Electrochemically induced DNA cleavage by copper-bipyridyl complex

Regulating CO and H2 Ratios in Syngas Produced from Photocatalytic CO2/H2O Reduction by Cu and Co Dual Active Centers on Carbon Nitride Hollow Nanospheres

For photocatalytic CO2 reduction to produce syngas, there are challenges in achieving a high catalytic efficiency and precise control over the product ratio. In this study, two non-noble metal complexes Cobpy and Cubpy (bpy = 2,2'-bipyridine) as cocatalysts for CO2 reduction and hydrogen evolution, respectively, were in situ supported on carbon nitride hollow nanospheres to construct a hybrid system for photocatalytic syngas production. The resulting CO/H2 ratio can be precisely regulated within a wide range of 0:1-9:1 by accurately controlling the content of the two complexes. The presence of the two complexes promotes the migration of photogenerated electrons of the carbon nitride. CO2 can be reduced to CO on the photoreduced species Co(bpy)2+ of Cobpy on CNHS, and H+ can be reduced to H2 on the photoreduced species Cu(bpy)2+ of Cubpy. Furthermore, this method is also applicable to other photocatalysts, such as CdS and TiO2 for generating syngas and regulating product ratios.

Dynamics of counterion binding during acoustic nebulisation of surfactant solutions

A metal ion (Cu(2+)) and a complex copper species, copper (II) bis-bipyridine, were used as alternate counterions in an aqueous surfactant solution of sodium dodecylbenzenesulfonate (SDBS) to investigate the dynamics of counterion interactions in an acoustic field. Sonoluminescence spectral studies showed that such counterions were able to replace sodium ions at the interface, even when the interface was rapidly oscillating under the acoustic field. Ultrasound induced nebulisation was then used to probe the interfacial profile of surfactant and bound counterions in a dynamic environment. At low bulk concentrations, the copper (II) bis-bipyridine cation was more effective at enhancing the loading of the dodecylbenzenesulfonate anion on the interface, due to its documented greater binding ability. However, at higher bulk concentrations, the movement of this cation is limited by its larger size and the smaller Cu(2+) cation is more effective in enhancing the loading of the dodecylbenzenesulfonate anion. The results show that under dynamic conditions, the surface concentrations are governed by mass transfer kinetics rather than equilibrium thermodynamics.

The interaction of taurine-salicylaldehyde Schiff base copper(II) complex with DNA and the determination of DNA using the complex as a fluorescence probe

The interaction of taurine-salicylaldehyde Schiff base copper(II) (Cu(TSSB)2(2+)) complex with DNA was explored by using UV-vis, fluorescence spectrophotometry, and voltammetry. In pH 7.4 Tris-HCl buffer solution, the binding constant of the Cu(TSSB)2(2+) complex interaction with DNA was 3.49 x 10(4) L mol(-1). Moreover, due to the fluorescence enhancing of Cu(TSSB)2(2+) complex in the presence of DNA, a method for determination of DNA with Cu(TSSB)2(2+) complex as a fluorescence probe was developed. The fluorescence spectra indicated that the maximum excitation and emission wavelength were 389 nm and 512 nm, respectively. Under optimal conditions, the calibration graphs are linear over the range of 0.03-9.03 microg mL(-1) for calf thymus DNA (CT-DNA), 0.10-36 microg mL(-1) for yeast DNA and 0.01-10.01 microg mL(-1) for salmon DNA (SM-DNA), respectively. The corresponding detection limits are 7 ng mL(-1) for CT-DNA, 3 ng mL(-1) for yeast DNA and 3 ng mL(-1) for SM-DNA. Using this method, DNA in synthetic samples was determined with satisfactory results.

Detection of DNA Damage Induced by Hydroquinone and Catechol Using an Electrochemical DNA Biosensor

DNA damage induced by hydroquinone and catechol was detected by an electrochemical method. Calf thymus DNA was immobilized onto the surface of a pretreated glassy carbon electrode (GCE(ox)) to form a DNA/GCE(ox) modified electrode. Then the DNA/GCE(ox) was incubated in acetate buffer solution containing hydroquinone or catechol at a constant potential for the desired time. Differential pulse voltammetric experiments were then performed. The anodic peaks corresponding to the oxidation of guanisine and adenosine on the electrode could be observed on voltammetric curves. The experimental results showed that DNA damage could be detected using electrochemical DNA biosensors. The extent of DNA damage could be electrochemically recognized via the change of the anodic peak current. DNA damage induced by hydroquinone was greater than that by catechol. The response conditions were optimized with respect to DNA concentration, pH, ionic strength, and other variables.

Electrochemical detection of scDNA cleavage in the presence of macrocyclic hexaaza–copper(II) complex

The hexaaza macrocyclic copper(II) complex Cu(II)L(L=1,8-Dihydroxyethyl-1,3,6,8,10,13-hexaazacyclotetradecane), which has octahedral structure similar to some natural complexes, is synthesized and purified. In this study, oxidative breakage DNA by the reaction of Cu(II)L with H2O2 and ascorbate has been investigated by gel electrophoresis experiments. In electrochemical experiments, the on scDNA-modified glassy carbon electrode(GCE) is cleaved by the Cu(II)L and redox changing of the metal catalyst without adding any other reagents. Above all, the need for concentration of scDNA is much lower than that of gel electrophoresis experiments and the process of the performance is easy. Furthermore, Cyclic Voltammetry (CV) and A.C. Impedance, which are performed to monitor scDNA cleavage at the scDNA-modified glassy carbon electrode (GCE), are fast, simple and highly efficient. The mechanism of the damage can be suggested: Fenton.

Synthesis and DNA binding of μ-[2,9-bis(2-imidazo[4,5-f][1,10]phenanthroline)-1,10-phenanthroline]bis[1,10-phenanthrolinecopper(II)]

A binuclear complex [(phen)Cu(mu-bipp)Cu(phen)](ClO(4))(4), where phen=1,10-phenanthroline and bipp=2,9-bis(2-imidazo[4,5-f][1,10]phenanthroline)-1,10-phenanthroline, has been synthesized and its interaction with calf-thymus DNA in the buffer containing 5mM Tris and 50mM NaCl has been studied by means of electronic absorption titration, luminescence titration and viscometric measurements. The absorbance of the complex in the range of 320-400 nm, which is mainly based on bipp showed no obvious change upon addition of DNA, while the peak at 270 nm, which is determined by both phen and bipp decreased by up to 18%. The emission band of the complex around 360 nm decreased remarkably in presence of DNA. The emission quenching of this complex by [Fe(CN)(6)](4-) was depressed greatly when bound to DNA. The relative viscosity of DNA was increased by this complex more significantly than a bipp directed intercalating reagent. These results suggest that this complex binds to calf thymus DNA by intercalation of the two phenanthrolinecopper terminals. The apparent intrinsic binding constant of the complexes with DNA was 1.6 x 10(4)M(-1) as determined by UV-visible titration.