the Ru-complex to heparin is established by employing molecular docking simulations based on the fluorescence and UV absorption results. The selectivity results of the fluorescence assay reveal that our complex displayed good fluorescence selectivity towards heparin over its analogues, such as chondroitin 4-sulfate (Chs) or hyaluronic acid (Hya), which have lower charge density and/or structural compatibility as compared to that of heparin. Quantification of heparin is also performed and a linear calibration curve is observed in the range of 0.01-4.87 U mL(-1) (the limit of detection is 0.01 U mL(-1)) for heparin detection in diluted FBS solution. This "one-step" fluorescence "switch on" assay for heparin detection is label-free, convenient, sensitive and selective, and has a long emission wavelength and large Stokes shift.

A naked-eye on-off-on molecular "light switch" based on a reversible "conformational switch" of G-quadruplex DNA.

Herein, we report a new strategy for developing an on-off-on molecular "light switch" by utilizing the pH value to control the "conformational switch" of G-quadruplex DNA. A novel ruthenium(II) complex with an emission enhancement factor of 150 was synthesized and introduced to detect the switch by the naked eye. The "light switch" can be repeatedly cycled off and on through the addition of H(+) and OH(-), respectively. The conformational transitions of G-quadruplex DNA in K(+) solution at different pH values in the acidic region were evidenced by circular dichroism and fluorescence titrations. Computational calculations by applying density functional theory (DFT)/time-dependent DFT and molecular docking were also carried out to gain insight into the "light-switch" mechanism.

Chaos-based wireless communication resisting multipath effects.

In additive white Gaussian noise channel, chaos has been shown to be the optimal coherent communication waveform in the sense of using a very simple matched filter to maximize the signal-to-noise ratio. Recently, Lyapunov exponent spectrum of the chaotic signals after being transmitted through a wireless channel has been shown to be unaltered, paving the way for wireless communication using chaos. In wireless communication systems, inter-symbol interference caused by multipath propagation is one of the main obstacles to achieve high bit transmission rate and low bit-error rate (BER). How to resist the multipath effect is a fundamental problem in a chaos-based wireless communication system (CWCS). In this paper, a CWCS is built to transmit chaotic signals generated by a hybrid dynamical system and then to filter the received signals by using the corresponding matched filter to decrease the noise effect and to detect the binary information. We find that the multipath effect can be effectively resisted by regrouping the return map of the received signal and by setting the corresponding threshold based on the available information. We show that the optimal threshold is a function of the channel parameters and of the information symbols. Practically, the channel parameters are time-variant, and the future information symbols are unavailable. In this case, a suboptimal threshold is proposed, and the BER using the suboptimal threshold is derived analytically. Simulation results show that the CWCS achieves a remarkable competitive performance even under inaccurate channel parameters.

Impacts of terminal modification of [Ru(phen)2dppz](2+) on the luminescence properties: a theoretical study.

[Ru(phen)2dppz](2+) and other closely related ruthenium(II) complexes containing π-extended ligands were found to be non or weakly emissive in water, while exhibiting significant luminescence intensity growth when bound to DNA, however, a satisfactory interpretation has not been provided on this "light switch" mechanism. In the present study, we investigated the vertical transitions and triplet excited states of [Ru(phen)2dppz](2+) (1), [Ru(phen)2dppzi](2+) (2) and [Ru(phen)2dppz-idzo](2+) (3) in the gas phase and aqueous solution, through time dependent-density functional theory (TDDFT). Based on the optimized (3)MLCT and (3)LLCT structures and energies, we found that the (3)MLCT state might be responsible for the emissions of the complexes. Interesting connections between the singlet vertical transitions and the luminescence properties were noticed. Through ZORA-TDDFT calculation with perturbative SOC, we evaluated the intersystem crossing between the lowest singlet excited state, and both (3)MLCT state and (3)LLCT state, which gave a reasonable explanation for the luminescence properties of these complexes.

Two structurally analogous ruthenium complexes as naked-eye and reversible molecular "light switch" for G-quadruplex DNA.

A pair of symmetrical furyl based ruthenium(II) complexes ([Ru(phen)2dpq-df](2+) (1) and [Ru(bpy)2dpq-df](2+) (2) (phen=1,10-phenanthroline, bpy=2,2'-bipyridine, dpq-df=dipyrido (3,2-a:2',3'-c) quinoxaline-difuran) have been prepared and characterized. The binding properties of both complexes toward G-quadruplex DNA have been investigated by fluorescence spectroscopy, UV-Vis spectroscopy, circular dichroism (CD), fluorescence resonance energy transfer (FRET) melting assays and molecular docking studies. The experimental results indicated that both Ru-complexes exhibited a remarkable "light switch" effect in the presence of hybrid G-quadruplex DNA. Interestingly, the "light switch" can be repeated off and on through the successive addition of Cu(2+) ions and EDTA, and all these behaviors can be observed even by the naked eyes. Moreover, FRET melting assay revealed that both complexes could be potential stabilizers for G-quadruplex architectures. The computational studies not only confirmed that the two complex molecules bound to one G-quadruplex DNA molecule, but also explained the "light switch" effect.

[Ru(bpy)2dppz-idzo]2+: a colorimetric molecular "light switch" and powerful stabilizer for G-quadruplex DNA.

A new ruthenium complex, [Ru(bpy)2dppz-idzo](2+) (bpy = 2,2'-bipyridine, dppz-idzo = dipyrido-[3,2-a:2',3'-c] phenazine-imidazolone), was synthesized and characterized. The luminescent titrations showed that the Ru-complex exhibited an outstanding "light switch" effect with an emission enhancement factor of about 300 in the presence of G-quadruplex DNA in a K(+) solution. This remarkable "light switch" behavior can even be observed by the naked eye under irradiation with UV light. To get an insight into the "light switch" mechanism, quantum-chemical calculations were performed based on the DFT/TDDFT/PCM method at the B3LYP/6-31G* level. Furthermore, the CD titrations and thermal melting experiments indicated that [Ru(bpy)2dppz-idzo](2+) could not only induce the formation of an antiparallel G-quadruplex structure in the absence of monocations, but also has the ability to stabilize the G-quadruplex architecture, implying potential applications in anticancer therapeutics. Both the "light switch" effect and the structure stabilization ability of [Ru(bpy)2dppz-idzo](2+) were found to be superior to the well-known DNA molecular "light switch" [Ru(bpy)2dppz](2+). Finally, a "sandwich-like" binding model was proposed on the basis of molecular docking simulations.

A comparative study of the interaction of two structurally analogous ruthenium complexes with human telomeric G-quadruplex DNA.

Two new polypyridine ligands and their corresponding ruthenium(II) complexes have been prepared and characterized. The interactions of both complexes with human telomere quadruplex DNA (both the antiparallel basket and the mixed-hybrid G-quadruplex) have been studied by circular dichroism (CD), CD melting, UV-visible (UV-Vis), fluorescent intercalator displacement (FID) assays and molecular docking studies. The results show that both complexes can stabilize G-quadruplexes DNA and two complexes show different binding affinity for different G-quadruplexes DNA. The 1:1 stoichiometry was confirmed in the buffered solutions by the UV-Vis spectrophotometer using Job's plot method and molecular docking studies. We have also investigated the interaction between the complexes and duplex DNA to gain some insight into the selectivity of the complexes for G-quadruplex structures. FID studies have shown that the complexes have a modest selectivity for G-quadruplex versus duplex DNA.

Role of endothelial cell injury in the pathogenesis of diabetic nephropathy / 中国糖尿病杂志

[Summary] Diabetic nephropathy is one of the major chronic microvascular complications of diabetes ,which is the leading cause of end‐stage renal disease ,as well as the main cause of death in diabetic patients. Glomerular endothelial cell is an important component of the glomerular filtration barrier ,which is directly related to the materials of circulation ,and it can be easily damaged by glucose ,lipid and inflammatory factors. Under the hyperglycemia ,the PKC pathway ,the polyol pathway and oxidative stress were activated ,producing an excess of advanced glycation end products and reactive oxygen species ,which damage the endothelial nitric oxide synthase ,reduce the generation of nitric oxide ,while produce a large number of Ang Ⅱ. Ang Ⅱ damage the endothelial cell. In addition ,there are crosstalk between glomerular endothelial cells and endothelial cells ,which also cause endothelial cell injury. Here ,we reviewed the role of endothelial cell injury in the pathogenesis of diabetic nephropathy.